Chase 2010 - Day 21 Discussion

[Paul Sherman]

Monday May 17th Looks like yet another Chase for Team 2! Am expecting another Slight Risk for Storms or Weakish Supercells mainly across parts of Western Texas and New Mexico. Looks like a Front will Straddle these parts and SE Upslope Flow will fire Storms off. Could be a few Surprises in Store as these Set-Ups yield Landspout type Tornadoes.

FAR ERN NM INTO ADJACENT PORTIONS OF W TX...

A FRONT FORECAST TO ARC WWD ACROSS TX AND THEN NWWD ACROSS THE HIGH

PLAINS OF NM/CO DURING THE AFTERNOON...SELY UPSLOPE FLOW JUST TO THE

COOL SIDE OF THE BOUNDARY...AND SOME DESTABILIZATION EXPECTED NEAR

AND S OF THE FRONT SHOULD COMBINE TO SUPPORT STORM DEVELOPMENT

ACROSS WRN AND PARTS OF CENTRAL TX AND NWWD ACROSS THE HIGH PLAINS

INTO CO DURING THE AFTERNOON.

MODEST WLY FLOW AT MID-LEVELS BUT PERSISTENT LOW-LEVEL SELYS WILL

RESULT IN A VEERING WIND PROFILE WITH HEIGHT...WITH SHEAR THUS

SUFFICIENT FOR MULTICELL/WEAK SUPERCELL STORMS.

THEREFORE...SCATTERED STRONGER/LOCALLY SEVERE STORMS WILL LIKELY

DEVELOP...WITH HAIL/WIND POTENTIAL THUS ANTICIPATED.

ADDITIONALLY...AN ISOLATED TORNADO OR TWO WILL BE POSSIBLE WITHIN

SELY FLOW REGIME TO THE COOL SIDE OF THE BOUNDARY OVER THE HIGH

PLAINS. STORMS SHOULD CONTINUE OVERNIGHT AS LOW-LEVEL JET

DEVELOPS...THOUGH SEVERE POTENTIAL SHOULD SLOWLY DIMINISH AS AIRMASS

SLOWLY STABILIZES AFTER DARK.

Paul S

[Nick F]

Looking at 00z WRF/NAM, best overlap of SBCAPE and 0-3km SR Helicity values makes me want to target Big Spring, TX for later today:

Wednesday is shapping up to be a good chase day, with potential for strong tornadoes perhaps across parts of OK, chance that we may see the day going Moderate Risk in further outlooks:

DAY 3 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0229 AM CDT MON MAY 17 2010

VALID 191200Z - 201200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN AND

CNTRL PLAINS...

...SRN AND CNTRL PLAINS...

A NEGATIVELY-TILTED UPPER-LEVEL TROUGH IS FORECAST TO MOVE INTO THE

HIGH PLAINS WEDNESDAY AS A WELL-DEVELOPED LOW-LEVEL JET STRENGTHENS

ACROSS THE SRN AND CNTRL PLAINS. ELEVATED THUNDERSTORMS MAY BE

ONGOING ALONG THE LOW-LEVEL JET AXIS IN THE SRN PLAINS WEDNESDAY

MORNING. IN RESPONSE TO THE LOW-LEVEL JET...MOISTURE SHOULD RETURN

QUICKLY NWD INTO NORTH TX AND OK. THIS SHOULD RESULT IN A BROAD

CORRIDOR OF MODERATE TO STRONG INSTABILITY ACROSS THE SLIGHT RISK

ESPECIALLY IN AREAS WHERE CONVECTION CLEARS DURING THE LATE MORNING.

IN ADDITION...DEEP LAYER SHEAR SHOULD INCREASE DURING THE DAY ACROSS

THE SRN PLAINS AS A MID-LEVEL JET IN THE BASE OF THE UPPER-LEVEL

TROUGH MOVES INTO THE REGION.

ETA-KF FORECAST SOUNDINGS ACROSS OK AND NORTH TX ARE QUITE

IMPRESSIVE WEDNESDAY AFTERNOON SHOWING 40 TO 50 KT OF DEEP LAYER

SHEAR WITH SFC DEWPOINTS IN THE UPPER 60S F AND MLCAPE VALUES AROUND

3000 J/KG. THIS COMBINED WITH STEEP MID-LEVEL LAPSE RATES SHOULD

EASILY SUPPORT SUPERCELLS WITH VERY LARGE HAIL POSSIBLE WITH THE

MORE INTENSE CORES. IN ADDITION...THE NAM AND GFS ARE IN RELATIVELY

GOOD AGREEMENT CONCERNING THE POSITION OF A 35 TO 45 KT JET MAX NEAR

850 MB IN CNTRL OK. THIS JET SHOULD PROVIDE FAVORABLE LOW-LEVEL

SHEAR PROFILES FOR TORNADOES WITH AN ISOLATED STRONG TORNADO THREAT

POSSIBLE FROM THE JET CENTER WWD ACROSS WRN OK WHERE 30 PERCENT AND

SIGNIFICANT SEVERE PROBABILITY CONTOURS HAVE BEEN ADDED. SEVERE

STORMS WILL ALSO BE POSSIBLE IN NW AND WCNTRL TX EARLY WEDNESDAY

EVENING. HOWEVER...THE MODELS SUGGEST THE CAP WILL LIMIT CONVECTIVE

COVERAGE SOUTH OF THE RED RIVER. SEVERE STORMS WILL ALSO BE POSSIBLE

NWWD ACROSS SRN KS INTO FAR ERN CO WHERE THE MODELS FORECAST

MODERATE INSTABILITY AND DEEP LAYER SHEAR.

THE MAIN UNCERTAINTIES CONCERNING THE SEVERE POTENTIAL WEDNESDAY

INVOLVE THE TIMING OF THE UPPER-LEVEL TROUGH. IF THE UPPER-LEVEL

TROUGH ENDS UP BEING SLOWER THAN IS CURRENTLY FORECAST AND THE

DRYLINE IS SETUP FURTHER WEST...THE WRN PARTS OF THE SLIGHT RISK

AREA WOULD BE FAVORED.

[Paul]

Doh, wednesday is changeover day!

[Nick F]

Ah, didn't realise it was as early as Wednesday. Might catch some of the severe risk though late Wednesday, as the risk extends into N-central TX. Even if staying in DFW area.

[chionomaniac]

You may have to hit the ground running with a westwards dash depending upon the times which everyone arrives. Thursday I think could be promising. Could be a good third tour

IN SPITE OF THE POTENTIAL FOR SEVERAL

SEVERE WEATHER EVENTS DURING THE UPCOMING WEEK...PREDICTABILITY

CONCERNING SEVERE WEATHER EXTENT FOR ANY GIVEN DAY REMAINS LOW.

http://www.spc.noaa.gov/products/exper/day4-8/

[nsrobins]

Today is definately worth the effort for upslope rollers and I suspect there'll be some good structure to be found, but it's tommorow that is grabbing my attention. The 21Z 18/5 sounding for Guymon is showing the effects of a SW'ly LLJ cranking up the helicity with shear enough to rotate supercells that move off the DL.

I'd be thinking of getting up to the OK panhandle, with DFW still reachable maybe the following day.

[Andy Bown]

Guys, I've just spent time catching up on the last 3 days worth of reports/pics/vidoes. Those from day 18 are incredible, that storm that someone called 'insane' on the footage was amazing just to watch for a few minutes, let alone actually be there lol!

[Paul Sherman]

Woohoo

I have Clearance to Chase this Risk for Strong Tornadoes on Wednesday!

If any of the Guests for Tour 3 that are arriving on Tuesday see this Message and want to Chase we will be leaving DFW Airport at about 1-2pm CDT! Paul is sending an E-Mail to you as well so hopefully you will get it. If you dont then Ian will be at the Airport to meet and greet you and take you back to the Hotel at Irving (DFW)

Talk about throwing the guys in at the deep end LOL

Paul S

[Nick F]

Be nice if tornadic sups fire within in easy reach, i.e. Witchita Falls area of north texas ... hopefully best dynamics won't shift too much by Weds eve.

[nsrobins]

Be nice if tornadic sups fire within in easy reach, i.e. Witchita Falls area of north texas ... hopefully best dynamics won't shift too much by Weds eve.

Re: Weds 19th

It wouldn't be the first time this season that the models have shunted the maximum instability axis further west as the high-res numbers are crunched, Nick. The NAM 12Z has a very nice DL bulge with the high gradient over Plainview, which alone would take me towards the Paducah area, and EHIs max out in the Paducah/Vernon TX area. My only worry is the initial shortwave pulse generates a complex (NAM composite) around 21Z that may inhibit discrete convection in it's wake, and areas just to the northwest of the above then become more favourable (up towards Shamrock, TX). I might be talking a load of roll clouds, but that's my take on the current NAM.

Whatever happens, it looks reachable from DFW and tornados look probable.

[craig1uk]

Extra day chasing, thank god I booked to go out early, thank you weather gods !!!!!!!!!!!

[Darren Bown]

The team are stopped in Lubbock at the moment for a break after that drive! Seems very clear on the ride up, but they are in the middle of SLGT risk for today.

[Nick F]

Re: Weds 19th

It wouldn't be the first time this season that the models have shunted the maximum instability axis further west as the high-res numbers are crunched, Nick. The NAM 12Z has a very nice DL bulge with the high gradient over Plainview, which alone would take me towards the Paducah area, and EHIs max out in the Paducah/Vernon TX area. My only worry is the initial shortwave pulse generates a complex (NAM composite) around 21Z that may inhibit discrete convection in it's wake, and areas just to the northwest of the above then become more favourable (up towards Shamrock, TX). I might be talking a load of roll clouds, but that's my take on the current NAM.

Whatever happens, it looks reachable from DFW and tornados look probable.

Yes, looking at the 12z WRF/NAM, it does look like initiation could be in the Childress-Witchita Falls area ahead of dry-line bulge and developing cyclone moving east across N TX, GFS a little further NE into SW/W central Oklahoma. Storms would perhaps need to be followed across the Red River into SW/W Oklahoma - where wind shear fields look better for tornado potential.

On to today, very little cap in place on the 12z (06z CDT) radiosonde ascent at Midland, W Texas earlier today.

- so no surprise storms have been kicking off early today with a severe warned MCS between Abilene and Ft Worth and a few storms near Big Spring. Should see further convective development across W Texas where the team are as temps continue to rise and LL moisture increases from the SE. Not much focus for forcing today apart from a weak boundary running east from Abilene, so outflow boundaries from earlier storms and local convergence likely to be the main mechanism, tornado threat looks low with high bases and shear lacking but potential for landspouts as temps rocket, main action will be large hail and gusty winds and some good lightning opps after dark as one or two MCS form and move SE tonight.

[Paul]

While the team are having some lunch, why not meet the tour 2 chasers:

http://www.netweather.tv/index.cgi?action=storm-chase-highlights;sess=

[Darren Bown]

Nice Paul! Seem like a lively bunch

Storms are kicking off over New Mexico atm

[Stuart]

Nice Paul

[Paul]

I can take no credit - it's Tom's work!

[Darren Bown]

OK, nice one Tom

[Stuart]

nice work Tom

[nsrobins]

The RUC delivers the best parameters for supercells not far from where you are now - say Seminole/Andrews area where the best of the rather slack shear profiles exist at 01Z. Slow storm motions with high bases could make for some great photo opportunities.

Edit - just spotted that cell sliding south of Roswell, NM showing signs of turning. If it survives it will enter a richer profile in an hour or so but it's crawling though - so you might have to meet it half way if you decide to intercept.

Edited May 17, 2010 by nsrobins

[davehsug]

To quote Homer, "theres a NEW Mexico now?" Spooky. I sent a bill to someone in New Mexico today

[ian cameron]

sat just west of hobbs NM watching the cells approch us will prob travel north to paralel the storm

[Darren Bown]

Looks like a beast from what we can see!

[Gorky]

Roswell Cell was a beauty.. Took loads of photos. Camera fell and my 10-20 lens is in a few bits now... but still working somehow... ND filter scratched up and a divot taken out of my tripod head Still. lightning is most intense Ive seen for daytime stuff... Just thankful my lens seems salvagable for now as I use it for most everything on the tour!

[Darren Bown]

Gratz guys, been watching relgiously on the live feed tonight, enjoy the rest of the lightning show, I'm off to bed