DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 090604
SWODY2
SPC AC 090603

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1203 AM CST SUN DEC 09 2012

VALID 101200Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS MON ACROSS PARTS OF NE MS...NRN
AND CNTRL AL...SERN TN...NRN GA...AND FAR WRN NC...

...SYNOPSIS...
BROAD UPPER TROUGHING IS EXPECTED TO PERSIST ACROSS MUCH OF INTERIOR
NORTH AMERICA THROUGH THIS FORECAST PERIOD. HOWEVER... SHORT WAVE
RIDGING MAY BUILD ACROSS THE CANADIAN ROCKIES AND PACIFIC
NORTHWEST...AHEAD OF A SIGNIFICANT SHORT WAVE TROUGH BEGINNING TO
DIG ACROSS THE NORTHEAST PACIFIC.

MODELS CONTINUE TO SUGGEST THAT ANY PHASING OF A PAIR OF SHORT WAVE
IMPULSES...NOW DIGGING ACROSS AND TO THE LEE OF THE ROCKIES...WILL
BE SHORT-LIVED...WITH THE NORTHERN IMPULSE FORECAST TO REMAIN FAIRLY
VIGOROUS...WHILE ACCELERATING NORTHEAST OF THE GREAT LAKES THROUGH
EASTERN CANADA. THE TRAILING SOUTHERN IMPULSE PROBABLY WILL BECOME
INCREASINGLY SHEARED AS IT LIFTS NORTHEAST OF THE SOUTHERN PLAINS
THROUGH THE OHIO VALLEY AND NORTHEAST. AND SECONDARY SURFACE WAVE
DEVELOPMENT ALONG A COLD FRONT APPROACHING THE APPALACHIANS AND
LOWER MISSISSIPPI VALLEY/WESTERN GULF COAST REGION IS EXPECTED TO
REMAIN WEAK. WHILE THE EASTWARD PROGRESSION OF THE SURFACE FRONT
OUTPACES COOLING ALOFT...FURTHER STRENGTHENING OF PRE-FRONTAL DEEP
LAYER MEAN FLOW FIELDS STILL DOES APPEAR POSSIBLE.

THE WEAK LAPSE RATES ALOFT WITHIN THE PRE-FRONTAL ENVIRONMENT WILL
LIMIT CAPE AND CONVECTIVE POTENTIAL MONDAY AND MONDAY NIGHT. WHILE
A BROAD AREA WITH THE RISK FOR THUNDERSTORMS IS BEING MAINTAINED
ACROSS MUCH OF THE EAST...PROBABILITIES FOR MOST AREAS DO APPEAR
GENERALLY NEAR THE MINIMUM 10 PERCENT THRESHOLD FOR A CATEGORICAL
THUNDERSTORM OUTLOOK. ONE EXCEPTION MAY BE ACROSS PARTS OF THE
CENTRAL AND EASTERN GULF STATES INTO THE SOUTHERN APPALACHIANS...
WHERE IT IS APPEARING MORE PROBABLE THAT THUNDERSTORM ACTIVITY WILL
BE ACCOMPANIED BY A SEVERE WEATHER THREAT.

...PARTS OF NE MS/NRN AND CNTRL AL...NRN GA...SERN TN...WRN NC...
THERE APPEARS INCREASING AGREEMENT AMONG VARIOUS MODELS THAT FORCING
FOR UPWARD VERTICAL MOTION WITH THE SOUTHERN IMPULSE MAY REMAIN
STRONG ENOUGH TO ENHANCE CONVECTIVE DEVELOPMENT ACROSS NORTHEAST
MISSISSIPPI INTO NORTHERN ALABAMA BY LATE MONDAY MORNING...BEFORE
SPREADING EAST NORTHEASTWARD THROUGH THE SOUTHERN APPALACHIANS BY
LATE AFTERNOON. PRE-FRONTAL MIXED LAYER CAPE IN FORECAST SOUNDINGS
ACROSS THIS REGION IS RATHER WEAK /GENERALLY AOB 500 J PER KG/...BUT
THE NAM...IN PARTICULAR...SUGGESTS IT WILL EXTEND THROUGH THE MIXED
PHASE LAYER FAVORABLE FOR CHARGE SEPARATION AND LIGHTNING. AND THE
CONVECTION PROBABLY WILL BE STRONG ENOUGH TO ENHANCE THE DOWNWARD
TRANSFER OF MOMENTUM ASSOCIATED WITH 45-50+ KT MEAN CLOUD BEARING
LAYER WIND FIELDS. THE EVOLUTION OF AN ORGANIZED CONVECTIVE SYSTEM
APPEARS POSSIBLE...WITH DAMAGING WIND GUSTS THE PRIMARY SEVERE
THREAT...BEFORE FORCING DIMINISHES AND ACTIVITY WEAKENS IN A MORE
STABLE ENVIRONMENT EAST OF THE SOUTHERN APPALACHIANS.

..KERR.. 12/09/2012

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.