SPC AC 100601
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0101 AM CDT THU AUG 10 2006
VALID 111200Z - 121200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS WRN MT...CENTRAL/WRN
ND...NWRN SD...
...SYNOPSIS...
PROGRESSIVE SHORTWAVE PATTERN IS EXPECTED FROM PACIFIC NW ACROSS NRN
PLAINS AND GREAT LAKES...SEWD OVER MID ATLANTIC AND OH VALLEY
REGIONS. HEIGHT FALLS ARE FCST TO SHIFT EWD OVER NWRN CONUS THROUGH
PERIOD...RESULTING IN SWLY FLOW ALOFT FROM ID ACROSS NRN ROCKIES AND
MUCH OF MT...WITH RIDGE FROM 4-CORNERS REGION NNEWD ACROSS DAKOTAS.
FARTHER DOWNSTREAM...SEVERAL SHORTWAVES ARE FCST TO PIVOT SEWD AND
EWD AROUND SRN PERIPHERY OF VORTEX NOW OVER NRN QUE. THIS SHOULD
RESULT IN HEIGHT FALLS AND COOLING ALOFT OVER PORTIONS NEW ENGLAND
AND NRN NY...COMBINING WITH MRGL LOW LEVEL MOISTURE IN SUPPORT OF
DIURNAL GEN TSTM POTENTIAL.
STRONG RIDGING ALOFT -- NOW DOMINATING SRN 1/2-2/3 OF CONUS...IS
FCST TO SHIFT WWD SOMEWHAT AS SHORTWAVE TROUGH NOW OVER MT MOVES
SEWD AND AMPLIFIES. THIS TROUGH SHOULD MOVE OVER E-CENTRAL/SRN
PLAINS AND LOWER-MID MS VALLEY. ASSOCIATED WEAK SFC LOW AND COLD
FRONT SHOULD MOVE SLOWLY SEWD ACROSS OZARKS..OK...ARKLATEX AND SRN
HIGH PLAINS REGIONS THROUGH PERIOD.
AT SFC...FRONTAL ZONE NOW MOVING SEWD ACROSS WRN QUE...CENTRAL ONT
AND UPPER GREAT LAKES REGIONS IS FCST TO REACH COASTAL VA AND NC
DURING DAY2...REINFORCING WEAK/PRE-EXISTING BAROCLINIC ZONE
CURRENTLY EVIDENT IN THIS AREA. FRONTAL ZONE IS EXPECTED TO EXTEND
WNWWD ACROSS LOWER OH/MID MS VALLEY REGIONS THEN NWWD ACROSS
CENTRAL/NRN LOW PLAINS.
...NRN PLAINS...
TSTMS ARE EXPECTED TO DEVELOP DURING AFTERNOON HOURS OVER ERN MT OR
EXTREME WRN SD. STRONGEST SVR THREAT MAY BE FARTHER N OVER
SASK...HOWEVER SRN EXTENSION/BACKBUILDING OF CONVECTION INVOF COLD
FRONT SHOULD POSE RISK OF SEVERE GUSTS AND HAIL OVER WRN PORTIONS
CATEGORICAL SLGT RISK AREA. BAND OF VIGOROUS FRONTOGENETIC FORCING
AND AT LEAST MRGL LOW LEVEL MOISTURE WILL COMBINE WITH DIURNAL
HEATING AND STEEP LOW-MIDLEVEL LAPSE RATES TO WEAKEN CINH. LINE OF
TSTMS MAY INCLUDE A FEW SUPERCELLS AND/OR BOW ECHOES GIVEN
FAVORABLE AMBIENT SHEAR PROFILES...I.E. ROUGHLY 45-50 KT EFFECTIVE
SHEAR AND STRONGLY CURVED LOW LEVEL HODOGRAPHS IN FCST SOUNDINGS.
FARTHER E...IN ABSENCE OF SIGNIFICANT BOUNDARY LAYER FORCING...AIR
MASS IS EXPECTED TO REMAIN CAPPED BY ELEVATED MIXED LAYER UNTIL
AFTER DARK. SVR POTENTIAL THEN WILL SHIFT EWD ACROSS ND AND PERHAPS
PORTIONS NWRN SD DURING EVENING AND OVERNIGHT HOURS ASSOCIATED WITH
MCS EVOLUTION. BOUNDARY LAYER WILL DECOUPLE SOMEWHAT...AIDING
DEVELOPMENT OF 35-45 KT SLY LLJ...BUT STILL LEAVING EFFECTIVE INFLOW
PARCELS NEARLY SFC-BASED. THEREFORE WIND DAMAGE WILL CONTINUE TO BE
POSSIBLE THROUGH 12/6Z-12/9Z TIME FRAME...ALONG WITH LARGE HAIL.
...NRN ROCKIES INTO CENTRAL MT...
STRENGTHENING DEEP-LAYER SHEAR AND LARGE SCALE ASCENT/COOLING ALOFT
ARE FCST AS PACIFIC NW TROUGH ADVANCES INTO THIS REGION DURING
AFTERNOON. WEAK CINH AND HEATING WILL SUPPORT SOME POTENTIAL FOR
SFC-BASED TSTMS WITH ISOLATED HAIL OR GUSTS NEAR SVR LEVELS. MAIN
LIMITING FACTOR WILL BE LACK OF ROBUST MOISTURE...IN POSTFRONTAL
ENVIRONMENT. THREAT APPEARS TOO MRGL FOR CATEGORICAL OUTLOOK
ATTM...AND SHOULD DIMINISH MARKEDLY AFTER DARK WHEN COMBINATION OF
DIABATIC COOLING AND SFC CAA RENDERS BOUNDARY LAYER TOO STABLE FOR
SFC-BASED CONVECTION.
...SERN CONUS TO SRN PLAINS...
SEVERAL POTENTIAL REGIONAL CONCENTRATIONS OF MULTICELL CONVECTION
ARE EVIDENT WITHIN THIS BROAD AREA...HOWEVER STRONG DEPENDENCE ON
MESOSCALE PROCESSES PRECLUDES MORE PRECISE OR ENHANCED SVR
PROBABILITIES ATTM. FRONTAL ZONES WILL BOUND AREA OF RICHEST SFC
MOISTURE FROM RED RIVER VALLEY REGION NEWD THROUGH OZARKS AND LOWER
OH VALLEY...ESEWD ACROSS CAROLINAS...AND SWD TO GULF COAST. THESE
FRONTS...ALONG WITH OUTFLOW AND SEA BREEZE BOUNDARIES IN MOIST
SECTOR...WILL PROVIDE BOUNDARY LAYER FORCING AS AIR MASS HE ATS AND
CINH WEAKENS DIURNALLY. DEEP-LATER WIND FIELDS AND VERTICAL SHEAR
PROFILES ARE EXPECTED TO REMAIN RATHER WEAK DURING DAY...SUPPORTING
MULTICELLULAR AND PULSE MODES OF CONNECTION WITH BRIEF STG-SVR
DOWNDRAFTS BEING MAIN THREAT. NOCTURNAL LLJ MAY DEVELOP AHEAD OF
MIDLEVEL SHORTWAVE TROUGH -- FROM N-CENTRAL TX INTO PORTIONS TN
VALLEY REGION...WHICH COULD SUPPORT EXTENDED TSTM POTENTIAL WITH
MRGL WIND DAMAGE THREAT AFTER DARK IN ITS VICINITY.
..EDWARDS.. 08/10/2006
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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