Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 231020
SWOMCD
SPC MCD 231019
MSZ000-LAZ000-231215-

MESOSCALE DISCUSSION 1982
NWS STORM PREDICTION CENTER NORMAN OK
0419 AM CST TUE DEC 23 2014

AREAS AFFECTED...PORTIONS OF SOUTHEAST MISSISSIPPI AND SOUTHEAST
LOUISIANA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 231019Z - 231215Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...SOME STRONG-THUNDERSTORM RISK WILL EXIST DURING THE
PRE-DAWN HOURS. IN THE SHORT-TERM...WW ISSUANCE WILL NOT BE
NECESSARY.

DISCUSSION...SFC ANALYSES INDICATE MOIST...MARINE-MODIFIED AIR
CONTINUING TO ADVANCE NWD...WITH MIDDLE-60S DEWPOINTS SPREADING NWD
ACROSS SERN LA/SERN MS. RICHER...MORE STRONGLY MODIFIED GULF
MOISTURE -- E.G. SFC DEWPOINTS IN THE LOWER 70S -- RESIDES S OF A
WARM FRONT ANALYZED JUST OFFSHORE FROM SERN LA. THE EARLIER 00Z LIX
RAOB AND MODIFICATIONS TO THIS SOUNDING SUGGEST THAT SUFFICIENTLY
HIGH THETA-E EXISTS IN THE BOUNDARY LAYER FOR 500-1000 J/KG OF
MLCAPE WITH SFC-BASED EFFECTIVE INFLOW LAYERS...ESPECIALLY WITHIN
ABOUT 100 MILES OF THE COAST. AREA RADARS AND LIGHTNING DATA
INDICATE A RECENT UPTICK IN CONVECTION W AND N OF LAKE
PONTCHARTRAIN. THIS ACTIVITY IS LIKELY ASSOCIATED WITH A NARROW
FILAMENT OF MID-LEVEL ASCENT PROGRESSING NEWD ON THE SERN PERIPHERY
OF BROADER CYCLONIC FLOW OVER THE CNTRL CONUS...PER MOISTURE-CHANNEL
IMAGERY.

UNTIL LARGER-SCALE ASCENT INCREASES LATER IN THE MORNING...ONLY A
GRADUAL INCREASE IN CONVECTIVE COVERAGE AND INTENSITY IS EXPECTED
DURING THE NEXT FEW HOURS UNDER THE INFLUENCE OF THE AFOREMENTIONED
ASCENT FILAMENT. LIX AND JAN VWPS SAMPLE OVER 50 KT OF MID-LEVEL
SWLYS THAT WILL OFFER SUFFICIENT DEEP SHEAR FOR SUSTAINED/ORGANIZED
CONVECTION. LOW-LEVEL FLOW IS PRESENTLY MODEST...THOUGH SUFFICIENT
DIRECTIONAL SHEAR EXISTS FOR THE POSSIBILITY OF GENERALLY WEAK
STORM-SCALE CIRCULATIONS AND PERHAPS A BRIEF/WEAK TORNADO.
CONVECTION EVOLVING ACROSS MARION AND JEFFERSON DAVIS COUNTIES IN
SERN MS HAS ALREADY EXHIBITED WEAK/ELONGATED CYCLONIC SHEAR ZONES.
SIMILAR TRENDS WILL LIKELY BE NOTED WITH CONVECTION ACROSS THE
REGION BEFORE DAWN. HOWEVER...NOTHING MORE THAN A BRIEF/WEAK TORNADO
OR PERHAPS A STRONG WIND GUST ARE EXPECTED WHILE LOW-LEVEL FLOW
REMAINS WEAK AND LARGE-SCALE ASCENT MODEST.

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

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

ATTN...WFO...MOB...JAN...LIX...LCH...

LAT...LON   29239240 29739290 30469199 31878985 31808866 30028855
            28908935 29239240



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