MESO: Mesoscale Discussion 1774

ACUS11 KWNS 042055
SWOMCD
SPC MCD 042054
SDZ000-NEZ000-COZ000-WYZ000-042230-

MESOSCALE DISCUSSION 1774
NWS STORM PREDICTION CENTER NORMAN OK
0354 PM CDT TUE AUG 04 2009

AREAS AFFECTED...PARTS OF ERN WY / SWRN SD / NEB PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 042054Z - 042230Z

ISOLD-SCTD TSTMS WILL LIKELY DEVELOP LATER THIS AFTERNOON INTO THIS
EVENING ACROSS PARTS OF THE CNTRL AND NRN HIGH PLAINS. THE MAIN
THREATS WITH THESE STORMS WILL BE LARGE HAIL AND SEVERE WIND GUSTS.

SURFACE MESOANALYSIS DEPICTS A STATIONARY FRONTAL BOUNDARY FROM NEAR
THE CO-NEB-KS BORDER NWWD INTO N-CNTRL WY WITH SEASONABLY MOIST
UPSLOPE FLOW ON THE SRN PERIPHERY OF ND SURFACE HIGH. MID-AFTERNOON
VISIBLE/RADAR MOSAIC IMAGERY SHOWS BUILDING CU FIELD/RECENTLY
DEVELOPED ISOLD TSTMS OVER THE HIGHER TERRAIN FROM THE COLORADO
FRONT RANGE NWD TO THE LARAMIE RANGE. THIS IS PARTLY DUE TO STRONG
DIABATIC HEATING AND WEAK LARGE SCALE ASCENT APPROACHING THE AREA IN
ASSOCIATION WITH A UPPER IMPULSE OVER NWRN WY. THIS FEATURE WILL
LIKELY TSTM DEVELOPMENT IN THE NEXT 1-3 HRS AS FURTHER
HEATING/UPSLOPE FLOW ACT TO DESTABILIZE THE AIRMASS AND WEAKEN THE
REMAINING CAP EVEN FURTHER.

40 KT 6 KM AGL FLOW ATOP STRONGLY VEERING /SELY-WLY/ LOW LEVEL WIND
PROFILE WILL SUPPORT STORM ORGANIZATION /INCLUDING SUPERCELLS/ AS
UPDRAFTS INTENSIFY AS THEY MOVE INTO MORE MOIST ENVIRONMENT E OF THE
HIGHER TERRAIN ALONG THE NEB/WY BORDER. STEEP LOW-MID LEVEL LAPSE
RATES WITHIN MODERATELY UNSTABLE ENVIRONMENT WILL SUPPORT BOTH A
LARGE HAIL AND DMGG WIND THREAT WITH TIME WITH AN ISOLD TORNADO
POSSIBLE AS WELL. THERE IS SOME UNCERTAINTY FARTHER S WITH REGARD
TO SEVERE POTENTIAL OVER NERN CO/SRN PORTION OF THE DISCUSSION AREA
AS THE DISTURBANCE EXERTS LESSENING INFLUENCE/FAVORABLE SUPPORT FOR
STRONG/SEVERE STORMS.

..SMITH.. 08/04/2009

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

ATTN...WFO...UNR...BOU...CYS...

LAT...LON 40630450 41900474 43970582 44670583 44740514 44400450
43590379 42200300 41050271 40270308 40160390 40630450

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