SWODY2
SPC AC 010531
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1231 AM CDT WED SEP 01 2010
VALID 021200Z - 031200Z
...THERE IS A SLGT RISK OF SVR TSTMS THU INTO THU NIGHT ACROSS PARTS
OF THE SOUTH CENTRAL PLAINS INTO PORTIONS OF THE UPPER MS VALLEY...
...SYNOPSIS...
MODELS CONTINUE TO INDICATE INCREASING AMPLIFICATION WITHIN A STRONG
BELT OF WESTERLIES ACROSS SOUTHERN CANADA AND THE NORTHERN TIER OF
THE U.S...AS HURRICANE EARL PROGRESSES ACROSS THE WESTERN ATLANTIC
TOWARD THE SOUTHERN MID ATLANTIC COASTAL VICINITY. THIS INCLUDES
THE LIKELIHOOD OF A BUILDING UPPER RIDGE ACROSS THE INTERMOUNTAIN
WEST INTO WESTERN CANADA...AND A DIGGING UPPER TROUGH ACROSS THE
UPPER MISSISSIPPI VALLEY AND GREAT LAKES REGION. THE LATTER FEATURE
APPEARS LIKELY TO BE ACCOMPANIED BY AN EVOLVING LOWER/MID
TROPOSPHERIC CYCLONE...BUT VARIABILITY PERSISTS AMONG MODEL DATA
CONCERNING SURFACE DEVELOPMENT...
PARTICULARLY ACROSS THE UPPER GREAT LAKES REGION THURSDAY NIGHT...AS
EARL CURVES NORTHWARD/NORTHEASTWARD OFF THE COAST.
...SOUTH CENTRAL PLAINS INTO THE GREAT LAKES...
CONSIDERABLE UNCERTAINTY REMAINS CONCERNING THE EXTENT OF THE
CONVECTIVE POTENTIAL FOR THURSDAY...NOT SO MUCH WHETHER STORMS WILL
DEVELOP...BUT JUST HOW CONDUCIVE THE ENVIRONMENT WILL ACTUALLY BE TO
THE DEVELOPMENT OF SEVERE STORMS. THE WARM SECTOR/PRE-FRONTAL
ENVIRONMENT ACROSS MUCH OF THE REGION IS EXPECTED TO REMAIN HIGHLY
MOIST...BUT MODELS SUGGEST THAT MID-LEVEL LAPSE RATES WILL BECOME
FAIRLY POOR...EXCEPT PERHAPS ACROSS THE SOUTH CENTRAL PLAINS INTO
PARTS OF THE LOWER MISSOURI VALLEY.
SEVERE POTENTIAL ACROSS EASTERN IOWA AND NORTHERN ILLINOIS...
NORTHEASTWARD INTO THE GREAT LAKES...WILL LARGELY BE DETERMINED BY
THE STRENGTH OF THE SURFACE WAVE PROGGED TO FORM EAST OF THE MID
MISSOURI VALLEY INTO THE UPPER GREAT LAKES REGION DURING THE DAY.
THIS REMAINS UNCLEAR...BUT IT DOES NOT APPEAR OUT OF THE QUESTION
THAT ENOUGH DESTABILIZATION AND STRENGTHENING OF SHEAR COULD TAKE
PLACE TO SUPPORT THE RISK FOR SUPERCELLS WITH TORNADOES. THE
PROBABILITY FOR THIS...HOWEVER...STILL SEEMS RELATIVELY LOW AT THE
PRESENT TIME.
TO THE SOUTHWEST...AN AXIS OF STRONGER SURFACE HEATING IS EXPECTED
TO CONTRIBUTE TO A HOT AND DEEPLY MIXED PRE-FRONTAL BOUNDARY
LAYER...PARTICULARLY ACROSS PARTS OF WESTERN/NORTHERN OKLAHOMA...AND
SOUTHERN/EASTERN KANSAS...PERHAPS WEST CENTRAL MISSOURI...WHERE FLOW
FIELDS AND SHEAR MAY BE MARKEDLY WEAKER. HOWEVER...IN THE PRESENCE
OF MIXED LAYER CAPE AROUND 2000 J/KG...VIGOROUS CONVECTIVE
DEVELOPMENT IS LIKELY IN RESPONSE TO FRONTAL FORCING...AIDED BY
DIFLUENT AND DIVERGENT UPPER FLOW NEAR THE BASE OF THE UPPER
TROUGH. THE RISK FOR ISOLATED STRONG DOWNBURSTS MAY TRANSITION TO
POTENTIAL FOR BROADER STRONG SURFACE GUSTS ALONG CONSOLIDATING
OUTFLOWS...ASSOCIATED WITH AN EVOLVING SQUALL LINE...THROUGH THE
LATE AFTERNOON AND EARLY EVENING HOURS. THE TENDENCY SHOULD BE FOR
ACTIVITY TO ADVANCE SOUTHEASTWARD...WHILE BUILDING SOUTHWESTWARD
ALONG THE FRONT TOWARD THE SOUTHERN HIGH PLAINS.
..KERR.. 09/01/2010
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