SPC AC 030603
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0103 AM CDT MON JUL 03 2006
VALID 031200Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE NRN/CENTRAL
HIGH PLAINS EWD TO THE GREAT LAKES/OH VALLEY AND NY...
...SYNOPSIS...
MID/UPPER LEVEL CLOSED LOW WILL TRACK ESEWD ACROSS NRN ONTARIO TODAY
MAINTAINING BROAD CYCLONIC FLOW REGIME FROM THE NRN PLAINS/UPPER MS
VALLEY ACROSS THE GREAT LAKES/OH VALLEY TO THE NERN STATES. PRIMARY
SHORT WAVE TROUGH ASSOCIATED WITH THIS UPPER LOW IS PROGGED TO MOVE
SEWD FROM THE UPPER MS VALLEY INTO THE GREAT LAKES REGION. SEVERAL
WEAK MID LEVEL IMPULSES SHOULD TRAVERSE THE SRN EXTENT OF STRONGER
FLOW ALOFT FROM THE CENTRAL PLAINS EWD THROUGH THE LOWER MO TO OH
VALLEYS AND OFF THE MID ATLANTIC COAST. MEANWHILE...UPSTREAM SHORT
WAVE TROUGH...CURRENTLY LOCATED ACROSS THE NRN INTERMOUNTAIN WEST...
IS EXPECTED TO TOP THE RIDGE AXIS OVER WRN MT EARLY TODAY AND THEN
TURN ESEWD ACROSS MT REACHING THE WRN DAKOTAS LATE TONIGHT.
IN THE LOW LEVELS...SURFACE BOUNDARY EXTENDING FROM OH WWD TO
CENTRAL IL THEN GENERALLY WSWWD ACROSS SRN IA TO WRN KS/ERN CO IS
EXPECTED TO REMAIN QUASI-STATIONARY THROUGH THE FORECAST PERIOD.
MEANWHILE...COLD FRONT ACCOMPANYING UPPER MS VALLEY/GREAT LAKES
SHORT WAVE TROUGH SHOULD EXTEND FROM THE MN ARROWHEAD SWWD TO ERN SD
AT 12Z TODAY AND THEN EXTEND FROM THE ERN U.P. OF MI ACROSS ERN WI
TO SERN IA BY 04/00Z.
...GREAT LAKES/OH VALLEY/PARTS OF UPPER AND MID MS VALLEY...
THUNDERSTORMS MAY BE ONGOING AT THE START OF THE PERIOD ESEWD FROM
IA INTO PARTS OF THE OH VALLEY. MODELS SUGGEST THIS ACTIVITY SHOULD
WEAKEN THIS MORNING. MOIST AIR MASS /SURFACE DEWPOINTS IN THE MID
60S TO AROUND 70/ ALREADY IN PLACE ALONG THE QUASI-STATIONARY
BOUNDARY EXTENDING FROM MID MS VALLEY INTO OH VALLEY IS EXPECTED TO
BECOME MODERATELY UNSTABLE TODAY. WEAK MID LEVEL IMPULSE PROGGED TO
MOVE ACROSS THIS REGION IS EXPECTED TO SUPPORT SCATTERED
THUNDERSTORM DEVELOPMENT THROUGH THE AFTERNOON WITH HAIL AND STRONG
WIND GUSTS BEING THE PRIMARY THREATS.
FARTHER N AND W...STRENGTHENING SWLY LOW LEVEL WINDS AHEAD OF THE
COLD FRONT WILL ALLOW MOISTURE TO RETURN NEWD INTO THE UPPER GREAT
LAKES REGION WITH SURFACE DEWPOINTS IN THE UPPER 50S TO AROUND 60
REACHING MUCH OF THE UPPER PENINSULA OF MI AND NRN LOWER MI.
SURFACE HEATING WITHIN THIS MOIST AIR MASS WILL RESULT IN MODERATE
INSTABILITY IN THE WARM SECTOR WITH STRONGEST INSTABILITY EXPECTED
ACROSS PARTS OF SRN WI/ERN IA AND NRN IL WHERE SURFACE DEWPOINTS
WILL BE GREATEST. THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE
COLD FRONT BY EARLY AFTERNOON FROM NERN NEB THROUGH SERN MN TO MUCH
OF THE WRN UPPER PENINSULA OF MI. ACTIVITY WILL THEN DEVELOP ESEWD
ACROSS THE GREAT LAKES REGION AND TOWARD THE LOWER MO AND OH VALLEYS
THIS EVENING/OVERNIGHT. MAINLY DEEP WNWLY WIND FIELDS SHOULD RESULT
IN BOWING LINE SEGMENTS WITH DAMAGING WINDS THE PRIMARY THREAT.
...CENTRAL/ERN NY AND WRN VT...
WEAK MID LEVEL IMPULSE AND ATTENDANT N-S ORIENTED SURFACE TROUGH ARE
PROGGED TO MOVE EWD ACROSS THIS REGION TODAY INTO THIS EVENING.
RESIDUAL MOISTURE ACROSS THIS REGION IS EXPECTED TO AID IN THE AIR
MASS BECOMING MODERATELY UNSTABLE BY AFTERNOON AND SUPPORTING
THUNDERSTORM DEVELOPMENT ALONG THE SURFACE TROUGH. THE INSTABILITY
COMBINED WITH FAVORABLE DEEP LAYER SHEAR IS EXPECTED TO RESULT IN A
SEVERE THREAT INTO THE EARLY EVENING.
...SRN MT SEWD TO NERN CO/NRN KS/NEB...
ASCENT AHEAD OF THE NRN INTERMOUNTAIN SHORT WAVE TROUGH IS EXPECTED
TO SPREAD ACROSS THE HIGHER TERRAIN OF SWRN MT/WRN WY BY EARLY
AFTERNOON SUPPORTING THUNDERSTORM DEVELOPMENT. DESPITE SOMEWHAT DRY
LOW LEVELS ACROSS SRN MT/WY...STEEP LAPSE RATES ARE EXPECTED TO
SUPPORT MLCAPE VALUES AROUND 1000 J/KG. GREATER MOISTURE INTO THE
CENTRAL PLAINS SHOULD RESULT IN A MODERATELY UNSTABLE AIR MASS
FARTHER SE ALONG THE WRN EXTENT OF THE SURFACE BOUNDARY FROM ERN CO
TO SRN NEB/NRN KS.
THUNDERSTORMS ARE EXPECTED TO DEVELOP AND SPREAD ESEWD INTO THE
NRN/CENTRAL HIGH PLAINS THIS AFTERNOON/EVENING WITH SUFFICIENT DEEP
LAYER SHEAR RESULTING IN HAIL/STRONG WIND GUSTS. INCREASING UPSLOPE
FLOW THIS EVENING INTO SERN MT MAY ALLOW STORMS TO PERSIST INTO THE
OVERNIGHT PERIOD AS THE SHORT WAVE TROUGH APPROACHES THE WRN
DAKOTAS...BUT DECREASING INSTABILITY SHOULD LIMIT THE SEVERE THREAT
LATER TONIGHT.
FARTHER SE...CONVERGENCE ALONG THE SURFACE BOUNDARY AND/OR UPSLOPE
FLOW WILL SUPPORT THUNDERSTORM DEVELOPMENT FROM ERN CO EWD INTO NEB
AND WRN/NRN KS. HAIL AND DAMAGING WINDS WILL ALSO BE A THREAT
ACROSS THESE STATES.
...CENTRAL/ERN ORE INTO SRN ID/NWRN UT...
A SHORT WAVE TROUGH APPROACHING ORE AND A SECOND IMPULSE APPROACHING
THE NRN INTERMOUNTAIN REGION THIS AFTERNOON/EVENING SHOULD SUPPORT
ISOLATED STRONG TO SEVERE STORMS FROM CENTRAL/ERN ORE INTO SRN ID
AND NWRN UT. AIR MASS ACROSS THESE REGIONS IS EXPECTED TO BECOME
MARGINALLY TO MODERATELY UNSTABLE WITH INCREASING DEEP LAYER SHEAR
SUPPORTING STORM ORGANIZATION FOR A FEW SEVERE STORMS.
..PETERS/GUYER.. 07/03/2006
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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