Wed 23rd May 2007

[Paul Sherman]

Moderate Risk Issued by the SPC For Wednesday 23rd May 2007. Steve & Group are in a perfect position for this today and I am sure they will report back with some amazing pictures later. I have a feeling some Nice Tornadoes will be possible later today given the Current Synopsis. The area from Liberal across to Barber County (Medicine Lodge) and around the Greensburg area look to have the best shot of Large and Destructive Tornadoes from 6-9pm this evening, lets hope the team score well on what could be their last chase day for this year.

Paul Sherman

[pottyprof]

Day 1 outlook from the SPC.

VALID 231200Z - 241200Z

...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT OVER

PORTIONS OF SWRN KS...NWRN OK AND THE OK/TX PNHDLS...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID MO VALLEY SWWD

INTO SRN HIGH PLAINS...

...SYNOPSIS...

UPPER LOW AND ATTENDANT SHORT WAVE TROUGH CURRENTLY LIFTING NEWD

THROUGH THE NRN AND CNTRL HIGH PLAINS WILL CONTINUE NEWD TODAY

THROUGH THE DAKOTAS AND UPPER MS VALLEY INTO ERN SASKATCHEWAN AND

MANITOBA BY THURSDAY MORNING. MEANWHILE...NEXT SHORT WAVE TROUGH

AND ASSOCIATED MID-LEVEL JET STREAK OVER THE GREAT BASIN WILL

TRANSLATE SEWD THROUGH THE FOUR CORNER REGION TODAY...EMERGING INTO

THE CNTRL AND SRN HIGH PLAINS TONIGHT.

IN THE LOW-LEVELS...SURFACE LOW ATTENDANT TO MAIN UPPER LOW WILL

DEVELOP NEWD FROM ERN ND INTO WRN ONTARIO BY THE END OF THE PERIOD

WHILE SECONDARY LEE CYCLONE CONSOLIDATES OVER SERN CO INTO NERN NM

LATER TODAY. WHILE ASSOCIATED COLD FRONT WILL ASSUME A SLOW EWD

PROGRESSION THROUGH THE NRN PLAINS AND UPPER MS VALLEY...THIS

BOUNDARY IS FORECAST TO BECOME QUASI-STATIONARY FROM ERN NEB/WRN IA

SWWD INTO CNTRL KS. SRN HIGH PLAINS CYCLOGENESIS MAY CAUSE WRN

EXTENSION OF THIS BOUNDARY TO RETREAT SLIGHTLY BY AFTERNOON OVER THE

NRN TX/OK PNHDLS AND FAR SWRN KS.

...UPPER MS VALLEY INTO MID MO VALLEY...

SCATTERED TSTMS ARE EXPECTED TO BE ONGOING AT THE ONSET OF THE

PERIOD ALONG FRONT...LARGELY DRIVEN BY DEEP LAYER FORCING FOR ASCENT

ASSOCIATED WITH UPPER LOW AND ATTENDANT SHORT WAVE TROUGH. CLOUDS

AND/OR PRECIPITATION WILL LINGER THROUGH MUCH OF THE DAY...LIMITING

DESTABILIZATION ESPECIALLY ACROSS THE ERN DAKOTAS INTO WRN MN.

LATEST MODEL GUIDANCE DOES SUGGEST THAT AIR MASS OVER ERN NEB/WRN IA

MAY DESTABILIZE SUFFICIENTLY SUCH THAT DIURNAL STORMS WILL BE

POSSIBLE BY AFTERNOON ALONG STALLED FRONT.

THE COMBINATION OF MLCAPES OF AROUND 1000 J/KG AND EFFECTIVE BULK

SHEARS /EBS/ OF 30-40 KT INDICATE THE POTENTIAL FOR ORGANIZED

STORMS...A FEW OF WHICH COULD BE SUPERCELLS WITH THE POTENTIAL FOR

MAINLY LARGE HAIL AND STRONG WIND GUSTS. TSTMS SHOULD GRADUALLY

EVOLVE INTO MORE A LINEAR STRUCTURE WITH TIME WITH THE HAIL/WIND

THREAT CONTINUING INTO THIS EVENING.

...KS INTO THE SRN HIGH PLAINS...

22/00Z REGIONAL SOUNDINGS ACROSS THE SRN PLAINS INDICATE THAT

BOUNDARY LAYER MOISTURE CONTINUES TO SLOWLY IMPROVE WITH MEAN MIXING

RATIOS OF 12-15 G/KG OBSERVED OVER THE LOWER ELEVATIONS OF TX/OK.

HOWEVER...OBSERVED SOUNDING DATA OVER THE SWRN U.S. INTO SRN HIGH

PLAINS SHOWED GENERALLY 6.5-7.0 C/KM MID-LEVEL LAPSE RATES WHICH

WILL TEMPER THE DEGREE OF WARM SECTOR INSTABILITY TODAY.

NONETHELESS...THE PRESENCE OF LOW/MID 60S DEWPOINTS AND DAYTIME

HEATING SHOULD CONTRIBUTE TO MLCAPES APPROACHING 1500-2500 J/KG BY

LATE AFTERNOON S OF FRONT.

TSTMS ARE EXPECTED TO BECOME INCREASINGLY LIKELY ALONG FRONT BY MID

TO LATE AFTERNOON FROM CNTRL KS SWWD INTO SWRN KS THE OK AND NRN TX

PNHDLS. ADDITIONAL STORMS WILL LIKELY INITIATE AT THIS TIME OVER

THE HIGHER TERRAIN OF S-CNTRL CO/N-CNTRL NM...PRIOR TO

MOVING/DEVELOPING EWD ALONG STATIONARY OR RETREATING FRONTAL

BOUNDARY.

THE STRONGEST DEEP LAYER VERTICAL SHEAR /EBS OF 45-55 KT/ WILL EXIST

OVER THE SRN HIGH PLAINS THROUGH THIS EVENING WITH EBS OF GENERALLY

30-40 KT FORECAST FARTHER E ALONG FRONT OVER CNTRL KS.

GIVEN THE DEGREE OF INSTABILITY...SUPERCELLS APPEAR LIKELY

ESPECIALLY ACROSS THE MODERATE RISK AREA. LARGE HAIL /SOME

SIGNIFICANT/ AND TORNADOES WILL BE THE PRIMARY SEVERE WEATHER

THREATS WITH THE MOST INTENSE STORMS. POTENTIAL FOR A STRONG

TORNADO OR TWO WILL EXIST THIS EVENING /00-03Z/ WITH ANY MATURE

SUPERCELLS AS 0-1 KM SRH INCREASES TO 200-300 M2/S2.

STORMS WILL LIKELY GROW UPSCALE INTO AN MCS OVERNIGHT WITH A HIGH

WIND AND HAIL THREAT SPREADING INTO CNTRL KS AND WRN OK.

..MEAD/GRAMS.. 05/23/2007

Tornado probability

[Nick F]

Yes, looks very similar to our few days around Kansas and NWern Oklahoma, with a slow moving cold front bringing squall line severe storms across central Kansas and W/NW Oklahoma:

Looking foward to following it later this evening as it all kicks off. South central Kansas looking good, long as the tornadoes keep away from Greensburg area!

[pottyprof]

Not a lot of cloud in the target area at the moment.

This should allow plenty of surface heating until the cap starts to break in the afternoon.

Plenty of CAPE available along the border too.

[Nick F]

Squall line beginning to take shape already along the cold front over Central Kansas, and it's only 11.37am:

Should see continual backbuilding on the SW of this this squall line as it pulses NE, cold front loooks to move very little over the next 6 or so hours.

00zUTC Thursday surface prog:

[pottyprof]

Things kicking off in the target area..