SPC AC 050611
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0111 AM CDT TUE JUN 05 2007
VALID 061200Z - 071200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF SRN ND...CENTRAL
AND ERN SD...CENTRAL AND ERN NEB...N CENTRAL KS...SWRN MN...NWRN
IA...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS A LARGE PORTIONS OF THE
NRN AND CENTRAL PLAINS AND INTO WRN OK/THE TX PANHANDLE...
...SYNOPSIS...
LARGE UPPER RIDGE PREVAILING ACROSS THE PLAINS AT THE START OF THE
PERIOD WILL BE SHUNTED EWD WITH TIME...AS LARGE UPPER LOW/TROUGH
MOVES OUT OF THE ROCKIES. THIS TROUGH WILL BE ACCOMPANIED BY AN
UNSEASONABLY STRONG /80 KT/ MID-LEVEL JET STREAK...WHICH WILL SPREAD
INTO THE PLAINS DURING THE SECOND HALF OF THE PERIOD.
AT THE SURFACE...980 MB LOW IS FORECAST TO MOVE SLOWLY EWD ACROSS
THE NRN HIGH PLAINS...REACHING ERN ND BY 07/12Z. A DRYLINE IS
FORECAST TO MIX EWD ACROSS THE HIGH PLAINS DURING THE
AFTERNOON...EVENTUALLY TO BE OVERTAKEN BY COLD FRONT WHICH SHOULD
EXTEND FROM THE ERN DAKOTAS SWD INTO ERN NEB...AND THEN SWWD ACROSS
CENTRAL KS INTO THE TX/OK PANHANDLES LATE IN THE PERIOD.
...THE PLAINS...
WIDESPREAD/POTENTIALLY-SIGNIFICANT SEVERE WEATHER EPISODE APPEARS
LIKELY ACROSS THE PLAINS...AS A VERY STRONG UPPER SYSTEM AND
ACCOMPANYING/UNSEASONABLY STRONG DEEP-LAYER WIND FIELD SPREAD INTO
THE PLAINS WHERE MOIST/VERY UNSTABLE AIRMASS IS ANTICIPATED.
AS ELEVATED MIXED LAYER SPREADS EWD ACROSS THE PLAINS...STRONG CAP
WILL DEVELOP ATOP A MOISTENING BOUNDARY LAYER. DAYTIME HEATING
COMBINED WITH A LARGE AREA OF UPPER 60S DEWPOINTS BENEATH STEEP
LAPSE RATES ALOFT WILL YIELD STRONG DESTABILIZATION -- WITH
MIXED-LAYER CAPE REACHING 3000 TO 4000 J/KG ACROSS A LARGE AREA.
THOUGH CAP WILL LIKELY SUPPRESS CONVECTIVE DEVELOPMENT ALONG/E OF
DRYLINE WELL INTO THE AFTERNOON...STORMS SHOULD DEVELOP NEAR THE
LOW...AND AHEAD OF THE FRONT/DRYLINE ACROSS THE CENTRAL DAKOTAS BY
LATE AFTERNOON. SWD EXTENT OF STORM DEVELOPMENT REMAINS A QUESTION
DUE TO CAPPING...THOUGH A STORM OR TWO MAY BREACH THE CAP AS FAR S
AS WRN OK/WRN N TX AND PERHAPS INTO THE TRANSPECOS REGION OF W TX.
WHILE CAPPING -- AND SUBSEQUENT POTENTIAL FOR STORM DEVELOPMENT --
APPEARS TO BE A POTENTIAL LIMITING FACTOR WITH RESPECT TO SEVERE
STORMS...CAPE/SHEAR COMBINATION WILL NOT...AS INCREASINGLY-STRONG
MID-LEVEL FLOW SPREADS INTO THE PLAINS THROUGH THE AFTERNOON. AS 70
KT LOW-LEVEL JET DEVELOPS DURING THE EVENING AND 60 TO 70 KT SWLY
MID-LEVEL FLOW SPREADS AS FAR E AS THE COLD FRONTAL ZONE...SHEAR
WILL BECOME INCREASINGLY-FAVORABLE FOR STRONG/LONG-LIVED SUPERCELLS.
OVERNIGHT...STORM MODE MAY BECOME A COMBINATION OF SUPERCELLS AND
SMALL-SCALE LINES/BOWS...THOUGH A TORNADO THREAT WILL LIKELY EXIST
THROUGH THE PERIOD IN ADDITION TO VERY LARGE HAIL AND DAMAGING
WINDS. GREATEST TORNADO THREAT -- INCLUDING THE POTENTIAL FOR A FEW
SIGNIFICANT TORNADOES -- APPEARS TO EXIST ACROSS CENTRAL AND ERN
PORTIONS OF NEB AND SD AND VICINITY THROUGH THE EVENING. DEPENDING
UPON EVOLUTION OF STORM MODE WITH TIME...POTENTIAL FOR MORE
WIDESPREAD/SIGNIFICANT WIND DAMAGE MAY ALSO INCREASE INTO THE
EVENING.
THOUGH STORM DEVELOPMENT BECOMES INCREASINGLY UNCERTAIN ACROSS
KS/WRN OK AND INTO WRN PARTS OF TX...ANY STORMS WHICH DO DEVELOP
WOULD QUICKLY BECOME SUPERCELLULAR GIVEN DEGREE OF INSTABILITY AND
SHEAR. THOUGH TORNADO THREAT MAY BE SOMEWHAT LESS THAN FURTHER N
WITH ANY OF THESE ISOLATED SUPERCELLS DUE TO DEEPER BOUNDARY
LAYER/HIGH CLOUD BASES...VERY LARGE HAIL AND DAMAGING WIND GUSTS --
ALONG WITH ISOLATED TORNADOES -- CAN BE EXPECTED NEAR ANY STORM.
OVERNIGHT...STORMS SHOULD PERSIST/MOVE EWD ACROSS NEB/THE DAKOTAS
INTO MN/IA AND EVENTUALLY WI/UPPER MI...AS INTENSE LOW-LEVEL JET
DRIVES VERY STRONG WARM ADVECTION ACROSS THE N CENTRAL CONUS.
POTENTIAL FOR SEVERE STORMS SHOULD PERSIST THROUGH THE END OF THE
PERIOD.
..GOSS.. 06/05/2007
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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