SPC AC 040706
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0206 AM CDT SAT AUG 04 2007
VALID 061200Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS N-CENTRAL PLAINS TO
UPPER MS VALLEY...
...SYNOPSIS...
STRONG SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY
OVER CANADIAN ROCKIES...IS EXPECTED TO MOVE EWD ACROSS MOST OF
CANADA THROUGH LATE DAY-3 PERIOD...REACHING FROM CENTRAL/ERN QUE SWD
ACROSS NEW ENGLAND IN 07/00Z-07/06Z TIME RANGE. ASSOCIATED SFC COLD
FRONT SHOULD MOVE EWD/SEWD OVER SAME AREA -- PRECEDED BY LOW LEVEL
SWLYS AND WAA REGIME. FRONTAL ZONE SHOULD EXTEND SWWD ACROSS SRN
LOWER MI/NRN OH/NRN INDIANA REGION AT 07/00Z...THEN WNWWD ACROSS
N-CENTRAL PLAINS AS WARM FRONT INTO SFC CYCLONE OVER SD. SFC
TROUGHING SHOULD CONNECT THIS LOW WITH ANOTHER OVER ERN CO/WRN KS
VICINITY. MAIN N-CENTRAL PLAINS SFC LOW SHOULD MOVE EWD TOWARD
UPPER MS VALLEY OVERNIGHT...WITH COLD FRONT MOVING SEWD ACROSS
CENTRAL HIGH PLAINS. SREF MEMBERS AND OPERATIONAL SPECTRAL/NAM
MODELS DO SHOW CONSIDERABLE VARIATION IN MORE PRECISE
PLACEMENT/STRENGTH OF SFC LOW...WITH ASSOCIATED ISALLOBARIC FORCING
AND BACKING OF SFC WINDS BEING CRUCIAL TO LOCATION OF GREATEST SVR
PROBABILITIES.
...CENTRAL/NRN PLAINS TO UPPER MS VALLEY...
BASIC PATTERN SHOULD BE CHARACTERIZED BY AREA OF SFC DEW POINTS 70S
F...BENEATH 30-40 KT WSWLY 500 MB FLOW...FROM NEAR SFC LOW EWD INVOF
WARM FRONT. MODIFIED NAM/NAM-KF SOUNDINGS SUGGEST VERY UNSTABLE AIR
MASS IS POSSIBLE WITH MLCAPES POSSIBLY NEAR 5000 J/KG...AND
FAVORABLE LOW LEVEL HODOGRAPHS FOR BOTH SUPERCELLS AND BOWS. ONE OR
MORE COMPLEXES OF TSTMS SHOULD EVOLVE DURING EVENING/OVERNIGHT
HOURS...SHIFTING SVR THREAT EWD TOWARD UPPER MS VALLEY. GIVEN
FAVORABLE SHEAR/THERMODYNAMIC PROFILES LIKELY TO OVERLAP SOMEWHERE
ACROSS OUTLOOK AREA IN THIS SYNOPTIC PATTERN...SMALLER AREA OF MORE
CONCENTRATED SVR PROBABILITIES MAY BE REQUIRED IN FUTURE
UPDATES...ONCE FCST PLACEMENT/GEOMETRY OF SFC FEATURES BECOMES MORE
CERTAIN.
ALTHOUGH STG SFC HEATING AND FAVORABLE MOISTURE WILL EXTEND SWD
ACROSS MUCH OF NEB/KS AND POSSIBLY INTO ERN CO...WEAKENING OF BOTH
DEEP-LAYER SHEAR PROFILES AND DEEP-LAYER LIFT ARE EXPECTED WITH SWD
EXTENT...RENDERING SVR POTENTIAL MORE CONDITIONAL AND ISOLATED.
...NERN CONUS...
NARROW CORRIDOR OF INCREASING LOW LEVEL THETAE SHOULD EXTEND NEWD
ACROSS MID-ATLANTIC AND NEW ENGLAND REGIONS AHEAD OF COLD
FRONT...DURING AFTERNOON/EARLY EVENING HOURS. MEANWHILE SRN LOBE OF
LARGE SCALE ASCENT ASSOCIATED WITH MID-UPPER TROUGH WILL PASS ACROSS
AT LEAST NRN NY AND NEW ENGLAND...PERHAPS EXTENDING SWD TOWARD NJ.
THIS REGIME MAY SUPPORT DEVELOPMENT OF TSTMS WITH POTENTIAL FOR
STG-SVR HAIL AND GUSTS...THOUGH STRENGTH OF MOISTURE RETURN IS IN
QUESTION AT THIS EARLY STAGE. THEREFORE MRGL SVR PROBABILITIES ARE
ASSIGNED ATTM.
..EDWARDS.. 08/04/2007
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1100Z
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