[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 220518
SWODY2
SPC AC 220516

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1216 AM CDT THU JUN 22 2006

VALID 231200Z - 241200Z

...THERE IS A SLGT RISK OF SVR TSTMS FRI/EARLY FRI EVE FROM PARTS OF
SRN NEW ENGLAND AND THE NRN MID ATLC COAST THRU THE OHIO VLY AND
OZARK PLATEAU....

...THERE IS A SLGT RISK OF SVR TSTMS FRI/EARLY FRI EVE ACROSS PARTS
OF THE N CNTRL PLAINS....

MODELS INDICATE THAT A VIGOROUS NORTHERN BRANCH SHORT WAVE
TROUGH...DIGGING THROUGH ONTARIO/QUEBEC TODAY...WILL QUICKLY LIFT
OUT OF QUEBEC THROUGH THE CANADIAN MARITIMES DURING THIS FORECAST
PERIOD.  AS THIS OCCURS...LINGERING BELT OF CYCLONIC MID-LEVEL FLOW
ACROSS MUCH OF THE GREAT LAKES/OHIO VALLEY INTO THE NORTHEAST WILL
GRADUALLY BEGIN TO WEAKEN.

STRONGER WESTERLIES...IN GENERAL...WILL CONTINUE TO RETREAT NORTH OF
THE CANADIAN/U.S. BORDER FRIDAY...AS AN UPPER RIDGE BUILDS ACROSS
THE WESTERN STATES...INTO THE CANADIAN ROCKIES.  HOWEVER...ONE MORE
FAIRLY SIGNIFICANT SOUTHERN STREAM SHORT WAVE TROUGH IS FORECAST TO
DIG AROUND NORTHEASTERN PERIPHERY OF RIDGE...ACROSS THE NORTHERN
PLAINS.  AND...MODELS SUGGEST THAT WEAK MID-LEVEL TROUGHING ALREADY
PRESENT ACROSS THE CENTRAL PLAINS...ON THE SOUTHERN FRINGE OF THE
WESTERLIES...WILL ACCELERATE EASTWARD TOWARD THE SOUTHERN
APPALACHIANS.  AS THIS OCCURS...THE SUBTROPICAL RIDGE CENTERED OVER
THE SOUTHEAST STATES WILL WEAKEN...AND A NARROW BELT OF MODERATE
MID-LEVEL FLOW MAY SHIFT EAST OF THE OHIO VALLEY THROUGH THE
NORTHERN MID ATLANTIC STATES BY THE PEAK HEATING HOURS.

...SRN NEW ENGLAND/NRN MID ATLANTIC THRU OH VLY/OZARK PLATEAU...
A FAIRLY SIGNIFICANT COLD FRONT ASSOCIATED WITH THE NORTHERN BRANCH
TROUGH APPEARS LIKELY TO BE IN THE PROCESS OF ADVANCING SOUTH/EAST
OF THE LOWER GREAT LAKES AND ST. LAWRENCE VALLEY BY 12Z FRIDAY. 
THIS FRONT MAY CONTINUE SOUTHWARD INTO/THROUGH THE NORTHERN MID
ATLANTIC COAST AND MUCH OF THE OHIO VALLEY BY THE END OF THE
FORECAST PERIOD...BEFORE BEGINNING TO WEAKEN.

THE FRONT LIKELY WILL BE PRECEDED BY A WEAK CONFLUENT ZONE OR
COMPOSITE OUTFLOW BOUNDARY...ASSOCIATED WITH EXTENSIVE CONVECTIVE
DEVELOPMENT TODAY...WHICH IS EXPECTED TO ALREADY EXTEND ACROSS THE
NORTHERN MID ATLANTIC COAST STATES AND OHIO VALLEY INTO THE OZARK
PLATEAU BY 12Z FRIDAY. WITH PERHAPS THE EXCEPTION OF SOUTHERN NEW
ENGLAND...THIS PRE-FRONTAL BOUNDARY IS EXPECTED TO BECOME THE
PRIMARY FOCUS FOR NEW CONVECTIVE DEVELOPMENT LATE FRIDAY MORNING AND
AFTERNOON.  THOUGH CLOUD COVER COULD BE CONSIDERABLE...ENOUGH
HEATING OF MOIST BOUNDARY LAYER WITH UPPER 60S+ SURFACE DEW POINTS
IS EXPECTED TO CONTRIBUTE TO MIXED LAYER CAPE UP TO AROUND 2000
J/KG.  AS INHIBITION WEAKENS... THUNDERSTORM ACTIVITY IS EXPECTED TO
BECOME NUMEROUS IN WEAK TO MODERATELY SHEARED WESTERLY MEAN FLOW
REGIME.  HAIL WILL BE POSSIBLE IN STRONGER CELLS...AND 30 KT MID
LEVEL FLOW MAY BE ENOUGH TO ENHANCE STORM MOTIONS AND DOWNBURST
POTENTIAL.

ACTIVITY ACROSS MOST AREAS WILL PROBABLY WEAKEN RELATIVELY QUICKLY
FRIDAY EVENING WITH LOSS OF DAYTIME HEATING.

...ROCKIES INTO PLAINS...
COMPOSITE OUTFLOW SLOWLY ADVANCING THROUGH THE SOUTH CENTRAL
PLAINS...AND MOIST UPSLOPE FLOW IN THE LEE OF THE ROCKIES TO THE
NORTH WILL SUPPORT SCATTERED THUNDERSTORM ACTIVITY FRIDAY AFTERNOON
AND EVENING.  VEERING WINDS WITH HEIGHT BENEATH WEAK NORTHWESTERLY
FLOW MAY CONTRIBUTE TO SUFFICIENT SHEAR FOR MID-LEVEL UPDRAFT
ROTATION ACROSS MUCH OF THE CENTRAL/NORTHERN HIGH PLAINS.  COVERAGE
OF THIS ACTIVITY MAY BECOME MOST CONCENTRATED DURING THE LATE
AFTERNOON FROM SOUTHEAST MONTANA/EASTERN WYOMING INTO THE WESTERN
DAKOTAS...ASSOCIATED WITH WARM ADVECTION REGIME DOWNSTREAM OF
APPROACHING SHORT WAVE.  THIS FORCING WILL SPREAD SOUTHEASTWARD
FRIDAY EVENING...BUT DUE TO MARGINAL LOW-LEVEL MOISTURE AND
LIKELIHOOD OF QUICK RADIATIONAL SURFACE COOLING...SEVERE THREAT
PROBABLY WILL NOT LAST LONG AFTER DARK.

..KERR.. 06/22/2006