SWODY2
SPC AC 221719
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1119 AM CST TUE FEB 22 2011
VALID 231200Z - 241200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS INDICATE THAT BLOCKING WILL PERSIST WITHIN THE LARGE-SCALE
PATTERN OVER THE EAST CENTRAL AND NORTHEAST PACIFIC...WITH A
DEVELOPING HIGH CENTER BECOMING MORE PROMINENT NEAR THE GULF OF
ALASKA BY LATE WEDNESDAY/WEDNESDAY NIGHT. AS THIS OCCURS...WITHIN
ONE BELT OF WESTERLIES EXTENDING DOWNSTREAM...A SIGNIFICANT CLOSED
LOW/TROUGH IS PROGGED TO CONTINUE EVOLVING AND DIGGING NEAR THE
PACIFIC NORTHWEST COAST. THIS APPEARS LIKELY TO CONTRIBUTE TO THE
NORTHEASTWARD ACCELERATION OF THE CLOSED LOW NOW DIGGING WITHIN
ANOTHER STREAM TO THE WEST AND SOUTH OF THE SOUTHERN CALIFORNIA
COAST.
WITH THE LARGE-SCALE MID/UPPER FLOW REMAINING AT LEAST BROADLY
CONFLUENT ACROSS MUCH OF THE INTERMOUNTAIN WEST...ROCKIES AND
PLAINS...GUIDANCE HAS BEEN CONSISTENT SUGGESTING THAT THE LATTER
CIRCULATION WILL WEAKEN CONSIDERABLY AS IT LIFTS ACROSS THE SOUTHERN
U.S./NORTHERN MEXICAN PLATEAU AND SOUTHERN ROCKIES DURING THIS
PERIOD. HOWEVER...FLOW WITHIN THE WESTERN PERIPHERY OF A BROAD
UPPER RIDGE OVER THE SOUTH CENTRAL AND SOUTHEASTERN STATES IS
PROGGED TO STRENGTHEN...AS IS LARGE-SCALE ASCENT WITHIN A DEVELOPING
LOWER/MID TROPOSPHERIC WARM ADVECTION REGIME FROM PARTS OF THE
SOUTHERN PLAINS INTO THE LOWER OHIO/TENNESSEE VALLEYS. COINCIDENT
WITH AN INCREASINGLY MOIST RETURN FLOW OFF THE WESTERN GULF OF
MEXICO...GENERALLY CHARACTERIZED BY PRECIPITABLE WATER OF 1 TO 1.25
INCHES...THIS IS EXPECTED TO SUPPORT A GROWING RISK FOR THUNDERSTORM
ACTIVITY WEDNESDAY NIGHT INTO THURSDAY.
...SOUTHERN PLAINS INTO LWR OH AND TENNESSEE VALLEYS...
ALTHOUGH MODELS INDICATE SUBSTANTIVE BOUNDARY LAYER MOISTENING WILL
OCCUR THROUGH MUCH OF THE SOUTHERN PLAINS AND LOWER MISSISSIPPI
VALLEY...STORM DEVELOPMENT IS EXPECTED TO BE SUPPRESSED DURING THE
DAY DUE TO WEAK FORCING/MID-LEVEL INHIBITION. DUE TO THE NATURE OF
THE EVOLVING FORCING AND TIME OF DAY...MUCH OF THE ANTICIPATED
CONVECTIVE DEVELOPMENT LATE WEDNESDAY NIGHT IS EXPECTED TO BE BASED
ABOVE A NEAR SURFACE STABLE LAYER. SO...THE RISK FOR SEVERE STORMS
SEEMS LIKELY TO REMAIN LOW...DESPITE INCREASINGLY FAVORABLE SHEAR IN
THE PRESENCE OF AT LEAST WEAK CAPE.
STEEPEST LOW- AND MID-LEVEL LAPSE RATES ARE EXPECTED TO BE FOCUSED
ON THE NOSE OF A RESIDUAL ELEVATED MIXED LAYER ACROSS PARTS OF
NORTHWEST TEXAS AND SOUTHWEST OKLAHOMA...WHERE STRENGTHENING UPPER
DIVERGENCE ASSOCIATED WITH THE APPROACHING IMPULSE MAY ENHANCE LIFT
TOWARD 12Z THURSDAY. THIS ENVIRONMENT SEEMS LIKELY TO PROVIDE THE
BEST POTENTIAL FOR AN ISOLATED STRONG TO SEVERE STORM WITH HAIL OR
STRONG SURFACE GUSTS.
..KERR.. 02/22/2011
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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.
No comments:
Post a Comment