Saturday, April 21, 2007

MESO: Mesoscale Discussion 0523

ACUS11 KWNS 211111
SWOMCD
SPC MCD 211111
KSZ000-NEZ000-TXZ000-OKZ000-211315-

MESOSCALE DISCUSSION 0523
NWS STORM PREDICTION CENTER NORMAN OK
0611 AM CDT SAT APR 21 2007

AREAS AFFECTED...NWRN KS THROUGH SWRN NEB

CONCERNING...OUTLOOK UPGRADE

VALID 211111Z - 211315Z

MODERATE RISK WILL BE EXTENDED NWD INTO SWRN NEB ON THE 13Z UPDATE.

THE ATMOSPHERE IS EXPECTED TO BECOME MODERATELY UNSTABLE FROM WRN TX
NWD THROUGH WRN AND CNTRL NEB THIS AFTERNOON. PRE-EXISTING LOW LEVEL
DEWPOINTS IN THE 50S...700-500 MB LAPSE RATES OF 8+ C/KM AND SURFACE
HEATING WILL CONTRIBUTE TO MLCAPE FROM 1500 TO 2000 J/KG. STORMS
WILL LIKELY DEVELOP OVER THE WRN HIGH PLAINS THIS AFTERNOON AS THE
PACIFIC FRONT MERGES WITH DRYLINE AND AS DEEP FORCING FOR ASCENT
INCREASES IN ADVANCE OF NEWD EJECTING SHORTWAVE TROUGH. STRONG DEEP
LAYER SHEAR WILL SUPPORT SUPERCELLS AS INITIAL MODE.
HOWEVER...DOMINANT MODE WILL LIKELY EVOLVE INTO LINE SEGMENTS OR
MIXED MODES WITH LINES AND SUPERCELLS. VERY LARGE HAIL AND ISOLATED
TORNADOES WILL BE THE INITIAL PRIMARY THREATS. HOWEVER...THE THREAT
WILL TRANSITION TO MAINLY LARGE HAIL AND DAMAGING WIND DURING THE
EVENING.

.DIAL.. 04/21/2007

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

ATTN...WFO...GID...LBF...DDC...GLD...LUB...AMA...

40690012 38139995 34040031 33200146 33650227 36280189
40260145

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