Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 240558
SWODY1
SPC AC 240556

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1256 AM CDT THU APR 24 2014

VALID 241200Z - 251200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE
LOWER-MIDDLE MS VALLEYS AND WRN TN VALLEY...

...SUMMARY...
SCATTERED STRONG TO SEVERE STORMS ARE EXPECTED TO FORM ALONG A
CORRIDOR FROM SOUTHEAST MISSOURI THROUGH ARKANSAS INTO NORTHERN
LOUISIANA THURSDAY AFTERNOON...AND THEN SPREAD INTO WESTERN
TENNESSEE AND NORTHWEST MISSISSIPPI THURSDAY EVENING.  LOCALLY
DAMAGING WINDS AND LARGE HAIL WILL BE THE PRIMARY THREATS.

...SYNOPSIS...

A PROGRESSIVE LOW-AMPLITUDE SYNOPTIC UPPER PATTERN WILL PERSIST
THURSDAY. OF PARTICULAR INTEREST IS A VORTICITY MAXIMUM OVER NM
EMBEDDED WITHIN THE BASE OF AN UPPER TROUGH. THIS FEATURE WILL MOVE
EAST INTO THE LOW-MIDDLE MS VALLEY THURSDAY AFTERNOON...THEN INTO
THE TN AND OH VALLEYS DURING THE EVENING AND OVERNIGHT. THE
ATTENDANT SFC LOW WILL DEVELOP NEWD THROUGH MO...IL AND
INDIANA...WHILE TRAILING COLD FRONT ADVANCES SEWD THROUGH THE MIDDLE
AND LOWER MS VALLEYS AND TX. BY 12Z FRIDAY THE FRONT WILL EXTEND
FROM A SFC LOW OVER THE OH VALLEY SWWD THROUGH MIDDLE TN...SRN LA
AND S TX.

...LOWER TO MIDDLE MS VALLEY AND WRN TN VALLEY AREAS...

MOIST AXIS WITH UPPER 50S TO NEAR 60F BOUNDARY-LAYER DEWPOINTS WILL
ADVECT INTO THE LOWER-MID MS VALLEY WARM SECTOR IN ASSOCIATION WITH
MIGRATORY 30-40 KT SSWLY LLJ. MEANWHILE...STEEP 7-8 C/KM MID-LEVEL
LAPSE RATES WILL SPREAD EWD ABOVE THE MOIST AXIS. AS TEMPERATURES
WARM TO NEAR 80F...MLCAPE SHOULD INCREASE TO 1000-1500 J/KG FROM
NERN TX INTO THE LOWER-MID MS VALLEY REGIONS. A CORRIDOR OF FOCUSED
DEEP-LAYER ASCENT WILL SHIFT EWD THROUGH MO AND ARKANSAS ALONG AND
JUST AHEAD OF THE COLD FRONT IN ASSOCIATION WITH THE PROGRESSIVE
SHORTWAVE TROUGH. AS THIS ZONE OF ASCENT INTERACTS WITH THE
DESTABILIZING BOUNDARY LAYER...STORMS ARE EXPECTED TO DEVELOP OVER
MO...ARKANSAS AND POSSIBLY NERN TX AND LA DURING THE AFTERNOON AND
SPREAD EWD TOWARD THE TN VALLEY REGION.

DEEP-LAYER WIND AND SHEAR PROFILES WILL STRENGTHEN IN VICINITY OF
THE DEVELOPING CONVECTION AS A 50 KT MID-LEVEL JET WITHIN BASE OF
UPPER TROUGH OVERTAKES THE COLD FRONT. EFFECTIVE BULK SHEAR
INCREASING TO AOA 40 KT WILL SUPPORT ORGANIZED STORMS INCLUDING A
FEW SUPERCELLS...BUT ACTIVITY MAY EVENTUALLY GROW UPSCALE INTO A
DOMINANT LINEAR MODE WITH EMBEDDED ORGANIZED STRUCTURES AND CONTINUE
EWD INTO THE TN VALLEY REGION. LARGE HAIL AND DAMAGING WIND GUSTS
WILL BE THE INITIAL PRIMARY THREATS...BUT A COUPLE OF TORNADOES WILL
ALSO BE POSSIBLE. DOMINANT THREAT IS EXPECTED TO TRANSITION TO
DAMAGING WIND DURING THE EVENING BEFORE DIMINISHING LATER THURSDAY
NIGHT.

..DIAL/LEITMAN.. 04/24/2014




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