Sunday, April 22, 2007

WATCHES: Tornado Watch - Number 164

WWUS20 KWNS 230203
SEL4
SPC WW 230203
IAZ000-MOZ000-NEZ000-230200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH - NUMBER 164
NWS STORM PREDICTION CENTER NORMAN OK
903 PM CDT SUN APR 22 2007

THE NWS STORM PREDICTION CENTER HAS CANCELLED
TORNADO WATCH NUMBER 164 ISSUED AT 155 PM CDT FOR PORTIONS OF

IOWA
MISSOURI
NEBRASKA

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WATCHES: Severe Thunderstorm Watch - Number 163

WWUS20 KWNS 230203
SEL3
SPC WW 230203
IAZ000-ILZ000-MOZ000-WIZ000-230200-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH - NUMBER 163
NWS STORM PREDICTION CENTER NORMAN OK
903 PM CDT SUN APR 22 2007

THE NWS STORM PREDICTION CENTER HAS CANCELLED
SEVERE THUNDERSTORM WATCH NUMBER 163 ISSUED AT 120 PM CDT FOR PORTIONS OF

IOWA
ILLINOIS
MISSOURI
WISCONSIN

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DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 230039
SWODY1
SPC AC 230037

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0737 PM CDT SUN APR 22 2007

VALID 230100Z - 231200Z

..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF IA FOR THE NEXT
HOUR OR SO....

..SYNOPSIS...
LATEST IR/WV IMAGERY SHOWS MID/UPPER LEVEL LOW HAS LIFTED NEWD AND
IS OVER NWRN IA THIS EVENING. NEXT MID/UPPER LEVEL TROUGH HAS
DROPPED INTO THE SRN GREAT BASIN. LATEST SURFACE ANALYSIS SHOW LOW
OVER NWRN IA WITH A WEAK PACIFIC FRONT EXTENDING SWD/SWWD THROUGH KS
INTO SWRN OK. AIR MASS AHEAD OF THIS BOUNDARY HAS BECOME MARGINALLY
UNSTABLE AS SURFACE DEW POINTS ARE IN THE LOW/MID 50S ACROSS IA INTO
SERN MN AND AMOUNT OF CLOUD COVER FROM TODAY'S CONVECTION HAS
LIMITED ANY FURTHER HEATING.

..IA...

PROBABILITIES FOR SEVERE CONTINUES TO DIMINISH RAPIDLY WITH VERY
LIMITED INSTABILITY. REMAINING DYNAMICS ASSOCIATED WITH CURRENT
CONVECTION WILL POSE WIDELY SCATTERED THUNDERSTORMS INTO THE EARLY
MORNING HOURS AS MID/UPPER LEVEL LOW CONTINUES TO MOVE NEWD ACROSS
NWRN WI INTO THE UPPER PENINSULA OF MI BY THE END OF THE PERIOD.
THERE MAY STILL BE LOW PROBABILITIES FOR ISOLATED MARGINAL SEVERE
OVER THE NEXT HOUR OR SO IN IA BEFORE TOTALLY DIMINISHING THROUGH
12Z DUE TO THE LACK OF SUFFICIENT THERMODYNAMICS.

..SERN OK...

ONLY A FEW SMALL THUNDERSTORMS ARE INDICATED ON RADAR AT THIS
TIME...AND THINK THAT THESE SHOULD DISSIPATE WITH LOSS OF HEATING
THE NEXT FEW HOURS.

..GREAT BASIN REGION...

LATEST LIGHTNING DATA DOES SHOW SCATTERED THUNDERSTORMS IN THE
VICINITY OF MID/UPPER LEVEL LOW DEVELOPING OVER CENTRAL/SRN NV.
THIS ACTIVITY IS EXPECTED TO CONTINUE FOR THE NEXT SEVERAL HOURS
BEFORE DIMINISHING OVERNIGHT.

.MCCARTHY.. 04/23/2007

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MESO: Mesoscale Discussion 0542

ACUS11 KWNS 222336
SWOMCD
SPC MCD 222336
IAZ000-MOZ000-230130-

MESOSCALE DISCUSSION 0542
NWS STORM PREDICTION CENTER NORMAN OK
0636 PM CDT SUN APR 22 2007

AREAS AFFECTED...PORTIONS CENTRAL/ERN IA.

CONCERNING...SEVERE THUNDERSTORM WATCH 163...

VALID 222336Z - 230130Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 163
CONTINUES.

HOWEVER...POTENTIAL SHOULD DIMINISH WITH TIME AS LOSS OF SFC HEATING
CAUSES BOUNDARY LAYER TO STABILIZE...REDUCING BUOYANCY OF
INFLOW-LAYER AIR MASS. BAND OF TSTMS MOVING NEWD FROM WW 164 MAY
PRODUCE OCCASIONAL HAIL/GUSTS TO SVR LEVELS DURING NEXT 1-2 HOURS AS
IT ENTERS WRN PORTION OF WW 163. MODIFIED RAOBS AND RUC SOUNDINGS
SUGGEST ROUGHLY 40-60 NM WIDE CORRIDOR OF SFC-BASED INFLOW REMAINS
AHEAD OF LINE FROM CENTRAL IA SWD TO VICINITY MO BORDER...S OF WHICH
CONVERGENCE DIMINISHES MARKEDLY. LIFT ALONG ASSOCIATED FORCING
BOUNDARY WILL BE SUFFICIENT TO MAINTAIN CONVECTION...PERHAPS EVEN AS
ELEVATED TSTMS ONCE SFC LAYER BEGINS TO DECOUPLE. AS ACTIVITY MOVES
EWD INTO PROGRESSIVELY MORE STABLE SFC AIR FROM ABOUT 00Z
ONWARD...THREAT FOR DAMAGING GUSTS WILL DIMINISH...THOUGH
ISOLATED/MRGL HAIL MAY STILL OCCUR WITH STRONGEST CELLS. IF THESE
TRENDS PROCEED AS ANTICIPATED...REMAINING PORTIONS WW MAY BE
CANCELED BEFORE SCHEDULED 2Z EXPIRATION.

.EDWARDS.. 04/22/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DVN...ARX...DMX...EAX...

40599219 40579356 41159357 41179380 41879375 42199373
42219395 42659399 42649434 43499442 43489206 42269208
42289229 41519232 41519246 41149242 41169212

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MESO: Mesoscale Discussion 0541

ACUS11 KWNS 222259
SWOMCD
SPC MCD 222259
MOZ000-IAZ000-MNZ000-SDZ000-NEZ000-230100-

MESOSCALE DISCUSSION 0541
NWS STORM PREDICTION CENTER NORMAN OK
0559 PM CDT SUN APR 22 2007

AREAS AFFECTED...PORTIONS NWRN/N-CNTRL MO...CENTRAL IA...SWRN SD AND
NWRN IA.

CONCERNING...TORNADO WATCH 164...

VALID 222259Z - 230100Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 164 CONTINUES.
HOWEVER...WW MAY BE CANCELED BEFORE SCHEDULED 2Z EXPIRATION.

PRIMARY BAND OF BOUNDARY LAYER CONVERGENCE WAS EVIDENT AT 2230Z FROM
NEAR STJ NNEWD THROUGH CENTRAL IA...PARALLEL TO AND ROUGHLY 30 NM W
OF I-35. NARROW WINDOW OF OPPORTUNITY REMAINS FOR THIS ACTIVITY TO
PRODUCE SVR HAIL...GUSTS AND PERHAPS A TORNADO OR TWO BEFORE MOVING
INTO AIR MASS CHARACTERIZED BY MORE STABLE SFC PARCELS. CONVECTIVE
POTENTIAL WILL DIMINISH CONSIDERABLY BEHIND THIS LINE AS BOUNDARY
LAYER FLOW VEERS...IN RESPONSE TO NEWD LIFT OF STRONGEST ISALLOBARIC
FORCING ACROSS ERN IA...SERN MN AND WI. THIS PROCESS WILL REDUCE
BOTH SHEAR AND CONVERGENCE IN LOW LEVELS. THEREFORE WW MAY BE
CLEARED FROM W-E ACROSS IA BEHIND INITIAL BAND OF CONVECTION.
MEANWHILE...FARTHER NW ACROSS NWRN IA AND SERN SD...A FEW STG CELLS
LINGER WITHIN CLUSTER OF CONVECTION AND PRECIP BENEATH COLD-CORE
VORTEX ALOFT. BRIEF/SMALL TORNADO CANNOT BE RULED OUT DURING NEXT
1-2 HOURS FROM DISCRETE ACTIVITY JUST SW-SE OF FSD. WITH
TIME...HOWEVER...REDUCTION IN SFC HEATING -- RELATED BOTH TO
WEAKENING INSOLATION AND TO STABILIZATION FROM PRECIP -- LIKEWISE
WILL DIMINISH BUOYANCY ENOUGH TO REMOVE SIGNIFICANT CONVECTIVE
POTENTIAL.

.EDWARDS.. 04/22/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DMX...EAX...FSD...OAX...

39829481 40589443 42129409 42769425 43139471 43259572
42959651 42889674 42859756 42829798 43049811 43249790
43489680 43529560 43329443 42469376 39569328 39629469

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WATCHES: Tornado Watch - Number 162

WWUS20 KWNS 222205
SEL2
SPC WW 222205
KSZ000-MOZ000-NEZ000-230000-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH - NUMBER 162
NWS STORM PREDICTION CENTER NORMAN OK
505 PM CDT SUN APR 22 2007

THE NWS STORM PREDICTION CENTER HAS CANCELLED
TORNADO WATCH NUMBER 162 ISSUED AT 1140 AM CDT FOR PORTIONS OF

KANSAS
MISSOURI
NEBRASKA

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MESO: Mesoscale Discussion 0540

ACUS11 KWNS 222051
SWOMCD
SPC MCD 222051
OKZ000-TXZ000-222315-

MESOSCALE DISCUSSION 0540
NWS STORM PREDICTION CENTER NORMAN OK
0351 PM CDT SUN APR 22 2007

AREAS AFFECTED...SCENTRAL/ERN OK...NCENTRAL TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 222051Z - 222315Z

AN ISOLATED SVR STORM OR TWO MAY DEVELOP ACROSS THE AREA...BUT
MARGINAL NATURE OF THE SVR THREAT SHOULD PRECLUDE THE ISSUANCE OF A
WW.

LATEST VISIBLE SATELLITE IMAGERY SHOWS TCU DEVELOPING ALONG A VERY
SLOW MOVING DRYLINE EXTENDING FROM NEAR BARTLESVILLE OK SSWWD TO
NEAR SHAWNEE OK TO NEAR JACKSBORO TX. AHEAD OF THIS
DRYLINE...INSTABILITY SLOWLY INCREASES WITH DWPTS IN THE LOWER 60S
AND TEMPERATURES NEAR 80 F...RESULTING IN 500-750 J/KG OF MLCAPE.
ALTHOUGH SLIGHT COOLING MAY OCCUR IN THE 700 MB LAYER THROUGH THE
REMAINDER OF THE AFTERNOON IN THE WAKE OF THE DEPARTING UPPER LOW
OVER NEB...A WELL PRONOUNCED MID LEVEL INVERSION CENTERED AROUND 600
MB /PER THE 18Z LAMONT SOUNDING/ EXISTS. THIS INVERSION AND
CONSEQUENT POOR MID LEVEL LAPSE RATES WILL LIMIT THE POTENTIAL FOR
UPDRAFT DEVELOPMENT AND STRENGTH. THUS DESPITE STRONG VERTICAL SHEAR
PROFILES...THE OVERALL SVR THREAT SHOULD BE MINIMAL ENOUGH THAT A WW
IS NOT EXPECTED ATTM.

.CROSBIE.. 04/22/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...TSA...FWD...OUN...

33179659 36649491 36949564 36749616 36349644 34699739
33379819 33069751

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MESO: Mesoscale Discussion 0539

ACUS11 KWNS 222007
SWOMCD
SPC MCD 222007
MOZ000-KSZ000-222200-

MESOSCALE DISCUSSION 0539
NWS STORM PREDICTION CENTER NORMAN OK
0307 PM CDT SUN APR 22 2007

AREAS AFFECTED...ERN KS AND WRN MO

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 222007Z - 222200Z

AN ISOLATED SVR STORM MAY DEVELOP OVER THE AREA IN THE NEXT FEW
HOURS...BUT GIVEN THE MARGINAL/LIMITED NATURE OF THE SVR THREAT...A
WW IS NOT EXPECTED ATTM.

LATEST VISIBLE IMAGERY INDICATES MODERATE CU DEVELOPING ALONG A
DRYLINE EXTENDING FROM NEAR TOP SWD TO 30 W OF CNU. RECENT RUC/NAM
FORECAST SOUNDINGS INDICATE THAT MID LEVEL INVERSION SHOULD REMAIN
STOUT ACROSS THE AREA /SOUTH OF THE NEWD EJECTING UPPER LOW OVER ERN
NEB/ AS EVIDENT BY THE STRONG DRYING NOTED ON WV IMAGERY. THUS
DESPITE INCREASING LOW LEVEL INSTABILITY...WITH MLCAPES AROUND
750-1000 J/KG...WEAK 700-500 MB LAPSE RATES SHOULD TEND TO LIMIT THE
UPDRAFT STRENGTH AND MAGNITUDE OF THE SVR TSTM THREAT ENOUGH THAT A
WW IS NOT ANTICIPATED.

.CROSBIE.. 04/22/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...SGF...EAX...TOP...ICT...

37119445 37619411 38679371 39359379 39409406 39399477
39049536 38689587 38089594 37419592 37119586 37089506

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DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 221954
SWODY1
SPC AC 221952

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0252 PM CDT SUN APR 22 2007

VALID 222000Z - 231200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MO VALLEY
AND UPPER MIDWEST...

..MO VALLEY/UPPER MIDWEST...
WATER VAPOR IMAGERY CURRENTLY SHOWS A QUICK MOVING NEGATIVELY TILTED
UPPER-LEVEL TROUGH OVER THE CNTRL PLAINS WITH THE UPPER-LOW CENTERED
JUST WEST OF OMAHA NEB. BANDED ZONES OF STRONG LARGE-SCALE ASCENT
ARE PRESENT AROUND THE UPPER-LEVEL TROUGH/LOW WHICH WILL SUSTAIN
SEVERAL LINES OF CONVECTION. THE CONVECTIVE LINES WILL MOVE NEWD
ACROSS THE REGION AND SHOULD EXPAND IN COVERAGE AND INTENSITY
EVENTUALLY AFFECTING ERN IA...WRN WI AND NW IL DURING THE OVERNIGHT
PERIOD.

THE LATEST FORECAST SOUNDINGS AND OBJECTIVE ANALYSIS ACROSS THE
REGION SHOW 0-6 KM SHEAR VALUES PRIMARILY IN THE 5O TO 65 KT RANGE
NEAR THE ONGOING CONVECTION. INSTABILITY REMAINS WEAK BUT SHOULD
INCREASE SOME LATE THIS AFTERNOON AND THE ENVIRONMENT MAY BECOME
SUPPORTIVE OF SUPERCELLS. IF A FEW SUPERCELLS DO DEVELOP LATE THIS
AFTERNOON...THE MOST LIKELY LOCATION WOULD BE FROM NW OF OMAHA NEB
EXTENDING EWD INTO WRN IA WHERE INSTABILITY AND LIFT IS FORECAST TO
BE MAXIMIZED. COLD TEMPS ALOFT MAY BE SUPPORTIVE OF LARGE HAIL
ESPECIALLY WITH SUPERCELLS THAT DEVELOP. IN ADDITION TO LARGE
HAIL...A FEW TORNADOES MAY OCCUR AS THE LOW-LEVEL JET STRENGTHENS
LATE THIS AFTERNOON AND EARLY THIS EVENING. SCATTERED WIND DAMAGE
EVENTS MAY ALSO OCCUR AS THE MCS MOVES NEWD ACROSS THE REGION THIS
EVENING PRIMARILY DUE TO STRONG LOW-LEVEL FLOW AND UNIDIRECTIONAL
WINDS BELOW 850 MB.

..NE TX/SE OK...
LATEST OBJECTIVE ANALYSIS SHOWS AN AXIS OF INSTABILITY LOCATED FROM
ECNTRL TX EXTENDING NEWD INTO SE OK. THIS AXIS SHOULD SHIFT ENEWD
LATE THIS AFTERNOON AND INSTABILITY SHOULD GRADUALLY CONTINUE TO
INCREASE. OBJECTIVE ANALYSIS ALSO SHOWS THE CAPPING INVERSION HAS
WEAKENED ACROSS PARTS OF NCNTRL/NERN TX. ALTHOUGH HIGHLY CONDITIONAL
ATTM...A FEW THUNDERSTORMS STILL MAY INITIATE LATE THIS AFTERNOON
AROUND THE DALLAS/FORT WORTH TX AREA AS MID-LEVEL MOISTURE INCREASES
FROM THE SOUTHWEST. LARGE-SCALE ASCENT WILL REMAIN WEAK BUT SHEAR
VALUES MAY BE MARGINALLY SUFFICIENT FOR HAIL AND STRONG GUSTY WINDS.
ANY MARGINAL SEVERE THREAT WOULD LIKELY BE CONFINED TO A SMALL
WINDOW FROM 22Z TO 01Z.

.BROYLES.. 04/22/2007

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MESO: Mesoscale Discussion 0538

ACUS11 KWNS 221825
SWOMCD
SPC MCD 221825
MOZ000-IAZ000-KSZ000-NEZ000-SDZ000-222000-

MESOSCALE DISCUSSION 0538
NWS STORM PREDICTION CENTER NORMAN OK
0125 PM CDT SUN APR 22 2007

AREAS AFFECTED...WRN IA AND NWRN MO

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 221825Z - 222000Z

A NEW TORNADO WATCH IS LIKELY ACROSS PARTS OF WRN IA AND PERHAPS
NWRN MO IN THE NEXT HOUR OR SO.

ENVIRONMENT EXPECTED TO BECOME INCREASINGLY SUPPORTIVE OF LOW-TOPPED
ROTATING STORMS ACROSS PARTS OF WRN IA...AND PERHAPS NWRN
MO...THROUGH LATE AFTERNOON AS DEEP-LAYER CYCLONE TRANSITIONS ENEWD
ACROSS THE REGION. STRONG SURFACE HEATING WAS OCCURRING AS
CONVECTIVE DEBRIS CLEARS THE AREA TO THE EAST. THIS SHOULD RESULT IN
INCREASED DESTABILIZATION AHEAD OF STORM ACTIVITY NOW DEVELOPING
WITHIN ERN PORTIONS OF TORNADO WATCH 162. LATEST OMAHA SOUNDING WAS
INDICATING ESSENTIALLY UNCAPPED AIR MASS WITH STRONG UNIDIRECTIONAL
SHEAR ABOVE THE LFC. WHILE LOW LEVEL SHEAR IN THE UPDRAFT SOURCE
REGION APPEARS LIMITED...ADDITIONAL HEATING IN THE BOUNDARY LAYER
COULD PROVIDE FOR ENHANCED VERTICAL STORM SCALE STRETCHING AS UPPER
FORCING BECOMES MORE CONDUCIVE TO MAINTAINING STORM COVERAGE ACROSS
THE REGION. DEVELOPMENT OF STRONGER LOW-LEVEL CAPE AND BACKED
SURFACE WINDS EAST OF THE SURFACE LOW TRACK SHOULD LEAD TO A GREATER
CHANCE FOR POTENTIALLY TORNADIC SUPERCELLS.

.CARBIN.. 04/22/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DMX...EAX...FSD...OAX...

39139474 39149389 39729328 41949417 43359495 43399600
42889655 41649637 40379550

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WATCHES: Severe Thunderstorm Watch Number 163

WWUS20 KWNS 221819
SEL3
SPC WW 221819
IAZ000-ILZ000-MOZ000-WIZ000-230200-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 163
NWS STORM PREDICTION CENTER NORMAN OK
120 PM CDT SUN APR 22 2007

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

CENTRAL AND EASTERN IOWA
WESTERN ILLINOIS
NORTHEAST MISSOURI
SOUTHWEST WISCONSIN

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 120 PM UNTIL 900
PM CDT.

HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 75
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES EAST
NORTHEAST OF MASON CITY IOWA TO 15 MILES SOUTH OF QUINCY
ILLINOIS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 162...

DISCUSSION...BAND OF SLIGHTLY ELEVATED TSTMS IN CNTRL/N CNTRL MO MAY
INCREASE IN INTENSITY AND BECOME MORE NEARLY SFC-BASED IN THE NEXT
COUPLE OF HOURS AS ACTIVITY ENCOUNTERS HEATED LOW-LEVEL ENVIRONMENT
E OF BAND. WIND FIELD AND LARGE SCALE ASCENT OVER REGION WILL
STRENGTHEN WITH CONTINUED ENE EJECTION OF NEB UPR LOW. OVERALL
SETUP MAY SUPPORT DEVELOPMENT OF DAMAGING WIND GUSTS...HAIL AND
POSSIBLY AN ISOLATED TORNADO WITH EMBEDDED SUSTAINED/SUPERCELL
STORMS.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM
MOTION VECTOR 22040.


..CORFIDI

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DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 221732
SWODY2
SPC AC 221731

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1231 PM CDT SUN APR 22 2007

VALID 231200Z - 241200Z

..THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF WRN OK AND NORTH
TX...

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...CNTRL PLAINS...HIGH PLAINS AND WRN OZARKS...

..SIGNIFICANT SEVERE THUNDERSTORM EVENT EXPECTED ACROSS PARTS OF
THE SRN PLAINS MONDAY AFTERNOON AND EVENING...

..SRN PLAINS...
LATEST WATER VAPOR IMAGERY SHOWS AN UPPER-LEVEL TROUGH ALONG THE
WEST COAST TODAY AND THIS FEATURE WILL MOVE EWD INTO THE FOUR
CORNERS REGION MONDAY. A WELL-DEFINED 80 TO 90 KT MID-LEVEL JET
ROUNDING THE BASE OF THE TROUGH AND A SRN STREAM JET OVER NRN MEXICO
AND CNTRL TX WILL BEGIN TO AFFECT THE REGION MONDAY AFTERNOON. THESE
FEATURES ALONG WITH SUBTLE LEAD SHORTWAVE TROUGH ACTIVITY WILL
PROVIDE STRONG LIFT SUPPORTING SCATTERED THUNDERSTORM CLUSTERS
ACROSS THE REGION MONDAY AFTERNOON. AS VERTICAL SHEAR INCREASES DUE
TO THE INFLUENCE OF THIS COMPLEX JET STRUCTURE ASSOCIATED WITH THE
UPPER-LEVEL TROUGH...A VERY HIGH POTENTIAL FOR SEVERE THUNDERSTORMS
WILL EXIST ACROSS THE REGION MONDAY AFTERNOON AND EVENING.

FORECAST SOUNDINGS FOR MONDAY AFTERNOON ACROSS THE REGION SHOW 0-6
KM SHEAR VALUES IN THE 40 TO 50 KT RANGE INCREASING INTO THE 50 TO
60 KT RANGE DURING THE EVENING. CONSIDERING MODERATE INSTABILITY
SHOULD BE PRESENT FROM THE RIO GRANDE VALLEY EXTENDING NWD INTO
NORTH TX AND OK...THE SHEAR WILL BE FAVORABLE FOR SUPERCELLS.
LOW-LEVEL SHEAR PROFILES ON FORECAST SOUNDINGS ALSO APPEAR FAVORABLE
FOR TORNADOES AND A SIGNIFICANT TORNADO THREAT MAY DEVELOP AS
SUPERCELLS MATURE LATE MONDAY AFTERNOON. A CLUSTER OF TORNADOES
APPEARS LIKELY ACROSS PARTS OF THE MODERATE RISK AREA WHERE STRONG
LOW-LEVEL SHEAR PROFILES WILL EXIST. IN ADDITION...A PLUME OF VERY
STEEP LAPSE RATES IS FORECAST TO MOVE EWD INTO NORTH TX AND SRN OK
BY LATE AFTERNOON ASSOCIATED WITH THE EXIT REGION OF THE MID-LEVEL
JET. THIS WILL PROVIDE SUPPORT FOR NUMEROUS LARGE HAIL EVENTS WITH
SUPERCELLS DURING THE LATE AFTERNOON AND EVENING. THE ATMOSPHERE
SHOULD ALSO BE SUPPORTIVE OF VERY LARGE HAIL WITH THE MOST INTENSE
STORMS. ISOLATED WIND DAMAGE WILL ALSO BE LIKELY WITH SUPERCELLS AND
BOW ECHOES ESPECIALLY AS MCS ORGANIZATION TAKES PLACE IN THE
EVENING.

..CNTRL PLAINS/HIGH PLAINS...
WATER VAPOR IMAGERY SHOWS AN UPPER-LEVEL TROUGH OVER THE WEST COAST
AND THIS FEATURE WILL MOVE EWD INTO THE FOUR CORNERS REGION MONDAY.
EAST OF THE UPPER-TROUGH...A DIFFLUENT UPPER-LEVEL PATTERN WILL
EXIST ACROSS THE HIGH PLAINS AND CNTRL PLAINS. ALTHOUGH THE JET
ENERGY ASSOCIATED WITH THE TROUGH WILL REMAIN SOUTH OF THE
REGION...THE DIFFLUENCE WILL BE FAVORABLE FOR SCATTERED THUNDERSTORM
DEVELOPMENT ALONG AN INSTABILITY AXIS LOCATED FROM SRN KS EXTENDING
NWWD INTO ERN CO. THUNDERSTORMS SHOULD INITIATE ALONG THE
INSTABILITY AXIS AND MOVE EWD INTO THE CNTRL PLAINS LATE MONDAY
AFTERNOON INTO THE EVENING.

FORECAST SOUNDINGS ACROSS THE REGION LATE MONDAY AFTERNOON SHOW 0-6
KM SHEAR VALUES IN THE 40 TO 50 KT RANGE LARGELY DUE TO STRONG
DIRECTIONAL TURNING BELOW 500 MB. THIS SHOULD BE SUFFICIENT FOR
SUPERCELLS ESPECIALLY IF POCKETS OF MODERATE INSTABILITY DEVELOP
ALONG THE MOIST AXIS MONDAY AFTERNOON. STEEP LAPSE RATES...STRONG
VERTICAL SHEAR AND COLD MID-LEVEL TEMPS SHOULD BE FAVORABLE FOR
LARGE HAIL. IN ADDITION...SFC DEWPOINTS ALONG THE MOIST AXIS ARE
FORECAST TO BE DRIER THAN AREAS FURTHER SOUTH WITH MAINLY 50S F
ACROSS KS AND ERN CO. THIS SHOULD BE CONDUCIVE FOR WIND DAMAGE WITH
SUPERCELLS AND BOW ECHOES ESPECIALLY ASSOCIATED WITH SHORT LINE
SEGMENTS. ALTHOUGH...LCL HEIGHTS WILL BE HIGHER THAN AREAS FURTHER
SOUTH...A TORNADO THREAT MAY ALSO EXIST WITH SUPERCELLS DUE TO THE
BACKED SFC WINDS AND ESPECIALLY WITH SUPERCELLS THAT CROSS ANY
PRE-EXISTING BOUNDARIES.

..MS VALLEY/OH AND TN VALLEYS...
AT THE SFC...A SLOW MOVING COLD FRONT SHOULD BE PRESENT FROM OZARK
REGION EXTENDING ENEWD INTO THE OH VALLEY. ALTHOUGH A FLAT
UPPER-LEVEL RIDGE IS FORECAST ACROSS THE REGION MONDAY...LOW-LEVEL
CONVERGENCE SHOULD BE SUPPORTIVE OF SCATTERED THUNDERSTORM
DEVELOPMENT ACROSS THE REGION MONDAY AFTERNOON AND EVENING. ALTHOUGH
THE SHEAR ENVIRONMENT IS NOT FORECAST TO BE THAT STRONG...ENOUGH
INSTABILITY MAY DEVELOP ALONG AND AHEAD OF THE FRONTAL BOUNDARY FOR
A MARGINAL SEVERE THREAT. HAIL AND STRONG GUSTY WINDS MAY ACCOMPANY
THE STRONGER THUNDERSTORMS ESPECIALLY NEAR PEAK HEATING.

FURTHER SOUTH THE SRN OZARKS AND WRN PART OF THE TN VALLEY...MODEL
FORECASTS DEVELOP INSTABILITY AND SCATTERED THUNDERSTORMS. IF THIS
OCCURS...VERTICAL SHEAR PROFILES SHOULD BE SUPPORTIVE OF MARGINALLY
SEVERE THUNDERSTORMS FROM THE LATE AFTERNOON TO EARLY EVENING.

.BROYLES.. 04/22/2007

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MESO: Mesoscale Discussion 0537

ACUS11 KWNS 221708
SWOMCD
SPC MCD 221707
ILZ000-WIZ000-IAZ000-MNZ000-221900-

MESOSCALE DISCUSSION 0537
NWS STORM PREDICTION CENTER NORMAN OK
1207 PM CDT SUN APR 22 2007

AREAS AFFECTED...IA...SERN MN....NRN IL...SWRN WI

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 221707Z - 221900Z

SEVERE STORM POTENTIAL MAY INCREASE ACROSS CNTRL/ERN IA OVER THE
NEXT FEW HOURS. HAIL AND POSSIBLE SEVERE WIND THREAT MAY SPREAD FROM
PARTS OF ERN IA TO SRN/SERN MN...NRN IL...AND PERHAPS SWRN
WI...THROUGH LATER TODAY. A WATCH COULD BE ISSUED WITHIN AN HOUR OR
TWO.

LEADING ARC OF VIGOROUS TSTMS MOVING INTO CNTRL IA ATTM APPEARS
LINKED TO ASCENT WITHIN WARM CONVEYOR BELT ASSOCIATED WITH LARGER
SCALE CYCLONE ACROSS THE CNTRL PLAINS. DESPITE LIMITED LOW LEVEL
MOISTURE...STRONG SHEAR AND POCKETS OF STEEPER MID LEVEL LAPSE RATES
HAVE OCCASIONALLY SUPPORTED BRIEF UPDRAFT INTENSIFICATION... AND
HAIL PRODUCTION...WITH THIS ACTIVITY THROUGH THE MORNING.

ANOTHER BAND OF STORMS WAS GRADUALLY INCREASING TO THE WEST OF THE
LEADING CONVECTION AND COULD EVOLVE SIMILARLY AS FIRST BAND...INTO
SECTIONS OF CNTRL IA...OVER THE NEXT 1-2 HOURS.

PROSPECTS FOR SURFACE-BASED STORM DEVELOPMENT WITHIN THESE BANDS
COULD IMPROVE AS AIR MASS BETWEEN THE CONVECTION GRADUALLY
DESTABILIZES THIS AFTERNOON. IN ADDITION...MUCH OF CNTRL/ERN
IA...SERN MN AND NRN IL CONTINUE TO EXPERIENCE STRONG SURFACE
HEATING AND STEEPENING BOUNDARY LAYER LAPSE RATES UNDER SUNNY SKIES.
COUPLED WITH INCREASING FORCING AND STRONGER MID LEVEL FLOW WITH
APPROACHING PLAINS SYSTEM...ONGOING ACTIVITY COULD POSE AN
INCREASING THREAT FOR DAMAGING SURFACE WINDS AS CONVECTIVE COLD POOL
MOVES INTO WARM/DRY DOWNSTREAM AIR MASS. THE POTENTIAL FOR THIS
TRANSITION WILL BE MONITORED OVER THE NEXT HOUR OR SO...AND A WATCH
MAY BE NEEDED IF THIS SCENARIO APPEARS INCREASINGLY LIKELY.

.CARBIN.. 04/22/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MKX...DVN...ARX...MPX...DMX...

43279455 43669471 44209424 44299344 44229220 43679118
42409004 41879002 41479026 41129100 40869229 40719348
41059434 41369457 41629467

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WATCHES: Tornado Watch Number 162

WWUS20 KWNS 221636
SEL2
SPC WW 221636
KSZ000-MOZ000-NEZ000-230000-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 162
NWS STORM PREDICTION CENTER NORMAN OK
1140 AM CDT SUN APR 22 2007

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

NORTHEAST KANSAS
EXTREME NORTHWEST MISSOURI
SOUTHEAST NEBRASKA

EFFECTIVE THIS SUNDAY MORNING AND EVENING FROM 1140 AM UNTIL 700
PM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE
MILES EAST AND WEST OF A LINE FROM 35 MILES NORTHWEST OF COLUMBUS
NEBRASKA TO 25 MILES EAST OF MANHATTAN KANSAS. FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU2).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

DISCUSSION...ENVIRONMENT EXPECTED TO BECOME INCREASINGLY SUPPORTIVE
OF RELATIVELY LOW-TOPPED ROTATING STORMS ACROSS FROM SOUTHEAST
NEB/NORTHEAST KS EAST TO EXTREME NORTHWEST MO THROUGH THE AFTERNOON
AS DEEP-LAYER CYCLONE TRANSITIONS ENEWD ACROSS THE REGION. POCKETS
OF STRONGER SURFACE HEATING WITHIN SYSTEM DRY SLOT WILL CONTRIBUTE
TO CONTINUED DESTABILIZATION AND INCREASING STORM COVERAGE AND
INTENSITY. IN ADDITION TO COOLING ALOFT AND ADEQUATE DEEP-LAYER
SHEAR FOR HAIL STORMS...ENHANCED LOW LEVEL SHEAR NEAR THE LOW...AND
UPDRAFT STRETCHING IN AREAS WITH GREATER LOW-LEVEL CAPE SHOULD LEAD
TO A GREATER CHANCE FOR SOME TORNADIC CELLS.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
400. MEAN STORM MOTION VECTOR 20035.


..CARBIN/CORFIDI

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DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 221630
SWODY1
SPC AC 221628

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CDT SUN APR 22 2007

VALID 221630Z - 231200Z

..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LWR MO AND
MID MS VLYS...

..SYNOPSIS...
NRN KS UPR LOW EXPECTED TO OPEN INTO A SHORTWAVE TROUGH LATER
TODAY/TONIGHT AS IT TURNS ENE AND IS ABSORBED INTO NRN STREAM FLOW.
THE UPR VORT SHOULD BE NEAR SUX BY THIS EVENING...NEARLY VERTICAL
WITH ASSOCIATED SFC CENTER. BY 12Z MONDAY THE SFC WAVE SHOULD REACH
SRN WI...50-60 KT MID LEVEL JET STREAK OVERSPREADING IND/WRN OH.

IN THE W...NEXT IN SERIES OF NEGATIVE TILT UPR SYSTEMS WILL AMPLIFY
SE INTO THE SRN GRT BASIN.

..LWR MO VLY...
WHILE KS/NEB LOW WILL WEAKEN OVER TIME...PRESENT WIND FIELD IS QUITE
STRONG AND WINDS WILL REMAIN MORE THAN ADEQUATE TO SUPPORT SVR TSTMS
THIS PERIOD. TODAY'S INITIAL THREAT LIKELY WILL BE CONFINED TO
SYSTEM DRY SLOT OVER THE LWR MO VLY...WHERE MODERATE HEATING WILL
OCCUR. TSTMS SHOULD FORM IN THE DRY SLOT BY EARLY AFTERNOON OVER SE
NEB AND N CNTRL/NE KS....WITH THE ACTIVITY THEN SPREADING E/NE INTO
NW MO AND SW IA /REF MCD #536/.

WIND PROFILES WILL SHOW RAPID SPATIAL/TEMPORAL VARIATION IN DRY
SLOT...COMPLICATING FORECAST OF PREDOMINANT STORM MODE/SVR THREAT.
THE STRONGEST LOW-LEVEL DIRECTIONAL SHEAR MAY REMAIN CONFINED TO SE
NEB...WHILE MORE FAVORABLE DEEP SHEAR ENVIRONMENT FOR SUSTAINED
SUPERCELLS WILL ACCOMPANY EJECTING MID LEVEL SPEED MAX FARTHER S
ACROSS NRN KS/NW MO. BEST COMBINATION OF THERMODYNAMICS AND
KINEMATICS FOR LOW-TOPPED SUPERCELLS/POSSIBLE TORNADOES THROUGH MID
AFTERNOON APPEARS TO BE AREA FROM BIE S AROUND MHK/TOP...WITH THE
PATTERN SHIFTING INTO NW MO A BIT LATER IN THE DAY. SBCAPE IN THIS
REGION SHOULD REACH 1000 J/KG...WITH 0-1 KM SHEAR AOA 200 M2/S2.

..CNTRL IA/CNTRL MO INTO SRN MN/IL/WI...
FARTHER E AND N...WARM CONVEYOR BELT BAND WILL LIMIT HEATING ACROSS
MUCH OF WRN MO AND WRN/CNTRL IA. COUPLED WITH LIMITED LOW LEVEL
MOISTURE SUPPLY...PROSPECTS FOR SFC-BASED STORM DEVELOPMENT WITHIN
THE BAND APPEAR LIMITED. ELEVATED ACTIVITY WITHIN THE CONVEYOR
MAY...HOWEVER...POSE A THREAT FOR MARGINALLY SVR HAIL IN IA. AHEAD
OF THE WARM CONVEYOR...SKIES SHOULD REMAIN MAINLY CLEAR ACROSS NE
MO/ERN IA AND SRN MN. COUPLED WITH INCREASING FORCING FOR ASCENT
WITH APPROACHING KS/NEB UPR SYSTEM...CANNOT RULE OUT POSSIBILITY
THAT A N/S LINE OF FORWARD-PROPAGATING STORMS MIGHT FORM ON LEADING
EDGE OF CONVEYOR BELT. GIVEN STRENGTHENING WIND FIELDS AND
STEEPENING LOW LEVEL LAPSE RATES...SUCH ACTIVITY COULD POSE A THREAT
FOR DAMAGING WIND/MARGINALLY SVR HAIL EWD INTO PARTS OF WI/IL.

..W CNTRL MO SW INTO ERN OK...
A CONDITIONAL THREAT FOR SVR STORMS WILL EXIST FROM W CNTRL MO AND E
CNTRL/SE KS INTO ERN OK LATER TODAY...WHERE SFC HEATING WILL
DESTABILIZE MOISTURE AXIS ALONG PREFRONTAL CONFLUENCE AXIS.
CONVERGENCE WILL BE WEAK/SHALLOW ALONG CONFLUENCE BAND. BUT 40-50
KT DEEP WLY SHEAR ORIENTED PERPENDICULAR TO BAND...AND EXPECTED
SBCAPE AOA 1000 J/KG...SUGGEST A CONDITIONAL PROBABILITY FOR A FEW
SUSTAINED LATE AFTERNOON/EARLY EVENING STORMS WITH HAIL/HIGH WIND.

.CORFIDI/CROSBIE.. 04/22/2007

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MESO: Mesoscale Discussion 0536

ACUS11 KWNS 221557
SWOMCD
SPC MCD 221557
MOZ000-IAZ000-KSZ000-NEZ000-221730-

MESOSCALE DISCUSSION 0536
NWS STORM PREDICTION CENTER NORMAN OK
1057 AM CDT SUN APR 22 2007

AREAS AFFECTED...SERN NE....SWRN IA...NWRN MO...NERN KS

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 221557Z - 221730Z

LATEST INDICATIONS SUGGEST THE NEED FOR A TORNADO WATCH ACROSS PARTS
OF SERN NEB/NERN KS AREAS BEFORE NOON CDT. THE WATCH AREA COULD
EXTEND EAST INTO PORTIONS OF SWRN IA AND NWRN MO.

LATEST SURFACE ANALYSIS AND LBF RADAR DEPICTED CENTER OF NEARLY
VERTICALLY STACKED AND COMPACT CYCLONE MOVING FROM PHILLIPS COUNTY
KS TOWARD HARLAN/FRANKLIN COUNTIES OF SCNTRL NEB. DEEP-LAYER
CONVERGENCE ASSOCIATED WITH THIS SYSTEM IS EXPECTED TO LEND SUPPORT
SOME INCREASE IN WARM SECTOR TSTM DEVELOPMENT OVER THE NEXT FEW
HOURS FROM NERN KS TO SERN NEB...AND THEN EWD ACROSS THE MO RIVER
VALLEY. ONGOING BOUNDARY LAYER WARMING/MIXING ACROSS SERN NEB HAS
ALREADY RESULTED IN THE DEVELOPMENT OF N-S ORIENTED HORIZONTAL
CONVECTIVE ROLL CLOUDS WHERE NOSE OF 70-80KT MID LEVEL JET HAS
SPREAD ATOP NARROW LOW LEVEL MOIST AXIS.

WIND PROFILER INFORMATION CURRENTLY SUGGESTS RELATIVELY LIMITED LOW
LEVEL TURNING...BUT MORE THAN ADEQUATE DEEP SHEAR FOR SUPERCELLS.
DEEP SHEAR MAY ACTUALLY WEAKEN AS UPPER GRADIENT RELAXES NEAR THE
LOW CENTER. HOWEVER...ENHANCED LOW LEVEL DIRECTIONAL SHEAR
WITHIN/NEAR DEEP-LAYER CYCLONE...INCREASING LOW LEVEL INSTABILITY
WITHIN SYSTEM DRY SLOT...AND STRONG ASCENT ON CYCLONIC SHEAR SIDE OF
MID LEVEL JET COULD FURTHER CONTRIBUTE TO MESOSCALE DYNAMICS
SUPPORTIVE OF ORGANIZING TSTMS. EXPECT ONE OR TWO BANDS OF ROBUST
SUPERCELLS WITH ATTENDANT THREATS OF WIND...LARGE HAIL...AND
TORNADOES TO EVOLVE FROM DEVELOPING CONVECTION OVER THE NEXT SEVERAL
HOURS.

.CARBIN.. 04/22/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DMX...EAX...OAX...TOP...ICT...GID...DDC...GLD...

39379964 40219982 41379883 41349676 41139540 40169448
39289483 38889588 38509764

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DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 221229
SWODY1
SPC AC 221227

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0727 AM CDT SUN APR 22 2007

VALID 221300Z - 231200Z

..THERE IS A SLGT RISK OF SVR TSTMS FROM CENTRAL PLAINS TO UPPER MS
VALLEY...

..CENTRAL PLAINS TO UPPER MS VALLEY...

VIRTUALLY STACKED SFC/UPR LOW OVER WRN KS THIS AM WILL CONTINUE
ENEWD INTO WRN IA BY THIS EVENING. BAND OF STRONG WIND FIELDS HAS
ROTATED TO S AND E QUAD OF THE SYSTEM AND WILL PROVIDE FAVORABLE
DEEP LAYER SHEAR THIS AFTERNOON/EVENING FOR SEVERE THUNDERSTORMS.
PRIMARY LIMITING PARAMETER FOR THE SEVERE THREAT TODAY WILL BE THE
OVERALL MARGINAL INSTABILITY. APPEARS FROM WATER VAPOR IMAGERY AND
SUPPORTED BY THE MODELS THAT A DRY SLOT IS ROTATING NEWD INTO
CENTRAL KS AHEAD OF THE LOW. THIS SHOULD ALLOW SUFFICIENT SURFACE
HEATING ACROSS ERN KS/WRN MO FOR TEMPS TO CLIMB INTO THE MID 70S
THIS AFTERNOON. WITH DEWPOINTS RISING INTO THE MID 50S IN THE SAME
AREA...MLCAPES COULD CLIMB TO 1000 J/KG.

BEST COMBINATION OF SHEAR AND INSTABILITY IN SUPPORT OF SUPERCELLS
BY EARLY THIS AFTERNOON SHOULD BE JUST IN ADVANCE OF THE STACKED LOW
VICINITY CENTRAL NE/KS BORDER HEADED TOWARD WRN IA. PRIMARY THREAT
TODAY SHOULD BE HAIL AND LOCALIZED DAMAGING WINDS BOTH FROM ANY
SUPERCELL THAT FORMS AND WITH LINE SEGMENTS THAT ARE LIKELY TO
DEVELOP BY LATE THIS AFTERNOON IN THE ZONE OF STRONG SHEAR AHEAD OF
THE LOW.

TORNADOS...IF THEY OCCUR WOULD BE MOST LIKELY IN THE ENHANCED
BOUNDARY LAYER SHEAR JUST AHEAD OF SURFACE LOW FROM NERN KS/SERN NE
EWD LATER THIS AFTERNOON. THE DEGREE OF TORNADO POTENTIAL IS
DEPENDENT ON AMOUNT OF HEATING THAT CAN OCCUR GIVEN THE LIMITED LOW
LEVEL MOISTURE.

.HALES/JEWELL.. 04/22/2007

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DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 220816
SWOD48
SPC AC 220816

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0316 AM CDT SUN APR 22 2007

VALID 251200Z - 301200Z

..DISCUSSION...

LATEST MEDIUM RANGE GUIDANCE REMAINS QUITE CONSISTENT IN
DEAMPLIFICATION OF SHORT WAVE TROUGH AS IT PROGRESSES FROM THE
CNTRL/SRN PLAINS INTO THE ERN STATES ON DAYS 4 THROUGH 6
/WED-FRI/...APRIL 25TH-27TH. MEANWHILE...NEXT UPSTREAM SYSTEM IS
FORECAST TO EMERGE FROM THE ROCKIES INTO PLAINS STATES ON DAY
6...FRIDAY APRIL 27TH...WITH SLIGHT MODEL DIFFERENCES IN THE
EVOLUTION OF THIS FEATURE AS IT AMPLIFIES OVER THE ERN STATES ON
DAYS 7 AND 8 /SAT-SUN/...APRIL 28TH AND 29TH.

THERE APPEARS TO BE SOME THREAT OF SEVERE WEATHER WEDNESDAY...APRIL
25TH OVER PORTIONS OF THE MID MS/LOWER OH VALLEYS INTO THE LOWER MS
VALLEY AHEAD OF WEAKENING UPPER TROUGH AND SURFACE COLD FRONT. THIS
THREAT MAY BE TEMPERED BY THE WEAKENING LAPSE RATES AND
INSTABILITY...AND OVERALL DECREASE IN STRENGTH OF THE SYNOPTIC
SYSTEM. THEREFORE...NO SEVERE REGIONAL AREA WILL BE INCLUDED. ANY
ADDITIONAL SEVERE WEATHER POTENTIAL LOOKS TO REMAIN RELATIVELY
ISOLATED THROUGH THE REMAINDER OF THE EXTENDED PERIOD.

.MEAD.. 04/22/2007

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WATCHES: Severe Thunderstorm Watch - Number 161

WWUS20 KWNS 220735
SEL1
SPC WW 220735
OKZ000-TXZ000-220800-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH - NUMBER 161
NWS STORM PREDICTION CENTER NORMAN OK
235 AM CDT SUN APR 22 2007

THE NWS STORM PREDICTION CENTER HAS CANCELLED
SEVERE THUNDERSTORM WATCH NUMBER 161 ISSUED AT 1100 PM CDT FOR PORTIONS OF

OKLAHOMA
TEXAS

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DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 220728
SWODY3
SPC AC 220726

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0226 AM CDT SUN APR 22 2007

VALID 241200Z - 251200Z

..THERE IS A MDT RISK OF SVR TSTMS OVER CNTRL PARTS OF KS/OK SWD
INTO NWRN AND N-CNTRL TX...

..THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL PLAINS AND LOWER
MO VALLEY SWD INTO PARTS OF WRN/CNTRL TX...

..SYNOPSIS...

LATEST SHORT AND MEDIUM RANGE MODEL GUIDANCE REMAIN CONSISTENT IN
THE EWD PROGRESSION OF MID AND UPPER-LEVEL LOW FROM THE CNTRL/SRN
ROCKIES INTO THE ADJACENT PLAINS THROUGH THE DAY THREE PERIOD. IN
THE LOW-LEVELS...SOME SMALL DIFFERENCES EXIST WITH REGARD TO THE
TRACK OF THE ATTENDANT SURFACE LOW FROM SWRN KS OR THE OK/NRN TX
PNHDLS TO CNTRL/SERN KS BY WEDNESDAY MORNING. ASSOCIATED WARM FRONT
WILL LIFT NWD THROUGH THE LOWER MO AND MID MS RIVER VALLEYS WHILE
DRYLINE SHIFTS EWD FROM THE ERN OK/TX PNHDLS INTO CNTRL OK SWD TO
CNTRL TX BY 25/12Z.

..SEVERE WEATHER OUTBREAK POSSIBLE TUESDAY AND TUESDAY NIGHT...

..CNTRL/SRN PLAINS...

INGREDIENTS APPEAR TO BE COMING TOGETHER FOR A FAIRLY CLASSIC SEVERE
WEATHER EPISODE OVER THE CNTRL AND SRN PLAINS AS 100-120 KT 250
MB/50-70 KT 500 MB JET STREAKS AND A CONCENTRATED ZONE OF HEIGHT
FALLS OVERSPREAD SYSTEM/S WARM SECTOR. A MOIST BOUNDARY LAYER AIR
MASS SHOULD BE IN PLACE /DEWPOINTS IN THE LOWER TO MID 60S/ BENEATH
STEEP MID-LEVEL LAPSE RATES CONTRIBUTING TO A MODERATELY UNSTABLE
AFTERNOON AIR MASS.

TSTMS ARE EXPECTED TO BECOME INCREASINGLY LIKELY BY AFTERNOON FROM
VICINITY OF SURFACE LOW OVER SWRN KS SWD ALONG DRYLINE INTO WRN OK
AND NWRN TX WITH STORMS MOVING/DEVELOPING EWD/NEWD THROUGH CNTRL AND
ERN PORTIONS OF KS/OK AND N TX MONDAY AFTERNOON AND NIGHT. WHILE
UNCERTAINTIES EXIST WITH RESPECT TO TIMING/LOCATION OF CONVECTIVE
INITIATION AND EVENTUAL CONVECTIVE MODE...THE COMBINATION OF STRONG
VERTICAL SHEAR AND MODERATE INSTABILITY OVER A LARGE AREA INDICATE A
HIGH POTENTIAL FOR NUMEROUS SUPERCELLS CAPABLE OF TORNADOES AND
LARGE HAIL.

THE SEVERE THREAT IS EXPECTED TO SPREAD AS FAR NE AS THE LOWER MO
AND MID MS VALLEYS WITHIN LOW-LEVEL WAA REGIME ALONG AND N OF WARM
FRONT...AND AS FAR SW AS SWRN TX ALONG DRYLINE.

.MEAD.. 04/22/2007

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WATCHES: Severe Thunderstorm Watch - Number 160

WWUS20 KWNS 220705
SEL0
SPC WW 220705
NEZ000-SDZ000-220900-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH - NUMBER 160
NWS STORM PREDICTION CENTER NORMAN OK
205 AM CDT SUN APR 22 2007

THE NWS STORM PREDICTION CENTER HAS CANCELLED
SEVERE THUNDERSTORM WATCH NUMBER 160 ISSUED AT 1035 PM CDT FOR PORTIONS OF

NEBRASKA
SOUTH DAKOTA

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WATCHES: Severe Thunderstorm Watch - Number 159

WWUS20 KWNS 220640
SEL9
SPC WW 220640
MNZ000-220700-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH - NUMBER 159
NWS STORM PREDICTION CENTER NORMAN OK
140 AM CDT SUN APR 22 2007

THE NWS STORM PREDICTION CENTER HAS CANCELLED
SEVERE THUNDERSTORM WATCH NUMBER 159 ISSUED AT 905 PM CDT FOR PORTIONS OF

MINNESOTA

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DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 220534
SWODY1
SPC AC 220533

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1233 AM CDT SUN APR 22 2007

VALID 221200Z - 231200Z

..THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL PLAINS TO
WI...

..SYNOPSIS...
MID/UPPER LEVEL LOW -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER
NERN NM AND SERN CO -- IS FCST TO CONTINUE EJECTING NEWD DURING
DAY-1 FROM WRN KS TO VICINITY IA/WI BORDER. NEARLY COLLOCATED SFC
LOW LIKEWISE WILL LIFT NEWD...MOVING FROM N-CENTRAL KS NEWD ACROSS
SERN NEB TO SWRN IA THROUGH AFTERNOON HOURS. SFC FRONTAL ZONE WILL
EXTEND NWD FROM THIS LOW ACROSS CENTRAL NEB...THEN NEWD OVER SERN SD
AND MN...DRIFTING EWD ACROSS NERN PLAINS AND UPPER MS VALLEY AS COLD
FRONT. DRYLINE WILL ARC SEWD THEN SWD FROM VICINITY SFC
LOW...ACROSS CENTRAL/ERN KS AND CENTRAL/ERN OK...MOVING NEWD ACROSS
KS/MO BORDER AND INTO NWRN MO BY AROUND 23/00Z.

FARTHER W...NEXT SIGNIFICANT TROUGH -- WHICH WILL SUBSTANTIALLY
IMPACT DAY-2 AND DAY-3 SVR POTENTIAL OVER CENTRAL CONUS -- IS FCST
TO MOVE INLAND FROM PACIFIC COAST. BROAD MID/UPPER LEVEL CYCLONE
SHOULD CONSOLIDATE BY 23/12Z CENTERED OVER NV. ISOLATED GEN TSTM
POTENTIAL EXISTS ACROSS PORTIONS WRN INTERMOUNTAIN REGION AND
WRN/NRN GREAT BASIN.

..CENTRAL PLAINS TO UPPER MS VALLEY...
PRIND SOME DESTABILIZATION WILL OCCUR BEHIND INITIAL ARC OF
CLOUDS/PRECIP THAT WILL MOVE NEWD ACROSS THIS AREA BY LATE MORNING
AND EARLY AFTERNOON. SCATTERED TSTMS ARE FCST TO DEVELOP AS EARLY
AS MIDDAY INVOF SFC LOW...BUILDING SEWD ALONG LEADING EDGE OF DRY
SLOT. THIS ACTIVITY WILL SHIFT NEWD ACROSS NERN KS...SERN
NEB...NERN MO..SWRN IA REGION.

FCST SOUNDINGS SUGGEST LIMITED SFC HEATING AND VERTICAL SHEAR
PROFILES E AND ESE OF SFC LOW SHOULD BE FAVORABLE...WITH 45-55 KT
DIURNAL LLJ ENLARGING HODOGRAPH. DURING TIME FRAME WHEN TSTMS
REMAIN RELATIVELY DISCRETE...0-1 KM SRH ABOVE 200 J/KG AND ROUGHLY
50 KT 0-6 KM SHEAR WILL FAVOR SUPERCELLS AND POTENTIAL FOR TORNADOES
OVER PORTIONS ERN KS AND W-CENTRAL/NWRN MO. DEEP-LAYER SHEAR
PROFILES SHOULD WEAKEN FARTHER NW ACROSS S-CENTRAL/E-CENTRAL
NEB...BENEATH COLD CORE REGION OF UPPER LOW. HOWEVER...FCST LOW
LEVEL LIFT AND VORTICITY ALSO WILL BE FAVORABLE FOR TORNADO
POTENTIAL CLOSER TO SFC/UPPER LOW...IN COLD CORE REGION. COMPLEX OF
SVR TSTMS WITH DAMAGING WIND AND LARGE HAIL MAY EVOLVE AND MOVE NEWD
ACROSS PORTIONS IA/NRN MO DURING EVENING HOURS.

SOME PORTION OF THIS AREA MAY REQUIRE UPGRADE ONCE SOME MESOSCALE
UNCERTAINTIES ARE RESOLVED REGARDING DESTABILIZATION AND TIMING/MODE
OF CONVECTIVE FORCING.

SCATTERED TSTMS ALSO MAY DEVELOP ALONG BAROCLINIC ZONE EXTENDING
POLEWARD OF LOW...WITH HAIL AND DAMAGING GUSTS POSSIBLE. THIS
POTENTIAL SHOULD BE MAINLY BEFORE DARK...AND STRONGLY TIED TO
STRENGTH/DURATION OF SFC HEATING ALONG AND S OF BAROCLINIC
BOUNDARY...WITH DEW POINTS GENERALLY 50S F.

..ERN OK...OZARKS...
SVR POTENTIAL BECOMES MUCH MORE CONDITIONAL WITH SWD EXTENT FROM
SERN KS AND SWRN MO SWD ACROSS ERN OK AND NWRN AR. VERTICAL SHEAR
PROFILES ARE FCST TO BE FAVORABLE FOR SUPERCELLS WITH 45-60 KT 500
MB FLOW AND 0-6 KM SHEAR VECTOR MAGNITUDES ALSO IN 45-60 KT RANGE.
SFC DEW POINTS MID 50S TO LOW 60S SHOULD BE
COMMON...HOWEVER...CONVECTIVE INITIATION AND ESPECIALLY SUSTAINED
TSTM POTENTIAL BECOMES LESS PROBABLE WITH DISTANCE FROM
COMPACT/DEEP-LAYER CYCLONE AND ASSOCIATED MID/UPPER LEVEL ASCENT
MAXIMA. WITH SWD EXTENT...PRIND LOW-MIDLEVEL LAPSE RATES ABOVE
BOUNDARY LAYER WILL DIMINISH...AND MLCINH WILL INCREASE. ALSO...
STRONGEST ISALLOBARIC FORCING WILL BE N OF THIS AREA --- FROM LOWER
MO VALLEY INTO IA -- SO SFC WINDS SHOULD HAVE WLY COMPONENT THAT
WILL LIMIT CONVERGENCE. ANY SUSTAINED CONVECTION THAT MAY DEVELOP
THIS AFTERNOON MAY PRODUCE LARGE HAIL AND DAMAGING GUSTS...BUT
POTENTIAL APPEARS TOO CONDITIONAL FOR CATEGORICAL OUTLOOK ATTM.

.EDWARDS/JEWELL.. 04/22/2007

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DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 220520
SWODY2
SPC AC 220519

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1219 AM CDT SUN APR 22 2007

VALID 231200Z - 241200Z

..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL AND SRN
PLAINS...

..SYNOPSIS...

MID AND UPPER-LEVEL TROUGH OVER THE GREAT BASIN IS EXPECTED TO
AMPLIFY THROUGH THE PERIOD AS IT TRANSLATES EWD INTO THE CNTRL AND
SRN ROCKIES BY TUESDAY MORNING. AS THIS OCCURS...DOWNSTREAM RIDGE
WILL IN TURN AMPLIFY OVER THE ERN GREAT PLAINS INTO MS
VALLEY...SUPPORTING EWD PROGRESSION OF WEAKENING SHORT WAVE TROUGH
FROM THE UPPER GREAT LAKES INTO NEW ENGLAND.

IN THE LOW-LEVELS...BROAD TROUGHING OVER THE HIGH PLAINS WILL
CONSOLIDATE INTO A LEE CYCLONE OVER SERN CO MONDAY AFTERNOON WITH
THIS FEATURE DEVELOPING GENERALLY EWD INTO SWRN KS OR THE OK/NRN TX
PNHDL. ATTENDANT WARM FRONT INITIALLY FROM SERN CO THROUGH
NRN/CNTRL OK AND NRN AR WILL LIFT NWD...REACHING THE KS/NEB BORDER
MONDAY NIGHT. MEANWHILE...DRYLINE WILL BECOME INCREASINGLY DEFINED
MONDAY OVER THE CNTRL/ERN TX/OK PNHDLS INTO SWRN KS. FARTHER TO THE
NE...COLD FRONT WILL RAPIDLY PUSH EWD THROUGH THE GREAT LAKES AND OH
VALLEY...EVENTUALLY REACHING THE NEW ENGLAND AND MID ATLANTIC COAST
TUESDAY MORNING.

..CNTRL/SRN PLAINS...

LATEST SHORT TERM MODEL GUIDANCE CONTINUES TO INDICATE THE POTENTIAL
FOR AN ACTIVE SEVERE WEATHER EPISODE ACROSS THE REGION MONDAY
AFTERNOON AND MONDAY NIGHT. HOWEVER...CONSIDERABLE UNCERTAINTY
EXISTS IN CONVECTIVE EVOLUTION WITHIN EXPANDING WARM SECTOR. GIVEN
THIS UNCERTAINTY /AS REFLECTED IN A BROADER AREA OF LOWER SEVERE
PROBABILITIES/...A CATEGORICAL SLIGHT RISK WILL BE MAINTAINED.

22/00Z OBSERVED SOUNDINGS FROM CRP/BRO INDICATE THAT THE QUALITY OF
BOUNDARY LAYER MOISTURE /MEAN MIXING RATIOS OF 12.5-13 G PER KG/ IS
GRADUALLY INCREASING ACROSS S TX...WITH THIS TYPE OF MOISTURE
PROFILE DEVELOPING NWD THROUGH TX AND OK INTO SRN KS DURING THE DAY
TWO PERIOD. THIS INCREASING MOISTURE BENEATH STEEP MID-LEVEL LAPSE
RATES ARE EXPECTED TO CONTRIBUTE TO THE DEVELOPMENT OF A MODERATELY
UNSTABLE AIR MASS WITH MLCAPES INCREASING TO 1000-2500 J/KG WITHIN
PRIMARY INSTABILITY AXIS.

AS MENTIONED ABOVE...CONSIDERABLE UNCERTAINTY EXISTS WITH REGARD TO
CONVECTIVE INITIATION MONDAY AFTERNOON AND EVENING WITHIN THIS AXIS
OF STRONGEST INSTABILITY. THE OPERATIONAL NAM/WRF REMAINS
CONSISTENT IN SUGGESTING THAT A WEAK LOW-LATITUDE SHORT WAVE TROUGH
WILL TRANSLATE FROM SWRN TX INTO OK...INITIATING TSTMS BY AFTERNOON
FROM THE VICINITY OF THE DRYLINE FROM W-CNTRL TX INTO THE ERN TX
PNHDL EWD INTO NWRN TX/CNTRL OK AND S-CNTRL KS. THE LATEST GFS ALSO
INITIATES A BAND OF DEEP CONVECTION A DISTANCE E OF THE DRYLINE FROM
NWRN TX THROUGH WRN/CNTRL OK INTO S-CNTRL KS. FINALLY...INDIVIDUAL
SREF MEMBERS INDICATE A WIDE ARRAY OF SOLUTIONS.

DESPITE THE UNCERTAINTY IN LOCATION OF STORM DEVELOPMENT...FORECAST
SOUNDINGS INDICATE THAT THE AMBIENT ENVIRONMENT WILL BE QUITE
FAVORABLE FOR SUPERCELLS CAPABLE OF TORNADOES AND LARGE HAIL /SOME
SIGNIFICANT/ OVER A FAIRLY LARGE AREA MONDAY AFTERNOON INTO NIGHT.
ADDITIONAL STORMS WILL BECOME INCREASINGLY LIKELY MONDAY NIGHT ALONG
RETREATING WARM FRONT FROM NERN CO ACROSS NRN KS INTO SRN NEB AS
ISENTROPIC ASCENT AND WAA ARE ENHANCED ALONG NOSE OF STRENGTHENING
LLJ. WHILE THE MAJORITY OF THIS ACTIVITY WILL LIKELY BE SLIGHTLY
ELEVATED WITH THE MAIN THREAT BEING LARGE HAIL...POTENTIAL WILL
EXIST FOR ISOLATED TORNADOES WITH ANY STORMS REMAINING SURFACE BASED
INVOF WARM FRONT.

..LOWER GREAT LAKES INTO OH VALLEY...

A MOIST AND WEAKLY UNSTABLE AIR MASS IS EXPECTED TO PERSIST AHEAD OF
COLD FRONT MONDAY WITH MLCAPES INCREASING TO 300-700 J/KG.
CONVERGENCE ALONG THIS BOUNDARY COUPLED WITH FORCING FOR ASCENT
ASSOCIATED WITH WEAKENING UPPER TROUGH SHOULD SUPPORT AN INCREASE IN
TSTM DEVELOPMENT BY AFTERNOON FROM ERN LOWER MI SWWD INTO SRN IND.
STORMS WILL MOVE/DEVELOP EWD THROUGH MUCH OF OH INTO WRN PARTS OF
NY/PA MONDAY EVENING.

WHILE LAPSE RATES AND RESULTANT INSTABILITY WILL NOT BE PARTICULARLY
STRONG...THE MODEST VERTICAL SHEAR WILL BE SUPPORTIVE OF A FEW
ORGANIZED STORMS CAPABLE OF LOCALLY DAMAGING WINDS AND PERHAPS A
TORNADO. SHOULD LATER MODEL RUNS INDICATE A MORE UNSTABLE
PRE-FRONTAL AIR MASS...PORTIONS OF DISCUSSION AREA MAY NEED TO BE
UPGRADED TO A SLIGHT RISK.

.MEAD.. 04/22/2007

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WATCHES: Severe Thunderstorm Watch - Number 158

WWUS20 KWNS 220503
SEL8
SPC WW 220503
MNZ000-NDZ000-220500-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH - NUMBER 158
NWS STORM PREDICTION CENTER NORMAN OK
1203 AM CDT SUN APR 22 2007

THE NWS STORM PREDICTION CENTER HAS CANCELLED
SEVERE THUNDERSTORM WATCH NUMBER 158 ISSUED AT 515 PM CDT FOR PORTIONS OF

MINNESOTA
NORTH DAKOTA

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WATCHES: Tornado Watch - Number 157

WWUS20 KWNS 220503
SEL7
SPC WW 220503
OKZ000-TXZ000-220500-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH - NUMBER 157
NWS STORM PREDICTION CENTER NORMAN OK
1203 AM CDT SUN APR 22 2007

THE NWS STORM PREDICTION CENTER HAS CANCELLED
TORNADO WATCH NUMBER 157 ISSUED AT 345 PM CDT FOR PORTIONS OF

OKLAHOMA
TEXAS

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MESO: Mesoscale Discussion 0535

ACUS11 KWNS 220426
SWOMCD
SPC MCD 220426
MNZ000-220630-

MESOSCALE DISCUSSION 0535
NWS STORM PREDICTION CENTER NORMAN OK
1126 PM CDT SAT APR 21 2007

AREAS AFFECTED...SERN ND...W CENTRAL AND CENTRAL MN INTO NERN MN

CONCERNING...SEVERE THUNDERSTORM WATCH 158...159...

VALID 220426Z - 220630Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
158...159...CONTINUES.

SCATTERED STRONG THUNDERSTORMS CONTINUE ALONG A BOUNDARY ASSOCIATED
WITH LARGE MCS OVER SD INTO MN. ANALYSIS OF THE 03Z RUN OF THE RUC
INDICATES THAT THIS ACTIVITY IS LOCATED IN FAVORABLE ENTRANCE REGION
OF UPR LVL JET STREAK THAT EXTENDS FROM ERN ND NEWD INTO CENTRAL
ONTARIO. THIS COMBINED WITH LOW LEVEL JET/ASSOCIATED WARM ADVECTION
FROM ERN KS INTO NWRN WI IS ENHANCING UPWARD ASCENT ACROSS THE
REGION. MOISTENING OF THE AIR MASS CONTINUE TO LOWER POTENTIAL
INSTABILITY AS MLCAPES ARE NOW DOWN TO AROUND 1000 J/KG. RUC MODEL
SOUNDINGS SHOW THAT MID LEVEL LAPSE RATES ARE AROUND 8C/KM
SUPPORTING HAIL AND DAMAGING WINDS FOR THE NEXT SEVERAL HOURS.

AREA NE OF WW158 AND 159 WILL HAVE TO BE MONITORED FOR AN ADDITIONAL
WW DUE TO THE POSSIBILITY OF ELEVATED CONVECTION WITH HAIL.

.MCCARTHY.. 04/22/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DLH...MPX...FGF...

47429474 47479448 47549401 47589328 47829250 47709186
47349199 46819284 46089313 45829378 46179435

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WATCHES: Severe Thunderstorm Watch Number 161

WWUS20 KWNS 220402
SEL1
SPC WW 220402
OKZ000-TXZ000-220800-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 161
NWS STORM PREDICTION CENTER NORMAN OK
1100 PM CDT SAT APR 21 2007

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

WESTERN OKLAHOMA
A SMALL PART OF NORTHWEST TEXAS

EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 1100 PM
UNTIL 300 AM CDT.

HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 40
STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES WEST
NORTHWEST OF ALVA OKLAHOMA TO 45 MILES SOUTHEAST OF CHILDRESS
TEXAS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED
WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 157...WW 158...WW
159...WW 160...

DISCUSSION...LINE OF INTENSE STORMS CONTINUES TO SHIFT QUICKLY EWD
TOWARDS WRN OK/NWRN TX LATE THIS EVENING. NARROW MUCAPE AXIS AND
INCREASING CINH INTO WRN OK SUGGESTS THIS BROKEN LINE OF STORMS MAY
WEAKEN OVER WRN OK OVERNIGHT. HOWEVER...ACTIVITY REMAINS QUITE
ORGANIZED ATTM AND LOW-DEEP LAYER SHEAR IS QUITE STRONG.
THEREFORE...ISOLATED DAMAGING WINDS AND LARGE HAIL MAY ACCOMPANY
THIS ACTIVITY FOR A FEW MORE HOURS BEFORE STORMS DIMINISH TONIGHT.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 26035.


..EVANS

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