SWODY1
SPC AC 061951
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0251 PM CDT THU OCT 06 2011
VALID 062000Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM FAR ERN WY/SERN MT EWD AND
SWD ACROSS WRN NEB AND INTO NERN CO/NWRN KS...
...CENTRAL/NRN HIGH PLAINS REGION...
ONGOING FORECAST REMAINS ON TRACK...WITH ONLY MINOR TWEAKS MADE TO
THE SEVERE PROBABILITY LINES THIS FORECAST. STORMS HAVE BEGUN TO
DEVELOP E OF THE HIGHER TERRAIN INTO SWRN SD AND VICINITY...AND
EXPECT CONVECTION TO CONTINUE EXPANDING ACROSS THIS AREA AND SWD
INTO WRN NEB WHERE 500 TO 1000 J/KG MIXED-LAYER CAPE IS NOW
INDICATED.
WITH DEEP-LAYER VEERING WITH HEIGHT AND STRENGTH OF THE OVERALL FLOW
FIELD...SHEAR WILL REMAIN SUPPORTIVE OF ROTATING/SUPERCELL STORMS
AND ASSOCIATED THREATS FOR HAIL...DAMAGING WINDS...AND POSSIBLY A
TORNADO OR TWO. HOWEVER...EVOLUTION TOWARD A MORE LINEAR MODE IS
EXPECTED WITH TIME...BEFORE STORMS BEGIN TO DECREASE IN INTENSITY
WITH DIURNAL COOLING LATER THIS EVENING.
..GOSS.. 10/06/2011
.PREV DISCUSSION... /ISSUED 1127 AM CDT THU OCT 06 2011/
...CNTRL HIGH PLAINS...
12Z H5 ANALYSIS DEPICTS A STRONG TROUGH WITH 120 METER/12 HR HEIGHT
FALLS BEGINNING TO EJECT NE THROUGH THE FOUR CORNERS REGION. THIS
FEATURE WILL CONTINUE INTO THE CNTRL HIGH PLAINS THIS AFTN/EVE.
ALTHOUGH LLVL MOISTURE WAS MEAGER THIS MORNING...H85 CHARTS INDICATE
THAT 8-14 DEG C DEW POINTS WERE EVIDENT FROM W TX INTO WRN SD AND
SOME OF THIS MOISTURE WILL MIX TO THE SFC THIS AFTN. BY LATE
AFTN...MLCAPES WILL REACH 500-750 J/KG ALONG/E OF THE DRYLINE/LEE
LOW IN AN AXIS FROM SE MT/WRN SD SWD INTO WRN KS WITH STEEPEST
MID-TROPOSPHERIC LAPSE RATE PLUME ACROSS NEB/SD NWD.
AS EXIT REGION OF A 75-80 KT H5 JET SPREADS NEWD THIS
AFTN...HIGH-BASED TSTMS WILL FORM OVER THE HIGHER TERRAIN OF WY/CO
18-20Z WITH POSSIBLE GUSTY WINDS. AS STORMS EVOLVE ENE AND
ENCOUNTER A COMPARATIVELY RICHER LLVL THETAE-E AXIS...STORMS WILL
GROW STRONGER AFTER 20Z AS MLCINH BEGINS TO WEAKEN OWING TO
ASCENT/MOISTENING. LATEST CONVECTION ALLOWING MODELS SUGGEST THAT
ACTIVITY WILL MATURE OVER WRN SD AND THE NEB PNHDL/WRN NEB 00-03Z.
EFFECTIVE VERTICAL SHEAR OF 45-55 KTS WILL BE MORE THAN SUFFICIENT
FOR INITIAL STORMS TO BE SUPERCELLS WITH LARGE HAIL. A COUPLE OF
TORNADOES CANNOT BE RULED OUT...PARTICULARLY NEAR THE LEE LOW OVER
SWRN SD AND NRN PORTIONS OF THE NEB PNHDL. HERE...ACTIVITY WILL
LIKELY REMAIN DISCRETE THE LONGEST AMIDST EFFECTIVE SRH OF 250+
M2/S2. AS FORCING FOR ASCENT INCREASES THROUGH THE EVENING AND
STORM MERGERS/COMPETITION INCREASE...EVENTUALLY EVOLUTION INTO A
NW-SE ORIENTED QLCS SHOULD OCCUR WITH SVR WINDS/HAIL...SPREADING
OVER SRN SD AND WRN NEB THROUGH LATE EVENING. ACTIVITY SHOULD
GRADUALLY WEAKEN AFTER DARK.
FARTHER S...THE LINE COULD BACKBUILD/DEVELOP SWD INTO THE STRONGER
CAP TOWARD WRN KS AFTER 00Z. WHILE A SVR WIND/HAIL REPORT CANNOT BE
RULED OUT THAT FAR S...HIGHEST SVR PROBABILITIES WILL EXIST FARTHER
N.
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