Mesoscale Discussion 840

MESOSCALE DISCUSSION 0840
NWS STORM PREDICTION CENTER NORMAN OK
0100 PM CDT FRI MAY 09 2008
AREAS AFFECTED...ERN WY...FAR SWRN SD...WRN NEB...NERN CO AND NWRN
KS
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 091800Z - 092030Z
TSTMS ARE EXPECTED TO DEVELOP ALONG THE FRONT RANGE OF ERN WY/NERN
CO OVER THE NEXT 2-3 HRS. A FEW OF THESE ARE EXPECTED TO BECOME SVR
WITH THE POTENTIAL FOR DMGG WINDS/LARGE HAIL AS THEY MOVE INTO FAR
SWRN SD...THE NEBRASKA PANHANDLE AND NWRN KS AFTER 21Z. THE AREA IS
BEING MONITORED FOR A POSSIBLE UPGRADE TO SLIGHT RISK AND A WW.
LATEST SFC ANALYSIS SHOWS A SFC LOW PRESSURE AREA OVER SERN WY /EAST
OF THE LARAMIE MTNS/. SFC PRESSURE FALLS HAVE ENSUED OVER MUCH OF
THE CENTRAL HIGH PLAINS AS A RESULT. LOW LEVEL MOISTURE REMAINS
MARGINAL ATTM...WITH SFC DWPTS IN THE LOWER-MID 40S IN A NARROW AXIS
EXTENDING FROM NWRN KS INTO NERN WY. FCST SOUNDINGS INDICATE A SFC
BASED PARCEL OF 63/42 WOULD SUPPORT SFC BASED TSTMS WITH MUCAPE
AROUND 1000 J/KG. A FEW TSTMS HAVE ALREADY DEVELOPED IN NERN
WY...WITH TSTM INITIATION ONLY 1-2 HRS AWAY IN SERN WY/NERN CO WHERE
CONVERGENCE IS EXPECTED TO BE MAXIMIZED. GIVEN STRENGTHENING MID
LEVEL WINDS /AHEAD OF ROCKIES SHORTWAVE TROUGH/ SUFFICIENT DEEP
LAYER SHEAR /50 KTS/ AND LOW WBZ HEIGHTS /AOB 4 KFT/ WILL SUPPORT
SUPERCELLS WITH THE THREAT FOR SVR HAIL/WIND. ALTHOUGH INITIALLY THE
STORMS WITHIN A MARGINAL INSTABILITY REGIME...GRADUALLY INCREASING
INSTABILITY /ESPECIALLY OVER SWRN NEB/NWRN KS/ MAY SUPPORT MORE
SUBSTANTIAL SVR THREAT IN THESE AREAS TOWARDS 00Z.
..CROSBIE.. 05/09/2008