MESO: Mesoscale Discussion 2168

ACUS11 KWNS 171017
SWOMCD
SPC MCD 171016
FLZ000-ALZ000-MSZ000-LAZ000-171215-

MESOSCALE DISCUSSION 2168
NWS STORM PREDICTION CENTER NORMAN OK
0416 AM CST MON DEC 17 2012

AREAS AFFECTED...FAR SERN MS/SWRN-SOUTH CENTRAL AL/WRN FL PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 171016Z - 171215Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...A SEVERE WEATHER THREAT /DAMAGING WINDS AND/OR A TORNADO/
MAY BE DEVELOPING EARLY THIS MORNING ALONG THE COASTAL AREAS OF SERN
MS...SWRN AL AND THE WRN FL PANHANDLE...WITH POTENTIAL TO MOVE A
LITTLE FARTHER INLAND OVER SWRN AL/WRN FL PANHANDLE. WW ISSUANCE IS
AT 40 PERCENT SINCE UNCERTAINTY REMAINS IN THE OVERALL STORM
COVERAGE INTO THE MORNING.

DISCUSSION...TRENDS DURING THE OVERNIGHT/EARLY THIS MORNING SHOWED A
PORTION OF THE CONVECTIVE OUTFLOW BOUNDARY THAT HAD MOVED INTO THE
NRN GULF OF MEXICO HAS RETURNED NWD...AND WAS IMPINGING UPON THE
COASTAL AREAS OF FAR SERN MS/SWRN AL /DAUPHIN ISLAND VICINITY/.
REGIONAL RADAR IMAGERY SHOWED CONVECTIVE CELLS MOVING INTO SRN
MOBILE COUNTY FROM OFFSHORE...WITH LIGHTNING ALSO DETECTED FARTHER
SSW OVER THE CHANDELEUR ISLANDS...WHERE A TRAILING PORTION OF THE
OUTFLOW BOUNDARY HAD BECOME ORIENTED NNE-SSW ALONG AND OFFSHORE OF
SERN LA.

SWLY MIDLEVEL WINDS OVER THE LOWER MS VALLEY-CENTRAL GULF COAST
STATES WILL CONTINUE TO STRENGTHEN THIS MORNING AS A PROGRESSIVE
SHORTWAVE TROUGH...CURRENTLY MOVING EWD ACROSS THE OZARKS-ARKLATEX
REGION PER MOISTURE CHANNEL IMAGERY...BECOMES NEGATIVELY TILTED.
THESE WINDS AND 30-35 KT SSWLY LLJ SUPPORT BULK SHEAR OF 40-55 KT
FOR ORGANIZED STORMS...WHILE EFFECTIVE SRH OF 100-200 M2/S2 INVOF
THE NWD MOVING BOUNDARY INTO THE DISCUSSION AREA WILL SUPPORT THE
POTENTIAL FOR LOW LEVEL ROTATION/AT LEAST A BRIEF TORNADO. MUCAPE
OF 200-400 J/KG N OF THE RETREATING BOUNDARY AND AOA 500 J/KG IN THE
WARM SECTOR SHOULD REMAIN MEAGER THROUGH THE MORNING AND WILL BE THE
MAIN LIMITING FACTOR FOR GREATER TSTM/SVR COVERAGE. AN ADDITIONAL
THREAT FOR AT LEAST A FEW STRONG TO SEVERE STORMS COULD DEVELOP
ALONG THE TRAILING EXTENT OF OVERNIGHT ELEVATED CONVECTION THAT
SHOULD MOVE INTO SWRN AL BETWEEN 11-12Z.

..PETERS/EDWARDS.. 12/17/2012

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

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

LAT...LON 29638923 30718891 31328798 31258688 30858631 30138664
30068723 29768820 29458862 29638923

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.