Monday, March 16, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 170052
SWODY1
SPC AC 170049

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0749 PM CDT MON MAR 16 2009

VALID 170100Z - 171200Z

...NO TSTM AREAS FORECAST...

...PACIFIC NW COAST TO ERN ID/WRN WY...

WATER VAPOR IMAGERY AND LATEST MODEL GUIDANCE INDICATE A TRAIN OF
VORTICITY MAXIMA SITUATED ALONG CYCLONIC SIDE OF MID AND HIGH-LEVEL
JET STREAKS WHICH ARE PRESENT FROM THE NERN PACIFIC EWD INTO THE NRN
PLAINS. FORCING FOR ASCENT ASSOCIATED WITH THESE EMBEDDED IMPULSES
COUPLED WITH A STEEP LAPSE RATE ENVIRONMENT HAVE CONTRIBUTED TO
ISOLATED TSTM DEVELOPMENT THIS AFTERNOON NEAR THE MOUTH OF THE
COLUMBIA RIVER AND FARTHER TO THE E OVER THE SNAKE RIVER VALLEY OF
SRN ID.

THE POTENTIAL FOR ISOLATED LIGHTNING STRIKES IS EXPECTED TO PERSIST
THROUGH 03-04Z...PRIMARILY OVER ERN ID INTO WRN WY IN ADVANCE OF
BETTER-DEFINED VORTICITY MAXIMUM TRANSLATING THROUGH THE NRN
ROCKIES. GIVEN THE ISOLATED NATURE AND ANTICIPATED SHORT DURATION
OF THIS LIGHTNING ACTIVITY...NO GENERAL THUNDER AREA WILL BE
INCLUDED IN THIS FORECAST.

...WV...

A WELL-DEFINED SHORT WAVE TROUGH OVER OH/ERN KY WILL CONTINUE
ESEWD...EVENTUALLY PHASING WITH A LOWER LATITUDE TROUGH MOVING
THROUGH THE SERN STATES TONIGHT. A CONCENTRATED ZONE OF FORCING FOR
ASCENT ASSOCIATED WITH THIS FEATURE HAS BEEN SUFFICIENT TO SUSTAIN
ISOLATED TSTMS THIS EVENING WITHIN AN ONLY MARGINALLY UNSTABLE AIR
MASS PER 00Z REGIONAL SOUNDINGS. SIMILAR TO ABOVE...EXPECT THE
LIGHTNING ACTIVITY TO PERSIST THROUGH 03-04Z PRIOR TO DIMINISHING.
NO GENERAL THUNDER AREA WILL BE ADDED.

...FL...

SURFACE COLD FRONT /AIDED BY CONVECTIVE OUTFLOW/ WILL CONTINUE TO
SHIFT SEWD THROUGH THE PENINSULA TONIGHT AS NERN EXTENSION OF
POSITIVELY-TILTED SHORT WAVE TROUGH MOVES THROUGH THE SRN
APPALACHIANS. LATEST REGIONAL RADAR DATA INDICATE MORE VIGOROUS
CONVECTIVE DEVELOPMENT NEAR FRONTAL ZONE APPROXIMATELY 50 SSW AAF.
HOWEVER...00Z FL SOUNDINGS INDICATE THAT MIDLEVEL LAPSE RATES REMAIN
QUITE POOR AND THIS SHOULD EFFECTIVELY PROHIBIT ANY TSTM THREAT
ONSHORE THROUGH TONIGHT.

..MEAD.. 03/17/2009

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