Monday, April 9, 2012

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 091959
SWODY1
SPC AC 091958

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT MON APR 09 2012

VALID 092000Z - 101200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SRN PLAINS...

--- UPDATES ---

...SWRN KS...NWRN OK...NERN TX PANHANDLE...
MOST PROBABLE SUPERCELLULAR GESTATION ZONE NEXT FEW HOURS WILL BE
INVOF WARM FRONT...ALONG OR E OF DRYLINE INTERSECTION...NEAR KS/OK
BORDER...N TO NNW OF GAG. LOW-LEVEL CAPE/VORTICITY/CONVERGENCE ARE
MAXIMIZED IN THIS AREA BASED ON MANUAL AND AUTOMATED
MESOANALYSES...AND SHOULD REMAIN SO PRIOR TO SUBSTANTIAL CONVECTIVE
DEVELOPMENT. NRN/ERN FRINGES OF RELATIVELY MAXIMIZED MOISTURE
CORRESPOND TO DIFFERENTIAL HEATING BOUNDARY PRODUCED BY STRATUS THAT
HAS BEEN ERODING FROM W-E DUE TO MIXING. TORNADO POTENTIAL AND RISK
FOR SUSTAINED SIGNIFICANT HAIL IS MAXIMIZED IN SOMEWHAT
NARROWER/MORE TIGHTLY FOCUSED CORRIDOR...WITHIN AND DOWNSHEAR FROM
THIS AREA...WHEN ACCOUNTING FOR LIKELY RIGHTWARD DEVIANCE OF ANY
MATURE SUPERCELL. REF SPC WW 151 AND MESOSCALE DISCUSSION 478 FOR
NEAR-TERM FCST DETAILS.

...NERN NM TO TX SOUTH PLAINS AND MOST OF PANHANDLE...
MRGL SVR WIND RISK IS EXTENDED SOMEWHAT NWD ACROSS NM TO ACCOUNT FOR
STG/DAMAGING GUST POTENTIAL WITH ACTIVITY BUILDING NW TCC.
CONVECTION IS LIKELY TO MOVE EWD WHILE OFFERING DOWNBURST POTENTIAL
THROUGH DEEP/WELL-MIXED/DRY BOUNDARY LAYER. ADDITIONAL DEVELOPMENT
IS OCCURRING WITHIN AREA OF MIDLEVEL ASCENT OVER CENTRAL PANHANDLE
OF TX...MANIFEST AS GROWING MIDLEVEL CLOUD DECK...MOVING EWD INTO
PROGRESSIVELY MORE FAVORABLE LOW-LEVEL MOISTURE. THIS ACTIVITY MAY
PRODUCE SVR HAIL...AND ISOLATED SIGNIFICANT HAIL...AS WELL AS
POTENTIALLY DAMAGING GUSTS. OTHERWISE...LITTLE ADJUSTMENT IS
JUSTIFIED ATTM TO OUTLOOK AREAS.

..EDWARDS.. 04/09/2012

.PREV DISCUSSION... /ISSUED 1107 AM CDT MON APR 09 2012/

...KS/OK/TX PANHANDLE...
MORNING WATER VAPOR LOOPS SHOW A BROAD ZONE OF NORTHWEST FLOW ALOFT
FROM THE NORTHERN PLAINS INTO THE MID ATLANTIC STATES AND CAROLINAS.
MEANWHILE...AN UPPER TROUGH IS MOVING INTO THE WESTERN STATES WITH
SEVERAL WEAK PERTURBATIONS MOVING THROUGH THE MEAN RIDGE AXIS OVER
THE ROCKIES. ONE SUCH SHORTWAVE TROUGH IS CURRENTLY OVER UT/CO AND
IS EXPECTED TO TRACK INTO THE CENTRAL PLAINS TONIGHT. AHEAD OF THIS
FEATURE...LARGE SCALE ASCENT IS INCREASING OVER PARTS OF ERN CO/SWRN
KS/WRN OK/TX PANHANDLE WHERE LOW CLOUDS ARE ERODING AND MOISTURE IS
INCREASING. PRESENT INDICATIONS ARE THAT MODERATE INSTABILITY WILL
DEVELOP BY MID AFTERNOON WITH AN AXIS OF 2000-3000 J/KG SBCAPE FROM
SOUTHWEST KS INTO WESTERN OK AND THE EASTERN TX PANHANDLE.

MODEL GUIDANCE IS IN STRONG AGREEMENT THAT SCATTERED THUNDERSTORMS
WILL BEGIN INTENSIFYING LATER THIS AFTERNOON OVER PARTS OF SOUTHWEST
KS AND NORTHWEST OK TO THE EAST OF A WEAK SURFACE LOW AND IN REGION
OF WEAK LOW LEVEL CONVERGENCE. STEEP MID LEVEL LAPSE
RATES...FAVORABLE EFFECTIVE SHEAR VALUES...AND SUFFICIENT CAPE WILL
PROMOTE SUPERCELL STORMS CAPABLE OF VERY LARGE HAIL AND DAMAGING
WINDS. LOW LEVEL WINDS ARE FORECAST TO STRENGTHEN THROUGH THE EARLY
EVENING...WHICH MAY ALSO SUPPORT A RISK OF A FEW TORNADOES AS THE
STORMS TRACK SOUTHEASTWARD ACROSS WESTERN OK. DUE TO UNCERTAINTY
REGARDING COVERAGE OF STORMS WILL MAINTAIN SLIGHT RISK.
HOWEVER...WILL RE-EVALUATE RISK CATEGORY FOR 20Z OUTLOOK UPDATE.

...WEST TX/SOUTHEAST NM...
WEAK SOUTHEASTERLY LOW LEVEL WINDS HAD TRANSPORTED 50S DEWPOINTS
INTO MUCH OF WEST TX AND SOUTHEAST NM TODAY. THIS REGION WILL SEE
FULL SUNSHINE AND RAPID HEATING THIS AFTERNOON WITH AFTERNOON MLCAPE
VALUES OF 1000-1500 J/KG. FORECAST SOUNDINGS IN THIS AREA FOR LATER
TODAY SHOW STEEP LOW/MID LEVEL LAPSE RATES AND RATHER HIGH PWAT
VALUES. THIS COMBINATION WILL SUPPORT THE DEVELOPMENT OF SCATTERED
THUNDERSTORMS CAPABLE OF GUSTY/DAMAGING WINDS AND HAIL.

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