MESO: Mesoscale Discussion 2273

ACUS11 KWNS 300734
SWOMCD
SPC MCD 300734
ALZ000-FLZ000-MSZ000-LAZ000-300900-

MESOSCALE DISCUSSION 2273
NWS STORM PREDICTION CENTER NORMAN OK
0134 AM CST SUN DEC 30 2007

AREAS AFFECTED...S-CNTRL AND SERN LA / SERN MS / SWRN AL / WRN FL
PNHDL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 300734Z - 300900Z

THE POTENTIAL WILL EXIST FOR MARGINALLY SEVERE HAIL WITH THE MOST
INTENSE ELEVATED STORMS EARLY THIS MORNING. IN ADDITION...LOCALLY
HEAVY RAINFALL WITH HOURLY RATES APPROACHING 1.0-1.5 INCHES WILL BE
POSSIBLE DUE TO TRAINING AND/OR BACKBUILDING OF STORMS.

LATEST MESOANALYSIS INDICATED A QUASI-STATIONARY BOUNDARY EXTENDING
FROM CNTRL GA SWWD THROUGH THE WRN FL PNHDL AND INTO THE NRN GULF OF
MEXICO. RUC OBJECTIVE FIELDS AND REGIONAL VWPS INDICATE THAT
WAA/ISENTROPIC ASCENT ASSOCIATED WITH A BROAD SWLY FLOW REGIME AT
850 MB IS LARGELY CONTRIBUTING TO ONGOING TSTMS N OF SURFACE FRONTAL
BOUNDARY. SHORT TERM MODEL GUIDANCE SUGGESTS THAT THIS AIR FLOW
PATTERN WILL CONTINUE THROUGH THE EARLY MORNING HOURS...GRADUALLY
STRENGTHENING WITH TIME IN RESPONSE TO APPROACH OF MIDLEVEL TROUGH
CURRENTLY OVER TX.

RUC PROXIMITY SOUNDINGS INDICATE THAT STORMS ARE ROOTED IN A
MOIST...ELEVATED AIR MASS ROUGHLY 0.5-1.5 KM AGL. THIS MOISTURE
COUPLED WITH RATHER STEEP MID-LEVEL LAPSE RATES ARE RESULTING IN
MODEST...ELEVATED INSTABILITY WITH MUCAPES OF 500-1000 J/KG.
MOREOVER...THESE DATA ALSO INDICATE THAT CLOUD BEARING SHEAR IS
SUPPORTIVE OF SOME UPDRAFT ROTATION WITH EFFECTIVE BULK SHEARS OF
35-40 KT. AS SUCH...SOME POTENTIAL WILL EXIST FOR ISOLATED...
MARGINALLY SEVERE HAIL WITH THE MOST INTENSE STORMS.
ADDITIONALLY...CORRIDORS OF LOCALLY EXCESSIVE RAINFALL WILL BE
POSSIBLE OWING TO TRAINING AND/OR BACKBUILDING STORMS WHERE HOURLY
RATES COULD APPROACH 1.0-1.5 INCHES.

.MEAD.. 12/30/2007

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

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

29589203 30909043 31948851 32308674 32208607 31618588
30758622 30018758 29338928 28959063 28899167

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