SWODY2
SPC AC 301728
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT WED JUN 30 2010
VALID 011200Z - 021200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM MT INTO WRN AND NRN ND...
...SYNOPSIS...
AMPLIFIED LONGWAVE UPPER FLOW PATTERN WILL PREVAIL OVER MUCH OF THE
CONUS/CANADA THROUGH THURSDAY. MODELS CONTINUE TO SHOW THE UPPER
MIDWEST/CENTRAL CANADA RIDGE AND THE NORTHEAST STATES TROUGH WILL
SHIFT EASTWARD THROUGH THE PERIOD...DOWNSTREAM OF A PROGRESSIVE
LONGWAVE TROUGH EXPECTED TO MOVE MORE INLAND ACROSS THE WRN STATES.
...NRN ROCKIES TO NRN PLAINS...
SHORTWAVE TROUGHS/IMPULSES ARE EXPECTED TO CONCURRENTLY TRACK NEWD
FROM WA AND THE NRN HIGH PLAINS INTO CANADA DURING THE FIRST HALF OF
THE PERIOD...WHILE A MORE PROMINENT SHORTWAVE TROUGH DIGS
SEWD...REACHING THE WA/ORE COAST BY 02/00Z. THIS LATTER SHORTWAVE
WILL MOVE INLAND ACROSS THE PACIFIC NW THURSDAY NIGHT RESULTING IN
DOWNSTREAM HEIGHT FALLS OVER THE NRN ROCKIES.
IN THE LOW LEVELS...A SURFACE FRONT IS EXPECTED TO STALL FROM
NERN-SWRN ND WITH THE TRAILING EXTENT RETREATING NWWD INTO SERN MT
BY AFTERNOON. THIS BOUNDARY FROM NRN WY/SERN MT TO WRN ND AND
UPSLOPE FLOW INTO HIGHER TERRAIN OF SWRN/WRN MT SHOULD BE THE
PRIMARY LOCATIONS FOR AFTERNOON TSTM DEVELOPMENT. STEEP LAPSE RATES
AND SURFACE HEATING COMBINED WITH RESIDUAL MOISTURE /SURFACE
DEWPOINTS IN THE MID-UPPER 50S ACROSS MT TO THE 60S IN WRN ND/ WILL
RESULT IN A MODERATELY-STRONGLY UNSTABLE AIR MASS.
EFFECTIVE BULK SHEAR 40-50 KT SUGGESTS A MIXED MODE OF SUPERCELLS/
LINEAR CLUSTERS CAPABLE OF LARGE HAIL...DAMAGING WINDS...AND PERHAPS
A BRIEF TORNADO OR TWO. WHILE THE OVERALL SEVERE WEATHER THREAT MAY
DIMINISH BY LATE EVENING AS NEAR-SURFACE INHIBITION INCREASES...
STRONGER STORMS/POTENTIAL MCS MAY BE SUSTAINED/SPREAD NORTHEASTWARD
ACROSS NRN MT/NW ND DURING THE LATE EVENING/OVERNIGHT HOURS WITH
APPROACH OF PACIFIC NW TROUGH.
...SOUTH TX...
REFERENCE NHC FORECASTS FOR THE LATEST DETAILS ON HURRICANE ALEX. IN
CONCERT WITH THE EXPECTED INLAND ADVANCEMENT OF ALEX ACROSS
NORTHEAST MEXICO ON THURSDAY...WILL CONTINUE LOW TORNADO/
CONVECTIVE-RELATED WIND PROBABILITIES ACROSS SOUTH TX AS
RIGHT-PERIPHERY ENHANCED WIND FIELDS AFFECT THE REGION.
...SOUTHEAST STATES...
A COLD FRONT WILL CONTINUE TO MOVE SLOWLY SWD INTO SRN AL/GA AS A
SURFACE HIGH SHIFTS E/SEWD FROM THE GREAT LAKES TOWARD THE
APPALACHIANS/EAST COAST. DIURNAL TSTM DEVELOPMENT WILL BE POSSIBLE
ACROSS THIS REGION...ESPECIALLY GIVEN THE LIKELIHOOD FOR INCREASED
LOW LEVEL CONVERGENCE AS THE FRONT INTERACTS/MERGES WITH SEA BREEZE
BOUNDARIES. WEAK LAPSE RATES AND A WEAKLY SHEARED ENVIRONMENT
SUGGEST STORMS WILL BE PULSE-TYPE WITH THE STRONGER CELLS CAPABLE OF
PRODUCING A FEW STRONG WIND GUSTS.
..PETERS.. 06/30/2010
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