[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 040557
SWODY1
SPC AC 040555

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1255 AM CDT TUE JUL 04 2006

VALID 041200Z - 051200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NERN AND MID ATLANTIC
STATES WWD INTO THE OH VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS ERN WY/SWRN SD/WRN
NEB...

...SYNOPSIS...
CLOSED UPPER LOW OVER NRN ONTARIO AND ATTENDANT TROUGH EXTENDING
ACROSS THE GREAT LAKES WILL MOVE SLOWLY ESEWD WITH BROAD CYCLONIC
FLOW CONTINUING FROM THE UPPER MS VALLEY THROUGH THE GREAT LAKES/OH
VALLEY REGION INTO THE MID ATLANTIC/NERN STATES.  AMPLIFICATION OF
GREAT LAKES TROUGH IS EXPECTED LATER TODAY/TONIGHT AS AN UPSTREAM
SHORT WAVE TROUGH TRACKS SEWD TOWARD THE WRN GREAT LAKES/MIDWEST AND
UPPER RIDGE BUILDS EWD OVER THE NRN HIGH PLAINS/CANADIAN PRAIRIE
PROVINCES.  MEANWHILE...A COUPLE OF MID LEVEL IMPULSES NOW LOCATED
OVER THE ERN PACIFIC /WEST OF CA/ WILL TRACK NNELY WITHIN ERN
PERIPHERY OF NERN PACIFIC CLOSED LOW CROSSING THE PACIFIC NORTHWEST
THIS FORECAST PERIOD.

...NERN/MID ATLANTIC STATES WWD ACROSS THE OH VALLEY...
AT THE SURFACE...A PRE-FRONTAL TROUGH IS EXPECTED TO MOVE SWD ACROSS
THE OH VALLEY AND EWD INTO NEW ENGLAND TODAY FOLLOWED BY A COLD
FRONT SPREADING EWD THROUGH ERN CANADA AND SEWD ACROSS THE LOWER
GREAT LAKES AND MID MS VALLEY. THE COLD FRONT SHOULD EXTEND FROM
NEW ENGLAND SWWD THROUGH THE OH VALLEY TO THE SRN PLAINS BY 12Z
WEDNESDAY.

THUNDERSTORMS SHOULD BE ONGOING AT 12Z TODAY FROM THE MID MS VALLEY
TO PARTS OF THE LOWER GREAT LAKES REGION.  SURFACE HEATING IS
EXPECTED ALONG/S OF THE PRE-FRONTAL TROUGH...AND ALSO WITHIN A
RATHER NARROW ZONE ACROSS THE SRN GREAT LAKES REGION IN THE WAKE OF
THE MORNING ACTIVITY AND AHEAD OF THE COLD FRONT.  DESPITE MODEST
LAPSE RATES...THE SURFACE HEATING WITHIN A MOIST AIR MASS WILL
RESULT IN MODERATE INSTABILITY.  DEEP WSWLY WINDS AT 30-40 KT WILL
SUPPORT SUFFICIENT DEEP LAYER SHEAR FOR ORGANIZED STORMS WITHIN THE
SLIGHT RISK AREA.  STRONG TO SEVERE STORMS SHOULD BE FOCUSED ALONG
THE PRE-FRONTAL TROUGH FROM SRN IND/SRN OH TO THE MID ATLANTIC
STATES AND NEW ENGLAND THROUGH THE AFTERNOON/EARLY EVENING.  THE
POTENTIAL FOR SEVERE STORMS IS ALSO EXPECTED ALONG THE PROGRESSIVE
COLD FRONT FROM THE LOWER GREAT LAKES/OH VALLEY TO UPSTATE NY/NRN
NEW ENGLAND.  UNI-DIRECTIONAL TROPOSPHERIC WINDS WITH GENERALLY
STRAIGHT HODOGRAPHS SUGGESTS LINE SEGMENTS WITH DAMAGING WINDS
SHOULD BE THE PRIMARY THREAT...THOUGH SPLITTING STORMS WILL BE
POSSIBLE.

...ERN WY INTO WRN PARTS OF SD/NEB...
WEAK MID LEVEL IMPULSES CURRENTLY MOVING ENEWD THROUGH THE NRN
INTERMOUNTAIN WEST PER WATER VAPOR IMAGERY ARE PROGGED TO TRACK SEWD
ACROSS THE NRN/CENTRAL HIGH PLAINS THIS AFTERNOON.  ESELY LOW LEVEL
FLOW PROGGED ACROSS THIS REGION AS SURFACE HIGH PRESSURE BUILDS SEWD
THROUGH THE MID MO VALLEY WILL ALLOW GREATER MOISTURE TO RETURN NWWD
INTO WRN NEB/ERN WY.  THIS MOISTURE WILL BE LOCATED BENEATH ERN
EXTENT OF STEEP LAPSE RATES BY PEAK HEATING RESULTING IN MODERATE
INSTABILITY.  MODEST NWLY MID LEVEL WINDS /20-25 KT/ EXPECTED ATOP
THE ESELY LOW LEVEL FLOW WILL PROVIDE FAVORABLE DEEP LAYER SHEAR
/30-40 KT/ FOR SUPERCELLS WITH HAIL AND DAMAGING WIND GUSTS. 
THUNDERSTORMS SHOULD INITIALLY DEVELOP ALONG THE HIGHER TERRAIN OF
ERN WY/SWRN SD...AND THEN DEVELOP SEWD INTO THE HIGH PLAINS.

...CENTRAL-ERN WA/NRN ORE/ID PANHANDLE...
SLY MID LEVEL WINDS ARE PROGGED TO STRENGTHEN ACROSS THE PACIFIC
NORTHWEST THIS FORECAST PERIOD AS THE NERN PACIFIC LOW MOVES SLOWLY
TO THE ESE AND A COUPLE OF SHORT WAVE TROUGHS TRACK NNEWD ACROSS
THIS REGION.  PLUME OF MID LEVEL MOISTURE LOCATED WITHIN SSWLY FLOW
ALOFT COMBINED WITH STEEP LAPSE RATES AND ASCENT AHEAD OF LEAD SHORT
WAVE TROUGH ARE EXPECTED TO SUPPORT THE POTENTIAL FOR HIGH BASED
THUNDERSTORMS THIS AFTERNOON INTO THE EVENING. ALTHOUGH DEEP LAYER
SHEAR SHOULD INCREASE...MARGINAL INSTABILITY /MLCAPE 500-1000 J/KG/
IS EXPECTED TO LIMIT THE OVERALL SEVERE THREAT.  STEEP LAPSE RATES
AND DEEP WELL MIXED BOUNDARY LAYER /INVERTED-V THERMODYNAMIC
PROFILES/ SUGGESTS THREAT FOR ISOLATED MICROBURSTS AND POSSIBLE
HAIL.

..PETERS/GUYER.. 07/04/2006