Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
San Antonio, TX...Detroit, MI...Columbus, OH...Austin, TX...Charlotte, NC...
SPC AC 091252
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0752 AM CDT THU APR 09 2015
VALID 091300Z - 101200Z
...THERE IS AN ENH RISK OF SVR TSTMS NRN IL AND MICHIANA AREA SWWD
ACROSS LOWER OH VALLEY TO ARKLATEX...
...THERE IS A SLGT RISK OF SVR TSTMS ELSEWHERE FROM ERN IA...SRN WI
AND SRN LOWER MI TO CENTRAL TX AND CENTRAL APPALACHIANS...
...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING SLGT RISK FROM
WI...IA AND LOWER MI TO PORTIONS CAROLINAS AND SW TX...
...SUMMARY...
SEVERE THUNDERSTORMS WILL OFFER AN ENHANCED RISK OF DAMAGING
WINDS...ALONG WITH POTENTIAL FOR AREAS OF LARGE HAIL AND A FEW
TORNADOES...THIS AFTERNOON AND EVENING. THE MAIN THREAT AREA
EXTENDS FROM PARTS OF THE MIDDLE AND UPPER MISSISSIPPI VALLEY AND
SOUTHERN LOWER MICHIGAN SOUTHWESTWARD TO NORTHEAST TEXAS.
...SYNOPSIS...
PROGRESSIVE UPPER-AIR PATTERN IS FCST ACROSS CONUS TODAY...WITH
PRIMARY PERTURBATION BEING POSITIVELY TILTED SHORTWAVE TROUGH NOW
EVIDENT IN MOISTURE-CHANNEL IMAGERY FROM WRN SD SSWWD ACROSS CENTRAL
HIGH PLAINS TO NRN NM. THIS FEATURE WILL BECOME MORE COMPACT AND
MOVE EWD TO SRN MN...IA...AND ERN KS BY 00Z...WITH AT LEAST BRIEF
CLOSURE OF 500-MB LOW POSSIBLE OVER IA. TROUGH THEN SHOULD MOVE
ENEWD ACROSS WI/IL TO LM AND LOWER MI BY END OF PERIOD...AS
SECONDARY VORTICITY MAX NOW NW OF LAKE WINNIPEG DIGS SEWD TO NRN MN.
FLOW BELT S AND SE OF MAJOR SHORTWAVE TROUGH CONTAINS SEVERAL
EMBEDDED/LOW-AMPLITUDE VORTICITY MAXIMA...MOST PRONOUNCED OF WHICH
IS SMALL SHORTWAVE TROUGH AND ACCOMPANYING MCV MOVING FROM NERN OK
INTO SWRN MO. THIS FEATURE IS EXPECTED TO MOVE ENEWD ACROSS MO THIS
MORNING AND OVER PARTS OF SRN IL TO CENTRAL/ERN INDIANA THIS
AFTERNOON. ANOTHER MCV OVER SRN/CENTRAL IL MAY BE AIDING
ENVIRONMENT FOR CONVECTION ACROSS WRN INDIANA. THIRD MCV IS MOVING
NEWD FROM NERN AR ACROSS SERN MO...AND WILL HEAD GENERALLY UP OH
VALLEY TODAY.
AT SFC...LOW WAS ANALYZED OVER NERN KS/SERN NEB REGION...WITH COLD
FRONT SWWD ACROSS SRN KS...NWRN OK...TX PANHANDLE...AND NERN NM. BY
00Z...AS CYCLONE DEEPENS AND EJECTS TO ERN IA...TRAILING COLD FRONT
WILL MOVE SEWD ACROSS MUCH OF CENTRAL/SRN PLAINS TO ERN MO...NWRN
AR...SERN OK...AND N-CENTRAL THROUGH SW TX. BY END OF PERIOD...SFC
CYCLONE SHOULD BE ESSENTIALLY STACKED BENEATH 500-MB VORTICITY
MAX...OVER LM OR LOWER MI...WITH OCCLUDED FRONT EWD ACROSS LH AND
COLD FRONT FROM ADJOINING PARTS OF ONT SWWD ACROSS OH...MID TN...WRN
LA...AND S-CENTRAL TX. WARM FRONT -- NOW ARCHING ENEWD FROM LOW
ACROSS NWRN MO...EXTREME SERN IA...NRN IL AND NRN INDIANA...HAS BEEN
RENDERED DIFFUSE IN PLACES BY PRECIP AND OUTFLOW. STILL...WARM
FRONT SHOULD MOVE NWD ACROSS ERN IA AND MOST OF NRN IL TODAY...ITS
PENETRATION INTO WI MORE UNCERTAIN BECAUSE OF ONGOING PRECIP AND ITS
REINFORCING/ STABILIZING EFFECTS ON AIR MASS NOW N OF FRONT. ERN
SEGMENT OF WARM FRONT MAY LIFT INTO PORTIONS OF SRN LOWER MI AS
WELL.
...PARTS OF WI/LM/LOWER MI TO NE/CENTRAL TX...
SCATTERED TO WIDELY SCATTERED SVR TSTMS IN BANDS...INITIALLY
COMPOSED OF SOME DISCRETE MULTICELLS AND SUPERCELLS...ARE EXPECTED
TO DEVELOP EPISODICALLY THROUGH THIS EVENING. ACTIVITY WILL OCCUR
ALONG/AHEAD OF SFC COLD FRONT...FROM SRN PARTS OF UPPER GREAT LAKES
REGION SWWD AT LEAST INTO ARKLATEX AREA. DAMAGING GUSTS...SPORADIC
LARGE HAIL...AND A FEW TORNADOES ARE POSSIBLE. GENERALLY...CAPE AND
MOISTURE WILL INCREASE SWD WHILE DEEP SHEAR AND LIFT INCREASE NWD.
ARC OF TSTMS -- POSSIBLY SEPARATED FROM AFOREMENTIONED
COLD-FRONTAL/WARM-SECTOR ACTIVITY -- MAY FORM ACROSS PARTS OF NERN
MO AND ERN IA FROM EARLY-MID AFTN AND MOVE NEWD IN REGION OF BACKED
SFC WINDS...RELATIVELY MAXIMIZED SRH AND ENHANCEMENTS TO
BOUNDARY-LAYER VORTICITY E OF SFC LOW AND NEAR WARM FRONT. AT LEAST
MRGLLY SVR HAIL...OCNL DAMAGING GUSTS...AND A FEW TORNADOES ALSO ARE
POSSIBLE IN THAT REGIME.
FARTHER E AND SE...OVER MUCH OF OUTLOOK AREAS FROM IL/INDIANA SWWD
THROUGH LOWER OH VALLEY...MOISTURE ADVECTION/TRANSPORT NNEWD FROM
RICH/DEEP BOUNDARY-LAYER PLUME SAMPLED BY 12Z SHV RAOB IS EXPECTED
TO SUPPORT SVR POTENTIAL...BENEATH INCREASING FLOW ALOFT.
UNCONDITIONAL CONVECTIVE FORECAST IS COMPLICATED BY PARADE OF MCVS
AND THEIR MESOBETA-SCALE UNDULATIONS OF MASS FIELDS AND
THERMODYNAMICS--LATTER MAINLY CAUSED BY CLOUDS/RAIN AND ASSOCIATED
ADJUSTMENTS TO AREAS OF DIABATIC SFC HEATING. POCKETS OF ENH/SLGT
OUTLOOK SWATH WILL BE RELATIVELY DEVOID OF SVR WHILE OTHERS WILL
EXPERIENCE RELATIVELY DENSE CONCENTRATIONS OF TSTMS AND SVR
POTENTIAL...IN BANDS AND CLUSTERS. THESE POCKETS SHOULD CORRESPOND
TO RELATIVE MINIMA AND MAXIMA IN CAPE FIELD AS THOSE EVOLVE...SINCE
ENTIRE SWATH WILL LIE BENEATH FAVORABLE DEEP/EFFECTIVE SHEAR FOR
ORGANIZED SVR.
FRONTAL LIFT WILL HELP BOOST PARCELS THROUGH EML AS FAR SW AS PARTS
OF NERN AND PERHAPS CENTRAL TX. INCREASING UNCERTAINTY EXISTS
FARTHER SW WHERE SHALLOWER FRONTAL LIFT...SHALLOWER MOIST LAYERS PER
12Z RAOBS...AND STRONGER CAPPING WILL FACTOR INTO CONDITIONAL SVR
POTENTIAL WITH LIKELY SHORTER DURATION...ACROSS CENTRAL/SW TX TO RIO
GRANDE. HOWEVER...ANY TSTMS THAT DEVELOP IN THIS AREA WILL POSE
THREAT FOR SVR HAIL AND GUSTS.
..EDWARDS/LEITMAN.. 04/09/2015
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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