SPC AC 131255
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0755 AM CDT THU MAY 13 2010
VALID 131300Z - 141200Z
...THERE IS A SLGT RISK OF SVR TSTMS TODAY THROUGH EARLY TONIGHT FOR
THE MID MS VALLEY AND OH VALLEY REGIONS...
...THERE IS A SLGT RISK OF SVR TSTMS ...
...MS/OH VALLEY REGION TODAY INTO EARLY TONIGHT...
A CLOSED LOW OVER THE DAKOTAS...WITH AN EMBEDDED SHORTWAVE
TROUGH/JET STREAK FARTHER S OVER KS/NEB...WILL PROGRESS ENEWD OVER
THE UPPER MS VALLEY TO THE UPPER GREAT LAKES BY EARLY FRIDAY. AN
ASSOCIATED SURFACE LOW INVOF SE IA/NW IL WILL DEVELOP NNEWD TOWARD
LAKE SUPERIOR...WHILE A TRAILING COLD FRONT MOVES ESEWD ACROSS
MO/IL/INDIANA. IN ADVANCE OF THE LOW...A WARM FRONT WILL ALSO MOVE
NEWD ACROSS INDIANA/OH/SRN LOWER MI TODAY.
ONGOING CONVECTION EXTENDS FROM LOWER MI SWWD ACROSS NRN IL TO
CENTRAL/SW MO AND NW AR/ERN OK. THE CONVECTION HAS BEEN FOCUSED
ALONG PRE-FRONTAL OUTFLOW BOUNDARIES FROM OVERNIGHT CONVECTION. ONE
BOWING SEGMENT WITH AN ORGANIZED MESOHIGH IS MOVING NEWD INTO SW MO
AND MAY PERSIST FOR A FEW HOURS...AND A NEWER BOWING SEGMENT HAS
DEVELOPED ALONG THE BOUNDARY CENTRAL IL. DAMAGING WINDS WILL
CONTINUE TO BE A THREAT WITH THESE CONVECTIVE SYSTEMS THIS MORNING
AS WEAK-MODERATE INSTABILITY IS MAINTAINED IN THE WARM SECTOR.
AS THE WARM FRONT MOVES NWD/NEWD TODAY...A WARM SECTOR CONSISTING OF
SURFACE TEMPERATURES IN THE 70S TO NEAR 80 F AND DEWPOINTS IN THE
MID-UPPER 60S WILL SPREAD NEWD ACROSS NRN IL/INDIANA/OH AND SRN
LOWER MI. MIDLEVEL LAPSE RATES WILL NOT BE AS STEEP AS PREVIOUS
DAYS FARTHER TO THE SW...BUT AFTERNOON MLCAPE VALUES COULD STILL
REACH 1500-2000 J/KG. VERTICAL SHEAR WILL REMAIN RATHER STRONG
INVOF THE WARM FRONT WITH LARGE LOW-LEVEL HODOGRAPH CURVATURE AND
EFFECTIVE BULK SHEAR OF 50-60 KT. IN THE OPEN WARM SECTOR...WIND
PROFILES WILL BE MORE UNIDIRECTIONAL WITH STRONG LOW-MIDLEVEL SPEED
SHEAR ACROSS AREAS AHEAD OF THE PRE-FRONTAL CONVECTION IN
MO/IL/INDIANA. THIS CONFIGURATION OF INSTABILITY AND VERTICAL SHEAR
WILL SUPPORT BOTH BOWING LINE SEGMENTS AND SUPERCELLS...WITH THE
POTENTIAL TO PRODUCE DAMAGING WINDS AND A COUPLE OF TORNADOES.
LATER THIS EVENING...THERE IS SOME POTENTIAL FOR STORMS TO
CONSOLIDATE INTO ANOTHER MCS WITH DAMAGING WINDS ALONG THE WARM
FRONT ACROSS SE LOWER MI/NRN OH/NW PA.
...SRN PLAINS THROUGH TONIGHT...
THE COLD FRONT IS MOVING ONLY SLOWLY SEWD ACROSS NW TX AND SRN OK
ATTM...AND WILL LIKELY STALL BY TONIGHT AS A LOW-LEVEL WAA REGIME
DEVELOPS OVER TX DOWNSTREAM FROM SHORTWAVE TROUGH MOVING EWD FROM
SRN CA. UNTIL THIS LOW-LEVEL RESPONSE OCCURS TONIGHT...LOW-LEVEL
WINDS ARE EXPECTED TO VEER AND WEAKEN AS THE CENTRAL PLAINS MIDLEVEL
TROUGH MOVES AWAY TO THE NE. THE NET RESULT WILL BE GRADUAL
WEAKENING OF DEEP-LAYER AND LOW-LEVEL SHEAR ACROSS THE TX WARM
SECTOR. HOWEVER...THE STRONG INSTABILITY NOTED IN THE PRE-FRONTAL
FWD SOUNDING SUGGESTS THAT A FEW STORMS COULD PRODUCE LARGE HAIL
TODAY ON THE IMMEDIATE COOL SIDE OF THE FRONT. OTHER ELEVATED
STORMS WITH SOME HAIL THREAT WILL DEVELOP FARTHER W OVERNIGHT IN THE
WAA REGIME.
..THOMPSON/HURLBUT.. 05/13/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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