SWODY1
SPC AC 020550
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1250 AM CDT THU OCT 02 2008
VALID 021200Z - 031200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
SYNOPTIC PATTERN WILL REMAIN CHARACTERIZED BY HIGH AMPLITUDE
TROUGHING IN ERN CONUS AND RIDGING IN W. SHORTWAVE UPPER CYCLONE --
STRENGTHENING OVER NRN ONT ATTM -- IS FCST TO DIG SSEWD INTO LARGE
SCALE TROUGH POSITION BY 3/00Z THEN TURN EWD. ASSOCIATED COLD AIR
ALOFT WILL CONTRIBUTE TO INSTABILITY IN SUPPORT OF GEN THUNDER
POTENTIAL OVER PORTIONS GREAT LAKES AND ADJACENT STATES.
MEANWHILE...STG SHORTWAVE TROUGH IS EVIDENT IN MOISTURE CHANNEL
IMAGERY W OF CA COAST...CROSSING 140W. THIS PERTURBATION IS FCST TO
EJECT NEWD OUT OF NERN PACIFIC MEAN TROUGH POSITION...AND ACROSS ORE
AROUND 03/00Z.
AT SFC...COLD FRONT NOW MOVING FARTHER OFFSHORE MOST OF E
COAST...AND SEWD OVER NRN FL -- WILL CONTINUE SEWD ACROSS FL WITH
MINIMAL CONVERGENCE. DESPITE SOME LEE THROUGHING OVER CENTRAL HIGH
PLAINS...TRAJECTORIES ASSOCIATED WITH SFC RIDGING ACROSS NWRN GULF
WILL PRECLUDE SUBSTANTIAL MOISTURE RETURN THIS PERIOD.
OF THE VARIOUS WIDELY DISPERSED AREAS OF GEN TSTM POTENTIAL...TWO
APPEAR TO HAVE CONDITIONAL SVR POTENTIAL...BUT TOO MRGL/ISOLATED TO
WARRANT GRID PROBABILITIES AOA 5-PERCENT ATTM. IN BOTH AREAS...
LACK OF MORE ROBUST MOISTURE/BUOYANCY SHOULD PRECLUDE ORGANIZED SVR
THREAT...THOUGH SOME GUSTS APCHG SVR LEVELS CANNOT BE RULED OUT.
...INTERIOR PACIFIC NW...
ARRIVAL OF SHORTWAVE TROUGH...WITH RESPECT TO AFTERNOON PEAK WARMING
OF BOUNDARY LAYER...IS EXPECTED TO CONTRIBUTE TO CONVECTIVE
POTENTIAL ACROSS MUCH OF WA AND CENTRAL/ERN ORE...JUXTAPOSED WITH
POCKETS OF RELATIVELY MAXIMIZED MOISTURE AND STRENGTHENING VERTICAL
SHEAR. STEEP LOW-MIDLEVEL LAPSE RATES...WELL-MIXED SUBCLOUD
LAYERS...HIGH DEW POINT DEPRESSIONS AND RESULTING WELL-MIXED
BOUNDARY LAYERS MAY FAVOR STG GUSTS OR MAINTENANCE OF SMALL HAIL
ALOFT TO SFC. HOWEVER...WEAKER LAPSE RATES ABOVE APPROXIMATELY 400
MB WILL HELP TO LIMIT BUOYANCY...AND ESPECIALLY POSITIVE AREA ABOVE
ROUGHLY -20 DEG C ISOTHERM. PRIND MLCAPES GENERALLY WILL REMAIN AOB
200 J/KG MOST AREAS.
...S-CENTRAL HIGH PLAINS...
ISOLATED TO WIDELY SCATTERED TSTMS SHOULD DEVELOP DURING MID-LATE
AFTERNOON HOURS AS HIGHER TERRAIN WARMS...REMOVING CINH. MODIFIED
NAM-KF FCST SOUNDINGS SUGGEST MLCAPES 500-750 J/KG ARE
POSSIBLE...SUPPORTED BY STEEP DEEP-LAYER LAPSE RATES AND SFC DEW
POINTS NEAR 40 F. DIRECTIONAL SHEAR WILL BE STG BENEATH NW FLOW
ALOFT...BUT WITH RELATIVELY MEAGER ABSOLUTE FLOWS LIMITING BULK
SHEAR VALUES.
..EDWARDS/HURLBUT.. 10/02/2008
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