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Wed 23rd May 2007


Paul Sherman

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Posted
  • Location: Leigh On Sea - Essex & Tornado Alley
  • Location: Leigh On Sea - Essex & Tornado Alley

    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

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    Posted
  • Location: Swallownest, Sheffield 83m ASL
  • Location: Swallownest, Sheffield 83m ASL

    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

    post-1669-1179920323_thumb.png

    Tornado probability

    post-1669-1179920339_thumb.png

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    Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

    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:

    post-1052-1179920419_thumb.png

    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!

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    Posted
  • Location: Swallownest, Sheffield 83m ASL
  • Location: Swallownest, Sheffield 83m ASL

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

    post-1669-1179920946_thumb.jpg

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

    post-1669-1179921401_thumb.png post-1669-1179921412_thumb.png

    Plenty of CAPE available along the border too.

    post-1669-1179921433_thumb.png

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    Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

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

    post-1052-1179938287_thumb.pngpost-1052-1179938312_thumb.png

    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:

    post-1052-1179938511_thumb.png

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    Posted
  • Location: Swallownest, Sheffield 83m ASL
  • Location: Swallownest, Sheffield 83m ASL

    Things kicking off in the target area..

    post-1669-1179957921_thumb.jpg

    post-1669-1179957946_thumb.jpg

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