SPC AC 151645
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1145 AM CDT FRI SEP 15 2006
VALID 151630Z - 161200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON OVER MUCH OF THE
CENTRAL INTERMOUNTAIN REGION....
...THERE IS A SLGT RISK OF SVR TSTMS LATER THIS AFTN AND TONIGHT
OVER PARTS OF THE SRN HI PLAINS AND CENTRAL PLAINS....
...SYNOPSIS...
LARGE MID/UPPER LEVEL LOW/TROUGH IS OVER THE NWRN U.S. THIS MORNING
EXTENDING EWD INTO THE NRN PLAINS AS SHORTWAVE TRACKS NEWD ACROSS
THE AREA. THERE IS ANOTHER MID/UPPER LEVEL LOW DRIFTING SEWD OVER
THE DELMARVA REGION LEAVING SHORTWAVE RIDGING FROM SERN TX NNEWD
THRU THE ERN GREAT LAKES. MORNING SURFACE ANALYSIS SHOWS A LOW OVER
THE TRIPLE POINT OF ND/SD/MT WITH A WARM FRONT THAT EXTENDS SSEWD
THRU CENTRAL KS INTO N CENTRAL OK...AND A QUASISTATIONARY BOUNDARY
THAT MEANDERS SWWD THRU NRN UT AND SRN CA.
...CENTRAL INTERMOUNTAIN REGION...
MODELS ARE CONSISTENT IS MOVING LOW/MID LEVEL COLD FRONT ACROSS THE
NRN AND CENTRAL INTERMOUNTAIN REGION. STRONG 500 MB JET OF 60-90 KT
WILL ADVANCE THRU THE NRN VALLEYS OF CA INTO CENTRAL CO PLACING
AREAS FROM NRN UT INTO WRN/CENTRAL CO IN FAVORABLE EXIT REGION TO
ENHANCE UPWARD ASCENT. ANALYSIS OF MODEL SOUNDINGS SHOW THAT AREAS
FROM NRN UT INTO WRN CO WILL EXPERIENCE SOME DAYTIME HEATING LATE
THIS MORNING INTO MID AFTERNOON STEEPENING LOW/MID LEVEL LAPSE RATES
WITHIN THE MID/UPPER LEVEL JET EXIT REGION. WITH MID/LOW LEVEL
LAPSE RATES EXPECTED AROUND 8.0 C/KM...THREAT FOR HAIL AND DAMAGING
WINDS EXISTS AS THUNDERSTORMS OCCUR FROM LATER THIS MORNING INTO
LATE THIS AFTERNOON.
...TX PANHANDLE NEWD AND NWD THRU THE CENTRAL PLAINS...
SURFACE DRYLINE/TROUGH WAS EVIDENT THIS MORNING FROM S CENTRAL NM
NEWD/NWD THRU ERN CO INTO THE SWRN NEB PANHANDLE. MODELS TAKE
MID/UPPER LEVEL SHORTWAVE CURRENTLY EXTENDING SWD FROM SERN ID THRU
ERN UT EWD...THEN NNEWD THIS AFTN AND TONIGHT IN A NEGATIVELY TILTED
MANNER EXTENDING FROM NERN WY INTO ERN KS BY THE END OF THE PERIOD.
STRONG LOW LEVEL JET OF 40-55 KT ALREADY EXTENDS FROM SWRN KS NWD
THRU ERN SD AND IS FORECAST TO INCREASE TO NEAR 60 KT OVER NERN
NEB/SERN SD BY THIS EVENING. THIS WILL BECOME COUPLED WITH MID
LEVEL JET STREAK OF 55-65 KT FROM NERN NM INTO CENTRAL KS...AND AN
UPPER LEVEL JET STREAK OF 90-100 KT WITH EXIT REGION OVER SWRN AND
CENTRAL KS. THUS...STRONG VERTICAL SHEAR PROFILES WILL BE IN PLACE
THRU MUCH OF THE PERIOD.
AIR MASS OVER PARTS OF THE CENTRAL/SRN PLAINS WILL BECOME MODERATELY
UNSTABLE WITH SBCAPE FORECAST BETWEEN 1500-2500 J/KG OVER THE
CENTRAL TX PANHANDLE BY 21Z...EXTENDING INTO S CENTRAL KS BY 00Z.
FORECAST SOUNDINGS SHOW INCREASED INSOLATION AS MAIN ROLE IN
DESTABILIZING AIR MASS...BUT THE NAM ALSO HOLDS ONTO WEAK WARM LAYER
AT MID LEVELS.
GIVEN THAT EXIT REGION WILL MOVE INTO AREAS OF CENTRAL KS BY THIS
EVENING AND MODERATE INSTABILITY...EXPECT STRONG/SEVERE
THUNDERSTORMS TO DEVELOP IN THE VICINITY OF THE LOW LEVEL JET AXIS
LATE THIS AFTERNOON AND TONIGHT. LOOKS LIKE THE MAIN THREATS WILL
BE HAIL AND DAMAGING WINDS...BUT GIVEN THE DEEP LAYER SHEAR IS
EXPECTED TO BE NEAR/AROUND 55 KT AND ASSOCIATED 0-3KM HELICITY IS
BETWEEN 300-400 M2/S2...ISOLATED TORNADOES COULD ALSO OCCUR.
..MCCARTHY/GRAMS.. 09/15/2006
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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