DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 231958
SWODY1
SPC AC 231957

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0257 PM CDT TUE OCT 23 2012

VALID 232000Z - 241200Z

...NO SVR TSTM AREAS FORECAST...

...SD TO ERN ND/NWRN MN...
FORCING FOR ASCENT ATTENDANT TO A SHORTWAVE TROUGH WILL CONTINUE TO
SPREAD NEWD ACROSS ERN ND AND NWRN MN THIS AFTERNOON AIDING IN
ADDITIONAL TSTM DEVELOPMENT. MEANWHILE...SUBSIDENCE IN THE WAKE OF
THIS TROUGH WILL RESULT IN A DIMINISHING TREND FOR DEEP CONVECTION
FROM SW-NE...WITH THIS TREND ALREADY UNDERWAY ACROSS SD AND SRN ND
PER THE LACK OF RECENT LIGHTNING STRIKES.

...GREAT LAKES AND OH VALLEY...
A PAIR OF SHORTWAVE TROUGHS MOVING EWD ACROSS THE UPPER GREAT LAKES
AND LOWER OH VALLEY WILL UNDERGO FURTHER WEAKENING AS THEY MOVE INTO
AN UPPER RIDGE AXIS EXTENDING FROM THE SERN STATES TO ONTARIO.
OVERALL TSTM COVERAGE IS EXPECTED TO DECREASE INTO THE EVENING AS
MASS FIELDS WEAKEN IN RESPONSE TO THE DEAMPLIFICATION OF THE
MIDLEVEL TROUGHS.

..PETERS.. 10/23/2012

.PREV DISCUSSION... /ISSUED 1129 AM CDT TUE OCT 23 2012/

...SYNOPSIS...
A BROAD TROUGH WILL PERSIST OVER THE PAC COAST AND NRN INTERMOUNTAIN

WEST...ALONG WITH A DOWNSTREAM RIDGE OVER THE UPPER MS VALLEY AND
GREAT LAKES. STEEP LAPSE RATE PROFILES WITH MARGINAL LOW-LEVEL
MOISTURE/BUOYANCY WILL SUPPORT A RISK FOR ISOLATED LOW-TOPPED
THUNDERSTORMS ALONG THE COAST FROM NRN CA TO WA. THERE WILL ALSO BE
A RISK FOR ISOLATED THUNDERSTORMS INTO THE SACRAMENTO VALLEY...WHERE
VERTICAL SHEAR WILL BE MARGINALLY FAVORABLE FOR LOW-TOPPED
SUPERCELLS. HOWEVER...THE EXPECTED VERY WEAK BUOYANCY SUGGESTS THAT
THE INTRODUCTION OF SEVERE STORM PROBABILITIES IS NOT NECESSARY.

OTHERWISE...CLUSTERS OF ELEVATED THUNDERSTORMS WILL CONTINUE ACROSS
THE GREAT LAKES/OH VALLEY REGIONS IN ASSOCIATION WITH LOW-LEVEL WAA
AND A WEAK EMBEDDED MIDLEVEL TROUGH MOVING EWD OVER IL/WI. FARTHER
TO THE W...THE LOW LEVELS WILL WARM/MOISTEN...BUT THIS WILL OCCUR
BENEATH A STRENGTHENING CAP SPREADING EWD FROM THE CENTRAL PLAINS.
CLOUDS WILL TEND TO LIMIT SURFACE HEATING INVOF THE SURFACE WARM
FRONT IN IA...AND THE CAP WILL BE MORE PRONOUNCED ALONG THE
DEVELOPING DRYLINE ACROSS KS/OK. THOUGH A CONDITIONAL SEVERE STORM
RISK EXISTS ACROSS THESE AREAS...THE PROBABILITY OF SURFACE-BASED
THUNDERSTORM INITIATION IS TOO LOW TO WARRANT THE INTRODUCTION OF
ANY UNCONDITIONAL SEVERE STORM PROBABILITIES.

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