[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 130614
SWODY1
SPC AC 130613

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1213 AM CST MON MAR 13 2006

VALID 131200Z - 141200Z

...THERE IS A MDT RISK OF SVR TSTMS FOR TODAY ACROSS MUCH OF
INDIANA...SRN LOWER MICHIGAN...KENTUCKY...OHIO...EXTREME NRN MIDDLE
TENNESSEE...WRN WEST VIRGINIA AND WRN PENNSYLVANIA...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE LOWER MS/TN RIVER
VALLEYS TO LOWER MI AND EWD TO MUCH OF NY/PA/NJ/DE/MD...

...SYNOPSIS...
UPPER TROUGH WITH CLOSED LOW EXPECTED TO BE OVER THE UPPER MS VALLEY
WILL BECOME NEGATIVELY TILTED TODAY AS THIS FEATURE TRACKS NEWD
ACROSS THE GREAT LAKES REGION TO ERN ONTARIO/SRN QUEBEC.  THIS WILL
RESULT IN STRENGTHENING WIND FIELDS AT ALL LEVELS...WITH 120-130 KT
SWLY MID-UPPER LEVEL JET EXPECTED ACROSS THE OH VALLEY TO LOWER
GREAT LAKES REGION BY LATE AFTERNOON.  SURFACE LOW EXPECTED TO BE
LOCATED OVER NRN IL REGION AT 12Z TODAY WILL UNDERGO STRONG
DEEPENING AS IT TRACKS NEWD ACROSS LOWER MI...AND THEN OCCLUDING
OVER SWRN QUEBEC BY 12Z TUESDAY...WITH POTENTIAL FOR A COASTAL LOW
ALONG COASTAL MA/ME AT END OF FORECAST PERIOD. 

...OH RIVER VALLEY/LOWER GREAT LAKES INTO MID ATLANTIC STATES AND
PART OF NORTHEAST STATES...
COLD FRONT TRAILING SSWWD FROM THE NRN IL SURFACE LOW INTO SERN MO
TO ERN TX WILL SPREAD EWD ACROSS THE OH/TN AND LOWER MS RIVER
VALLEYS TODAY...REACHING WRN NEW ENGLAND SWD TO THE MID ATLANTIC
STATES AND SWWD THROUGH SERN STATES TO NRN GULF BY 12Z TUESDAY. 
DESPITE SOME QUESTION WITH REGARDS TO SURFACE HEATING ACROSS THE OH
RIVER VALLEY TODAY GIVEN EXTENSIVE CLOUDINESS DUE TO ONGOING STORMS
ATTM ACROSS THE MID MS RIVER VALLEY SPREADING EWD...LOW-LEVEL
MOISTURE RETURN WILL CONTRIBUTE TO AT LEAST MARGINAL INSTABILITY.

POTENTIAL EXISTS FOR AN ONGOING LINE OF STORMS TO TRACK EWD ACROSS
THE SRN GREAT LAKES/OH RIVER VALLEY THROUGH THE FIRST PART OF THE
PERIOD...WITH SECONDARY LINE OF STORMS POSSIBLE ALONG THE COLD AS
NARROW AXIS OF INSTABILITY DEVELOPS IN WAKE OF INITIAL ACTIVITY. 
00Z WRF-NMM SUGGESTS POTENTIAL FOR DISCRETE STORMS WITH THE
PRE-FRONTAL ACTIVITY INCREASING THE POTENTIAL FOR TORNADOES
ESPECIALLY ACROSS THE LOWER OH RIVER VALLEY INTO SRN LOWER MI INTO
THE AFTERNOON.

STRONG DEEP LAYER AND LOW-LEVEL SHEAR WILL SUPPORT A THREAT FOR
TORNADOES...BUT THE GREATEST THREAT IS EXPECTED TO BE FROM DAMAGING
WINDS...ESPECIALLY GIVEN THE POTENTIAL FOR ONE OR MORE ROUNDS OF
STORMS ACROSS THE MODERATE RISK AREA.  50-60 KT SWLY LLJ ACROSS THE
MODERATE RISK AREA WILL ENHANCE THE THREAT FOR DAMAGING WINDS.
 
DAMAGING WIND THREAT SHOULD DIMINISH THIS EVENING INTO CENTRAL PA
WITH DECREASING INSTABILITY.  HOWEVER...POTENTIAL FOR ELEVATED
SEVERE STORMS EXISTS INTO PARTS OF NY AFTER DARK GIVEN SUFFICIENT
EFFECTIVE BULK SHEAR AND INSTABILITY.

...ERN PA TO PARTS OF DELMARVA...
WARM FRONT EXTENDING EWD FROM SURFACE LOW IS EXPECTED TO RETREAT NWD
INTO UPSTATE NY TO OFF THE MA COAST BY 00Z...WITH A SECOND WARM
FRONT/SURFACE BOUNDARY EXTENDING SEWD ACROSS NRN TO ERN PA TO NJ
LATE THIS AFTERNOON.  THE INTERSECTION OF THIS LATTER BOUNDARY
ACROSS ERN PA WITH A LEE TROUGH MAY SUPPORT A FOCUS FOR AFTERNOON
THUNDERSTORM DEVELOPMENT...GIVEN SURFACE DEWPOINTS IN THE 60S WITH
STRONG SURFACE HEATING.  DEEP LAYER SHEAR AND INSTABILITY WILL BE
SUFFICIENT FOR SUPERCELLS WITH LOW-LEVEL SHEAR ALONG THE SURFACE
BOUNDARIES ENHANCING THE TORNADO POTENTIAL.

...TN/LOWER MS RIVER VALLEYS INTO SRN APPALACHIANS...
ALTHOUGH MODELS INDICATED STRONGER MASS FIELDS WILL BE FOCUSED
FARTHER TO THE NORTH...GREATER INSTABILITY IS EXPECTED FROM TN SWD
GIVEN SURFACE DEWPOINTS IN THE MID-UPPER 60S.  DEEP LAYER SHEAR WILL
BE STRONG SUPPORTING A THREAT FOR ORGANIZED STORMS AS THE COLD FRONT
MOVES EWD ACROSS THE TN/LOWER MS RIVER VALLEYS.

..PETERS/GRAMS.. 03/13/2006