MESO: Mesoscale Discussion 1735

ACUS11 KWNS 180937
SWOMCD
SPC MCD 180936
FLZ000-ALZ000-181130-

MESOSCALE DISCUSSION 1735
NWS STORM PREDICTION CENTER NORMAN OK
0436 AM CDT SUN AUG 18 2013

AREAS AFFECTED...WRN FL PANHANDLE...SWRN AL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 180936Z - 181130Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ROTATING STORMS OFF THE GULF COAST MAY PRODUCE A BRIEF
TORNADO OR LOCALIZED DAMAGING WINDS AS THEY MOVE ASHORE THIS
MORNING. BUT WITH A SUBSTANTIAL DECREASE IN INSTABILITY WITH INLAND
EXTENT...THIS THREAT SHOULD REMAIN TOO MARGINAL TO WARRANT A WW
ISSUANCE.

DISCUSSION...09Z SURFACE ANALYSIS PLACED A 1012 MB CYCLONE NEAR THE
MOUTH OF THE MS RIVER WITH A SLOW-MOVING WARM FRONT EXTENDING EWD TO
JUST OF N OF AAF. A PERSISTENT STORM CLUSTER WITH REGENERATIVE
UPDRAFTS HAS BEEN SUSTAINED IN THE WARM SECTOR OFF THE COAST TO THE
S/SW OF THE MOB/PNS AREA. A LONGER-LIVED ROTATING CELL HAD BEEN
ANCHORED NEARLY DIRECTLY S OF PNS...BUT WEAKENED SUBSTANTIALLY AS IT
ACCELERATED NWD TOWARDS THE COAST. ALTHOUGH AIR MASS N OF THE WARM
FRONT IS CHARACTERIZED BY UPPER 60S TO LOWER 70S SURFACE DEW
POINTS...RR SOUNDINGS SUGGEST INSTABILITY IS QUITE LIMITED WITH POOR
LAPSE RATES AMIDST A SATURATED THERMODYNAMIC PROFILE.
NEVERTHELESS...WITH 15-20 KT 0-1 KM SHEAR NOTED IN MOB/EVX VWP
DATA...A WATERSPOUT MOVING ASHORE AS A BRIEF TORNADO CANNOT BE RULED
OUT.

..GRAMS/GOSS.. 08/18/2013

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

ATTN...WFO...TAE...MOB...

LAT...LON 30358827 30668829 30928793 30918669 30878626 30768582
30538558 30348550 30108562 30138588 30148716 30138829
30358827

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