Day 10 - Discussion

[Paul Sherman]

Currently Sat in Abilene on th I20 With a Chase Target of Gainesville

ETD :- 930am

ETA :- 1230pm

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0757 AM CDT WED MAY 07 2008

VALID 071300Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS TODAY THROUGH TONIGHT FOR PARTS

OF THE SRN PLAINS TO THE LOWER MS VALLEY...

...SRN PLAINS TO PARTS OF THE LOWER MS VALLEY THROUGH TONIGHT...

A STRONG MID LEVEL SHORTWAVE TROUGH OVER SE NM/W TX THIS MORNING

WILL EJECT ENEWD TO THE RED RIVER VALLEY BY LATE AFTERNOON...AND

THEN CONTINUE OVER AR TONIGHT. THIS MID LEVEL TROUGH WILL BE

ACCOMPANIED BY A SURFACE CYCLONE WHICH WILL DEVELOP ENEWD FROM NW TX

TO NW AR BY THE END OF THE PERIOD. A 70-80 KT SSWLY MID LEVEL JET

AND ASSOCIATED 50 KT LLJ WILL PRECEDE THE MID LEVEL WAVE TODAY INTO

TONIGHT ACROSS TX/OK/LA/AR.

WIDESPREAD OVERNIGHT CONVECTION HAS MUDDLED THE SURFACE PATTERN THIS

MORNING AND APPEARS TO HAVE REDUCED THE POTENTIAL FOR SEVERE STORMS

ACROSS NW TX AND WRN/NRN OK. INSTEAD...THE GREATER SEVERE STORM

THREAT WILL SHIFT EWD TO NEAR AND E OF I-35/I-44 IN S CENTRAL/SE OK

AND N CENTRAL/NE TX THIS AFTERNOON...IMMEDIATELY IN ADVANCE OF THE

SURFACE CYCLONE AND OUTSIDE THE AREAS OVERTURNED BY WIDESPREAD

CONVECTION THIS MORNING. IT APPEARS THERE WILL BE A NARROW CORRIDOR

ACROSS N/NE TX INTO SE OK THIS AFTERNOON WHERE THE STEEPER MID LEVEL

LAPSE RATES OVERLAP THE LOW-LEVEL MOISTURE AXIS...ON THE W SIDE OF

THE STRONGER LOW-LEVEL SHEAR. CONVECTIVE INITIATION SHOULD BE

FOCUSED NEAR AND JUST E OF THE SURFACE LOW NEAR THE RED RIVER

TODAY...AND ALONG THE TRAILING DRYLINE THIS AFTERNOON INTO N/NE TX.

FORECAST SOUNDINGS IN THIS AREA ARE SUPPORTIVE OF SUPERCELLS CAPABLE

OF PRODUCING LARGE HAIL...DAMAGING WINDS...AND A FEW TORNADOES. A

POTENTIAL LIMITING FACTOR TODAY WILL BE CLOUDS REDUCING SURFACE

HEATING ACROSS THE RED RIVER VALLEY.

STRONG LOW-LEVEL FLOW AND SHEAR ARE EXPECTED THIS AFTERNOON FROM NRN

LA INTO AR. HOWEVER...SATELLITE DERIVED PRECIPITABLE WATER

ESTIMATES AND OBSERVED SOUNDINGS HAVE SHOWN SUBSTANTIAL DRYING ABOVE

THE SURFACE ACROSS THE NW GULF REGION. SOME OF THE DRY AIR WILL

LIKELY MIX DOWN INTO THE BOUNDARY LAYER THIS AFTERNOON AND REDUCE

DEWPOINTS/SURFACE-BASED INSTABILITY ACROSS LA/AR...LEAVING A NARROW

INSTABILITY CORRIDOR ALONG THE DRYLINE ACROSS OK/TX. LOW-LEVEL

MOISTURE WILL BE MORE SHELTERED FROM MIXING ACROSS SRN/SERN

MO...THOUGH CLOUDS/COOLER SURFACE TEMPERATURES WILL TEND TO LIMIT

DESTABILIZATION SOMEWHAT. FINALLY...LOW-LEVEL MOISTURE MAY RECOVER

SOME OVERNIGHT INTO THE LA/AR AREA AS THE SYNOPTIC SYSTEM MOVES EWD

INTO AR AND VERTICAL SHEAR REMAINS STRONG. THERE WILL BE SOME

THREAT FOR DAMAGING WINDS AND AN ISOLATED TORNADO OR TWO...THOUGH

CONVECTIVE COVERAGE/MODE ARE IN QUESTION LATE TONIGHT AND RELATIVELY

LOWER PROBABILITIES ARE WARRANTED COMPARED TO AREAS FARTHER W THIS

AFTERNOON/EVENING.

[NL]

Teams destination for todays chase.

[MAF]

current Radar for the area http://radar.weather.gov/radar.php?rid=fws...111&loop=no

hi Guys, looks like you may get some decent Thunderstorms on the route you have chosen. just checking out the Hazardous Weather Outlook on SPC and it says

DAY ONE...THROUGH TONIGHT.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS ALL OF NORTH

TEXAS TODAY AS A DRYLINE AND A POWER LEVEL LEVEL DISTURBANCE MOVE

ACROSS THE REGION. THE SEVERE WEATHER THREAT WILL END FROM WEST TO

EAST LATE THIS AFTERNOON AND EVENING AS THE DRY LINE MOVES TO OUR

EAST. LARGE HAIL...DAMAGING WINDS AS WELL AS HEAVY RAIN AND CLOUD TO

GROUND LIGHTNING ARE POSSIBLE. ONE OR TWO TORNADOES MAY ALSO OCCUR.

good luck and keep safe. hope the winscreens are up to any more batterings

[NL]

The team left Abilene about a 45mins ago, slight change to their target area from

Gainesville TX to Sherman TX, a 30 mile jaunt further east.

[MAF]

thanks mate. will check out new location now

[Azores Hi]

Sherman TX

Surely a good omen that!

[MAF]

Sherman looking better then Gainesville

current reports from NOAA

Today: Showers and thunderstorms, mainly before 1pm. Some of the storms could be severe. High near 76. South wind between 15 and 20 mph, with gusts as high as 25 mph. Chance of precipitation is 80%.

Tonight: Showers and thunderstorms likely, mainly before 7pm. Some of the storms could be severe. Mostly cloudy, with a low around 59. South wind around 15 mph becoming west northwest. Winds could gust as high as 20 mph. Chance of precipitation is 60%.

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH TEXAS.

.DAY ONE...THROUGH TONIGHT.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS ALL OF NORTH

TEXAS TODAY AS A DRYLINE AND A POWER LEVEL LEVEL DISTURBANCE MOVE

ACROSS THE REGION. THE SEVERE WEATHER THREAT WILL END FROM WEST TO

EAST LATE THIS AFTERNOON AND EVENING AS THE DRY LINE MOVES TO OUR

EAST. LARGE HAIL...DAMAGING WINDS AS WELL AS HEAVY RAIN AND CLOUD TO

GROUND LIGHTNING ARE POSSIBLE. ONE OR TWO TORNADOES MAY ALSO OCCUR.

[Hilton]

Upgraded to a moderate risk for NE TX / SE OK with an enhanced tornado threat. Will be leaving Norman for somewhere in an Ardmore-Durant-Sherman-Gainsville area by 12.

[NL]

Good luck Hilton and stay safe..! lookin like some higher end EF,s this late afternoon/ evening.

[Stu]

Blasting East towards NE TX (GainesVille) to set up for the Mod risk area - current thinking is that there will be a 2 -3 hour opportunity before it all lines out. Web Cam Stream will be up today.

[Roger J Smith]

Plans sound good, teams may run into developing tornadic cells even before they reach Sherman, I can see rapid development past half hour around Mineral Wells which is about where the travelling teams would be now.

The 12z obs came in pretty much on track from the earlier models and so the timing and degree of forcing is about the same as expected, should really blow up fast today with the ongoing height and thickness crash.

I'm expecting tornado risk to peak 18z to 20z ... well within the comfort zone for the UK readers today.

Radar link for you:

www.radar.weather.gov/radar.php?product=NCR&rid=FDR&loop=yes

(make sure you enable Autorefresh lower right)

[NL]

Watched quite a bit of your stream yesterday Stu, hoping the stream is a bit more continuous

today than it was yesterday.... better WiFi coverage over NE Texas SW Oklahoma..? Good luck and i'll be

tuning in.

Latest Visible and IR images.

[MAF]

update for the Meoscale discussion

MESOSCALE DISCUSSION 0810

NWS STORM PREDICTION CENTER NORMAN OK

1159 AM CDT WED MAY 07 2008

AREAS AFFECTED...SRN TX PNHDL INTO PARTS OF NW TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 071659Z - 071830Z

TRENDS ARE BEING MONITORED FOR AN INCREASING SEVERE THREAT AND THE

POSSIBILITY OF A WW.

AN INCREASE IN CONVECTIVE DEVELOPMENT IS ONGOING WEST OF LUBBOCK.

THIS APPEARS TO BE IN RESPONSE TO FORCING NEAR A MID-LEVEL CYCLONIC

VORTICITY...WITHIN BROADER SCALE CIRCULATION SHIFTING OUT OF THE

SOUTHERN ROCKIES INTO THE SOUTHERN HIGH PLAINS. THE LOW-LEVEL

ENVIRONMENT ALONG/AHEAD OF THE SURFACE COLD FRONT NOW SLOWLY NOSING

THROUGH THE SOUTHERN TEXAS PANHANDLE HAS BECOME WEAKLY UNSTABLE WITH

NEGLIGIBLE CAP...AND IT IS POSSIBLE STORMS COULD CONTINUE TO

INCREASE ACROSS AND EAST/SOUTHEAST OF LUBBOCK THROUGH 19-20Z. IF

THIS OCCURS...LAPSE RATES BENEATH MID-LEVEL COLD POCKET ARE BECOMING

VERY STEEP...CONTRIBUTING TO A RISK FOR DAMAGING DOWNBURSTS AND SOME

MARGINALLY SEVERE HAIL IN STRONGER CELLS.

HOWEVER...MUCH OF MODEL GUIDANCE IS SUGGESTIVE THAT THE MAIN

MID-LEVEL VORTICITY CENTER WILL RAPIDLY DEVELOP EAST SOUTHEASTWARD

TOWARD THE TRIPLE POINT LOW BETWEEN ABILENE AND WICHITA FALLS BY

EARLY AFTERNOON...WHERE DESTABILIZATION AND DEEP LAYER SHEAR

PROBABLY WILL BE MUCH MORE SUPPORTIVE OF SUPERCELLS. AND... THOUGH

THE MAIN SOUTHERLY LOW-LEVEL JET IS WELL TO THE EAST...

SOUTHEASTERLY BOUNDARY LAYER WINDS MAY CONTRIBUTE TO SUFFICIENTLY

LARGE LOW-LEVEL HODOGRAPHS FOR A TORNADO THREAT...PARTICULARLY GIVEN

THE PRESENCE OF FAVORABLE AMBIENT VERTICAL VORTICITY.

[NL]

SPC are predicting a few strong tornadoes.

http://www.spc.noaa.gov/products/outlook/pwo.html

[Roger J Smith]

UPDATE _ May 7/08 _ 1830z (1330 CDT)

The cells most likely to become tornadic are presently developing south of Wichita Falls TX. Another area of strong activity further west is likely to develop into a secondary squall line feature and represents the wrap-around moisture interacting with the dry air mass that has reached a line just west of Wichita Falls to just east of Abilene.

With the dry air feeding into the high risk zone north of DFW ahead of these two prime severe weather producers, the stage is now set for tornadic development as strong low level southerly winds shear rapidly to westerly along the remnants of the dry line. Dry line features usually become P front features by the longitude of MWL to DFW due to long transport of the desert-origin air over moist surfaces, therefore you can look for the "dry line" to be led by dew points 40-50 F rather than 20-30 F as is the case further west in Texas.

The team may have halted their eastward progress with this set-up becoming apparent, but if they have reached Sherman I think the tornadic activity will come fairly rapidly towards them, so backtracking would not be a major issue, although at the moment I would like to be around Valley View to Decatur slightly WSW of Sherman. This is about where I think the tornado risk should max out.

I also believe that the secondary squall line feature could develop severe weather and even a tornado or two, with a dry slot of about 1-2 hours between the two lines as they develop further this afternoon.

[NL]

Tornado watch issued

http://www.spc.noaa.gov/products/watch/ww0273.html

[Nick F]

We're sat at Denny's Restaurant at Denton (north of DFW on the I-35), just had a bite to eat, and we are contemplating heading north to Gainesville then east to Sherman and wait in that general area for the cold front to the west (through Witchita falls) to move east and engage the very warm moist air currently here, should trigger severe storms in the MODERATE risk area which we are in. Hopefully a few tornadoes will form too! Quite a few other chasers on stormtrack seem to be targeting this general area too.

Currently partly cloudy with altocumulus, warm and humid (dew points heading towards 70F!), some good breaks apppearing with sunshine, cold front should arrive in this area in next 2-3 hrs, storm motions quite fast today though!

[Azores Hi]

Good luck Nick, great potential for you guys today, if you can keep up! Looking forward to the footage already. Keep up the good work!

[NL]

Teams current location.

[Roger J Smith]

In the 19z Texas obs, notice there's a NW 30G45 at a mesonet station west of Graham while Graham itself reports SW 20 or so. This is to the south of the radar echoes near Wichita Falls. Looks like the front is about to activate. The echoes developing near Guthrie show the potential of the second line of storms that I mentioned.

[NL]

Something brewing in Parker County 45 mile SW of Denton

[NL]

The storms around south/ central Oklahoma are shifting along at over 50 Knots..!!

[Louise]

Good luck with this today guys, hope you get some great footage for us stuck in the UK!

[ian cameron]

Update From Paul S on Ian's account

We are sitting tight in Gainsville and have elected not to Chase the stupid fast moving Supercell about 60 miles North of here, our attention is drawn to a new storm that is going to track near to Sherman, we will move east on 82 and watch it come to us.

Paul Sherman

[NL]

New Tornado watch issued for east central texas.

TornadoWatch - 0200Z

WWUS20 KWNS 072042

SEL4

SPC WW 072042

TXZ000-080200-

URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 274

NWS STORM PREDICTION CENTER NORMAN OK

345 PM CDT WED MAY 7 2008

THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF

EAST CENTRAL TEXAS

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 345 PM UNTIL

900 PM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 55 STATUTE

MILES EAST AND WEST OF A LINE FROM 45 MILES SOUTHEAST OF TEMPLE

TEXAS TO 50 MILES NORTH NORTHEAST OF CORSICANA TEXAS. FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU4).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 273...

DISCUSSION...SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG

SURFACE DRYLINE FROM WEST OF TPL TO NEAR DAL. THESE STORMS WILL

THEN TRACK EASTWARD ACROSS THE WATCH AREA DURING THE EVENING.

SUPERCELLS CAPABLE OF TORNADOES...LARGE HAIL...AND DAMAGING WINDS

ARE POSSIBLE.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

500. MEAN STORM MOTION VECTOR 25035.

...HART