SPC AC 281944
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0244 PM CDT WED JUN 28 2006
VALID 282000Z - 291200Z
...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN/EARLY EVE
ACROSS PARTS OF THE SRN ATLANTIC COAST STATES....
...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN/EARLY EVE ACROSS
PARTS OF THE GREAT LAKES/OH VALLEY....
...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN AND EVE FROM
PARTS OF THE NRN SIERRA NEVADA INTO THE LEE OF THE SRN CASCADES....
...SOUTH ATLANTIC COAST STATES...
AN IMPULSE EMANATING FROM THE LOWER LATITUDE ATLANTIC...WHICH
PROGRESSED INLAND ACROSS THE MID ATLANTIC REGION YESTERDAY...IS NOW
RAPIDLY LIFTING THROUGH NEW ENGLAND INTO THE CANADIAN MARITIMES.
CONSIDERABLE DRYING HAS OCCURRED ACROSS MUCH OF THE EASTERN U.S. IN
ITS WAKE...THE EXCEPTION BEING THE FLORIDA PENINSULA INTO PARTS OF
THE SOUTH ATLANTIC COAST STATES...WHERE PRECIPITABLE WATER CONTENT
REMAINS HIGH...AND MIXED LAYER CAPE IS IN EXCESS OF 2000 J/KG.
WEAK LOW-LEVEL CONFLUENT ZONE FROM SOUTH CENTRAL GEORGIA INTO THE
SOUTH CAROLINA PIEDMONT...AND PERHAPS AN OLD OUTFLOW BOUNDARY ACROSS
NORTHERN FLORIDA...SEEM TO BE PROVIDING THE FOCUS FOR ONGOING
CONVECTIVE DEVELOPMENT. THIS ACTIVITY APPEARS LIKELY TO
PERSIST/INCREASE LATE THIS AFTERNOON...PERHAPS CONSOLIDATING INTO A
GROWING CLUSTER OF STORMS ACROSS SOUTHEAST GEORGIA INTO COASTAL
SOUTH CAROLINA. THIS MAY BE AIDED BY FORCING ASSOCIATED WITH A WEAK
SHORT WAVE TROUGH EMBEDDED WITHIN BROADER SCALE UPPER TROUGHING EAST
OF THE MISSISSIPPI VALLEY...AND SHIFTING TOWARD THE ATLANTIC COAST
STATES. MEAN FLOW IS GENERALLY ONLY WEAK TO MODERATE IN STRENGTH IN
THE BASE OF THIS TROUGH...BUT MAY BE ENOUGH TO ENHANCING POTENTIAL
FOR STRONG GUSTY WINDS IN STORMS AS THEY PROGRESS INTO/THROUGH
ENVIRONMENT INLAND OF COASTAL AREAS WHICH HAS HEATED TO AROUND 90F.
...GREAT LAKES/OHIO VALLEY...
A BELT OF 30 TO 40 KT SOUTHWESTERLY MID-LEVEL FLOW...AHEAD OF UPPER
TROUGH AXIS...EXTENDS ALONG/WEST OF THE SOUTHERN APPALACHIANS
THROUGH THE LOWER GREAT LAKES AND NORTHEAST. THIS COULD ENHANCE
POTENTIAL FOR GUSTY WINDS NEAR STORMS NOW DEVELOPING INTO THE LOWER
GREAT LAKES/UPPER OHIO VALLEY...AHEAD OF ANOTHER IMPULSE LIFTING OUT
OF THE TENNESSEE VALLEY. HOWEVER...THE MAIN SEVERE THREAT LATE THIS
AFTERNOON SEEMS TO BE AHEAD OF MORE SIGNIFICANT MID-LEVEL CYCLONIC
VORTICITY CENTER/SHORT WAVE TROUGH BEGINNING TO SHIFT EAST OF THE
UPPER GREAT LAKES REGION. MID-LEVEL LAPSE RATES ARE A BIT
STEEPER/CONVECTIVE INSTABILITY A BIT STRONGER WITH LEADING EDGE OF
MID-LEVEL COOL POCKET SPREADING ACROSS MICHIGAN/INDIANA. THIS
SHOULD CONTINUE TO CONTRIBUTE TO FAVORABLE ENVIRONMENT FOR GUSTY
WINDS AND HAIL IN STRONGER STORMS...BEFORE ACTIVITY WEAKENS WITH
LOSS OF DAYTIME HEATING AS IT PROGRESSES INTO THE LOWER GREAT LAKES.
...WESTERN STATES...
WEAK SUBTROPICAL IMPULSES MIGRATING AROUND THE PERIPHERY OF THE
WESTERN U.S. RIDGE WILL ENHANCE CONVECTIVE DEVELOPMENT LATE THIS
AFTERNOON AND EVENING...FROM PARTS OF THE CENTRAL ROCKIES INTO THE
SOUTHERN ROCKIES/HIGH PLAINS...AND FROM THE NORTHERN SIERRA
NEVADA/SISKIYOUS INTO THE NORTHERN ROCKIES. STRONG SURFACE HEATING
IS CONTRIBUTING TO STEEP LAPSE RATES ACROSS MUCH OF THIS
REGION...AND THERMODYNAMIC PROFILES WITH LARGE LOW-LEVEL
TEMPERATURE/DEW POINTS SPREADS WILL BE FAVORABLE FOR A FEW
DOWNBURSTS...IN ADDITION TO SOME SMALL HAIL. THIS POTENTIAL APPEARS
GREATEST AHEAD OF MID-LEVEL CIRCULATION SLOWLY LIFTING TOWARD
NORTHERN CALIFORNIA...WHERE ONE OR MORE CONVECTIVE CLUSTERS ARE
POSSIBLE LATE THIS AFTERNOON AND EVENING.
**FOR MORE SPECIFIC INFORMATION CONCERNING ONGOING OR IMMINENT
CONVECTIVE THREATS...PLEASE REFER TO THE LATEST SPC MESOSCALE
DISCUSSIONS.
..KERR.. 06/28/2006
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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