SPC AC 091257
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0757 AM CDT MON MAR 09 2009
VALID 091300Z - 101200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM WRN AND NW TX NNE INTO
PARTS OF OK...KS...AND MO...
...SYNOPSIS...
WEAK SPLIT FLOW WILL PREVAIL ACROSS THE WRN AND CNTRL U.S. AS NRN
STREAM TROUGH CONTINUES TO AMPLIFY SSE INTO THE GRT BASIN/CNTRL
RCKYS...AND SRN BRANCH JET PERSISTS IN AN ANTICYCLONIC ARC FROM
AZ/NM THROUGH THE CNTRL PLNS TO THE UPR GRT LKS. A SERIES OF WEAK
SRN STREAM DISTURBANCES WILL MOVE NEWD FROM THE SRN RCKYS TO THE
CNTRL PLNS IN THE FAST SW FLOW.
AT THE SFC...LEE CYCLONE SHOULD REMAIN NEARLY STNRY OVER SE CO
THROUGH THE PERIOD AS WARM FRONT NOW ALONG THE RED RVR MOVES N
ACROSS OK AND MOST OF AR LATER TODAY...AND ACCELERATES NE INTO THE
MID MS VLY TONIGHT/EARLY TUE. S TO SSELY SFC FLOW SHOULD ALLOW LOW
LVL MOISTURE /WITH PWS AOA 1.25 INCHES/ NOW OVER CNTRL/E TX TO
OVERSPREAD MUCH OF OK AND S CNTRL/ERN KS BY EVE. AT THE SAME TIME
...SFC DRYLINE SHOULD MIX E INTO NW TX/WRN OK AND SW KS...WHILE
ARCTIC FRONT ASSOCIATED WITH NRN STREAM JET CONTINUES SE ACROSS THE
CNTRL PLNS/LWR MO VLY.
LARGELY IN RESPONSE TO CONTINUED NE MOVEMENT OF SRN STREAM IMPULSE
NOW IN AZ...EXPECT A WEAK SFC WAVE WILL FORM TONIGHT ALONG
STRENGTHENING FRONTAL ZONE IN SRN KS. THIS WAVE SHOULD MOVE NE TO
NEAR MKC BY 12Z TUE.
...PARTS OF TX/OK AND SE KS INTO THE MID MS VLY...
SUSTAINED MOISTURE INFLOW SHOULD LEAD TO A GRADUAL INCREASE IN
ELEVATED CONVECTION TODAY OVER PARTS OF TX AND OK...WITH THE
CONVECTION GRADUALLY BECOMING INCREASINGLY SFC-BASED. MID LVL LAPSE
RATES ALONG AND S OF SRN BRANCH JET WILL...HOWEVER...REMAIN
WEAK...AND THICKENING MID/UPR CLOUDS WILL LIMIT DIURNAL
DESTABILIZATION. NEVERTHELESS...BY LATE AFTN MUCAPE OF AT LEAST 500
J/KG SHOULD EXIST ALONG WRN FRINGE OF LOW LVL MOIST AXIS FROM W
CNTRL TX NNE INTO NW OK/S CNTRL KS. THIS MAY SUPPORT DEVELOPMENT OF
A FEW SFC-BASED STORMS BY LATE AFTN ALONG DRY LINE IN OK AND PERHAPS
TX...WITH MORE CONCENTRATED ACTIVITY INVOF DRY LINE/WARM FRONT
INTERSECTION FROM NW/N CNTRL OK INTO S CNTRL/SE KS.
WEAK INSTABILITY WILL BE A LIMITING FACTOR. BUT THE WIND FIELD WILL
BE FAVORABLE FOR SUSTAINED SUPERCELLS...WITH 35-40 KT SSWLY LLJ
VEERING/INCREASING TO 70-80 KT WSW FLOW AT 500 MB. GIVEN ABSENCE OF
STRONG FORCING AT EITHER UPR OR LWR LVLS...AND WEAK CAP...SETUP
COULD YIELD A FEW LONGER-LIVED DISCRETE/SEMI-DISCRETE STORMS. THESE
WILL POSE A THREAT FOR TORNADOES...IN ADDITION TO HAIL AND LOCALLY
DMGG WIND. THE GREATEST TORNADO THREAT SHOULD OCCUR LATE THIS AFTN
AND EARLY THIS EVE FROM CNTRL/NW OK NNE INTO S CNTRL/SE KS. THE
TORNADO THREAT COULD PERSIST INTO LATER TONIGHT NEWD ALONG WARM
FRONT INTO WRN MO. A MORE ISOLD TORNADO THREAT WILL EXIST WITH ANY
SUSTAINED DRYLINE STORMS OVER WRN OK AND WRN N TX.
LATER TONIGHT AND EARLY TUE THE STORMS SHOULD EVOLVE INTO A
LOOSELY-ORGANIZED CLUSTER INVOF WARM FRONT/SFC WAVE OVER MO.
INCREASING UVV AND CONTINUING PRESENCE OF STRONG WIND FIELD SUGGEST
THAT THIS ACTIVITY COULD YIELD DMGG WIND...IN ADDITION TO A
CONTINUING THREAT FOR HAIL AND ISOLD TORNADOES...PERHAPS AS FAR E AS
IL. ELEVATED STORMS WITH HAIL ALSO MAY OCCUR N OF WARM FRONT FROM
NRN MO EWD INTO NRN IL/IND.
FARTHER S...AN AREA OF STORMS ALSO MAY PERSIST AND/OR REDEVELOP NEAR
THE DRYLINE OVER W TX THROUGH THE EVE AND OVERNIGHT AS WEAK SRN
STREAM DISTURBANCES CONTINUE MOVING NE ACROSS REGION. THESE TOO
COULD POSE A RISK FOR SVR HAIL AND WIND.
..CORFIDI/HURLBUT.. 03/09/2009
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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