SWODY1
SPC AC 171631
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1131 AM CDT WED JUN 17 2009
VALID 171630Z - 181200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS MUCH OF NEB...SWRN
IA...NWRN MO AND FAR NRN KS...
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL PLAINS EWD
INTO THE OH/TN VALLEYS AND SEWD INTO THE SERN STATES...
AN ACTIVE CONVECTIVE DAY IS ANTICIPATED THIS AFTERNOON AND EVENING
FROM THE CENTRAL PLAINS AND MID/UPPER MS VALLEY REGION SEWD THROUGH
THE TN/OH VALLEYS AND INTO THE SERN STATES.
...NEB/NRN KS/IA/MO...
WITH UPPER TROUGH IN THE WEST AND RIDGE IN THE SOUTH CENTRAL
STATES...A BAND OF STRONGER MID LEVEL WINDS...35 TO 50 KT...EXTENDED
ACROSS THE REGION. WEAK SURFACE LOW WAS LOCATED WEST OF DDC THIS
MORNING...WITH A WEAK BOUNDARY EXTENDING NEWD FROM THIS SYSTEM INTO
FAR SERN NEB AND THEN ESEWD ACROSS NRN MO. AS THIS SURFACE LOW
SHIFTS SLOWLY NWD THIS AFTERNOON...A HOT AND VERY MOIST AIR MASS
WILL GRADUALLY SPREAD NWD. MORNING ANALYSIS ALREADY INDICATES
MLCAPES NEAR 3000 J/KG AND WITH ADDITIONAL WARMING...SHOULD BE AOA
4000 J/KG ALONG AND SOUTH OF THE BOUNDARY.
ELEVATED THUNDERSTORMS WERE OCCURRING THIS MORNING IN NEB...WITHIN
AREA OF LOW LEVEL WARM ADVECTION. IN TIME...THESE STORMS ARE
EXPECTED TO BECOME SURFACE BASED...WITH MORE STORMS LIKELY TO
DEVELOP IN EXTREME NERN CO/WRN NEB AS LARGE SCALE LIFTING SHIFTS IN
FROM THE WEST. ONCE SURFACE BASED STORMS DEVELOP...THE COMBINATION
OF EXTREME INSTABILITY AND EFFECTIVE SHEAR AT 40-50 KT WILL LIKELY
RESULT IN INTENSE SUPERCELLS WITH VERY LARGE HAIL. ALSO...SURFACE
LOW OVER WRN KS SHOULD BACK LOW LEVEL WINDS AND STRONGLY VEERING
WINDS IN THE BOUNDARY LAYER WILL BE FAVORABLE FOR A FEW TORNADOES.
BY EARLY EVENING...THESE STORMS ARE LIKELY TO CONSOLIDATE INTO A
LINEAR SYSTEM/EMBEDDED BOWS ACROSS ERN NEB/FAR NRN KS...AS LOW LEVEL
JET STRENGTHENS. A FAST-MOVING MCS WITH WIDESPREAD WIND DAMAGE IS
POSSIBLE OVERNIGHT INTO IA/NRN MO.
...SRN MN/NORTHERN IA...
WV IMAGERY INDICATES A REMNANT UPPER LOW WAS LOCATED OVER WRN MN AND
WAS MOVING SLOWLY NEWD. AT THE SURFACE A WEAK FRONT/TROUGH STRETCHED
FROM NRN IA NWWD ALONG THE ND/MN BORDER. ALTHOUGH INSTABILITY WILL
NOT BE PARTICULARLY STRONG...MLCAPES AOB 1000 J/KG...STRONGLY
VEERING AND STRENGTHENING WINDS WITH HEIGHT WILL RESULT IN
CONSIDERABLE VERTICAL SHEAR FOR SUPERCELLS. AMBIENT LOW LEVEL
VORTICITY AND STEEP LAPSE RATES WILL SUPPORT ISOLATED
TORNADOES...ALONG WITH HAIL AND DAMAGING WINDS. THE STORMS SHOULD
WEAKEN SHORTLY AFTER SUNSET WITH LOSS OF DAYTIME HEATING.
...SERN OH/SWRN PA/WV...
AT LATE MORNING...A WEAK SURFACE LOW WAS LOCATED IN NRN OH...WITH A
WARM FRONT EXTENDING SEWD ACROSS ERN OH/WV. A WEAK COLD FRONT
STRETCHED FROM THE SURFACE LOW WWD ACROSS NRN IN/IL WITH A LARGE
WARM SECTOR SOUTH AND WEST OF THE PREVIOUSLY MENTIONED FRONT. STORMS
ARE MOST LIKELY ALONG AND EAST OF THE FRONT WHERE LOW LEVEL FORCING
WILL BE THE GREATEST...THOUGH EXTENSIVE CLOUDS AND COOL SURFACE
TEMPERATURES SHOULD TEMPER THE THREAT EAST OF THE WARM FRONT. STORM
INITIATION AND EVOLUTION IN THE WARM SECTOR IS MORE UNCERTAIN AS DUE
TO CONSIDERABLE CLOUDS AND WHAT APPEARS TO BE WEAK CONVERGENCE.
HOWEVER...IF STORMS DO DEVELOP NEAR THE FRONT...
SUFFICIENT SHEAR AND INSTABILITY WILL EXIST FOR A FEW SUPERCELLS
WITH A TORNADO OR TWO POSSIBLE.
...TN/KY SEWD INTO THE SERN STATES...
NORTHWEST MID LEVEL WINDS AT 30-40 KT SHOULD PERSIST ACROSS THE
REGION THROUGH THE PERIOD. AT THE SURFACE...A BACK DOOR
QUASI-STATIONARY FRONT STRETCHED FROM NEAR THE SC/GA BORDER NWWD
INTO THE SRN APPALACHIANS. ELEVATED CONVECTION HAS BEEN OCCURRING
OVER TN/KY...BUT HAVE SO FAR THE ACTIVITY HAS BEEN WEAK. WITH
HEATING THE TN STORMS ARE EXPECTED TO INTENSIFY AND OTHER STORMS ARE
LIKELY TO DEVELOP/INTENSIFY IN AREA WHERE STRONG DIFFERENTIAL
HEATING OCCURS. MODERATE INSTABILITY AND 30-40 KT DEEP LAYER SHEAR
WILL SUPPORT A DAMAGING WIND/HAIL THREAT INTO THE EVENING HOURS.
...ERN NM/WRN TX/SWRN KS...
TEMPERATURES NEAR 100 DEGREES ARE EXPECTED LATE THIS AFTERNOON
OVER PORTIONS OF WRN TX/FAR ERN NM. VISIBLE AND WV IMAGERY SHOWS
MID/HIGH LEVEL MOISTURE STREAMING NWD FROM MEXICO INTO THIS
REGION...WITH A POSSIBLE MCV ABOUT 30 SE CNM. STRONG HEATING
COMBINED WITH WEAK DRYLINE CONVERGENCE AND LIFT ASSOCIATED WITH MCV
SHOULD AID IN HIGH BASED STORMS THIS AFTERNOON. LARGE
TEMPERATURE/DEWPOINT SPREADS WOULD FAVOR STRONG WIND GUSTS WITH THE
HEAVIER RAIN CORES.
..IMY/HURLBUT.. 06/17/2009
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment