Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 270455
SWODY1
SPC AC 270454

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1154 PM CDT SUN APR 26 2015

VALID 271200Z - 281200Z

...THERE IS AN ENH RISK OF SVR TSTMS FOR SRN LA...

...THERE IS A SLGT RISK OF SVR TSTMS FROM EAST TX TO LA AND SRN
MS/AL...

...THERE IS A MRGL RISK OF SVR TSTMS FOR MUCH OF E TX TO THE CNTRL
GULF COAST...

...THERE IS A MRGL RISK OF SVR TSTMS FOR PARTS OF SOUTH FL...

...SUMMARY...
SCATTERED SEVERE THUNDERSTORMS WILL DEVELOP ACROSS PARTS OF
LOUISIANA THIS MORNING AND AFTERNOON. ADDITIONAL STRONG TO SEVERE
THUNDERSTORMS ARE POSSIBLE OVER EAST TEXAS...WHILE ISOLATED STRONG
STORMS ARE POSSIBLE OVER SOUTH FLORIDA.

...SYNOPSIS...
A SRN STREAM CLOSED LOW-MIDLEVEL CYCLONE WILL SLOWLY MOVE EWD ACROSS
THE SRN PLAINS. AN ATTENDANT UPPER JET WILL EXTEND FROM S TX ACROSS
THE CNTRL GULF COAST. AT THE SFC...WEAK LOW PRESSURE WILL DEVELOP
OVER E TX. SEGMENT OF A COLD FRONT WILL BECOME QUASISTATIONARY
ACROSS THE SOUTHEAST...KEEPING A MARITIME TROPICAL AIR MASS CONFINED
TO NEAR THE GULF COAST.

...E TX INTO THE CNTRL GULF COAST...
AN MCS SHOULD BE ONGOING EARLY MON MORNING NEAR THE SABINE VALLEY
INTO WRN LA. THIS FEATURE IS EXPECTED TO CONTINUE PROGRESSING EWD
ACROSS THE CNTRL GULF COAST STATES THROUGH LATE MORNING...WITH AN
ACCOMPANYING DMGG WIND AND ISOLATED TORNADO RISK
POSSIBLE...ESPECIALLY ALONG/S OF A QUASI-STATIONARY BAROCLINIC ZONE
ORIENTED GENERALLY W-E. 27/00Z LIX SOUNDING AND SFC OBS SAMPLED RICH
LOW-LEVEL MOISTURE AND STEEP MIDLEVEL LAPSE RATES IN PLACE...AND
MLCAPE VALUES SHOULD REACH 1000-1500 J/KG AHEAD OF THE QLCS.
HERE...TSTMS MAY ALSO DEVELOP INVOF THE BAROCLINIC ZONE AMIDST WEAK
LOW-LEVEL WAA...AND AN ISOLATED TORNADO THREAT CANNOT BE RULED OUT.

MEANWHILE...AIR MASS RECOVERY SHOULD OCCUR ACROSS E TX INTO SWRN LA
IN THE WAKE OF MORNING CONVECTION...ALTHOUGH TO WHAT DEGREE IT CAN
DESTABILIZE GIVEN THE PRESENCE OF CLOUD COVER REMAINS UNCERTAIN.
HOWEVER...MOST MODEL GUIDANCE SUGGESTS A NARROW CORRIDOR OF MODERATE
INSTABILITY WILL EXIST /ROUGHLY FROM HOUSTON TO DALLAS/ IN
CONJUNCTION WITH DEWPOINTS IN THE 60S E OF A WEAK SFC LOW AND
ATTENDANT PACIFIC FRONT. VERTICAL WIND PROFILES WOULD BE SUFFICIENT
FOR SUPERCELLS...BUT CONVECTIVE INITIATION/EVOLUTION WILL BE
DEPENDENT ON PRESENCE/POSITION OF OUTFLOW BOUNDARIES...AND WHETHER
ENOUGH HEATING CAN OCCUR TO OVERCOME CINH AND SUPPORT SFC-BASED
CONVECTION. SCATTERED TSTMS MAY CONTINUE INTO THE LATE EVENING
ACROSS THE SABINE VALLEY AND ACROSS LA/SRN MS.

...SOUTH FL...
AFTERNOON SEA BREEZE TSTMS ARE FORECAST TO DEVELOP OVER SOUTH FL
AMIDST VERY WARM DAYTIME TEMPERATURES IN THE 90S. ALTHOUGH LOW-LEVEL
FLOW WILL BE WEAK...30-40 KT OF MIDLEVEL WLYS COULD SUPPORT
MARGINALLY ORGANIZED CONVECTION CAPABLE OF PRODUCING LOCALIZED
STRONG WIND GUSTS AND HAIL.

..ROGERS/PETERS.. 04/27/2015




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