[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 280608
SWODY2
SPC AC 280607

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0107 AM CDT SUN MAY 28 2006

VALID 291200Z - 301200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER MS VALLEY SWD
THROUGH PARTS OF THE CENTRAL/SRN PLAINS...

...SYNOPSIS...
STRONG RIDGE IS EXPECTED TO REMAIN CENTERED FROM THE CENTRAL GULF
COAST STATES NWD TO HUDSON BAY.  HEIGHTS IN THE WEST WILL BEGIN TO
RISE AS STRONG SHORT WAVE TROUGH PROGGED TO MOVE NEWD INTO THE NRN
HIGH PLAINS AND ALBERTA/SASKATCHEWAN BY LATE DAY 1 CONTINUES TO
TRACK NEWD INTO CENTRAL CANADA.

...UPPER MS VALLEY TO SRN PLAINS...
SURFACE FRONT ASSOCIATED WITH THE CANADIAN SHORT WAVE TROUGH IS
EXPECTED TO EXTEND FROM WRN MN SSWWD THROUGH ERN NEB TO THE OK/NRN
TX PANHANDLES AT 12Z MONDAY.  THIS BOUNDARY WILL MOVE EWD THROUGH
THE PERIOD AND SHOULD EXTEND FROM ERN MN TO ERN KS INTO WRN OK/NW TX
BY LATE MONDAY AFTERNOON /TOWARD 30/00Z/.  DRY LINE IS EXPECTED TO
EXTEND SWD FROM NWRN OK WHERE IT INTERSECTS COLD FRONT AND THEN TO
THE TX BIG BEND REGION.  ALTHOUGH THE UPPER TROUGH WILL BE MOVING
NEWD INTO CANADA...THE ENTRANCE REGION OF A STRONG SWLY MID LEVEL
JET ACCOMPANYING THIS SYSTEM IS EXPECTED TO PROVIDE FAVORABLE ASCENT
FOR UPWARD VERTICAL MOTION ACROSS UPPER MS VALLEY INTO IA.

THUNDERSTORM CLUSTER...POTENTIALLY SEVERE...IS EXPECTED TO BE
ONGOING AT THE START OF DAY 2 ACROSS PARTS OF THE ERN DAKOTAS INTO
WRN MN.  THIS ACTIVITY SHOULD DECREASE IN INTENSITY MONDAY MORNING
AS IT SPREADS ENE ACROSS MN...GIVEN A WEAKENING TREND IN THE LLJ
ACROSS THIS AREA.  STRONG SURFACE HEATING /UNSEASONABLY WARM
TEMPERATURES MONDAY AFTERNOON/ EXPECTED TO PERSIST INTO DAY 2 PERIOD
ALONG/E OF FRONT COMBINED WITH VERY MOIST AIR MASS AND STEEP MID
LEVEL LAPSE RATES WILL SUPPORT VERY STRONG INSTABILITY.  ALTHOUGH
STRONGER MID LEVEL WINDS ARE EXPECTED TO REMAIN ATOP THE
POST-FRONTAL AIR MASS...AT LEAST 25-30 KT OF MID LEVEL FLOW SHOULD
BE LOCATED FROM THE UPPER MS VALLEY SWD INTO ERN KS/NRN OK AIDING IN
STORM ORGANIZATION.

LARGE SCALE ASCENT WITHIN MID LEVEL JET ENTRANCE COMBINED WITH LOW
LEVEL CONVERGENCE ALONG THE FRONT WILL ALLOW THUNDERSTORMS TO
DEVELOP BY EARLY-MID AFTERNOON ACROSS MN WITH ACTIVITY DEVELOPING
SWD ALONG THE FRONT INTO IA.  GIVEN VERY STRONG INSTABILITY AND
MODERATE DEEP LAYER SHEAR ORIENTED PARALLEL TO SURFACE BOUNDARY...
STORM MODE SHOULD BE LINEAR WITH POTENTIAL FOR EMBEDDED SUPERCELLS
WITHIN THE LINE OF ACTIVITY.  POTENTIAL EXISTS FOR VERY LARGE HAIL
WITH THE STRONGEST STORMS GIVEN THE DEGREE OF INSTABILITY FORECAST. 
THE STORMS OVER MN/IA WILL MOVE EWD INTO WI/NRN IL MONDAY
EVENING...BUT SEVERE THREAT SHOULD DIMINISH WITH EWD EXTENT GIVEN
DECREASING INSTABILITY MONDAY NIGHT.  

FARTHER S...THE LACK OF STRONGER UPPER FORCING SUGGESTS SURFACE
HEATING WILL BE THE PRIMARY IMPETUS IN WEAKENING THE CAP FOR
THUNDERSTORM DEVELOPMENT JUST AFTER PEAK HEATING ALONG THE FRONT AND
DRY LINE IN KS/WRN OK INTO W TX.  DEEP LAYER SHEAR IS EXPECTED TO BE
SUFFICIENT /AROUND 25 KT/ FOR ORGANIZED STORMS...WITH LARGE HAIL AND
DAMAGING WINDS BEING THE PRIMARY THREATS.

MODELS SUGGEST THE POTENTIAL FOR ONE OR TWO MCS/S TO DEVELOP MONDAY
NIGHT...WITH ONE OVER KS AND/OR OK AND THE SECOND ACROSS IA/NRN MO
INTO WRN IL.  THESE MCS/S WILL BE MAINTAINED BY STRENGTHENING
NOCTURNAL SSWLY LLJ EXTENDING INTO THESE REGIONS COMBINED WITH
SUFFICIENT EFFECTIVE BULK SHEAR/INSTABILITY FOR A CONTINUED SEVERE
POTENTIAL OVERNIGHT.

...WRN NEW ENGLAND/CENTRAL-ERN NY INTO NERN PA...
MODELS TEND TO AGREE THAT AN MCS TOPPING THE RIDGE LATE DAY 1 ACROSS
SERN ONTARIO/SRN QUEBEC SHOULD BE ENTERING THE U.S. IN UPSTATE
NY/NRN VT TOWARD 12Z MONDAY.  THIS CLUSTER OF STORMS SHOULD BE IN
THE DECAYING PHASE MONDAY MORNING AS IT TRACKS SEWD ACROSS NEW
ENGLAND.  OUTFLOW BOUNDARY ASSOCIATED WITH THIS MCS MAY PROVIDE A
FOCUS FOR AFTERNOON/EARLY EVENING THUNDERSTORMS ACROSS PARTS OF WRN
NEW ENGLAND INTO ERN/CENTRAL NY AND NERN PA.  AIR MASS ACROSS THESE
REGIONS SHOULD BECOME MODERATELY UNSTABLE.  THIS COMBINED WITH
MODEST LAPSE RATES /AROUND 6.5 C/KM/ AND 30 KT OF NWLY MID LEVEL
FLOW MAY ALLOW FOR A FEW STORMS TO PRODUCE MARGINALLY SEVERE HAIL
AND/OR A STRONG WIND GUST.  THUS...HAVE INTRODUCED A LOW SEVERE
PROBABILITY /5%/.

..PETERS.. 05/28/2006