[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 301727
SWODY2
SPC AC 301725

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1125 AM CST THU NOV 30 2006

VALID 011200Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE OH/TN VLYS NEWD INTO
THE MID-ATLANTIC REGION AND NEW ENGLAND...

...OH VLY/CNTRL APPALACHIANS NEWD TO NEW ENGLAND/MID-ATLANTIC...
SYNOPTIC REGIME APPEARS SUPPORTIVE OF A LOW INSTABILITY/HIGH SHEAR
SERIAL-TYPE DERECHO EVENT ACROSS PARTS OF THE REGION FRI AND FRI
NIGHT. POTENTIAL EXISTS FOR WIDESPREAD DAMAGING WINDS AND ISOLD
TORNADOES...PARTICULARLY ACROSS CNTRL/ERN PA...PARTS OF MD AND SRN
NY.

POWERFUL NEGATIVE-TILT UPPER LOW AND ASSOCD 120+ KT H5 JET WILL
TRANSLATE FROM THE LWR OH VLY EARLY FRI TO SRN QUE BY 12Z SAT. 
IMPRESSIVE LARGE SCALE HEIGHT FALLS OF 150-300 METERS WILL SPREAD
NEWD...WITH THE STRONGEST FALLS SHIFTING THROUGH THE OH VLY INTO
PA/NY DURING FRI AFTN/EVE.  AT THE SFC...PRIMARY OCCLUSION WILL
TRAVEL FROM NRN IND INTO SWRN ONTARIO BY FRI EVE.  NEW CYCLOGENESIS
IS LIKELY OVER NCNTRL PA OR SCNTRL NY FRI MORNING...WITH THE LOW
THEN MOVING INTO NWRN MAINE/SRN QUE BY 12Z SATURDAY.  A TRAILING
COLD FRONT WILL SWEEP EWD ACROSS THE APPALACHIANS DURING FRI
AFTN/EVE...THEN OFFSHORE BY EARLY SATURDAY MORNING.

A STRONGLY FORCED...LOW-TOPPED CONVECTIVE LINE IS EXPECTED TO BE
ONGOING EARLY FRI MORNING FROM THE OCCLUDED LOW OVER IND SWD INTO
THE MID-TN VLY.  AHEAD OF THIS LINE...A STRONG SSWLY LLJ IN EXCESS
OF 50-60 KTS WILL SHIFT EWD FROM THE OH/TN VLYS.  AS A
RESULT...SUBSTANTIAL BOUNDARY LAYER MOISTURE...NOW EVIDENT AS SFC
DEW POINTS AOA 60 DEG F OVER THE SERN STATES...WILL ADVECT NWD. 
GIVEN STEEPENING MID-LEVEL LAPSE RATES SPREADING EWD ATOP THIS MOIST
AXIS...MODEST DESTABILIZATION IS EXPECTED AHEAD OF THE FRONT. 
STRONGEST INSTABILITY /MUCAPES OF A FEW HUNDRED J/KG/ SHOULD DEVELOP
ACROSS PARTS OF PA AND NY DURING PEAK HEATING FRI.
AS A RESULT...TSTMS WILL LIKELY INTENSIFY OVER THESE AREAS AFTER
18Z.  FORECAST SOUNDINGS INDICATE THAT TSTMS WILL LIKELY BECOME
SFC-BASED...ESPECIALLY ALONG AND IMMEDIATELY EAST OF THE SPINE OF
THE APPALACHIANS AND THEN RAPIDLY TRANSLATE ENEWD INTO SCNTRL NY/ERN
PA/NRN MD BY FRI EVE.

AMBIENT WINDS WILL BE QUITE STRONG WITH THIS SYSTEM WITH 70 KTS JUST
OFF THE SURFACE...INCREASING CONFIDENCE THAT CONVECTIVE DOWNDRAFTS
WILL BE CAPABLE OF DAMAGING WINDS.  WHILE THE WIND DAMAGE THREAT
WILL EXIST FROM THE ONSET OF THE FCST PERIOD OVER THE MID-OH VLY SWD
INTO ERN PORTIONS OF KY/TN...THE THREAT WILL INCREASE AND PEAK BY
AFTN OVER NY/PA AND NRN MD AS THE LINE ENCOUNTERS THE MORE
SUBSTANTIAL INSTABILITY/LOW-LEVEL LAPSE RATES.
EMBEDDED BOWING/LEWP STRUCTURES WILL BE CAPABLE OF CORRIDORS OF
DAMAGING WINDS...ESPECIALLY GIVEN THE FORECAST 50-60+KT
STORM MOTIONS. MOREOVER...THE STRONGER INSTABILITY OVER NY/PA MAY
EVEN SUPPORT SUPERCELLS...BOTH EMBEDDED WITHIN THE LINE AND POSSIBLY
IN THE WARM SECTOR...WITH A THREAT OF ISOLATED TORNADOES GIVEN THE
STRONG LOW-LEVEL SHEAR AND LOW LCL HEIGHTS.

THIS STRONGLY FORCED...FAST MOVING CONVECTIVE LINE WILL SWEEP
THROUGH THE HUDSON VALLEY AND DE RIVER VLY LATE FRI AFTN/EVE
AND MUCH OF NEW ENGLAND FRI NIGHT WITH ATTENDANT DAMAGING WINDS.
NRN EXTENT OF THE DAMAGING WIND THREAT SHOULD BE MODULATED BY AN E-W
FRONT THAT SHOULD REMAIN ACROSS AT LEAST SRN MAINE OVERNIGHT.

..RACY.. 11/30/2006