SPC AC 240551
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1251 AM CDT THU APR 24 2008
VALID 241200Z - 251200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS SWRN/SCNTRL NEB AND
NCNTRL/CNTRL KS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS A LARGE PART OF THE
CNTRL PLAINS INTO THE CORN BELT...
...PLAINS AND MS VLY REGION...
A COMPLEX UPR TROUGH WILL CONTINUE EWD THROUGH THE WRN TWO-THIRDS OF
THE COUNTRY ON THU. LEAD WAVES CURRENTLY MOVING ACROSS BOTH THE NRN
AND SRN PLAINS WILL GRADUALLY SHIFT ENEWD ACROSS THE UPR GRTLKS
REGION AND MIDWEST BY THU NIGHT. MEANWHILE...PRIMARY UPR SHORTWAVE
TROUGH WILL TRANSLATE FROM THE CNTRL ROCKIES INTO THE CNTRL/NRN
PLAINS STATES THU EVE/NIGHT.
AT THE SFC...AN EXISTING BAROCLINIC ZONE WILL EXTEND FROM THE CNTRL
DAKOTAS SWWD INTO WY AT 12Z THU. THIS BOUNDARY WILL SHIFT SEWD
BEHIND ONE OF THE LEAD WAVES...SETTLING INTO NWRN MN...ERN SD AND
NWRN NEB BY EARLY AFTN. TO THE S...A SECONDARY LEE LOW OVER THE
CNTRL HIGH PLAINS WILL DEEPEN WITH APPROACH OF THE MAIN TROUGH THU
AFTN...THEN DEVELOP NEWD INTO SERN NEB BY LATE THU NIGHT. TO THE S
OF THIS LOW...A DRYLINE WILL MIX EWD INTO SWRN NEB...WRN KS...WRN OK
AND THE WRN EDWARDS PLATEAU OF TX BY THU EVE.
ONGOING TSTM CLUSTERS AT 12Z THU WILL LIKELY BE FAVORING ENHANCED
WARM ADVECTION REGIMES DOWNSTREAM OF THE LEAD UPR IMPULSES...NAMELY
ACROSS THE ERN PLAINS NWD INTO THE MO OZARKS AND ACROSS PORTIONS OF
THE ERN DAKOTAS AND UPR MS VLY. VEERING LLJ IN WAKE OF THE UPR
IMPULSES WILL LIKELY FEED UNSTABLE PARCELS INTO THE SWRN EDGES OF
THESE CLUSTERS WELL INTO THU AFTN. IF LOCAL POCKETS OF HEATING CAN
MATERIALIZE...ISOLD MULTICELL PULSE TYPE STORMS COULD RESULT WITH
HAIL AND DMGG WIND GUSTS FROM THE OZARKS NWD INTO PARTS OF THE UPR
MS VLY REGION.
PRIMARY SVR EVENT SHOULD UNFOLD LATE THU AFTN/NIGHT UPSTREAM OVER
THE HEART OF THE PLAINS. FIRST INITIATION IS EXPECTED ALONG THE
SEWD MOVING COLD FRONT FROM PARTS OF MN SWWD INTO ERN SD WHERE
WEAKEST CONVECTIVE INHIBITION WILL EXIST AMIDST A TONGUE OF 50S SFC
DEW POINTS. HERE...FLOW ALOFT REMAINS CYCLONIC IN WAKE OF THE LEAD
WAVE...AND GIVEN COOL TEMPERATURE PROFILES ALOFT...ISOLD HAIL/GUSTY
WINDS CAN BE EXPECTED WITH THESE STORMS.
FARTHER S...AS STRONGER LARGE SCALE HEIGHT FALLS SPREAD INTO THE
CNTRL/NRN HIGH PLAINS...LLJ WILL BACK AND INCREASE S OF THE COLD
FRONT AND E OF THE DRYLINE BY THU EVE. BOUNDARY LAYER MOISTURE
SHOULD BE ABLE TO SURGE BACK NWD BENEATH RECOVERING MID-LVL LAPSE
RATES THROUGH WRN/CNTRL PARTS OF BOTH KS/NEB. THIS WILL CONTRIBUTE
TO MLCAPES APPROACHING 2500 J/KG.
IF SUFFICIENT HEATING CAN ERASE INHIBITION...SURFACE-BASED
INITIATION WILL BE POSSIBLE FROM SWRN/SCNTRL NEB SWD INTO PARTS OF
WRN/CNTRL KS. ROUGHLY 35-40 KTS OF EFFECTIVE SHEAR AND MAGNITUDE OF
LAPSE RATES WILL BE FAVORABLE FOR SUPERCELLS WITH VERY LARGE HAIL
AND ISOLD TORNADOES. INHIBITION WILL LIKELY BE COMPARATIVELY STRONG
AT MORE SLY LATITUDES...BUT UNCERTAINTY EXISTS ON THE SRN
DELINEATION OF THE SVR POTENTIAL.
AS THE EVENING WEARS ON...HIGHER-BASED TSTMS THAT DEVELOP IN
CONJUCTION WITH THE MAIN UPR IMPULSE OVER THE HIGH PLAINS WILL
LIKELY CONGEAL WITH THE EARLY EVE INITIATED STORMS OVER SRN NEB AND
NRN/CNTRL KS. THIS ACTIVITY WILL LIKELY GROW UPSCALE INTO AN MCS OR
TWO AND PROGRESS EWD TOWARD THE MO RVR OVERNIGHT WITH THREATS FOR
DMGG WINDS/HAIL.
LASTLY...FARTHER S ACROSS TX...A NARROW ZONE VCNTY THE DRYLINE WILL
BECOME QUITE UNSTABLE. BUT...CAP WILL REMAIN STRONG AND IT IS
DOUBTFUL THAT TSTMS WILL INITIATE. BUT...IF A ROGUE TSTM CAN MANAGE
TO FORM...SUPERCELL STRUCTURES WITH LARGE HAIL WILL BE PSBL /5
PERCENT SVR PROBABILITIES/. ANOTHER POSSIBILITY WILL BE FOR TSTMS
THAT DEVELOP ALONG THE MEXICAN MOUNTAINS TO MOVE EWD INTO FAR S TX.
GIVEN ROUGHLY 40-50 KTS OF WLY MID-LVL FLOW...ANY SUPERCELL THAT CAN
APPROACH THE RIO GRANDE WILL LIKELY GIVE LARGE HAIL/DMGG WIND GUSTS
BEFORE DIMINISHING IN THE LOWER ELEVATIONS OF SCNTRL TX.
..RACY/JEWELL.. 04/24/2008
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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