SWODY3
SPC AC 030708
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0208 AM CDT FRI AUG 03 2007
VALID 051200Z - 061200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
ACTIVE NRN STREAM FLOW PATTERN IS FCST...WITH RELATIVELY TIGHT
HEIGHT GRADIENT ALOFT DEVELOPING OVER NRN PLAINS AND GREAT LAKES.
THIS WILL BE IN RESPONSE TO BUILDING HEIGHTS ACROSS LOWER MS VALLEY
AND SHORTWAVE TROUGH MOVING EWD ACROSS MB AND HUDSON BAY REGION.
SEVERAL SHORTWAVE PERTURBATIONS WILL REINFORCE PERSISTENT
TROUGHING...BOTH ACROSS PACIFIC NW REGION AND OVER SERN CONUS. ONE
OR MORE MCV'S FROM PRIOR CONVECTIVE COMPLEXES ALSO MAY BE EMBEDDED
WITHIN FLOW BELT FROM NRN PLAINS TO MID ATLANTIC.
AT SFC...FRONTAL ZONE -- PERHAPS MODULATED ON MESOSCALE BY
OUTFLOWS...SHOULD EXTEND FROM MID ATLANTIC ACROSS LOWER MI...THEN
DIFFUSELY WWD TO CENTRAL PLAINS. COLD FRONT ASSOCIATED WITH
CANADIAN SHORTWAVE TROUGH WILL MOVE SEWD OVER DAKOTAS AND MT.
..NRN PLAINS...UPPER MS VALLEY TO UPPER GREAT LAKES...
STRONGEST BOUNDARY LAYER THETAE AND BUOYANCY ARE EXPECTED OVER
CENTRAL PLAINS INTO IA...PERHAPS AS FAR E AS PORTIONS NRN IL/SRN
WI...ALONG AND S OF OLDER BAROCLINIC ZONE. MOST FAVORABLE
DEEP-LAYER VERTICAL SHEAR SHOULD BE DISPLACED FARTHER N INVOF NEWER
SFC COLD FRONT OVER NRN PLAINS...AND NEAR LOWER MI SFC LOW...EACH OF
WHICH MAY BE CHARACTERIZED BY RELATIVE WEAKNESSES IN LOW LEVEL
MOISTURE AND/OR SFC FLOW. SPECIFIC FOCI FOR CONVECTION ALSO WILL
DEPEND STRONGLY ON MESOSCALE FEATURES...SFC AND ALOFT. GIVEN THESE
DISPLACEMENTS AND UNCERTAINTIES...BROAD AREA OF MRGL/CONDITIONAL SVR
PROBABILITIES IS ASSIGNED ATTM...TO BE REFINED IN FUTURE OUTLOOKS.
..UPPER GREAT LAKES TO OH VALLEY AND MID-ATLANTIC...
MCS MAY BE ONGOING AT BEGINNING OF PERIOD...EXTENDING DAY-2
CONVECTIVE POTENTIAL EWD IN CORRIDOR ACROSS SOME PORTION UPPER GREAT
LAKES TO MID ATLANTIC REGION. WEAKNESSES OF BOTH BOUNDARY LAYER
THETAE AND LAPSE RATES ALOFT SHOULD LIMIT AVAILABLE BUOYANCY THROUGH
MUCH OF THIS CORRIDOR...THOUGH ANY MCV ASSOCIATED WITH EARLY COMPLEX
COULD PROVIDE MESOSCALE SHEAR/LIFT ENHANCEMENTS. ATTM ANY SVR
POTENTIAL WITH SUCH REGIME APPEARS TOO CONDITIONAL/MRGL TO WARRANT
CATEGORICAL OUTLOOK ATTM.
..NRN ROCKIES AREA...
ISOLATED TO WIDELY SCATTERED TSTMS MAY FORM DURING AFTERNOON/EVENING
IN MRGL LOW LEVEL MOISTURE BUT FAVORABLE DEEP-LAYER SHEAR...BENEATH
MID-UPPER LEVEL SWLY JET...OVER PORTIONS WRN/SRN MT OR NRN WY.
POST-FRONTAL/NELY FLOW MAY AID IN BOTH LIFT AND VERTICAL SHEAR AS
WELL. LACK OF MORE ROBUST MOISTURE AND OF STRONGER UPPER FORCING
INDICATES MRGL SVR THREAT.
.EDWARDS.. 08/03/2007
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