MESO: Mesoscale Discussion 1983

ACUS11 KWNS 250552
SWOMCD
SPC MCD 250551
INZ000-KYZ000-ILZ000-MOZ000-250745-

MESOSCALE DISCUSSION 1983
NWS STORM PREDICTION CENTER NORMAN OK
1251 AM CDT TUE SEP 25 2012

AREAS AFFECTED...MID-MS VALLEY

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 250551Z - 250745Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ELEVATED TSTMS WILL INCREASE IN COVERAGE FROM NRN/CNTRL MO
INTO SRN IL. A RISK FOR MARGINALLY SEVERE HAIL WILL EXIST WITHIN THE
STRONGER CORES.

DISCUSSION...ELEVATED TSTMS HAVE COMMENCED ACROSS NRN MO WITHIN A
CORRIDOR OF ROBUST 850-700 MB WARM THETA-E ADVECTION. ALTHOUGH BASES
APPEAR TO BE ROOTED AROUND 700 MB PER METAR CEILING HEIGHTS...THIS
DEVELOPMENT IS BEING FED ON THE PERIPHERY OF A N/S-ORIENTED AXIS OF
MUCAPE FROM 1000-1500 J/KG CENTERED ACROSS THE OZARK PLATEAU.
ALTHOUGH STRONG LOW-LEVEL SHEAR EXISTS BELOW THE CLOUD BASE...NEARLY
UNIDIRECTIONAL MODERATE WLYS IN THE CLOUD-BEARING LAYER SHOULD YIELD
ONLY WEAK SPEED SHEAR WHICH WILL LARGELY MITIGATE SUSTAINED UPDRAFT
ROTATION. THIS SHOULD LIMIT HAIL GROWTH POTENTIAL DESPITE THE
PRESENCE OF STEEP MID-LEVEL LAPSE RATES.

00Z WRF-NSSL/NMM RUNS WERE A BIT SLOW WITH DEVELOPMENT...BUT THEIR
SCENARIO APPEARS REASONABLE WITH CONVECTION GROWING UPSCALE INTO A
CLUSTER. RELATIVELY COOL AND DRY SURFACE CONDITIONS /ESPECIALLY
DOWNSTREAM WITH ERN EXTENT/ BENEATH A FAIRLY STOUT EML SHOULD LIMIT
PENETRATION OF STRONGER DOWNDRAFTS TO THE SURFACE.

..GRAMS/THOMPSON.. 09/25/2012

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

ATTN...WFO...IND...PAH...ILX...LSX...EAX...

LAT...LON 40379321 39939097 39128790 38768745 38348736 37568778
37308843 37228901 37638993 38059097 38989286 39619406
39859416 40189405 40379321

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