SWODY1
SPC AC 221955
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0255 PM CDT THU JUL 22 2010
VALID 222000Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER MS VALLEY EWD
INTO NEB...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS A SMALL PART OF SERN
ND/NERN SD AND SWRN MN...
...ND/SD/MN...
WEAK SURFACE LOW AND TROUGH WAS LOCATED ACROSS FAR ERN SD/ND AT MID
AFTERNOON. MOSTLY CLOUDY SKIES HAVE COVERED MUCH OF THE REGION AND
HAS LIMITED DESTABILIZATION. ALTHOUGH ELEVATED STORMS HAD DEVELOPED
ACROSS PARTS OF FAR ERN ND AND NWRN MN...IT IS UNCERTAIN IF SURFACE
BASED STORMS WILL DEVELOP GIVEN WEAKENING SURFACE CONVERGENCE AND
UPPER FORCING SHIFTING NEWD INTO SRN CANADA. HOWEVER...GIVEN THAT
TEMPERATURES MAY WARM A FEW DEGREES MORE IN FAR SERN ND/NERN SD AND
SWRN MN...A SMALL SLIGHT RISK AREA HAS BEEN MAINTAINED FOR THIS
AREA.
...NRN ID AND WRN MT...
UPPER LOW OVER BRITISH COLUMBIA IS FORECAST TO MOVE SEWD INTO SRN
ALBERTA BY LATE TONIGHT. THIS WILL RESULT IN A 50-60 KT MID LEVEL
JET MAX TO SPREAD ESEWD FROM WA INTO SRN MT. ALTHOUGH INSTABILITY IS
NOT FORECAST TO BE PARTICULARLY STRONG...THE COMBINATION OF FORCING
ASSOCIATED WITH UPPER LOW/SPEED MAX AND STEEPENING LAPSE RATES
SHOULD RESULT IN FAVORABLE VERTICAL SOUNDINGS FOR THUNDERSTORMS TO
DEVELOP. STRENGTHENING WIND FIELDS WILL PROVIDE SUFFICIENT DEEP
LAYER SHEAR FOR SUPERCELLS...WITH A THREAT FOR ISOLATED HAIL AND
GUSTY WINDS.
...UPPER MS VALLEY EWD INTO NEB...
FORECAST LOOKS ON TRACK...REFERENCE MD/S 1415 AND 1416.
...SOUTH FL...
NO CHANGES FROM PREVIOUS OUTLOOK.
..IMY.. 07/22/2010
.PREV DISCUSSION... /ISSUED 1058 AM CDT THU JUL 22 2010/
...UPPER MS VALLEY INTO NEB...
RELATIVELY FAST ZONAL FLOW IS PRESENT ONCE AGAIN TODAY OVER THE
NORTHERN TIER OF STATES...WHILE A FLAT RIDGE EXTENDS FROM THE
SOUTHEAST INTO THE DESERT SOUTHWEST. A LARGE REMNANT MCS IS
TRACKING EASTWARD ACROSS MN/WI. THIS SYSTEM HAS SIGNIFICANTLY
MODIFIED THE NEARBY ENVIRONMENT WITH STRONG SOUTHWESTERLY LOW LEVEL
FLOW BEING OBSERVED ON THE SOUTHWEST FLANK ACROSS IA. THE TRAILING
CONVERGENCE ZONE ASSOCIATED WITH THE MCS WILL LIKELY PERSIST FROM
SOUTHERN WI INTO CENTRAL IA...AND SHOULD PROVIDE THE FOCUS FOR
REDEVELOPMENT OF THUNDERSTORMS LATER THIS AFTERNOON. MORNING CLOUDS
ARE RAPIDLY ERODING...SUGGESTING SUBSTANTIAL DESTABILIZATION MAY
OCCUR. FORECAST SOUNDINGS SHOW MLCAPE VALUES OF 1500-2500 J/KG AND
SUFFICIENT EFFECTIVE SHEAR FOR ORGANIZATION AND A FEW SUPERCELLS.
GIVEN THE LOCALLY ENHANCED LOW LEVEL WINDS AND SHEAR DUE TO THE
MCS...THERE IS A THREAT OF ISOLATED TORNADOES IN PARTS OF SOUTHERN
WI/NORTHERN IA/NORTHERN IL LATER THIS AFTERNOON. OTHERWISE...
DAMAGING WINDS AND HAIL ARE THE MAIN THREATS.
FARTHER SOUTHWEST...SURFACE BOUNDARY WILL EXTEND FROM WESTERN IA
INTO SOUTHWEST NEB AND NORTHWEST KS. VERTICAL SHEAR WEAKENS WITH
SOUTHWARD EXTENT...BUT STRONG CAPE VALUES MAY BE SUFFICIENT FOR
ISOLATED SEVERE STORMS CAPABLE OF HAIL AND DAMAGING WINDS.
...ND/SD/MN...
WATER VAPOR LOOPS SHOW A WELL-DEFINED SHORTWAVE TROUGH MOVING ACROSS
MT/ND. THIS FEATURE WILL TRACK EASTWARD AND HELP TO INITIATE
SCATTERED AFTERNOON THUNDERSTORMS OVER EASTERN ND/SD AND WESTERN MN.
PERSISTENT LOW CLOUDS WILL SLOW DAYTIME HEATING AND
DESTABILIZATION. HOWEVER...SUFFICIENT CAPE IS EXPECTED FOR A FEW
STRONG/SEVERE STORMS BY LATE AFTERNOON AND EVENING CAPABLE OF
DAMAGING WINDS AND HAIL.
...SOUTH FL...
TD 3 IS EXPECTED TO BEGIN TO APPROACH SOUTH FL AND THE KEYS LATE
TONIGHT. STRONGER LOW LEVEL SHEAR NEAR OUTER BANDS COULD POSE A
LIMITED THREAT FOR BRIEF TORNADOES AFTER 06Z.
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