SPC AC 040630
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0130 AM CDT FRI MAY 04 2007
VALID 051200Z - 061200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF CNTRL AND ERN
NEB...CNTRL KS...NW OK AND CNTRL OK...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE GREAT
PLAINS AND LOWER OH VALLEY...
...SEVERE WEATHER OUTBREAK WITH TORNADOES POSSIBLE SATURDAY AND
SATURDAY NIGHT ACROSS PARTS OF THE GREAT PLAINS...
...GREAT PLAINS REGION...
A POTENT UPPER-LEVEL TROUGH OVER THE WRN U.S. IS FORECAST TO MOVE
SLOWLY EWD INTO THE ROCKIES AS AN IMPRESSIVE 100 KT MID-LEVEL JET
EJECTS OUT OF THE BASE OF THE TROUGH NEWD ACROSS THE PLAINS SATURDAY
AND SATURDAY NIGHT. MODEL FORECASTS HAVE BEEN INCREASINGLY
AGGRESSIVE RUN TO RUN CONCERNING THE TIMING OF THE UPPER-LEVEL
TROUGH AND IT APPEARS THAT THE BRUNT OF LARGE-SCALE ASCENT WITH THE
UPPER-LEVEL TROUGH WILL COME EWD INTO THE PLAINS ON DAY 2. THIS
SHOULD RESULT IN STORM DEVELOPMENT BECOMING WIDESPREAD FROM THE NRN
AND CNTRL PLAINS EXTENDING SWD INTO PARTS OF THE SRN PLAINS. IN
ADDITION...A BROAD 50 KT LOW-LEVEL JET WILL BE IN PLACE ACROSS THE
PLAINS WITH A QUALITY WARM SECTOR WHICH WILL LIKELY RESULT IN A
THREAT FOR SUPERCELLS OVER A LARGE AREA SATURDAY AFTERNOON AND
EVENING. LOW-LEVEL SHEAR PROFILES ALSO APPEAR FAVORABLE FOR
TORNADOES ACROSS THE PLAINS REGION ON DAY 2.
THE MAIN UNCERTAINTY CONCERNING DAY 2 WILL BE HOW CONVECTION ON
FRIDAY NIGHT AND SATURDAY MORNING WILL AFFECT PORTIONS OF THE WARM
SECTOR. THE CURRENT THINKING IS THAT STORM COVERAGE WILL BE GREATEST
LATE FRIDAY NIGHT FROM A WARM FRONT IN SCNTRL NEB EXTENDING NWD INTO
SRN SD. STORMS FURTHER SOUTH ALONG THE DRYLINE SHOULD BECOME
ISOLATED ENOUGH BY SATURDAY MORNING THAT EFFECTS REDUCING
DESTABILIZATION ON SATURDAY SHOULD BE MINIMAL.
CONCERNING THE THREAT FOR SIGNIFICANT SEVERE...FORECAST SOUNDINGS
EAST OF A DRYLINE ACROSS SCNTRL NEB...CNTRL KS...WRN OK AND
NORTHWEST TX SHOW IMPRESSIVE LOW-LEVEL SHEAR PROFILES WITH SFC
DEWPOINTS RANGING FROM 65 TO 70 F. THIS COMBINED WITH THE AMOUNT OF
INSTABILITY AND FORCING SUGGEST SOME SIGNIFICANT TORNADOES MAY OCCUR
EAST OF THE DRYLINE ACROSS THE MODERATE RISK AREA. A CONCENTRATED
THREAT AREA FOR SIGNIFICANT TORNADOES MAY ALSO EXIST WITH SUPERCELLS
THAT TRACK EWD ALONG THE WARM FRONT ACROSS PARTS OF SRN AND CNTRL
NEB. CONCERNING LARGE HAIL...AN ELEVATED MIXED LAYER ASSOCIATED WITH
THE MID-LEVEL JET SHOULD SPREAD EWD INTO THE PLAINS SATURDAY. STEEP
MID-LEVEL LAPSE RATES ASSOCIATED WITH THIS LAYER COMBINED WITH THE
AMOUNT OF INSTABILITY AND VERTICAL SHEAR SHOULD BE SUFFICIENT FOR
VERY LARGE HAIL WITH THE STRONGER SUPERCELLS.
SEVERE WEATHER COVERAGE SHOULD BE LESS ACROSS THE NRN PLAINS WHERE
INSTABILITY WILL NOT BE AS GREAT. ALSO...A DECREASE IN SEVERE
WEATHER COVERAGE SHOULD EXIST ACROSS WCNTRL TX WHERE VERTICAL SHEAR
WILL BE WEAKER DUE TO LESS OF AN INFLUENCE FROM THE MID-LEVEL JET.
THE STRONG INSTABILITY ACROSS PARTS OF THE PLAINS AND AMOUNT OF
LARGE-SCALE FORCING WITH THE UPPER-LEVEL TROUGH SHOULD SUSTAIN
SEVERAL MCS CLUSTERS OVERNIGHT WITH A SEVERE THREAT LIKELY
CONTINUING ACROSS PARTS OF THE PLAINS THROUGH LATE IN THE PERIOD.
...LOWER OH VALLEY...
AT THE SFC...A STATIONARY FRONT WILL LIKELY EXTEND SEWD FROM THE
CNTRL PLAINS INTO MO AND THE MID MS VALLEY SATURDAY. ALTHOUGH AN
UPPER-LEVEL RIDGE IS FORECAST ACROSS THIS REGION SATURDAY...FORECAST
SOUNDINGS SHOW STRONGLY VEERING WIND PROFILES AT THE LOW TO
MID-LEVELS MAINLY FROM THE STATIONARY FRONT NEWD. IN
ADDITION...POCKETS OF MODERATE INSTABILITY SHOULD DEVELOP ON THE
COOL SIDE OF THE BOUNDARY WHICH IS SUPPORTED BY THE NAM...GFS AND
NAMKF SOLUTIONS. THIS SHOULD BE SUFFICIENT FOR A FEW SEVERE STORM
CLUSTERS IN THE LATE AFTERNOON AND EARLY EVENING.
HOWEVER...LARGE-SCALE ASCENT SHOULD REMAIN WEAK AND STORM COVERAGE
SHOULD REMAIN ISOLATED TO SCATTERED ACROSS THE REGION WITH THE
GREATEST THREAT LIKELY CONCENTRATED AROUND PEAK HEATING.
..BROYLES.. 05/04/2007
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
|
