[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 120611
SWODY2
SPC AC 120610

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1210 AM CST SUN MAR 12 2006

VALID 131200Z - 141200Z

...THERE IS A SLGT RISK OF SVR TSTMS MONDAY ACROSS MUCH OF THE OH/TN
VALLEYS...THE MID ATLANTIC COAST STATES...AND PARTS OF THE CNTRL/ERN
GULF STATES....

A VERY STRONG MID/UPPER JET STREAK CONTINUES TO NOSE AROUND THE BASE
OF A BROAD COLD UPPER TROUGH...WHICH ENCOMPASSES MUCH OF THE WESTERN
UNITED STATES. MODELS CONTINUE TO SUGGEST THAT THE MOST SIGNIFICANT
IMPULSE EMBEDDED WITHIN THIS FEATURE WILL LIFT OUT OF THE SOUTHERN
ROCKIES TODAY. AS THIS OCCURS...THE BROADER SCALE TROUGHING WILL
FOLLOW SUIT.  POLAR TROUGH IS PROGGED TO REMAIN IN PHASE WITH THE
SUBTROPICAL STREAM...AND PROGRESS INTO THE EASTERN HALF OF THE
NATION BY LATE MONDAY NIGHT OR EARLY TUESDAY.

A SIGNIFICANT SURFACE CYCLONE ACCOMPANYING UPPER SYSTEM IS EXPECTED
TO APPROACH THE GREAT LAKES REGION BY 12Z MONDAY...BEFORE CONTINUING
TO DEEPEN AND LIFT THROUGH THE EASTERN CANADIAN PROVINCES.  A COLD
INTRUSION IN ITS WAKE WILL BEGIN TO OVERSPREAD MOST THE NATION EAST
OF THE ROCKIES...LIKELY ADVANCING THROUGH ALL BUT EASTERN GULF AND
SOUTH ATLANTIC COASTAL AREAS BY 12Z TUESDAY.

IN ADVANCE OF THE COLD FRONT...AN INFLUX OF SEASONABLY HIGH BOUNDARY
LAYER MOISTURE OFF THE GULF OF MEXICO AND WESTERN ATLANTIC WILL
OCCUR THROUGH MUCH OF THE EASTERN STATES.  THIS WILL CONTRIBUTE TO
POTENTIALLY UNSTABLE ENVIRONMENT...WHICH SHOULD BE SUPPORTIVE OF
WIDESPREAD CONVECTIVE DEVELOPMENT...AND THE CONTINUATION OF A SEVERE
WEATHER OUTBREAK ALREADY UNDERWAY ACROSS PARTS OF THE MIDDLE
MISSISSIPPI VALLEY.

...GREAT LAKES/OHIO AND TN VALLEYS INTO MID ATLANTIC STATES...
WHILE SUBSTANTIAL SEVERE POTENTIAL SEEMS LIKELY TO CONTINUE INTO THE
NORTHEAST QUARTER OF THE NATION MONDAY...UNCERTAINTIES BEGIN TO
ARISE BY THE BEGINNING OF THE PERIOD WHICH COULD TEMPER THREAT...AT
LEAST IN TERMS OF NUMBERS OF "SIGNIFICANT" SEVERE EVENTS.  A SQUALL
LINE MAY BE ONGOING ACROSS THE LOWER OHIO VALLEY AT 12Z
MONDAY...WHICH SEEMS LIKELY TO WEAKEN AS IT BEGINS TO OUTRUN PRIMARY
UPPER TROUGH AND BETTER PRE-FRONTAL INSTABILITY.

THE SURFACE WARM SECTOR WILL BE BROAD...WITH 60F+ SURFACE DEW POINTS
WIDESPREAD EAST OF THE MISSISSIPPI VALLEY...LIKELY ACROSS ALL BUT
NORTHERN NEW ENGLAND.  HOWEVER...SUBSTANTIAL CLOUD COVER MAY LIMIT
INSOLATION...AND NORTHEASTWARD ADVECTION OF ELEVATED MIXED LAYER OUT
OF THE PLATEAU REGION SEEMS LIKELY TO BECOME SUPPRESSED BY EARLY
MONDAY.  ALL OF THIS IS EXPECTED TO LIMIT PEAK MIXED LAYER
INSTABILITY TO AROUND 1000 J/KG...IN A RELATIVELY NARROW CORRIDOR
AHEAD OF COLD FRONT AS IT ADVANCES TOWARD THE APPALACHIANS MONDAY
AFTERNOON...PERHAPS SOUTH OF WARM FRONT...ACROSS EASTERN
MARYLAND/PENNSYLVANIA.

STILL...INSTABILITY SHOULD BE SUFFICIENT IN STRONGLY SHEARED REGIME
TO SUPPORT SEVERE THUNDERSTORMS WITH DAMAGING WINDS AND AT LEAST
MARGINALLY SEVERE HAIL.  ISOLATED SUPERCELLS WILL ALSO BE
POSSIBLE...ALONG WITH POTENTIAL FOR TORNADOES.

STORMS SEEM LIKELY TO DEVELOP TO THE LEE OF THE NORTH CENTRAL
APPALACHIANS...AHEAD OF WEAKENING CONVECTIVE LINE...BY MONDAY
AFTERNOON.  THIS ACTIVITY SHOULD EVENTUALLY DEVELOP EASTWARD TOWARD
NORTHERN MID ATLANTIC COASTAL AREAS...BUT SEVERE THREAT IS EXPECTED
TO DIMINISH AS CONVECTION OVERSPREADS MARINE LAYER IN IMMEDIATE
VICINITY OF COASTAL AREAS INTO SOUTHERN NEW ENGLAND.

OTHERWISE...PRE-FRONTAL LINES OF STRONG/SEVERE STORMS ARE EXPECTED
TO DEVELOP THROUGH THE OHIO/TENNESSEE VALLEYS DURING THE PEAK
HEATING HOURS. ACTIVITY MAY DEVELOP IN A MORE SCATTERED FASHION AS
FAR SOUTH AS THE CENTRAL/EASTERN GULF STATES...BUT DIMINISHING
TRENDS ARE EXPECTED BY MONDAY EVENING EAST OF THE CENTRAL/SOUTHERN
APPALACHIANS.

..KERR.. 03/12/2006