Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 211630
SWODY1
SPC AC 211628

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CDT MON APR 21 2014

VALID 211630Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN OK AND THE ARKLATEX
SWWD INTO CNTRL TX...

...SUMMARY...
ISOLATED SEVERE STORMS MAY DEVELOP FROM PARTS OF THE ARKLATEX REGION
TO SOUTH-CENTRAL TEXAS THIS AFTERNOON AND EVENING.

...SYNOPSIS...
PATTERN WILL BECOME SOMEWHAT MORE AMPLIFIED THIS PERIOD AS HEIGHTS
RISE OVER THE RCKYS...DOWNSTREAM FROM FAIRLY POTENT/PROGRESSIVE UPR
LOW/TROUGH APPROACHING THE PACIFIC NW. AS THIS OCCURS...THE LAST IN
A SERIES OF IMPULSES COMPRISING THE SRN PLNS SRN BRANCH TROUGH WILL
TRACK FROM CNTRL OK/N CNTRL TX ESE TO THE ARKLATEX THIS EVE...AND
INTO THE LWR MS VLY EARLY TUE. THE FEATURE SHOULD GRADUALLY WEAKEN
AS IT BECOMES ABSORBED WITHIN AMPLIFYING NRN STREAM TROUGH NOW OVER
THE UPR MS VLY/UPR GRT LKS.

FLOW WILL REMAIN WEAK AT THE SFC. THE MAIN FEATURES OF NOTE
AFFECTING TSTM DEVELOPMENT WILL BE /1/ W-E OUTFLOW BOUNDARY NEAR THE
RED RVR AND /2/ SW-NE LEE TROUGH/DRY LINE IN CNTRL TX. THE OUTFLOW
BOUNDARY SHOULD REMAIN NEARLY STNRY TODAY WHILE THE TROUGH ADVANCES
SE AND IS OVERTAKEN BY WEAK UPSTREAM COLD FRONT NOW OVER NW TX.

SCTD TSTMS EXPECTED TO FORM ALONG THE OUTFLOW BOUNDARY...AND TO A
LESSER EXTENT ALONG THE LEE TROUGH/DRY LINE...MAY POSE A RISK FOR
HAIL AND LOCALLY DMGG WIND FROM SRN OK AND THE ARKLATEX SWWD INTO
CNTRL TX THIS AFTN AND EVE.

...ARKLATEX/SRN OK SW INTO CNTRL TX...
TSTMS SHOULD FORM ALONG STALLED OUTFLOW BOUNDARY NEAR THE RED RVR
THIS AFTN IN RESPONSE TO SFC HEATING...MAXIMIZED SFC
CONVERGENCE...AND THE CONTINUED ESEWD ADVANCE OF OK UPR IMPULSE.
LATER IN THE DAY...MORE SCTD DEVELOPMENT SHOULD OCCUR SWWD IN ZONE
OF WEAKER CONVERGENCE ALONG DRY LINE/LEE TROUGH.

WHILE BUOYANCY WILL NOT BE EXTREME /AFTN MLCAPE EXPECTED TO RANGE
FROM AROUND 500 J/KG IN SRN OK TO ABOVE 1500 J/KG IN CNTRL TX/...IT
WILL BE SUFFICIENT FOR STRONG UPDRAFTS CAPABLE OF SVR HAIL GIVEN
RELATIVELY COOL MID-LVL TEMPERATURES WITH UPR TROUGH. AND...WHILE
THE MID-TROPOSPHERIC FLOW WILL REMAIN COMPARATIVELY MODEST AS THE
UPR IMPULSE WEAKENS...30-35 KT WNWLY DEEP SHEAR SHOULD FOSTER SOME
UPDRAFT ORGANIZATION/SUSTENANCE.

THE OVERALL SETUP APPEARS MOST FAVORABLE FOR STRONG MULTICELLS
THAT...ESPECIALLY ALONG THE OUTFLOW BOUNDARY...SHOULD MERGE INTO ESE
TO SE-MOVING CLUSTERS WITH HAIL AND EMBEDDED SMALL BOWING SEGMENTS
WITH LOCALLY DMGG WIND OVER N CNTRL/NE TX. THE STORMS MAY REMAIN
SOMEWHAT MORE DISCRETE SWWD ALONG TROUGH/DRY LINE...WHERE ONE OR TWO
COULD EXHIBIT TRANSIENT SUPERCELL CHARACTERISTICS. MOST OF THE
ACTIVITY SHOULD DIMINISH FAIRLY QUICKLY AFTER SUNSET.

..CORFIDI/JEWELL.. 04/21/2014




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