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...Nashville, TN...
SPC AC 090544
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1244 AM CDT THU APR 09 2015
VALID 091200Z - 101200Z
...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PARTS OF NE TX...FAR SE
OK...NRN LA...AR...NW MS...WRN TN...KY...SE MO...IL...FAR SRN
WI...IND AND WRN OH...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...LOWER TO MID MS VALLEY...OZARKS...OH VALLEY...SRN GREAT
LAKES AND CNTRL APPALACHIAN MTNS...
...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...LOWER TO MID MS VALLEY...OZARKS...TN VALLEY...OH
VALLEY...SRN GREAT LAKES AND CNTRL APPALACHIANS...
...SUMMARY...
SEVERE THUNDERSTORMS ARE LIKELY TODAY INTO TONIGHT FROM PARTS OF THE
SOUTHERN PLAINS...NORTHEASTWARD INTO THE LOWER TO MID MISSISSIPPI
VALLEY...OHIO VALLEY AND SOUTHERN GREAT LAKES REGION. THIS WILL
INCLUDE THE RISK FOR DAMAGING WIND GUSTS AND LARGE HAIL. A FEW
TORNADOES MAY OCCUR WITH A STRONG TORNADO POSSIBLE.
...OH VALLEY/SRN GREAT LAKES/CNTRL APPALACHIANS...
AN UPPER-LEVEL TROUGH WILL MOVE QUICKLY EWD ACROSS THE CNTRL AND NRN
PLAINS TODAY AS A SFC LOW MOVES NEWD INTO THE UPPER MS VALLEY. A
TRAILING COLD FRONT WILL MOVE EWD INTO THE MID MS VALLEY THIS
AFTERNOON. A WARM FRONT IS FORECAST TO MOVE NWD INTO THE SRN GREAT
LAKES...ALONG WHICH SCATTERED THUNDERSTORMS MAY BE ONGOING THIS
MORNING. CONVECTIVE COVERAGE SHOULD GRADUALLY INCREASE ACROSS THE OH
VALLEY AND SRN GREAT LAKES REGION DURING THE DAY AS A LOW-LEVEL JET
MOVES INTO THE REGION FROM THE SOUTHWEST. STRENGTHENING WARM
ADVECTION AND SFC HEATING MAY RESULT IN POCKETS OF MODERATE
INSTABILITY BY EARLY AFTERNOON. AS THE COLD FRONT SWEEPS EWD ACROSS
THE MID MS VALLEY THIS AFTERNOON...SFC-BASED THUNDERSTORMS SHOULD
DEVELOP ALONG AND AHEAD OF THE FRONT WITH OTHER CELLS INITIATING EWD
ACROSS THE WARM SECTOR IN THE OH VALLEY. THE DEVELOPMENT OF SEVERAL
LINE SEGMENTS OR A SEMI-CONTINUOUS SQUALL LINE MAY OCCUR FROM THE
LATE AFTERNOON INTO THE EVENING ACROSS THE REGION.
NAM FORECAST SOUNDINGS AT 00Z/FRIDAY FROM ST LOUIS NEWD TO
INDIANAPOLIS SHOW MLCAPE VALUES OF 1000 TO 1500 J/KG WITH SFC
DEWPOINTS IN THE LOWER 60S F. THIS COMBINED WITH 40 TO 50 KT OF FLOW
JUST ABOVE THE BOUNDARY LAYER SHOULD SUPPORT SEVERE STORMS WITH WIND
DAMAGE POTENTIAL. LINE SEGMENTS THAT CAN ORGANIZE IN AREAS WHERE
INSTABILITY BECOMES MAXIMIZED COULD DEVELOP AN ENHANCED WIND-DAMAGE
THREAT. THE SHEAR ENVIRONMENT SHOULD ALSO SUPPORT SUPERCELL
DEVELOPMENT BUT THIS WILL DEPEND UPON THE PREFERRED STORM MODE. THE
MOST FAVORABLE AREA FOR SUPERCELLS WOULD BE IN CNTRL AND NRN IL
WHERE THE LOW AND MID-LEVEL JET IS FORECAST TO COUPLE JUST AHEAD OF
A VORTICITY MAX. ANOTHER AREA OF POTENTIAL FOR SUPERCELLS COULD BE
ACROSS THE OH VALLEY WHERE CELLS MAY TEND TO BE DISCRETE AND MODELS
FORECAST A POCKET OF MODERATE INSTABILITY. ANY SUPERCELL THAT CAN
ORGANIZE WILL HAVE POTENTIAL FOR HAIL AND POSSIBLY TORNADOES. A
STRONG TORNADO CAN NOT BE RULED OUT ACROSS THE REGION BUT THIS
SHOULD DEPEND ON MESOSCALE FACTORS. DUE TO UNCERTAINTY CONCERNING
THE LOCATION...WILL DEFER TO LATER OUTLOOKS.
FURTHER SOUTHEAST...AN ISOLATED SEVERE THREAT MAY ALSO DEVELOP
ACROSS THE CNTRL APPALACHIAN MTNS BUT ANY POTENTIAL FOR WIND DAMAGE
WOULD LIKELY BE LESS WITH SEWD EXTEND DUE TO WEAKER LOW-LEVEL FLOW.
...SRN PLAINS/LOWER TO MID MS VALLEY...
WEST-SOUTHWEST MID-LEVEL FLOW WILL BE IN PLACE TODAY AS AN
UPPER-LEVEL TROUGH MOVES THROUGH THE CNTRL PLAINS. AT THE SFC...A
COLD FRONT WILL ADVANCE SEWD ACROSS THE OZARKS AND SRN PLAINS.
THUNDERSTORM DEVELOPMENT WILL BE LIKELY AHEAD OF THE FRONT FROM SE
MO SWWD ACROSS AR INTO NE TX BY WHERE MODERATE INSTABILITY SHOULD BE
IN PLACE BY LATE AFTERNOON. STORM COVERAGE SHOULD GRADUALLY INCREASE
AS LOW-LEVEL CONVERGENCE BECOMES ENHANCED ALONG THE FRONT. SEVERAL
CLUSTERS OF STORMS OR LINE SEGMENTS ARE FORECAST TO ORGANIZE AND
MOVE SEWD ACROSS THE LOWER TO MID MS VALLEY FROM LATE THIS AFTERNOON
INTO THE EVENING.
FORECAST SOUNDINGS AHEAD OF THE FRONT FROM TEXARKANA NEWD TO LITTLE
ROCK AT 00Z/FRIDAY SHOW SFC DEWPOINTS IN THE MID 60S F WITH MLCAPE
IN THE 1500 TO 2000 J/KG RANGE. IN ADDITION...WIND PROFILES VEER
STRONGLY WITH HEIGHT WITH 0-6 KM SHEAR IN THE 45 TO 50 KT RANGE.
THIS ENVIRONMENT SHOULD SUPPORT SUPERCELL DEVELOPMENT BUT THE NUMBER
OF SUPERCELLS WILL LIKELY DEPEND UPON THE PREFERRED STORM MODE.
SUPERCELLS SHOULD BE CAPABLE OF PRODUCING LARGE HAIL AND WIND DAMAGE
AND POSSIBLY A TORNADO OR TWO. COMPARED TO SUPERCELL
POTENTIAL...LINE SEGMENTS APPEAR EQUALLY LIKELY AS CELLS DEVELOP
ALONG THE FRONT. THE WIND-DAMAGE THREAT MAY BECOME ENHANCED
ESPECIALLY IF A SQUALL LINE OR MORE ORGANIZED LINE SEGMENT CAN
PERSIST INTO THE EARLY AND MID EVENING. MODEL FORECASTS SUGGEST THAT
THE SEVERE THREAT COULD AFFECT AREAS OF THE TN VALLEY LATER IN THE
EVENING ALONG THE MOIST AXIS WHERE SFC DEWPOINTS SHOULD BE IN THE
MID TO UPPER 60S F.
..BROYLES/PICCA.. 04/09/2015
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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