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Chase 2009 Day 6 Discussion


Paul Sherman

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

    post-24-1241158628_thumb.png - 10% Which could be Upgraded :lol:

    DAY 1 CONVECTIVE OUTLOOK

    NWS STORM PREDICTION CENTER NORMAN OK

    1244 AM CDT FRI MAY 01 2009

    VALID 011200Z - 021200Z

    ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS A LARGE PART OF THE SRN

    PLNS EWD INTO THE MID-SOUTH AND OH/TN VLYS...

    ...SYNOPSIS...

    UPR TROUGH WILL DEEPEN SLIGHTLY ACROSS THE MIDWEST...GREAT LAKES AND

    NERN STATES ON FRIDAY AS THE HUDSON BAY VORTEX REPOSITIONS SWD. A

    SEPARATE BELT OF MODEST FLOW WILL EXIST ACROSS THE SRN PLNS INTO THE

    MID-ATLANTIC REGION. EMBEDDED CONVECTIVELY ENHANCED DISTURBANCES

    WILL EXIST WITHIN THIS JET. NEXT MID-LVL SHORTWAVE TROUGH...NOW

    OVER THE ERN PACIFIC BASIN...WILL QUICKLY TRANSLATE EWD...ARRIVING

    INTO CA BY EARLY SATURDAY.

    IN THE LWR LEVELS...SYNOPTIC CDFNT TIED TO THE AMPLIFYING NRN STREAM

    UPR WAVE WILL SETTLE SEWD...REACHING NEW ENGLAND...THE OH VLY...AND

    SRN PLNS STATES BY FRIDAY NIGHT. A MYRIAD OF PRE-FRONTAL OUTFLOW

    BOUNDARIES WILL LIKELY EXIST THROUGHOUT THE OH/TN/LWR MS VLYS AND

    SRN PLNS. A DRYLINE WILL MIX EWD INTO NWRN TX AND THE ERN EDWARDS

    PLATEAU.

    ...SRN PLNS INTO THE MID-SOUTH...

    SEVERAL TSTM CLUSTERS ARE EXPECTED TO BE ONGOING FRIDAY MORNING

    ACROSS THE OZARKS AND ERN OK ALONG THE NOSE OF A VEERING LLJ.

    STORMS MAY ALREADY BE PRODUCING LARGE HAIL AND GUSTY WINDS. AIR

    MASS DOWNSTREAM ACROSS THE MID-SOUTH WILL LIKELY HEAT SIMILAR TO

    THURSDAY AND MAY BE COMPARATIVELY MORE UNSTABLE OWING TO STEEPER

    MID-LVL LAPSE RATES WITH MLCAPES OF 1500-2000 J/KG EXPECTED. THE

    FLOW ALOFT WILL BE SOMEWHAT WEAK...WELL REMOVED FROM THE PRIMARY

    TROUGH ACROSS THE MIDWEST. HOWEVER...CORRIDORS OF STRONGER FLOW MAY

    EVOLVE WITH ANY MCV THAT MAY DEVELOP...AND GIVEN AT LEAST MODEST

    BUOYANCY...MULTICELL STORMS MAY PRODUCE SPORADIC DMGG WIND AND LARGE

    HAIL.

    HIGHER SVR PROBABILITIES WILL DEVELOP UPSTREAM BY LATE FRIDAY AFTN

    AND EVENING. TRAILING OUTFLOW FROM OVERNIGHT STORMS WILL LIKELY

    STALL ACROSS SRN OK AND ADJOIN WITH A TRIPLE POINT OVER FAR SW

    OK/WRN N TX. STRONG HEATING IN COMBINATION WITH MID-UPR 60S SFC DEW

    POINTS AND 8-8.5 C/KM MID-LVL LAPSE RATES WILL CONTRIBUTE TO AN

    EXTREME UNSTABLE ENVIRONMENT OVER SRN OK/NRN TX WITH MLCAPES OF

    3000-4000 J/KG. AS SBCINH WEAKENS...INGREDIENTS WILL BE FAVORABLE

    FOR RAPID TSTM INITIATION INVOF THE TRIPLE POINT AND POINTS EWD

    ALONG/N OF THE OUTFLOW BOUNDARY. BULK SHEAR OF 30-35 KTS AND

    EXTREME INSTABILITY WILL RESULT IN SUPERCELLS WITH VERY LARGE HAIL.

    A FEW TORNADOES WILL BE POSSIBLE WITH MATURING DISCRETE CELLS ACROSS

    EXTREME SWRN OK AND WRN N TX THROUGH EARLY EVENING. ANY SUPERCELL

    SPLITS WILL MOVE NWD...POSSIBLY INTO CNTRL OK DURING THE EVE WITH A

    LARGE HAIL THREAT.

    WNWLY H5 FLOW OF 30-35 KTS AND PERSISTENT MOIST BOUNDARY LAYER

    INFLOW DURING THE EVENING ALONG WITH GROWING COLD POOLS MAY LEAD TO

    A FORWARD PROPAGATING MCS /BOW ECHO/ THAT DEVELOPS ACROSS SRN OK AND

    N TX...WITH THE APEX FAVORING THE EVENTUAL RESTING PLACE OF THE

    OUTFLOW BOUNDARY...PROBABLY INVOF THE RED RIVER FRIDAY EVENING.

    DMGG WINDS AND LARGE HAIL WILL BE LIKELY. TAIL-END OF THE MCS MAY

    CONTINUE TO BACKBUILD SEWD TOWARD I-20 AND MAINTAIN CYCLIC SUPERCELL

    CHARACTER INTO LATE EVE WITH DMGG WINDS/LARGE HAIL AND ISOLD

    TORNADOES.

    ONCE THE FINAL LATITUDINAL PLACEMENTS OF THE AFOREMENTIONED

    BOUNDARIES ARE BETTER KNOWN...PARTS OF THE REGION MAY NEED AN

    UPGRADE TO A MDT RISK.

    Going to be a Late One Tomorrow even after Chasing as Tornadoes could be occuring as we book into the Hotel after the Chase

    Paul S

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    Posted
  • Location: SE London
  • Location: SE London

    Latest update for status report #219

    VALID 010625Z - 010740Z

    THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.

    WRN PORTIONS WW MAY BE CLEARED IN NEXT 1-2 HOURS GVIEN CURRENT

    WEAKENING TRENDS WITH LONE REMAINING SUPERCELL IN CENTRAL OK.

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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)

    Yep, looks like it could go moderate - especially over NW/N-central TX. Looking at the models, Dryline triple point looks like being the focus for some possible tornadic supercells in a triangle of NW TX between Childress and Guthrie to Witchita Falls ... some big CAPE and strong helicity values modelled roughly in this area by WRF:

    WRF Tds 00z Sat, showing dryline triple point with cold front over NW TX (as I've marked):

    post-1052-1241160658_thumb.png

    WRF SB/MUCAPE 00z Sat:

    post-1052-1241160287_thumb.pngpost-1052-1241160300_thumb.png

    Some strong 0-1km and 0-3km SRH values in this general area

    post-1052-1241160939_thumb.pngpost-1052-1241160950_thumb.png

    Certainly would head down to Wichita Falls or perhaps Childress and see what happens ... could be very productive.

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    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    Morning all. I missed last nights chase but heard you bagged the only supercell. Well done.

    It looks promising today with a compact area to focus on. I reckon that I would sit up in Vernon and wait to see what happens. Looks good road network there and hopefully bandwidth!

    c

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    Posted
  • Location: Gosport, Hampshire.
  • Location: Gosport, Hampshire.

    A classic chase day with the potential for slow moving well defined tornadoes within a low shear high instability climate. I agree with Nick, this one could go moderate. Locating the triple will be key to success. I usually draw a line between the contrast of low to high dew points. Low to high temps can also be use here. TP can be recognised by studying this line to recognise the intersection of occlusion and cold front by a pressure drop and wind veer.

    Classic chase day potentially. I would be getting to Witchita Fall by mid afternoon and then check the surface obs.

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    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    Latests obs (1009Z) show the dry line on the TX/NM border with the triple point near Clovis.

    http://www.hpc.ncep.noaa.gov/sfc/lrgnamsfcwbg.gif

    Some good differences in dewpoints there already though I am not too sure how nighttime affects this.

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    Posted
  • Location: Scarborough, North Yorkshire - 80m ASL
  • Weather Preferences: Tornadoey
  • Location: Scarborough, North Yorkshire - 80m ASL

    Not had chance to look at the models today, but yesterday, I was tending towards Wichita Falls or perhaps even further south. Seems like the sort of setup where you could get adiscrete cell or two forming off the dryline bulge forecast down in TX. I think the triangular area bounded by Throckmorton, Graham and Breckenridge might be the place to be for intiation. Will update my thoughts at 5pm-ish :unsure:

    Also, I'm sure we'll get an upgrade to the tor chances next update (to 10% hatched at least) and over a slightly larger area. Shear and Cape values are both suitable for strong tornadoes. Looks like it could be good day. Most models break out a few areas of precip this far south, but the only concern would be with a strongish cap which might limit the southern extent of the action and keep cells up near the triple point (as happened yesterday)

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

    Going to get the troops ready to roll at about 11am and head for Lunch at Witchita Falls (Tx) and see how things are panning out from there, big concern about River Crossings today in the Tornado Area on two counts, firstly there are not many of them so finding a Supercell with good road options could be tough and secondly the Flood Options, Witchita Falls and the Red River has recieved over 6" of Rain this week and the River is already in Flood at the Moment.

    We will do our best with what road options we have but I think The Storms have a greater Chance of dropping Tubes than yesterday.

    Paul S

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    Posted
  • Location: SE London
  • Location: SE London

    morning Paul, yes i was going to ask you about the rainfall situation out there. understand there is potential for lots off flooding.

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    Posted
  • Location: Cumbria UK
  • Weather Preferences: Cloud 9
  • Location: Cumbria UK
    looking good Paul

    Morning to you and the chase team :)

    and a good morning to you too.

    Tom

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    Posted
  • Location: Leigh On Sea - Essex & Tornado Alley
  • Location: Leigh On Sea - Essex & Tornado Alley
    morning Paul, yes i was going to ask you about the rainfall situation out there. understand there is potential for lots off flooding.

    Yes Mick

    It is a big concern, Will NOT Be taking any dirt roads today for obvious reasons, the ground down there is absolutely Saturated and Flash Flood Advisories have been going off all week for the Red River around the Witchita Falls area so certainly one to watch.

    Paul S

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    Posted
  • Location: SE London
  • Location: SE London

    well lets hope the weather plays the game and stays close to major routes today :)

    its a glorious day here in C London and Trafalgar Square/Whitehall is packed with tourists/may day procession.

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    what camera are you using for the shots you have got,

    woud love to be out there with you guys all i do is wait for a good thunderstorm here in uk.

    none as yet my way though

    good pics any funnel clouds spotted yet.

    all the best

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    Posted
  • Location: East Renfrewshire 180m asl
  • Location: East Renfrewshire 180m asl
    what camera are you using for the shots you have got,

    woud love to be out there with you guys all i do is wait for a good thunderstorm here in uk.

    none as yet my way though

    good pics any funnel clouds spotted yet.

    all the best

    There is a video of a small funnel posted in the day 5 pictures topic i think.

    Equipment topic: http://www.netweather.tv/forum/index.php?showtopic=54288 Should have peoples camera type :)

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    Posted
  • Location: Leeds
  • Location: Leeds
    There is a video of a small funnel posted in the other topic i think.

    Equipment topic: http://www.netweather.tv/forum/index.php?showtopic=54288 Should have peoples camera type :)

    Lets get one like this today guys

    http://www.youtube.com/watch?v=I2qf7Re0K8E...feature=related

    I'll be following you again tonight. I trust you're doing Wichita Falls way. :)

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    Posted
  • Location: South Shields Tyne & Wear half mile from the coast.
  • Location: South Shields Tyne & Wear half mile from the coast.

    Moderate risk issued.

    DAY 1 CONVECTIVE OUTLOOK

    NWS STORM PREDICTION CENTER NORMAN OK

    1131 AM CDT FRI MAY 01 2009

    VALID 011630Z - 021200Z

    ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF SOUTHERN

    OKLAHOMA AND PARTS OF NORTHERN TEXAS...

    ...THERE IS A SLGT RISK OF SVR TSTMS AROUND THE MODERATE FROM NWRN

    TX TO THE LOWER OH VALLEY...

    ...THERE IS A SLGT RISK OF SVR TSTMS IN THE MID ATLANTIC REGION...

    ...SWRN OK INTO NRN TX...

    MODERATE TO STRONG INSTABILITY AND /SBCAPE TO 4000 J PER KG/ AND

    DEEP LAYER SHEAR 30-40 KT /SUFFICIENT FOR SUPERCELLS/ SHOULD

    CONTINUE TO EVOLVE AHEAD OF THE ADVANCING COLD FRONT AND DRYLINE

    FROM SWRN OK ACROSS THE RED RIVER VALLEY THIS AFTERNOON. THERE IS

    NEARLY UNANIMOUS AGREEMENT ACROSS A BROAD RANGE OF AVAILABLE MODEL

    GUIDANCE THAT SURFACE-BASED CONVECTION WILL INITIATE BY EARLY

    EVENING NEAR FRONT/OUTFLOW/DRYLINE TRIPLE POINT AROUND SPS.

    WHILE SYNOPTIC SCALE FORCING FOR ASCENT ACROSS THIS AREA OF INTEREST

    IS EXPECTED TO BE WEAK IT WILL NOT NECESSARY BE HOSTILE TO STORM

    DEVELOPMENT AS EVIDENCED IN THE NAM/GFS GUIDANCE AND RELATIVELY FLAT

    MID-LEVEL HEIGHT PATTERN AND WLY 500MB WINDS AOB 30KT. THE EXISTENCE

    OF STRONG LOW LEVEL FORCING ON THE MESOSCALE APPEARS TO AID

    CONVECTIVE INITIATION IN A STRONGLY UNSTABLE AND SUFFICIENT SHEARED

    ENVIRONMENT FOR STORMS TO QUICKLY ACQUIRE SUPERCELLULAR STRUCTURE.

    MAGNITUDE OF CAPE WILL SUPPORT ROBUST UPDRAFTS AND MAY COMPENSATE

    SOMEWHAT FOR LACK OF STRONG SYNOPTIC ASCENT WITH STROM MERGERS AND

    COLD POOL DEVELOPMENT AIDING UPSCALE ORGANIZATION ACROSS NRN TX

    THROUGH THE EVENING.

    GIVEN THE STRONG SIGNAL FOR STORM DEVELOPMENT...AND DEGREE OF

    DESTABILIZATION EXPECTED...A SMALL HIGHER PROBABILITY HAIL AREA HAS

    BEEN ADDED TO THIS FORECAST. BASEBALL OR LARGER HAIL APPEARS QUITE

    POSSIBLE WITH THESE STORMS...ESPECIALLY WITHIN A FEW HOURS OF

    INITIATION. LACK OF STRONGER DEEP SHEAR AND WEAK LARGER SCALE

    FORCING MAY LIMIT STORM COVERAGE. THIS FACTOR...AND GENERALLY

    MARGINAL FORECAST HODOGRAPH STRUCTURE...INDICATE TORNADO POTENTIAL

    MAY BE LIMITED IN TIME/SPACE. HOWEVER...MOIST BOUNDARY LAYER AND

    LIKELIHOOD FOR SOME STORM-SCALE AND MESOSCALE ENHANCEMENT TO THE LOW

    LEVEL WIND FIELD...MAY PLAY A ROLE IN FAVORING A TORNADIC SUPERCELL

    OR TWO IN THIS REGIME.

    EVENTUALLY...STRONG INSTABILITY AND RESULTANT COLD POOLS SHOULD

    RESULT IN A SMALL MCS ACROSS THE RED RIVER/NWRN TX. THE POTENTIAL

    FOR BOWING LINE SEGMENTS/SUPERCELLS WITH SEVERE HAIL AND WIND COULD

    SHIFT ESEWD ACROSS FAR NRN TX/DFW THROUGH EVENING/LATE EVENING.

    ...NERN OK TO AR AND ACROSS LWR/MID MS VALLEY...

    LEADING PORTION OF SYNOPTIC FRONTAL ZONE ACROSS NW AND NCNTRL OK IS

    BEING REINFORCED BY ONGOING MCS NOW SPREADING ESEWD ACROSS NERN OK

    AND THE OZARKS. MODEST CONTINUING INFLUX OF LOW LEVEL MOISTURE AND

    MASS CONVERGENCE INTO THE MCS OUTFLOW/COLD POOL WILL MAINTAIN SOME

    POTENTIAL FOR SEVERE HAIL AND WIND FROM NERN OK ACROSS AR THIS

    AFTERNOON. POSSIBLE MCV EVOLVING FROM THIS ONGOING SYSTEM MAY

    SUPPORT THE DEVELOPMENT AND PERSISTENCE OF ADDITIONAL STORMS ALONG

    THE STALLING COLD FRONT...ALONG A LIT-MEM-BNA LINE...THROUGH LATE

    TONIGHT. GENERALLY WEAKER DEEP LAYER FLOW ACROSS THIS ZONE SUGGESTS

    THAT PRIMARY THREAT MAY BECOME EXCESSIVE RAIN. HOWEVER...A FEW

    SEVERE STORMS ALSO APPEAR POSSIBLE IN THIS CORRIDOR THROUGH EARLY

    SAT.

    ...LOWER/MID OH VALLEY...

    A MARGINALLY UNSTABLE AIR MASS AHEAD OF THE SLOWLY ADVANCING COLD

    FRONT ACROSS THIS AREA SHOULD LEAD TO AN INCREASE IN SHOWERS AND

    THUNDERSTORMS THROUGH THIS AFTERNOON. DESPITE WEAK LAPSE

    RATES...DEEP LAYER WLY FLOW MAY SUPPORT SOME ORGANIZATION TO THIS

    ACTIVITY INTO THE EVENING HOURS WITH WIND AND MARGINALLY SEVERE HAIL

    BEING THE PRIMARY HAZARDS.

    ...MID-ATLANTIC...

    LOW AMPLITUDE SHORT WAVE TROUGH AND DIURNAL DESTABILIZATION WILL

    CONTRIBUTE TO AN INCREASING CHANCE FOR THUNDERSTORM DEVELOPMENT

    ALONG ADVANCING LEE/SYNOPTIC TROUGH THIS AFTERNOON.WARMING INTO THE

    70S SHOULD YIELD SBCAPE AROUND 500-1000 J/KG. THIS INSTABILITY ALONG

    WITH UNIDIRECTIONAL WLY WINDS AT 30-40 KT BETWEEN 850-300 MB SHOULD

    BE SUFFICIENT FOR SPORADIC WIND DAMAGE WITH THE SQUALL LINE...BEFORE

    IT PASSES OFF THE ATLANTIC SEABOARD THIS EVENING.

    ..CARBIN/GUYER.. 05/01/2009

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    Posted
  • Location: East Renfrewshire 180m asl
  • Location: East Renfrewshire 180m asl
    Lets get one like this today guys

    http://www.youtube.com/watch?v=I2qf7Re0K8E...feature=related

    I'll be following you again tonight. I trust you're doing Wichita Falls way. :)

    I'm not out there until next friday... but i'll be watching again tonight.

    They are heading Wichita Falls way yeah.

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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)
    GIVEN THE STRONG SIGNAL FOR STORM DEVELOPMENT...AND DEGREE OF

    DESTABILIZATION EXPECTED...A SMALL HIGHER PROBABILITY HAIL AREA HAS

    BEEN ADDED TO THIS FORECAST. BASEBALL OR LARGER HAIL APPEARS QUITE

    POSSIBLE WITH THESE STORMS...ESPECIALLY WITHIN A FEW HOURS OF

    INITIATION. LACK OF STRONGER DEEP SHEAR AND WEAK LARGER SCALE

    FORCING MAY LIMIT STORM COVERAGE. THIS FACTOR...AND GENERALLY

    MARGINAL FORECAST HODOGRAPH STRUCTURE...INDICATE TORNADO POTENTIAL

    MAY BE LIMITED IN TIME/SPACE. HOWEVER...MOIST BOUNDARY LAYER AND

    LIKELIHOOD FOR SOME STORM-SCALE AND MESOSCALE ENHANCEMENT TO THE LOW

    LEVEL WIND FIELD...MAY PLAY A ROLE IN FAVORING A TORNADIC SUPERCELL

    OR TWO IN THIS REGIME.

    Maybe an idea for the team not to core punch today ... LOL.

    Could be some Gorrilla Size Hail! Not suprised though, hourly meso charts already bullseyeing 4500 j/kg of SBCAPE just SW of Childress in the likely area if intiation in the Moderate risk area:

    post-1052-1241197211_thumb.png

    Bit of a cap to contend with though, so we will need to wait for UVV forcing from the dryline/triple point as it arrives later.

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    thanks for that guys. does your web feed have any sound at all would be great if there was.

    how do you rate a nikon d80 with 18-135 lense as got one but want to know best cam for this type of photography

    many thanks

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