[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 151737
SWODY2
SPC AC 151736

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1136 AM CST WED FEB 15 2006

VALID 161200Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS THU AFTN/EVE ACROSS PARTS OF
THE MIDDLE MISSISSIPPI/LOWER OHIO VALLEY....

MODELS SUGGEST POSITIVELY TILTED BROADER-SCALE TROUGHING WILL
PERSIST ACROSS MUCH OF THE NORTHERN INTERMOUNTAIN REGION AND PACIFIC
COAST STATES THROUGH THIS FORECAST PERIOD.  DOWNSTREAM... FLOW
REGIME IS ACTUALLY FORECAST TO TREND TOWARD MORE OF AN ANTICYCLONIC
REGIME...FROM THE FOUR CORNERS REGION THROUGH THE CENTRAL AND
SOUTHERN PLAINS...EVENTUALLY EASTWARD INTO THE LOWER OHIO VALLEY BY
EARLY FRIDAY.  THIS WILL OCCUR NORTH OF BUILDING SUBTROPICAL
RIDGE...CENTERED OVER SOUTHERN MEXICO AND THE BAY OF CAMPECHE...AND
IN WAKE OF SIGNIFICANT SHORT WAVE TROUGH ACCELERATING OUT OF THE
WESTERN TROUGH...AND AROUND SOUTHERN PERIPHERY OF LINGERING SOUTH
CENTRAL CANADIAN POLAR LOW.

MODELS CONTINUE TO INDICATE THAT FORCING ASSOCIATED WITH SHORT WAVE
IMPULSE WILL SUPPORT FAIRLY STRONG LOW-LEVEL CYCLOGENESIS ALONG
FRONTAL ZONE CURRENTLY STALLED ACROSS THE SOUTH CENTRAL PLAINS AND
MIDDLE MISSISSIPPI VALLEY INTO THE LOWER GREAT LAKES REGION.  THIS
WILL BE ACCOMPANIED BY A DEEPER SOUTHWARD SURGE OF AN ARCTIC AIR
MASS WHICH IS ALREADY NOSING THROUGH THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY.  HOWEVER...AHEAD OF THE COLD INTRUSION...A
RETURN FLOW OF MOISTURE ASSOCIATED WITH DEVELOPING SURFACE WAVE IS
ALREADY ONGOING.  IN THE PRESENCE OF STRONG FORCING FOR UPWARD
VERTICAL MOTION AND STRONG SHEAR...THIS SEEMS LIKELY TO BECOME OF
SUFFICIENT MAGNITUDE TO SUPPORT INCREASING SEVERE THUNDERSTORM
POTENTIAL BY LATE THURSDAY FROM PARTS OF THE OZARK PLATEAU INTO THE
LOWER GREAT LAKES.

...MIDDLE MISSISSIPPI/LOWER OHIO VALLEY REGION...
TONGUE OF MID 50S+ SURFACE DEW POINTS...NOW ADVECTING OFF THE
WESTERN GULF OF MEXICO INTO EAST TEXAS...APPEARS LIKELY TO CONTINUE
TO SPREAD NORTHWARD THROUGH MUCH OF THE MIDDLE MISSISSIPPI BY 12Z
THURSDAY...THEN EASTWARD THROUGH THE LOWER OHIO VALLEY BY LATE
THURSDAY AFTERNOON.  THOUGH SCATTERED THUNDERSTORM ACTIVITY MAY BE
ONGOING EARLY IN THE PERIOD ACROSS PARTS OF SOUTHERN IOWA/NORTHERN
MISSOURI/WEST CENTRAL ILLINOIS...WHERE STEEPER ISENTROPIC ASCENT
WILL EXIST NEAR FRONTAL ZONE...MOIST LAYER TO THE SOUTH IS EXPECTED
TO BE CAPPED BY AN ELEVATED MIXED LAYER EMANATING FROM THE SOUTHERN
ROCKIES/PLATEAU REGION.

THIS IS EXPECTED TO REMAIN THE CASE THROUGH MUCH OF THE DAY...UNTIL
MID/UPPER FLOW BECOMES INCREASINGLY CYCLONIC...AS CORE OF 100+ KT
500 MB JET BEGINS TO DEVELOP EAST NORTHEAST OF THE OZARK PLATEAU. 
IN CONJUNCTION WITH DEEPENING SURFACE LOW... PROGGED TO THE
NORTHEAST OF THE MIDDLE MISSISSIPPI VALLEY BY MID AFTERNOON...AND
STRENGTHENING FRONTOGENETIC FORCING...LIFT IS EXPECTED TO SUPPORT
INCREASING THUNDERSTORM ACTIVITY FROM PARTS OF EAST
CENTRAL/SOUTHEAST MISSOURI INTO CENTRAL/SOUTHERN ILLINOIS BY AROUND
21Z.

DEEP LAYER SHEAR PROFILES WILL BE MORE THAN SUFFICIENT FOR
SUPERCELLS...WHICH MODEL FORECAST SOUNDINGS SUGGEST SHOULD BE
SUPPORTED BY MIXED LAYER/MOST UNSTABLE CAPE IN EXCESS OF 500 J/KG
...PERHAPS APPROACHING 1000 J/KG.  SOME DISCREPANCIES EXIST AMONG
THE MODELS CONCERNING THE POSSIBLE PRESENCE OF A SHALLOW
SURFACE-BASED STABLE LAYER EVEN IN THE WARM SECTOR...WHICH MAY
IMPACT TORNADO POTENTIAL.  AT THE PRESENT TIME...IT APPEARS LOW-
LEVEL THERMODYNAMIC STRUCTURE COULD BECOME SUPPORTIVE OF TORNADOES
IN STRONG LOW-LEVEL SHEAR REGIME NEAR/SOUTHWEST OF ST. LOUIS MO EAST
NORTHEASTWARD INTO PARTS OF WEST CENTRAL INDIANA.  IF THIS
OCCURS...AN ISOLATED STRONG TORNADO IS POSSIBLE.  OTHERWISE...A  FEW
SEVERE THUNDERSTORMS WITH LARGE HAIL/DAMAGING WINDS ARE EXPECTED TO
DEVELOP ALONG EVOLVING SQUALL LINE AS IT DEVELOPS EASTWARD INTO THE
LOWER OHIO VALLEY EARLY THURSDAY EVENING.

CYCLONE WILL CONTINUE TO DEEPEN AS IT SHIFTS ACROSS THE SOUTHERN/
LOWER GREAT LAKES REGION THURSDAY NIGHT INTO EARLY FRIDAY. 
HOWEVER...LOW-LEVEL DESTABILIZATION MAY NOT BECOME SUFFICIENT TO
MAINTAIN CONVECTIVE/SEVERE POTENTIAL.

..KERR.. 02/15/2006

...NOTICE...
THE STATION RELATIVE POINTS IN THIS PRODUCT WERE
DISCONTINUED ON 14 FEBRUARY 2006 AND ARE NOW AVAILABLE
IN THE FOLLOWING PRODUCTS:

   WMO HEADER:       AWIPS ID:
   WUUS01            PTSDY1
   WUUS02            PTSDY2
   WUUS03            PTSDY3

A SERVICE CHANGE NOTICE ...SCN05-39... PROVIDES DETAILS
ON THIS TRANSITION. FOR ADDITIONAL DETAILS SEE THE FOLLOWING
WEB ADDRESS USING LOWER CASE LETTERS:
WWW.NWS.NOAA.GOV/OM/NOTIF.HTM