[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 121731
SWODY2
SPC AC 121731

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1131 AM CST SUN MAR 12 2006

VALID 131200Z - 141200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER SERN INDIANA...MUCH OF
OH...WRN PA...WRN/CNTRL WV...AND CNTRL/ERN KY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE LOWER MS VALLEY/SERN
STATES...AND PARTS OF THE MID ATLANTIC REGION AND SRN NEW ENGLAND...

...SYNOPSIS...
VERY DYNAMIC AND PROGRESSIVE UPPER AIR PATTERN IS FORECAST TO
CONTINUE INTO DAY 2 OVER THE ERN HALF OF THE NATION. UPPER LOW IS
EXPECTED TO BE OVER THE UPPER MS VALLEY AT THE START OF THE
PERIOD..AND MOVE ENEWD ACROSS THE NRN GREAT LAKES BY LATE AFTERNOON
CONTINUING INTO ERN ONTARIO BY 14/12Z. THE UPPER SYSTEM IS FORECAST
TO CONTINUE INTENSIFYING DURING THE PERIOD WITH 12-HR 500 MB HEIGHT
FALLS INCREASING TO 240-270M...IN RESPONSE TO 120-130 KT  MID LEVEL
JET STREAK ACCELERATING ACROSS THE MID MS VALLEY AND GREAT LAKES
REGION.

AT THE SURFACE...A LOW OVER THE ERN IA/NWRN IL AREA AT 12Z IS
FORECAST DEEPEN AS IT TRACKS NEWD TOWARD NRN LOWER MI BY LATE
AFTERNOON REACHING WRN QUEBEC BY THE END OF THE PERIOD.  A STRONG
COLD FRONT EXTENDING SWD FROM THE LOW ALONG A CENTRAL IL..CENTRAL
AR..S CENTRAL TX LINE AT 12Z WILL MOVE EWD TO A CENTRAL OH..MIDDLE
TN..SWRN LA LINE BY 00Z...CONTINUING OVERNIGHT REACHING NEW
ENGLAND...THE MIDDLE ATLANTIC COAST...THEN SWWD ACROSS CENTRAL
SC..NWRN FL INTO THE NORTH CENTRAL GULF BY THE END OF PERIOD.  A
WARM FRONT WILL LIFT NWD ACROSS THE GREAT LAKES IN ADVANCE OF THE
SURFACE LOW...BUT ITS NWD MOVEMENT ACROSS THE COASTAL PARTS OF THE
MID ATLANTIC STATES MAY BE INHIBITED BY FLOW OFF COOL MARINE LAYER.

...OH VALLEY AND LOWER GREAT LAKES INTO MID ATLANTIC STATES...
MODEL GUIDANCE FROM THE 12Z ETA AND GFS...09Z ETAKF CONTROL RUN FROM
SREF...AND 00Z HIGH RESOLUTION WRF-NMM ALL INDICATE A PRE-COLD
FRONTAL LINE OF STRONG/SEVERE CONVECTION WILL BE ONGOING AT THE
START OF THE PERIOD FROM INDIANA INTO WRN PARTS OF KY/TN AND SRN AR.
 THIS CONVECTION WILL BE MOVING EWD THROUGH A BROAD WARM SECTOR
WHERE STRONG SSWLY LOW LEVEL WINDS ARE ADVECTING MOISTURE ACROSS THE
OH VALLEY TOWARD THE LOWER GREAT LAKES.  SURFACE DEW POINTS WILL
GENERALLY BE IN THE 55-60F RANGE ACROSS NRN PARTS OF THE WARM SECTOR
INCREASING TO 60-65F FROM PARTS OF THE OH RIVER SWD.  RESULTANT
EXTENSIVE CLOUD COVER SPREADING DOWNSTREAM FROM THE MORNING
CONVECTION WILL LIKELY INHIBIT DIURNAL HEATING ACROSS PARTS OF THE
OH VALLEY/LOWER GREAT LAKES.  COUPLED WITH MODEST MID LEVEL LAPSE
RATES OVER THE WARM SECTOR...IT APPEARS THAT MLCAPE WILL BE LIMITED
TO MAXIMUM OF VALUES OF 500-1000 J/KG.

STRONG DEEP LAYER VERTICAL SHEAR /50-60 KT IN THE LOWEST 6
KM/...CLOCKWISE TURNING LOW LEVEL HODOGRAPHS AND ASSOCIATED 150-250
M2/S2 0-1 KM SRH...AND INCREASING ISALLOBARIC FORCING WILL ENHANCE
QUASI-LINEAR CONVECTIVE ORGANIZATION WITH LEADING BAND SPREADING EWD
THROUGH THE DAY.  THIS WILL MAINTAIN THREAT FOR PRIMARILY WIDESPREAD
DAMAGING WIND GUSTS AND MARGINAL HAIL...ALTHOUGH ISOLATED TORNADOES
WILL ALSO BE POSSIBLE ASSOCIATED WITH EMBEDDED SUPERCELLS OR ANY
DISCRETE CELLS THAT MAY DEVELOP GIVEN THE STRONG LOW LEVEL SHEAR. 
IN ADDITION...THERE IS POTENTIAL FOR ADDITIONAL STORMS TO DEVELOP
NEAR THE COLD FRONT DURING THE AFTERNOON IF AIR MASS RECOVERY OCCURS
IN THE WAKE OF THE INITIAL CONVECTION. THIS MAY RESULT IN MULTIPLE
BANDS OF SEVERE STORMS PROGRESSING EWD ACROSS THIS REGION DURING THE
AFTERNOON AND EVENING HOURS.

ALTHOUGH LOW LEVEL MOISTURE/INSTABILITY IS FORECAST TO DIMINISH WITH
EASTWARD EXTEND INTO WRN/CENTRAL PARTS OF NY/PA/WV...THE VERY STRONG
WIND FIELDS AT ALL LEVELS COUPLED WITH THE EWD SURGE OF THE COLD
FRONT SUGGESTS POTENTIAL FOR LOW-TOP SQUALL LINE SEGMENTS TO SPREAD
RAPIDLY EWD...CONTINUING A THREAT FOR DAMAGING WIND GUSTS FROM THE
EVENING INTO THE OVERNIGHT HOURS.  GIVEN THE UNCERTAINTY IN THE NWD
PROGRESSION OF WARM FRONT ACROSS THE MID ATLANTIC REGION AND NEW
ENGLAND...POTENTIAL FOR DAMAGING WINDS MAY DIMINISH WITH NEWD EXTENT
OVER THIS AREA AS STORMS BECOME INCREASINGLY ELEVATED NORTH/EAST OF
THE WARM FRONT..ALTHOUGH MARGINAL HAIL MAY PERSIST WITH ELEVATED
CELLS.

...TN/LOWER MS VALLEYS INTO SRN APPALACHIANS...
STRONG DEEP LAYER SHEAR WILL EXTEND SWD ACROSS THIS REGION...AND
INCREASING MOISTURE/INSTABILITY COUPLED WITH A WEAK CAP WILL PROMOTE
EWD DEVELOPMENT OF STRONG/SEVERE STORMS ACROSS PARTS OF THE SERN
STATES.  THIS ACTIVITY IS EXPECTED TO SPREAD EWD TOWARD THE SRN
APPALACHIANS DURING THE EVENING HORUS BEFORE DIMINISHING BY 06-09Z. 
DAMAGING WINDS AND HAIL WILL BE THE PRIMARY THREATS.

..WEISS.. 03/12/2006