Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 191853
SWOMCD
SPC MCD 191852
LAZ000-ARZ000-TXZ000-OKZ000-191945-

MESOSCALE DISCUSSION 0379
NWS STORM PREDICTION CENTER NORMAN OK
0152 PM CDT SUN APR 19 2015

AREAS AFFECTED...SOUTHWEST AR...WESTERN LA...EAST TX INCLUDING THE
UPPER TX COAST

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 191852Z - 191945Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...ISOLATED TO WIDELY SCATTERED STORMS WILL DEVELOP BY 21Z
AHEAD OF A COLD FRONT ACROSS EAST TEXAS. THESE STORMS WILL TRACK
EAST TOWARD THE UPPER TX COAST AND WESTERN LA. LARGE HAIL AND STRONG
WINDS WILL BE THE MAIN THREATS...BUT A TORNADO OR TWO CANNOT BE
RULED OUT. THE AREA IS BEING MONITORED FOR WATCH ISSUANCE BY 21Z.

DISCUSSION...TEMPERATURES HAVE WARMED TO THE UPPER 70S TO LOW 80S
FROM THE UPPER TX COAST TOWARD THE ARKLATEX/SABINE VALLEY...WITH
DEWPOINTS FROM THE MID/UPPER 60S ACROSS SOUTHERN PORTIONS OF THE MCD
AREA TO THE LOW 60S FURTHER NORTH. 18Z MESOANALYSIS AND FORECAST RAP
SOUNDINGS SUGGEST SOME CAPPING STILL EXISTS ACROSS THE AREA BUT
SHOULD ERODE BY AROUND 20-21Z. ONCE THIS OCCURS...STRONG SURFACE
BASED INSTABILITY WILL LEAD TO THUNDERSTORM DEVELOPMENT NEAR/JUST
AHEAD OF THE COLD FRONT. FORCING FOR ASCENT IS NOT AS STRONG AS
FURTHER NORTH CLOSER TO THE UPPER TROUGH...BUT ISOLATED TO WIDELY
SCATTERED SUPERCELLS WILL BE POSSIBLE. STORMS MAY REMAIN
SEMI-DISCRETE AT FIRST BEFORE TRANSITIONING TOWARD BOWING SEGMENTS.
STEEP MIDLEVEL LAPSE RATES AND EFFECTIVE SHEAR NEAR 35 KT WILL
SUPPORT ROTATING UPDRAFTS AND LARGE HAIL WILL BE POSSIBLE.
FURTHERMORE...DCAPE VALUES AOA 1200 J/KG AND SOME DRIER MIDLEVEL AIR
COULD RESULT IN SOME STRONG/LOCALLY DAMAGING WINDS WITH THE
STRONGEST STORMS. WHILE THE TORNADO THREAT SHOULD REMAIN
LOW...MODEST LOW-LEVEL DIRECTIONAL SHEAR EXISTS ACROSS THIS
AREA...WITH THE SHV VAD WIND PROFILE INDICATING 0-1KM SRH NEAR 100
M2/S2. AS SUCH...ANY STORM THAT CAN REMAIN DISCRETE COULD POSE A
BRIEF TORNADO THREAT.

..LEITMAN/HART.. 04/19/2015

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...LZK...LCH...SHV...HGX...FWD...EWX...

LAT...LON   30459248 31319202 32029208 32839242 33519307 33809396
            33779498 32799520 31999553 31269604 29919751 29639758
            29369746 29159717 29059673 28959602 29179471 30029317
            30459248



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