Thursday, April 16, 2009

MESO: Mesoscale Discussion 0481

ACUS11 KWNS 161621
SWOMCD
SPC MCD 161620
OKZ000-TXZ000-KSZ000-COZ000-161815-

MESOSCALE DISCUSSION 0481
NWS STORM PREDICTION CENTER NORMAN OK
1120 AM CDT THU APR 16 2009

AREAS AFFECTED...PORTIONS NW TX...ERN/NRN TX PANHANDLE...CENTRAL/ERN
OK PANHANDLE...WRN OK...WRN KS...EXTREME ERN CO.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 161620Z - 161815Z

POTENTIAL IS INCREASING FOR ISOLATED TO WIDELY SCATTERED AND
MARGINAL SVR HAIL...WITHIN GROWING PLUME OF CONVECTION NOW EVIDENT
FROM SW OK ACROSS NERN TX PANHANDLE TO VICINITY KS/CO BORDER. WHILE
THIS ACTIVITY MOVES N WITH GRADUAL INTENSIFICATION...SOME
BACKBUILDING/FILLING ALSO IS POSSIBLE ACROSS PORTIONS NW TX AND
CENTRAL/NRN PANHANDLE. THIS IS SEPARATE FROM MID-LATE
AFTERNOON/SFC-BASED SVR THREAT DISCUSSED IN DAY-1 OUTLOOK...AND IS
NOT EXPECTED TO BE AS WELL-ORGANIZED.

12Z UPPER AIR ANALYZES AND RUC GUIDANCE INDICATE INCREASING LOW
LEVEL MOISTURE -- ESPECIALLY IN 925-850 MB LAYER -- ASSOCIATED WITH
BROAD/40-50KT SSELY LLJ. MAX MOISTURE TRANSPORT SHOULD CONTINUE
ACROSS THIS REGION...PERHAPS SHIFTING SLIGHTLY WWD AS
PANHANDLES/SWRN KS/SERN CO SEGMENT OF LLJ BACKS AND INTENSIFIES
SOMEWHAT THROUGH EARLY AFTERNOON. THIS REGIME GRADUALLY WILL BECOME
INCREASINGLY JUXTAPOSED WITH ERN EDGE OF MORE ROBUST LARGE-SCALE
ASCENT AND COOLING ALOFT AS CENTER OF BROAD UPPER CYCLONE PIVOTS EWD
THROUGH 4-CORNERS AREA. MODIFIED 12Z RAOBS AND RUC SOUNDINGS
INDICATE ELEVATED MUCAPE IN 1000-1500 J/KG RANGE. PRIMARY LIMITING
FACTOR APPEARS TO BE LACK OF MORE ROBUST SHEAR FOR ELEVATED LIFTED
PARCELS. WITH STRONGEST DEEP-LAYER WINDS REMAINING W OF THIS AREA
AT LEAST UNTIL EARLY-MID AFTERNOON...FCST SOUNDINGS SHOW ONLY SMALL
CHANGES WITH HEIGHT IN DIRECTION/SPEED OF FLOW THROUGH
INFLOW-BUOYANT LAYERS. THIS SHOULD KEEP EFFECTIVE SHEAR MAGNITUDES
BELOW 30 KT IN MOST OF DISCUSSION AREA UNTIL INFLOW PARCELS BECOME
SFC-BASED...LIKELY AROUND MID-AFTERNOON NEAR W EDGE OF THIS
CLOUD/PRECIP AREA WHERE HEATING IS STRONGER. KINEMATIC GEOMETRY
ALSO SHOULD CONTRIBUTE TOWARD MIXTURE OF MULTICELL CLUSTERS AND
LINEAR MODAL TENDENCIES.

..EDWARDS.. 04/16/2009

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

ATTN...WFO...FWD...OUN...GID...DDC...SJT...GLD...LUB...AMA...
PUB...

LAT...LON 32599925 34199979 35720127 37760205 38650253 39570240
39920079 39369944 36479867 35019818 33579837 32899892
32599925

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