DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 251233
SWODY1
SPC AC 251230

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0730 AM CDT FRI OCT 25 2013

VALID 251300Z - 261200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
LARGE-SCALE PATTERN OVER NORTH AMERICAN MIDLATITUDES WILL REMAIN
CHARACTERIZED BY ERN TROUGHING...AND WRN RIDGING PENETRATED BY THREE
PRIMARY MID-UPPER CYCLONES ON SMALLER SCALES...
1. LOW INITIALLY LOCATED OVER SRN UT/NRN AZ...FCST TO MOVE SLOWLY
EWD TO ENEWD THROUGH PERIOD...WHILE WEAKENING. BY 12Z...THIS
FEATURE SHOULD DEVOLVE INTO OPEN-WAVE TROUGH EXTENDING FROM NRN NM
NEWD OVER CENTRAL HIGH PLAINS. BY THAT TIME...THIS PERTURBATION
WILL BEGIN TO LINK WITH SWRN FRINGE OF NWLY FLOW ALOFT ASSOCIATED
WITH ERN CONUS TROUGH...AND REINFORCED BY STG SHORTWAVE DIGGING SEWD
ACROSS UPPER GREAT LAKES.
2. SMALL BUT PRONOUNCED MID-UPPER CYCLONE NOW DRIFTING EWD OVER
VANCOUVER ISLAND...ALMOST DIRECTLY IN MEAN-RIDGE POSITION. THIS
PERTURBATION SHOULD TURN SSEWD AND DRIFT VERY SLOWLY ACROSS OLYMPIC
PENINSULA/PUGET SOUND REGION.
3. BROAD MID-UPPER CYCLONE WITH MULTIPLE/EMBEDDED MESOSCALE
CIRCULATIONS EVIDENT IN MOISTURE CHANNEL IMAGERY...BUT GENERALLY
CENTERED NEAR 38N133W OFFSHORE NRN CA. THIS FEATURE SHOULD DRIFT
SWD THROUGH PERIOD.

OF THESE CYCLONES...ONLY SWRN CONUS FEATURE WILL EXERT ANY
SUBSTANTIAL INFLUENCE ON CONVECTIVE POTENTIAL TODAY.

...4-CORNERS REGION TO SRN ROCKIES AND SRN HIGH PLAINS...
WIDELY SCATTERED TO SCATTERED TSTMS ARE POSSIBLE...SOME OF WHICH MAY
PRODUCE SMALL/SUB-SVR HAIL MAINLY DURING AFTN/EVENING. SVR THREAT
IS TOO LOW FOR AOA 5% PROBABILITIES...GIVEN LACK OF GREATER
MAGNITUDE TO BOTH CAPE AND DEEP SHEAR.

EXPANSIVE FIELD OF DIFLUENT FLOW ALOFT...JUXTAPOSED WITH MIDLEVEL
UVV OVER AZ...OVERLIES BROAD PLUME OF PAC MOISTURE TRANSPORT AND
LOW-LEVEL WAA CONVEYOR WRAPPING INTO ERN SEMICIRCLE OF MID-UPPER
CYCLONE. ALTHOUGH WAVE ALOFT WILL WEAKEN GRADUALLY WITH TIME...THIS
REGIME WILL SHIFT EWD ATOP MRGL BUT INCREASING GULF MOISTURE IN LOW
LEVELS. WIDELY SCATTERED TO ISOLATED TSTMS HAVE PERSISTED ALL NIGHT
INTO EARLY MORNING HOURS IN THIS REGIME...AND EPISODIC/EMBEDDED
THUNDER IS LIKELY WITHIN PRECIP PLUME THROUGHOUT REMAINDER PERIOD AS
IT SHIFTS SLOWLY EWD ACROSS GEN TSTM OUTLOOK. GREATEST COVERAGE MAY
OCCUR OVER PORTIONS 4-CORNERS AREA SEWD ACROSS NWRN NM...ESPECIALLY
CUMULATIVELY FROM AFTN INTO EARLY OVERNIGHT HOURS -- GIVEN SLOW
MOVEMENT OF PARENT SYSTEM...AND POTENTIAL FOR PATCHES OF FAVORABLE
DIABATIC SFC HEATING TO UNDERLIE COOLING AIR ALOFT FROM MID-AFTN
INTO EVENING. MLCAPE MAY REACH NEAR 500 J/KG OVER PORTIONS
CENTRAL/SRN NM TODAY.

..EDWARDS/COHEN.. 10/25/2013

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