SWODY2
SPC AC 310546
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1246 AM CDT SAT MAY 31 2008
VALID 011200Z - 021200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE NRN/CNTRL
HIGH PLAINS EWD ACROSS KS/OK...THE LOWER MS VALLEY TO THE SERN
ATLANTIC COAST...
...SYNOPSIS...
PROGRESSIVE LARGE-SCALE PATTERN WILL CONTINUE THROUGH THE DAY TWO
PERIOD...FEATURING AMPLIFYING TROUGH ALONG THE EAST COAST AND A SLOW
MOVING UPPER LOW AND ATTENDANT TROUGH IN THE WEST. MORE
SPECIFICALLY...A SERIES OF SMALLER-SCALE SHORT WAVE TROUGHS FROM THE
UPPER MIDWEST INTO OH VALLEY WILL TRANSLATE SEWD THROUGH THE
PERIOD...CONTRIBUTING TO HEIGHT FALLS AND INTENSIFICATION OF
LARGER-SCALE TROUGH FROM THE CNTRL APPALACHIANS TO SERN ATLANTIC
COAST. IN THE WEST...A SHORT WAVE TROUGH INITIALLY OVER THE GREAT
BASIN WILL LIFT NEWD INTO THE NRN/CNTRL HIGH PLAINS BY SUNDAY NIGHT.
FINALLY...THERE IS SOME INDICATION THAT A WEAK IMPULSE OR TWO MAY
CREST CNTRL U.S. RIDGE OVER THE CNTRL PLAINS BEFORE MOVING MORE SEWD
TOWARD THE LOWER OH VALLEY.
IN THE LOW LEVELS...COLD FRONT ATTENDANT TO ERN U.S. TROUGH IS
FORECAST TO MOVE SEWD THROUGH THE CNTRL APPALACHIANS INTO SERN
STATES WITH WRN EXTENSION OF BOUNDARY REMAINING MORE
QUASI-STATIONARY FROM THE LOWER MS VALLEY WWD THROUGH OK AND THE TX
PNHDL WHERE IT INTERSECTS INTENSIFYING LEE TROUGH OVER THE HIGH
PLAINS.
...NRN/CNTRL HIGH PLAINS...
AS MENTIONED ABOVE...LEE TROUGH WILL INTENSIFY THROUGH THE PERIOD
FROM CNTRL MT SEWD THROUGH CNTRL/ERN WY INTO ERN CO WITH BOUNDARY
LAYER ALONG AND E OF THIS FEATURE GRADUALLY MOISTENING OWING TO
PERSISTENT SELY FLOW. THIS INCREASE IN MOISTURE WILL OCCUR BENEATH
ERN EDGE OF STEEP MIDLEVEL LAPSE RATE PLUME CENTERED OVER THE
CNTRL/SRN ROCKIES WITH AIR MASS BECOMING MODERATELY UNSTABLE AS FAR
N AS THE BLACK HILLS WITH MLCAPES APPROACHING 1000-1500 J/KG.
LATEST MODEL GUIDANCE REMAINS RELATIVELY CONSISTENT IN SUGGESTING
THAT THE GREATEST LIKELIHOOD OF DIURNAL TSTM DEVELOPMENT WILL OCCUR
OVER PORTIONS OF ERN WY/WRN SD SWD INTO THE NEB PNHDL...PERHAPS IN
ASSOCIATION WITH LEADING EDGE OF HEIGHT FALLS ATTENDANT SHORT WAVE
TROUGH MOVING THROUGH THE CNTRL ROCKIES. VERTICAL SHEAR PROFILES
WILL BE SUPPORTIVE OF SUPERCELLS WITH 40-50 KT OF EFFECTIVE BULK
SHEAR. WHILE LARGE HAIL AND DAMAGING WINDS APPEAR TO BE THE PRIMARY
SEVERE THREATS...A TORNADO OR TWO IS POSSIBLE WITH ANY MORE
INTENSE...ROTATING STORMS.
STORM INITIATION BECOMES MORE UNCERTAIN SWD ALONG LEE
TROUGH...HOWEVER IT DOES APPEAR THAT AT LEAST ISOLATED STORMS WILL
BE POSSIBLE DURING THE LATE AFTERNOON AND EVENING HOURS. HERE
TOO...VERTICAL SHEAR WILL BE SUFFICIENT FOR SUPERCELLS CAPABLE OF
HAIL...HIGH WINDS AND PERHAPS AN ISOLATED TORNADO.
TSTMS /MAINLY ELEVATED/ MAY BECOME MORE NUMEROUS SUNDAY NIGHT EWD
ACROSS NEB AND SD AS LLJ JET INTENSIFIES AHEAD OF SHORT WAVE TROUGH
MOVING INTO THE CNTRL HIGH PLAINS. THE PRESENCE OF STEEP MIDLEVEL
LAPSE RATES MAY PROMOTE A FEW STRONGER UPDRAFTS WITH THE POTENTIAL
FOR MARGINALLY SEVERE HAIL.
...KS/OK EWD TO THE SERN ATLANTIC COAST...
LATEST MODEL GUIDANCE IS IN GENERALLY GOOD AGREEMENT IN SUGGESTING
THAT A CLUSTER OF TSTMS MAY BE IN PROGRESS SUNDAY MORNING ALONG OR N
OF STATIONARY BOUNDARY OVER SERN KS/NERN OK INTO PARTS OF SRN MO/NRN
AR. DOWNSTREAM AIR MASS OVER THE LOWER MS VALLEY WILL BE QUITE
MOIST WITH DEWPOINTS IN THE 60S TO LOWER 70S...CONTRIBUTING TO
AFTERNOON MLCAPES OF 1500-2500 J/KG. THIS INSTABILITY COUPLED WITH
WNWLY MID TO UPPER-LEVEL WIND FIELDS SUGGESTS THAT MORNING STORMS
MAY WELL INTENSIFY THROUGH THE DAY /PERHAPS EVOLVING INTO A
FORWARD-PROPAGATING MCS/ WITH THE THREAT OF DAMAGING WINDS AND LARGE
HAIL SPREADING EWD/SEWD INTO THE LOWER MS VALLEY.
ADDITIONAL CLUSTERS OF TSTMS WILL BE POSSIBLE ALONG/AHEAD OF
LOW-LEVEL BAROCLINIC ZONE FROM NRN PORTIONS OF AL/GA INTO THE
CAROLINAS AS WEAK HEIGHT FALLS ACT ON A MODERATELY UNSTABLE /MLCAPES
OF 1000-2000 J PER KG/ AIR MASS. VERTICAL SHEAR WILL BE SOMEWHAT
MARGINAL...BUT GIVEN THE MODERATE INSTABILITY...POTENTIAL WILL EXIST
FOR UPSCALE GROWTH INTO CLUSTERS OR LINES WITH HAIL AND DAMAGING
WINDS BEING THE PRIMARY HAZARDS.
FINALLY...A MUCH MORE CONDITIONAL THREAT OF DIURNAL...SEVERE STORMS
WILL EXIST ALONG QUASI-STATIONARY BOUNDARY OVER SRN KS/NRN OK.
MODEL GUIDANCE INDICATES LITTLE IN THE WAY OF LARGE-SCALE FORCING
MECHANISMS AND THE PRESENCE OF A STRONG CAP. HOWEVER...STRONG
DIABATIC HEATING AND SUSTAINED COVERAGE ALONG SYNOPTIC FRONT AND ANY
RESIDUAL OUTFLOW BOUNDARIES MAY BE SUFFICIENT TO INITIATE AN
ISOLATED STORM OR TWO. SHOULD THIS OCCUR...THE COMBINATION OF
MODERATE/STRONG INSTABILITY AND MODERATELY STRONG VERTICAL SHEAR
INDICATE A HIGH LIKELIHOOD OF SUPERCELLS CAPABLE OF LARGE
HAIL...DAMAGING WINDS AND TORNADOES.
...UPPER MIDWEST INTO OH VALLEY...
RESIDUAL BOUNDARY LAYER MOISTURE COUPLED WITH RELATIVELY COOL
MIDLEVEL TEMPERATURES ARE EXPECTED TO CONTRIBUTE TO POCKETS OF
MODEST INSTABILITY SUNDAY AFTERNOON. SEVERAL WEAK IMPULSES WILL
MOVE SEWD ACROSS REGION FOCUSING SCATTERED TSTMS ALONG ONE OR
MULTIPLE...LOW-LEVEL CONFLUENCE ZONES. A FEW STRONG/SEVERE STORMS
WILL BE POSSIBLE WITH THE POTENTIAL FOR MARGINALLY SEVERE HAIL AND
LOCALLY GUSTY WINDS.
..MEAD.. 05/31/2008
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