MESO: Mesoscale Discussion 1520

ACUS11 KWNS 202045
SWOMCD
SPC MCD 202045
ARZ000-LAZ000-TXZ000-OKZ000-202315-

MESOSCALE DISCUSSION 1520
NWS STORM PREDICTION CENTER NORMAN OK
0345 PM CDT FRI JUL 20 2012

AREAS AFFECTED...SRN/WRN OK...NRN TX...ERN TX PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 202045Z - 202315Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...A VERY ISOLATED SVR MICROBURST POTENTIAL WILL EXIST THIS
AFTERNOON...AND THE ISSUANCE OF A WW IS UNLIKELY.

DISCUSSION...OKLAHOMA MESONET OBSERVATIONS INDICATE THAT A SFC
HOT-THERMAL AXIS -- TEMPS FROM 105 TO 109 DEGREES -- ARCS FROM NW OK
THROUGH THE OKC METRO AREA AND FARTHER SE INTO SERN OK. A SFC TROUGH
ALIGNS WITH THERMAL AXIS...WITH A REMNANT/DIFFUSE STATIONARY FRONT
DRAPED NEARLY W-E JUST NORTH OF THE THERMAL AXIS. OVERLAPPING THE
SRN FRINGES OF THE HOTTEST SFC TEMPERATURES...A RIBBON OF ENHANCED
MID-LEVEL MOISTURE PER WATER VAPOR IMAGERY EXTENDS FROM THE ERN TX
PANHANDLE TROUGH SRN OK/NRN TX AND FARTHER EAST ACROSS SRN AR/NRN
LA...WITH 700-MB DEWPOINTS IN EXCESS OF 6C PER 12Z RAOBS. DEEP
BOUNDARY-LAYER CIRCULATIONS AMIDST THIS RELATIVE MAXIMUM IN MOISTURE
HAVE ALLOWED VERY ISOLATED STORMS TO DEVELOP. THIS DEVELOPMENT HAS
BEEN AIDED BY ASCENT ALONG THE TROUGH...AND PERHAPS BY A REMNANT
MID-LEVEL CIRCULATION NEAR THE INTERSECTION OF I-35 AND THE RED
RIVER WHICH HAS BECOME INCREASINGLY ILL-DEFINED THROUGH THE DAY.

WEAK FLOW THROUGH THE LOW/MID LEVELS PER AREA VWP DATA WILL FOSTER A
PULSE CONVECTIVE MODE AND DISORGANIZED CONVECTION...MOVING SLOWLY
SSWWD/SWWD. HOWEVER...VERY STEEP LOW-LEVEL LAPSE RATES OWING TO THE
HOT SFC TEMPERATURES -- SUPPORTING DCAPE WELL IN EXCESS OF
1000 J/KG -- WILL PROMOTE STRONG MICROBURSTS THROUGH THE AFTERNOON.
GIVEN THESE THERMODYNAMIC CONDITIONS...VERY ISOLATED INSTANCES OF
SVR WIND GUSTS CANNOT BE RULED OUT WITH THE STRONGEST STORMS.

..COHEN/HART.. 07/20/2012

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

ATTN...WFO...LZK...SHV...TSA...FWD...OUN...SJT...LUB...AMA...

LAT...LON 32159580 32439762 33089917 34370007 35910037 36380004
36259920 35249783 34619584 34359417 34139344 33619315
32829352 32309421 32159580

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