SWODY2
SPC AC 100556
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1256 AM CDT SUN OCT 10 2010
VALID 111200Z - 121200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE SRN
PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS FROM A PORTION OF THE OH VALLEY
INTO THE MID ATLANTIC REGION...
...SYNOPSIS...
BLOCKING PATTERN WILL CONTINUE THROUGH MONDAY. BEING CUTOFF FROM
POLAR WLYS...CNTRL U.S. UPPER LOW WILL MOVE ONLY VERY SLOWLY AND IS
FORECAST TO DRIFT SEWD THROUGH KS INTO OK. SEVERAL VORTICITY MAXIMA
WILL ROTATE THROUGH BASE OF UPPER LOW THROUGH TX AND THE LOWER MS
VALLEY. FARTHER EAST A STRONG IMPULSE WILL DROP SEWD THROUGH THE
GREAT LAKES AND OH VALLEY RESULTING IN AMPLIFICATION OF UPPER TROUGH
OVER THE NERN STATES. AT THE SURFACE A WEAK FRONT INITIALLY FROM THE
MID MS VALLEY SWWD THROUGH OK...CNTRL AND SWRN TX WILL MOVE SLOWLY
SEWD. FRONTAL ZONE WILL PERSIST FROM THE NERN STATES INTO THE OH
VALLEY AND GREAT LAKES REGION. ANOTHER FRONT ACCOMPANYING A NRN
STREAM SHORTWAVE TROUGH WILL SURGE SEWD THROUGH NRN HIGH PLAINS.
...ERN OK THROUGH CNTRL AND ERN TX...
AS SURFACE RIDGE SHIFTS FARTHER EAST...AXIS OF PARTIALLY MODIFIED
GULF AIR WITH MID 50S TO LOW 60S F DEWPOINTS WILL BEGIN RETURNING
NWD THROUGH TX AND OK SUNDAY INTO MONDAY BENEATH PLUME OF STEEP
MID-LEVEL LAPSE RATES. THIS IN CONJUNCTION WITH DIABATIC HEATING
SHOULD CONTRIBUTE TO 1000-1500 J/KG MLCAPE ACROSS A LARGE PART OF
CNTRL AND ERN TX...ERN OK INTO A PORTION OF THE LOWER MS VALLEY. AS
THE BOUNDARY LAYER DESTABILIZES STORMS WILL LIKELY REDEVELOP AND
INTENSIFY DURING THE DAY ALONG AND EAST OF THE FRONT FROM ERN OK
INTO CNTRL AND ERN TX. STORM COVERAGE WILL BE MODULATED BY VORTICITY
MAXIMA ROTATING THROUGH BASE OF UPPER TROUGH. GIVEN THE EQUIVALENT
BAROTROPIC NATURE OF THE UPPER LOW...VERTICAL SHEAR WITHIN MOST OF
WARM SECTOR IS NOT FORECAST TO BE PARTICULARLY STRONG WITH 30-35 KT
EXPECTED...BUT WILL BE AT LEAST MARGINALLY SUFFICIENT FOR ORGANIZED
STORMS. STEEP LAPSE RATES...COLD AIR ALOFT AND POTENTIAL FOR SOME
UPDRAFTS TO ROTATE WILL SUPPORT A RISK FOR ISOLATED LARGE HAIL.
ISOLATED STRONG TO DAMAGING WIND GUSTS COULD ALSO ACCOMPANY THE
STRONGER STORMS.
...OH VALLEY THROUGH MID ATLANTIC AND PORTION OF NERN STATES...
NW-SE ORIENTED BAROCLINIC ZONE WILL PERSIST FROM THE GREAT LAKES
SEWD THROUGH THE OH VALLEY AND MID ATLANTIC. THIS BOUNDARY WILL
RESIDE BENEATH MODERATE MID-UPPER FLOW ALONG SRN PERIPHERY OF LARGE
SCALE TROUGH. A SIGNIFICANT SHORTWAVE TROUGH WILL DROP SEWD INTO THE
GREAT LAKES MONDAY AFTERNOON...REACHING THE OH VALLEY BY EVENING.
POTENTIAL EXISTS FOR WEAKER IMPULSES TO MOVE THROUGH THIS REGION IN
ADVANCE OF PRIMARY VORT MAX. PLUME OF 7-7.5 C/KM 700-500 MB LAPSE
RATES...COLD AIR ALOFT...NEAR 50 F DEWPOINTS AND DIABATIC WARMING
WILL SUPPORT 500-1000 J/KG MLCAPE. A FEW STORMS MAY DEVELOP DURING
THE AFTERNOON ALONG THE FRONT. STORM COVERAGE SHOULD INCREASE DURING
THE EVENING WITH THE APPROACH OF THE SEWD ADVANCING SHORTWAVE
TROUGH. THERE IS SOME CONCERN THAT FORCING FOR GREATER STORM
COVERAGE WILL NOT BE FAVORABLY TIMED WITH PEAK INSTABILITY FOR A
MORE ROBUST SEVERE THREAT. HOWEVER...IT APPEARS MODEST INSTABILITY
AND NWLY UNIDIRECTIONAL 30-40 KT EFFECTIVE SHEAR WILL BE SUFFICIENT
FOR A THREAT OF ISOLATED HAIL AND STRONG TO DAMAGING WIND GUSTS FROM
THE AFTERNOON INTO THE EVENING.
..DIAL.. 10/10/2010
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