SPC AC 071230
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0730 AM CDT SUN JUN 07 2009
VALID 071300Z - 081200Z
...THERE IS A MDT RISK OF SVR TSTMS OVER PORTIONS OF NERN KS/SERN
NEB/SWRN IA/NWRN MO...
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL HIGH PLAINS
INTO THE MID MS RIVER VALLEY...
...CENTRAL PLAINS ACROSS THE MID MS RIVER VALLEY...
WV IMAGERY INDICATES MID/UPPER LEVEL VORT CENTER EJECTING NEWD
ACROSS THE 4-CORNERS REGION THIS MORNING. 50-60 KT SWLY MID LEVEL
JET ATTENDANT TO THIS SYSTEM WILL OVERSPREAD THE CENTRAL PLAINS
THROUGH THE AFTERNOON AS IMPULSE EJECTS ACROSS THE CENTRAL ROCKIES.
INCREASING DEEP ASCENT...STRENGTHENING SHEAR AND PERSISTENT BOUNDARY
LAYER MOISTENING ACROSS THE SRN PLAINS UNDER IMPRESSIVE EML /AS
EVIDENCED ON 12Z SOUNDINGS/ SHOULD LEAD TO A REGIONAL OUTBREAK OF
SEVERE THUNDERSTORMS LATE TODAY THROUGH TONIGHT.
SURFACE FRONT NOW EXTENDING FROM SRN WI/NERN IA SWWD INTO SWRN KS
WILL LIKELY STALL TODAY...WITH TRIPLE POINT LOW DEEPENING OVER SWRN
KS AHEAD OF APPROACHING SYSTEM. IN ADDITION....OUTFLOW BOUNDARY
FROM SATURDAY NIGHT/S MCS SHOULD PERSIST OVER NERN KS/SERN NEB AND
THE IA/MO BORDER REGION THROUGH THE AFTERNOON. COLD FRONT WILL
LIKELY SURGE SWD ACROSS THE CENTRAL HIGH PLAINS LATER THIS
EVENING/OVERNIGHT BEHIND MAIN LOW CENTER WHICH WILL EJECT NEWD INTO
CENTRAL IA ATTENDANT TO UPPER SYSTEM BY THE END OF THE PERIOD.
CAPPING WILL LIKELY KEEP WARM SECTOR RELATIVELY VOID OF DEEP MOIST
CONVECTION FOR MUCH OF THE DAY. HOWEVER...STRONG HEATING AND
INCREASING ASCENT SHOULD SUPPORT RAPID DEVELOPMENT OF SEVERE
THUNDERSTORMS LATE IN THE DAY/THIS EVENING NEAR THE FRONT ONCE CAP
BREAKS. VERY STEEP LAPSE RATES AND PRESENCE OF STRONG INSTABILITY
SHOULD FOSTER DEVELOPMENT OF VERY LARGE HAIL AS STORMS MATURE INTO
SUPERCELLS QUICKLY GIVEN 40-50 KT EFFECTIVE SHEAR. INCREASED SELY
LOW LEVEL FLOW THROUGH THE EVENING /INVOF 35-45 KT LLJ/ WILL ALSO
FAVOR LARGE LOW LEVEL HODOGRAPHS AND THE POTENTIAL FOR TORNADOES.
SEVERE THREAT WILL SPREAD ACROSS ERN KS/ERN NEB INTO IA/NRN MO
DURING THE LATE EVENING...IMMEDIATELY AHEAD OF SFC LOW. ONE OR MORE
COMPLEXES /INCLUDING POSSIBILITY OF DAMAGING BOW ECHOES/ SHOULD
EVOLVE INTO THE MID MS VALLEY DURING THE OVERNIGHT HOURS INVOF
WSW-ENE ORIENTED SURFACE FRONT. LARGE HAIL AND DAMAGING WINDS WILL
BECOME THE PRIMARY SEVERE THREATS AS MCS/S MATURE.
...CENTRAL HIGH PLAINS...
APPEARS SURFACE FRONT WILL STALL ALONG THE FRONT RANGE AND SUSTAIN
UPSLOPE FLOW INTO NERN CO AS SURFACE LOW NEAR N-CENTRAL CO ALLOWS
FLOW TO BECOME MORE SELY. INFLUX OF MID 50S F SURFACE DEW
POINTS...STEEP LAPSE RATES AND STRENGTHENING VERTICAL MOTION AHEAD
OF APPROACHING SHORTWAVE TROUGH SHOULD SUPPORT SECOND AREA OF
SUPERCELLS INTO THIS REGION LATER TODAY. HODOGRAPHS ARE FORECAST TO
BE A BIT MORE STRAIGHT OVER THIS AREA AND SHOULD SUPPORT SPLITTING
STORMS...WITH POTENTIAL FOR VERY LARGE HAIL AND ISOLATED TORNADOES.
THIS ACTIVITY WILL LIKELY EVOLVE AS A STRONG TO SEVERE MCS AND TRACK
NEWD JUST BEHIND SURFACE COLD FRONT INTO ERN NEB OVERNIGHT.
...SRN HIGH PLAINS...
ISOLATED-SCATTERED THUNDERSTORMS WILL ONCE AGAIN DEVELOP ALONG
DRYLINE ACROSS WEST TX AS TEMPERATURES RISE INTO THE UPPER 90S TO
NEAR 100F. HIGH BASED CONVECTION MAY PRODUCE A FEW SEVERE WIND
GUSTS OR LARGE HAIL BEFORE DIMINISHING DURING THE MID TO LATE
EVENING.
...FL...
A FEW STRONG STORMS MAY ALSO DEVELOP ALONG THE EAST COAST OF SOUTH
FL. FORECAST SOUNDINGS SUGGEST SUFFICIENT CAPE FOR ROBUST UPDRAFTS
WITHIN MARGINAL SHEARED ENVIRONMENT. ISOLATED LARGE HAIL OR
MICROBURSTS ARE THE THREATS WITH THIS DIURNAL ACTIVITY.
..EVANS/HURLBUT.. 06/07/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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