SPC AC 221630
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1030 AM CST SAT DEC 22 2007
VALID 221630Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER A SMALL PART OF THE LWR
MS/LWR OH VLYS...
...SYNOPSIS...
STRONG /80+ KT FLOW AT 500 MB/ SRN HI PLNS TROUGH EXPECTED TO
ACCELERATE ENE AND...LATER...NE INTO THE LWR OH VLY THIS PERIOD AS
SYSTEM PARTLY PHASES WITH NRN STREAM UPR LOW DROPPING SE ACROSS THE
DAKOTAS. SFC LOW NOW NEAR MLC SHOULD CONTINUE NE TO NEAR VIH THIS
EVENING...BEFORE DEEPENING MARKEDLY AS IT ARCS N/NE TO NEAR MKE BY
12Z SUNDAY. TRAILING COLD FRONT EXPECTED TO STRENGTHEN AS IT SURGES
SE ACROSS THE LWR MS VLY THIS EVENING...AND E/NE INTO THE LWR OH VLY
EARLY SUNDAY.
...LWR MS INTO MID MS/LWR OH VLYS...
WINDS AT ALL LEVELS WILL RESPOND TO OVERALL STRENGTHENING OF PHASING
UPR SYSTEMS TODAY/TONIGHT...WITH 100+ KT 500MB JET STREAK EXPECTED
TO EXTEND FROM THE ARLATEX NE INTO PARTS OF IL/IND AND OH BY EARLY
SUNDAY. COUPLED WITH A 50-60KT SSWLY LLJ...THIS WILL YIELD A
KINEMATIC ENVIRONMENT VERY FAVORABLE FOR SVR STORMS BY LATE THIS
AFTN/EVENING FROM ERN AR AND WRN/NRN MS INTO WRN TN/SE MO/ERN AR.
HOWEVER ...SATELLITE AND SFC OBS CONTINUE TO SHOW THAT LOW LVL
MOISTURE RETURN WILL BE SCANT. WHILE SFC DEWPOINTS SHOULD REACH THE
UPR 50S/LOW 60S NWD INTO PARTS OF LA/AR AND MS...PRESSURE PATTERN
WILL CONTINUE TO ENCOURAGE ADVECTION OF SHALLOW/COOL WEDGE AIR MASS
NOW OVER AL/GA WWD INTO MS AND THE NERN GULF.
BY LATE IN THE DAY A NARROW TONGUE OF MODIFIED GULF AIR SHOULD EXIST
AS FAR N AS SE AR/WRN MS. WHILE CONTINUING PRESENCE OF WARM AIR IN
THE 850-700 MB LAYER WILL LIMIT INSTABILITY...MODEST HEATING SHOULD
BOOST MLCAPE TO AOA 250 J/KG. COMBINATION OF EVEN WEAK INSTABILITY
WITH FRONTAL UPLIFT AND THE POTENT WIND PROFILES WILL POSE SOME
CONCERN FOR DAMAGING WIND/BRIEF TORNADO THREAT AS A LINE OF NEAR
SFC-BASED CONVECTION/ STORMS LIKELY FORMS FROM SE MO SWD ACROSS ERN
AR INTO NERN LA LATE THIS AFTERNOON. BUT GIVEN VERY WEAK
INSTABILITY/LOW LVL LAPSE RATES ...THE THREAT OF AN ORGANIZED SVR
WIND EVENT SEEMS LOW.
FARTHER N...POTENTIAL WILL EXIST FOR CONTINUED REDEVELOPMENT OF A
LOW-TOPPED...RAPIDLY-MOVING LINE OF CONVECTION/STORMS NE INTO PARTS
OF THE MID MS AND LWR OH VLYS THIS EVENING INTO EARLY SUNDAY AS
FRONTAL CIRCULATION INTENSIFIES CLOSER TO DEEPENING SFC LOW.
RELATIVELY MILD LOW LVL AIR IN PLACE /ENHANCED BY DOWNSLOPE FLOW OFF
THE CNTRL APLCNS/ MAY BOOST CONVECTIVE POTENTIAL IN REGION OF
STRENGTHENING STRONG GRADIENT WINDS. THIS ACTIVITY MAY POSE A
CONTINUED THREAT FOR AT ISOLATED DAMAGING WIND INTO THE NIGHT.
..CORFIDI.. 12/22/2007
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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