SWODY2
SPC AC 111723
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1223 PM CDT SUN MAR 11 2012
VALID 121200Z - 131200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM NERN IL INTO MUCH OF LOWER
MI...
...SYNOPSIS...
A POTENT UPPER LOW WILL MOVE FROM IA/MN NEWD TOWARD LAKE SUPERIOR BY
00Z WITH A 70+ KT MIDLEVEL SPEED MAX AND SUBSTANTIAL HEIGHT FALLS
SPREADING INTO LOWER MI. AT THE SURFACE...A BROAD LOW PRESSURE
TROUGH WILL EXTEND FROM WRN WI INTO NRN IL BY AFTERNOON...PUSHING
INTO LOWER MI THROUGH EARLY EVENING. THIS TROUGH WILL SERVE AS A
FOCUS FOR SEVERE STORM DEVELOPMENT.
TO THE S...A TRAILING FRONT WILL STALL FROM ERN MO INTO AR AND NRN
TX. E OF THIS FRONT OVER THE WARM SECTOR...SLY LOW LEVEL FLOW WILL
HELP BRING MID TO UPPER 50S F DEWPOINTS AS FAR N AS CHICAGO...WITH
LOWER 60S F INTO THE LOWER OH VALLEY.
...NERN IL/SERN WI INTO LOWER MI...
WIDESPREAD MORNING RAIN WILL LIKELY EXIST FROM LOWER MI INTO
IND...OH...AND ERN KY/TN ASSOCIATED WITH LOW LEVEL WARM ADVECTION.
THIS ACTIVITY SHOULD LIFT RAPIDLY NEWD AS THE DRY SLOT SPREADS OVER
MUCH OF IL AND IND BY MIDDAY. WITH COOL TEMPERATURES ALOFT AND
DAYTIME HEATING...LAPSE RATE PROFILES WILL BE RELATIVELY STEEP...AND
LITTLE CONVECTIVE INHIBITION SHOULD EXIST BY AFTERNOON.
THERE ARE MODEL DIFFERENCES THAT LEND A DEGREE OF UNCERTAINTY TO
THIS SEVERE SCENARIO. FOR EXAMPLE...THE GFS MODEL SUGGESTS MUCH LESS
INSTABILITY...AND FASTER VEERING OF THE LOW LEVEL FLOW...RESULTING
IN VERY LITTLE SEVERE THREAT OVER IL...AND PERHAPS ONLY ISOLATED
INTO LOWER MI. HOWEVER...THE NAM/NAMKF SOLUTIONS INDICATE A
SUBSTANTIAL THREAT OF SUPERCELLS...INCLUDING LARGE HAIL AND
TORNADOES.
GIVEN STRONG FORCING WITH THE UPPER SYSTEM...AT LEAST ISOLATED
SEVERE THUNDERSTORMS APPEAR LIKELY...ALONG AND JUST AHEAD OF THE
DEVELOPING SYNOPTIC COLD FRONT. TIMING OF SEVERE WEATHER WOULD BEGIN
NEAR 21Z SRN WI/NRN IL...AND WOULD CONTINUE THROUGH ABOUT 03Z INTO
LOWER MI.
...KY AND TN INTO NRN MS AND AL...
MORNING SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED TO BE ONGOING
EARLY MON ACROSS TN/MS/AL. THIS ACTIVITY SHOULD NOT BE SEVERE. LATER
IN THE DAY...COVERAGE OF ANY NEW DEVELOPMENT IS UNCERTAIN AHEAD OF
THE STALLING FRONT. WHILE LOW LEVEL MOISTURE WILL BE IN PLACE AND
HEATING WILL OCCUR...RATHER DRY MIDLEVEL AIR WILL EXIST...WITH SOME
CAP NEAR THE 700 MB LAYER...ALTHOUGH WEAK. THE VERY WEAK CONVERGENCE
COUPLED WITH DRY AIR ALOFT MAY HAMPER DEVELOPMENT...BUT AT LEAST A
FEW STORMS ARE EXPECTED TO DEVELOP AND MAINTAIN THEMSELVES FOR A
WHILE DURING THE PEAK HEATING HOURS. THERE WILL BE A HIGH
CONDITIONAL PROBABILITY OF HAIL FROM WRN KY/TN INTO MS AND AL.
..JEWELL.. 03/11/2012
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