SWODY2
SPC AC 090558
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT MON APR 09 2012
VALID 101200Z - 111200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PART OF THE SRN HIGH
PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS PART OF NRN/CENTRAL LA INTO
SWRN MS...
...SYNOPSIS...
A SHORTWAVE TROUGH AMPLIFYING INTO THE BASE OF THE LONGWAVE
TROUGH...LOCATED OFF THE WEST COAST...WILL AID IN SHIFTING THIS
PARENT TROUGH INLAND ON D2/TUE...WHILE THE NEXT UPSTREAM TROUGH
BEGINS TO MOVE SEWD THROUGH THE NERN PACIFIC. THE EVOLUTION OVER
THE ERN PACIFIC/WRN U.S. WILL RESULT IN AN EWD SHIFT OF THE ROCKIES
RIDGE INTO THE ADJACENT HIGH PLAINS...MAINTAINING A NWLY FLOW REGIME
FOR ONE MORE DAY FROM THE CENTRAL TO SERN STATES.
AT THE SURFACE...A FRONT EXTENDING FROM THE TN VALLEY AND MID SOUTH
WWD INTO OK AND THE TX PANHANDLE EARLY TUESDAY MORNING WILL SHIFT
SWD...WITH MODEL UNCERTAINTY CONTINUING WITH RESPECT TO HOW FAR S
THIS BOUNDARY MOVES BY 12Z WEDNESDAY. THE PORTION OF THIS BOUNDARY
MOVING INTO THE LOWER MS VALLEY/CENTRAL GULF COAST STATES IS
EXPECTED TO ADVANCE FARTHER THAN THE PORTION MOVING INTO NRN TX AS
THE FORMER AREA WILL BE CLOSER TO STRONGER NWLY FLOW ALOFT.
...SRN HIGH PLAINS...
SELY LOW LEVEL WINDS DEVELOPING INTO THE SRN HIGH PLAINS ON TUESDAY
WILL ALLOW MOISTURE RETURN WNWWD BENEATH STEEP MIDLEVEL LAPSE RATES
/7.5-8 C PER KM/. THESE FACTORS COMBINED WITH SURFACE HEATING WILL
CONTRIBUTE TO A MODERATELY UNSTABLE AIR MASS DEVELOPING BY PEAK
HEATING WITH WEAKENING INHIBITION FOR SURFACE BASED TSTM
DEVELOPMENT. GIVEN THE RIDGE AXIS SHIFTING EWD ACROSS THIS REGION
AND OVERALL LACK OF FORCING ALOFT...INITIAL TSTM COVERAGE MAY TEND
TO BE LOW...BUT VERTICALLY VEERING WIND PROFILES AND EFFECTIVE BULK
SHEAR OF 35-40 KT WILL SUPPORT STORM ORGANIZATION. HAIL AND STRONG
WIND GUSTS WILL BE THE PRIMARY THREATS...THOUGH A TORNADO THREAT
CANNOT BE RULED OUT GIVEN LOW LEVEL WINDS VEERING WITH HEIGHT.
MODELS CONTINUE TO SUGGEST UPSCALE GROWTH OF TSTMS TUESDAY EVENING/
NIGHT ACROSS W TX INTO WRN OK AS THE LLJ VEERS...WITH A THREAT FOR
SEVERE WEATHER SHIFTING EWD INTO WRN OK/NWRN TX.
...PARTS OF LA/SWRN MS...
THE CONTINUED NWLY FLOW REGIME ALOFT EXTENDING INTO THE GULF
COAST/SERN STATES THIS FORECAST PERIOD WILL MAINTAIN AN EWD
EXTENSION OF THE STEEP MIDLEVEL LAPSE RATE PLUME ACROSS THIS REGION.
A CLUSTER OF STORMS /POTENTIALLY A FORWARD PROPAGATING MCS/ SHOULD
BE ONGOING ACROSS PARTS OF ERN OK/AR INTO NERN TX AND NRN LA AT 12Z
TUESDAY. SURFACE HEATING ALONG AND S OF THE ONGOING ACTIVITY
COMBINED WITH SURFACE DEWPOINTS INTO THE LOWER 60S AND MIDLEVEL
LAPSE RATES /NEAR 7 C PER KM/ SHOULD RESULT IN MUCAPE AROUND 1000
J/KG OVER PARTS OF NRN LA/SWRN MS. DESPITE RELATIVELY WEAK LOW LEVEL
WINDS/SHEAR...30-35 KT NWLY MIDLEVEL WINDS WILL RESULT IN STRONGER
BULK SHEAR FOR ORGANIZED STORMS. CONFIDENCE IS HIGHER WITH THIS
OUTLOOK ISSUANCE FOR STRONGER INSTABILITY AND GREATER STORM COVERAGE
WITHIN THE NWLY FLOW REGIME TO WARRANT A CATEGORICAL SLIGHT RISK...
WITH HAIL AND STRONG WIND GUSTS BEING THE PRIMARY THREATS.
...EAST THROUGH NRN TX...
A SURFACE WIND SHIFT BOUNDARY SHOULD RESIDE WNWWD FROM NRN LA
THROUGH NERN TO NRN TX NEAR THE RED RIVER VALLEY ON TUESDAY...AND
POTENTIALLY REINFORCED ON THE ERN EXTENT BY OUTFLOW ATTENDANT TO AN
ONGOING MCS OVER ERN OK/AR/NERN TX/NRN LA AT 12Z TUESDAY. RESIDUAL
MOISTURE ALONG THE SURFACE BOUNDARY COMBINED WITH MODEST MIDLEVEL
LAPSE RATES AND SURFACE HEATING WILL CONTRIBUTE TO MUCAPE UP TO 1000
J/KG. MODELS SUGGEST OVERALL TSTM COVERAGE SHOULD BE LESS THAN
EXPECTED INTO THE LOWER MS VALLEY...AND THUS WILL MAINTAIN LOWER
SEVERE WEATHER PROBABILITIES ACROSS THIS REGION.
..PETERS.. 04/09/2012
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