Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 231340
SWOMCD
SPC MCD 231339
ALZ000-MSZ000-LAZ000-231615-

MESOSCALE DISCUSSION 1983
NWS STORM PREDICTION CENTER NORMAN OK
0739 AM CST TUE DEC 23 2014

AREAS AFFECTED...PORTIONS OF MISSSISSIPPI...LOUISIANA...WESTERN
ALABAMA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 231339Z - 231615Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THE AREA IS BEING MONITORED FOR AN INCREASING RISK OF
SEVERE THUNDERSTORMS...INCLUDING TORNADOES...THIS MORNING. THE
ISSUANCE OF A TORNADO WATCH WILL BE POSSIBLE DURING THE NEXT FEW
HOURS.

DISCUSSION...MOISTURE-CHANNEL IMAGERY IMPLIES THAT THE LEADING EDGE
OF STRONGER DCVA PRECEDING A SHORTWAVE TROUGH CROSSING THE SRN
PLAINS IS ENCROACHING UPON THE WRN EXTENT OF INLAND-EXTENDING GULF
MOISTURE -- E.G. MIDDLE 60S SFC DEWPOINTS ANALYZED ACROSS SRN LA/MS.
SMALL...SHALLOW REFLECTIVITY CORES ARE NOW BEING DETECTED FROM
E-CNTRL TX TO SWRN LA. THIS IS EVIDENCE OF THE INTERACTION OF
STRONGER ASCENT OVERTAKING THE WRN FRINGES OF NON-ZERO
BUOYANCY...WITH SFC-BASED EFFECTIVE INFLOW LAYERS EXISTING E OF A
SFC TROUGH ANALYZED FROM N-CNTRL AL TO VICKSBURG MS TO NEAR BEAUMONT
TX. E OF THIS TROUGH...LIX/LCH RAOBS AT 12Z SAMPLE AROUND 1250 J/KG
OF MLCAPE AIDED BY MODESTLY STEEP MID-LEVEL LAPSE RATES. INLAND
PENETRATION OF HIGHER-BUOYANCY/THETA-E AIR WILL BE FACILITATED BY
STRENGTHENING POLEWARD MASS FLUXES PRECEDING THE SHORTWAVE
TROUGH...WITH RELATED ASCENT RESULTING IN A BLOSSOMING OF CONVECTION
NEAR/E OF THE SFC TROUGH THIS MORNING.

WITH AREA VWPS SAMPLING 50-60 KT OF 0-6-KM BULK SHEAR...MIXED-MODE
CONVECTION INCLUDING SUPERCELLS/QLCS SEGMENTS SHOULD ENSUE...WITH
DMGG WIND GUSTS AND SVR HAIL POSSIBLE. ELONGATING/CURVED LOW-LEVEL
HODOGRAPHS MAY ALSO SUPPORT A FEW TORNADOES...ESPECIALLY WITH MORE
DISCRETE CONVECTION EVOLVING ACROSS SRN LA/SRN MS WHICH WILL BE IN
CONTACT WITH RICHEST LOW-LEVEL MOISTURE. ULTIMATELY...UNCERTAINTY IN
THE TIMING OF THE MORE SUBSTANTIAL INCREASE IN SVR-TSTM POTENTIAL
EXTENDS TO WW ISSUANCE TIMING. BY MID DAY...A WW WILL PROBABLY BE
REQUIRED...THOUGH WW ISSUANCE IS POSSIBLE IN THE SHORT-TERM.

..COHEN/EDWARDS.. 12/23/2014

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

ATTN...WFO...BMX...MOB...JAN...LIX...LCH...SHV...

LAT...LON   29539315 30149325 31259233 33298982 33548807 32828761
            31218842 29398929 29059079 29329253 29539315



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