Severe Storm Outlook Narrative (AC)
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000
ACUS02 KWNS 301714
SWODY2
SPC AC 301713

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1213 PM CDT SAT APR 30 2016

VALID 011200Z - 021200Z

...THERE IS A MRGL RISK OF SVR TSTMS FROM CNTRL TX NEWD ACROSS THE
OH RIVER...

...SUMMARY...
SCATTERED STRONG TO SEVERE STORMS ARE POSSIBLE FROM PORTIONS OF
TEXAS INTO THE OHIO VALLEY WITH A THREAT OF HAIL AND WIND.

...SYNOPSIS...
A BELT OF STRONG SWLY FLOW ALOFT WILL EXTEND FROM THE SRN PLAINS
INTO THE NERN STATES WITH TWO LOW-AMPLITUDE WAVES. ONE WILL MOVE
FROM IL/IN EWD ACROSS THE OH VALLEY LATE IN THE AFTERNOON THROUGH
EVENING WITH A WEAK SFC LOW ACROSS THE AREA. TO THE SW...AN INVERTED
SFC TROUGH WILL EXIST FROM THE LOWER RIO GRANDE VALLEY INTO SERN TX
AND LA...WITH SUBSTANTIAL MOISTURE AND INSTABILITY IN PLACE.
MEANWHILE...A POLAR AIR MASS WILL CONTINUE TO SURGE SWD OVER WRN
TX...WITH THE LEADING FRONT THROUGH ALL BUT FAR SERN TX BY MON
MORNING. THE RESULT WILL BE A RELATIVELY LARGE AREA OF ISOLATED
SEVERE THUNDERSTORM POTENTIAL FROM LATE AFTERNOON INTO THE EVENING.

...INDIANA...OHIO...KENTUCKY...
WEAK SLY SFC FLOW WILL KEEP LOWER 60S F DEWPOINTS IN PLACE ACROSS
THE OH RIVER AND NEAR A DEVELOPING SFC LOW. DAYTIME HEATING WILL
ALLOW DESTABILIZATION TO OCCUR WITH MLCAPE AROUND 1500 J/KG.
PRIMARILY WLY FLOW WILL RESULT IN STRAIGHT LINE HODOGRAPHS FAVORABLE
FOR SPLITTING CELLS WITH A THREAT OF HAIL. THE LATE ARRIVAL OF THE
SHORTWAVE TROUGH AND LACK OF MUCH WARM ADVECTION SUGGESTS ISOLATED
SEVERE COVERAGE. HOWEVER...AN UPGRADE TO SLIGHT RISK MAY OCCUR IF
STORM COVERAGE EXPECTATIONS INCREASE.

...CNTRL INTO SERN TX...
NEUTRAL TO RISING HEIGHTS ALOFT WILL EXIST WITH MODESTLY STRONG MID
TO UPPER LEVEL FLOW PERSISTING OVER THE REGION. WEAK CONVERGENCE
WILL EXIST OVER MUCH OF ERN TX INTO WRN LA AS SELY SFC WINDS BRING
TROPICAL MOISTURE FARTHER INLAND. HEATING WILL LEAD TO STRONG
INSTABILITY WITH MLCAPE OF 2000 TO PERHAPS 3000 J/KG. SOME MODELS
INCLUDING THE ECMWF PRODUCE A SUBSTANTIAL AREA OF THUNDERSTORMS
ACROSS MUCH OF CNTRL TO ERN TX DURING THE EVENING...APPROACHING THE
TX COAST BY MON MORNING. GIVEN RATHER WEAK FORCING AND POTENTIAL FOR
CAPPING AHEAD OF THE FRONT...WILL DEFER ANY POTENTIAL SLIGHT RISK TO
LATER OUTLOOKS. LONG STRAIGHT LINE HODOGRAPHS...STEEP LAPSE RATES
ALOFT AND AMPLE MOISTURE WILL CONDITIONALLY FAVOR LARGE DAMAGING
HAIL.

..JEWELL.. 04/30/2016

$$



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