DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 240527
SWODY1
SPC AC 240524

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1124 PM CST FRI NOV 23 2007

VALID 241200Z - 251200Z

..NO SVR TSTM AREAS FORECAST...

..SYNOPSIS...
THE SHARP UPPER RIDGE ALONG THE PACIFIC COAST IS BEGINNING TO BREAK
DOWN...AS A SIGNIFICANT UPSTREAM SHORT WAVE IMPULSE APPROACHES THE
PACIFIC NORTHWEST/BRITISH COLUMBIA COASTAL AREAS. AND...MODELS
INDICATE THAT THIS PROCESS WILL CONTINUE THROUGH THIS FORECAST
PERIOD...AS THE IMPULSE PROGRESSES INLAND ACROSS THE
CANADIAN/NORTHERN U.S. ROCKIES. AS THIS OCCURS...A MORE COMPLEX BUT
LESS AMPLIFIED SPLIT UPPER FLOW IS PROGGED TO EVOLVE.

STABLE...CONTINENTAL POLAR AIR...ASSOCIATED PRIMARILY WITH
PERTURBATIONS WITHIN THE NORTHERN STREAM...HAS INFILTRATED MUCH OF
THE NATION. THIS WILL BE SLOW TO MODIFY...ALTHOUGH THE CENTER OF
THE PROMINENT SURFACE RIDGE IS PROGGED TO SHIFT FROM THE LEE OF THE
CENTRAL APPALACHIANS INTO THE WESTERN ATLANTIC. MODELS INDICATE
THAT ANOTHER WEAKER SURFACE HIGH CENTER WILL SHIFT SOUTHEAST OF THE
CENTRAL ROCKIES THROUGH THE CENTRAL PLAINS BEFORE WEAKENING LATER
TODAY/TONIGHT...AS A SURFACE TROUGH GRADUALLY DEVELOPS NORTHEASTWARD
OUT OF THE WESTERN GULF OF MEXICO THROUGH WESTERN GULF COASTAL AREAS
AND THE LOWER MISSISSIPPI VALLEY. THIS IS PROGGED TO OCCUR AS THE
SOUTHERN BRANCH CLOSED LOW/TROUGH...NOW EVOLVING ACROSS THE
NORTHWESTERN MEXICAN PLATEAU...REMAINS PROGRESSIVE...AND SLOWLY
APPROACHES THE LOWER RIO GRANDE VALLEY.

WHILE THE SURFACE TROUGH WILL PROBABLY BECOME A FOCUS FOR LOW-LEVEL
MOISTENING...WEAK DESTABILIZATION...AND THUNDERSTORM
ACTIVITY...SIGNIFICANT BOUNDARY LAYER DESTABILIZATION IS EXPECTED TO
REMAIN CONFINED TO THE OPEN WATERS OF THE GULF OF MEXICO. THIS
SEEMS LIKELY TO NEGATE ANY APPRECIABLE SEVERE POTENTIAL THROUGH AT
LEAST 12Z SUNDAY.

..TEXAS INTO LOWER MISSISSIPPI VALLEY...
ON THE NOSE OF A STRENGTHENING SOUTHERLY LOW-LEVEL JET...
WARMING/MOISTENING IN THE 850-700 MB LAYER IS EXPECTED TO CONTRIBUTE
TO WEAK DESTABILIZATION...AND INCREASINGLY FAVORABLE THERMODYNAMIC
PROFILES FOR THUNDERSTORMS FROM SOUTH CENTRAL THOUGH EASTERN TEXAS
BY DAYBREAK. THIS ACTIVITY WILL THEN LIKELY DEVELOP NORTHEASTWARD
TOWARD THE LOWER MISSISSIPPI VALLEY DURING THE DAY...BEFORE
GRADUALLY DIMINISHING...AS MID/UPPER FORCING... ENHANCED BY THE
RIGHT ENTRANCE REGION OF A HIGH-LEVEL JET STREAK...BEGINS TO LIFT
NORTH OF BETTER LOW-LEVEL MOISTURE RETURN.

MODELS ARE THEN SUGGESTIVE THAT ANOTHER MID-LEVEL IMPULSE EMANATING
FROM SOUTHWESTERLY FLOW OUT OF THE MEXICAN PLATEAU... AHEAD OF MAIN
CLOSED LOW...WILL SUPPORT ANOTHER WAVE OF THUNDERSTORM ACTIVITY
LATER TODAY/TONIGHT. THIS IS EXPECTED TO OVERSPREAD MUCH OF
SOUTHEAST TEXAS INTO THE ARKLATEX REGION BY EARLY SUNDAY.

DESPITE THE RATHER HIGH LIKELIHOOD OF THUNDERSTORM ACTIVITY...THE
ANTICIPATED ELEVATED NATURE ABOVE A SHARP LOW-LEVEL INVERSION LAYER
APPEARS TO PRECLUDE THE RISK OF TORNADOES/DAMAGING WIND GUSTS...EVEN
ALONG MID/UPPER TEXAS COASTAL AREAS. AND...WEAK CAPE ...GENERALLY
ON THE ORDER OF 500 J/KG OR LESS...SHOULD LIMIT UPDRAFT
STRENGTH...MINIMIZING THE POTENTIAL FOR SEVERE HAIL.

.KERR.. 11/24/2007

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