MESO: Mesoscale Discussion 1406

ACUS11 KWNS 022017
SWOMCD
SPC MCD 022017
NEZ000-SDZ000-MTZ000-WYZ000-022145-

MESOSCALE DISCUSSION 1406
NWS STORM PREDICTION CENTER NORMAN OK
0317 PM CDT THU JUL 02 2009

AREAS AFFECTED...MT...WY...SD...NE

CONCERNING...SEVERE THUNDERSTORM WATCH 538...

VALID 022017Z - 022145Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 538
CONTINUES.

A NEW WATCH MAY BE NEEDED TO THE SOUTH OF EXISTING SVR TSTM WATCH
538 WITHIN A FEW HOURS. MEANWHILE...SEVERE WEATHER POTENTIAL
CONTINUES ACROSS PARTS OF SERN MT...NERN WY AND ADJACENT PORTIONS OF
WRN SD.

RELATIVELY WEAK SYNOPTIC SCALE FORCING AND LIMITED SHEAR ACROSS MUCH
OF THE REGION ARE LEADING TO DIFFICULT FORECAST SCENARIO THROUGH THE
REST OF THE AFTERNOON. AN AXIS OF MODEST INSTABILITY /MLCAPE AROUND
1000 J PER KG/ EXISTS ACROSS PORTIONS OF SERN MT AND WRN SD...AND
EXTENDS SWD ACROSS THE NEB PNHDL. STORM DEVELOPMENT IN THE PAST FEW
HOURS APPEARS TO HAVE BEEN TIED PRIMARILY TO TERRAIN/OROGRAPHIC
INFLUENCES WITH LOW LEVEL UPSLOPE FLOW AND WEAK INHIBITION LEADING
TO CONVECTIVE INITIATION. AN INCREASE IN DEEP-LAYER EFFECTIVE SHEAR
AND ADDITIONAL DEVELOPMENT APPEARS UNDERWAY AS MID LEVEL
IMPULSE/SPEED MAX SPREADS EAST FROM NRN WY OVER THE NEXT FEW HOURS.

ADDITIONALLY...CHANCES FOR AT LEAST ISOLATED SEVERE STORM
DEVELOPMENT MAY INCREASE IN SERN WY AND ADJACENT WRN NEB THROUGH THE
EVENING AS WY SHORT WAVE TROUGH AND DIURNAL DESTABILIZATION
CONTRIBUTE TO POTENTIAL INITIATION. MODEST SHEAR IS ALREADY IN PLACE
THIS AREA WITH LOW LEVEL ELY WINDS TOPPED BY ABOUT 20-25KT WLY FLOW
IN THE MID LEVELS. IF STORMS APPEAR MORE LIKELY...A NEW WATCH MAY BE
NEEDED.

..CARBIN.. 07/02/2009

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

ATTN...WFO...LBF...UNR...CYS...BYZ...GGW...RIW...

LAT...LON 47470799 47220623 47230527 47340413 45890411 45880291
44550198 43040199 41020195 41020493 43450500 43460546
43500705 44470726 45530805 46110747 47470799

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