Model Watch For Tour 2

[Gorky]

Looking at the models at the moment and the GFS is a bit more promising with a potential decent chase day or two Wednesday onwards. Still imagine it's going to be a trip to Yellowstone for a couple of days to start my trip off though

Sat in Toronto Airport at the moment awaiting my connection to Denver and then the chase begins tomorrow!

[Ross B]

Good luck Nathan! Will more than likely see you out there again this year

[DubWeatherAddict]

Is there gonna be a "Model Watch For Tour 3 " thread soon????? .........I nagging for some model runs ! :

[Nick F]

Looking increasingly hopeful with this evening's model output that severe storms will return to the southern Plains/southern High Plains mid-week onwards, from what looks like a quiet few days coming up. A deep upper trough currently just off the Pacific West Coast of the US will make inroads east across the Mountain West early next week, once we get rid of the pesky upper low over eastern US - we should see moisture return across the southern Plains. And we could start to see some dryline magic days appear from Weds onwards into the next weekend across the southern High Plains of TX/OK intitially then the dryline progressing slowly eastwards with each passing day across TX/OK/KS before its retreat west overnight. Hopefully we may see a slower trough across the Mountain West/Rockies which may allow a 're-loading pattern of severe weather days across the Plains.

[Thermohaline Conveyor]

A quiet period on the cards in the next few days across the Plains as a ridge of high pressure extends. ECM00Zand GFS18Z and 00Z multi-model guidance suites are beginning to suggest the possibility of a vortex developing to the W of TX and OK during the middle of this coming week which could increase WAA from the deep S and move E to affect many parts of TX and OK in the form of severe thunderstorms, greatly enhancing the risk of a few tornadoes. This pattern has only recently evolved in the last few runs on GFS and a single run on ECM, so caution advised. Areas of focus initially W TX/W OK and perhaps more widepsread and to the E of these regions for the end of next week extending into more E states too. Otherwise the weekend and the early part of next week looks generally quiet in nature.

Just an update. All guidance now favours this pattern of increased activity from Wednesday onwards now, with the end of this coming week into next weekend looking increasingly active across E TX and E OK. Through Wed/Sun period the dryline undulates nicely across C TX and C OK which is of course the focus for more severe storms firing that have the potential to become tornadic. The risk prior to Wednesday remains very minimal as high pressure remains stubborn with cooler/drier air remaining intact. The risk across TX could be some-what mitigated due to a strong subsidence inversion - so less certainty here - but in proximity of the vortex moving from the W across C/SE OK things look better with more widespread initiation. As for specific kinematic parameters and of course wind-shear/energy levels these will need to be covered in more detailed closer to T+24 mesoscale.

[Gorky]

I'm aiming to be back in the plains for Wednesday Evening. Will be leaving Yellowstone late Monday and staying in Either Cody, if they've cleared the 20ft deep avalanche off the road from the East Entrance, or heading south to Jackson. I'm keeping an eye on a more northern play for Wednesday with upslope flow just east of Denver as that would be easier for me to travel to. 50 dews would be enough for some storms there. However, I have very poor signal here in Yellowstone so cannot really check the models (a minute or 2 per image to load) and this has likely changed by now

Amazing up here.. Had some light snow earlier and the walkways were covered in ice this morning. When I got onto the SPC earlier, I was on the outer edge of a See text 5% hail and wind risk too! The avalanche West of Cody added an extra 200 miles to my journey unfortunately... Just a small detour by American standards!

[Nick F]

For Wednesday and maybe Thursday this week 12z ECM & 18z NAM suggest potential for some upslope storms over the High Plains of Colorado down through OK and TX Panhandles, 12z GFS also from Colorado Plains down further east through KS, wern OK and n-central TX along dry line though moisture return/CAPE looks fairly meagre N of Texas on ECM and NAM and N of TX/W Oklahoma from gfs ... so no real feel yet of where the best severe potential will be yet. Potential for some LP supercell structures perhaps over the High Plains still.

[nsrobins]

In a nutshell, OK Panhandle for Weds evening and W KS for Thursday with an increasing chance of severe storms here.

[Nick F]

Yes, looks like a reversal of fortunes on the cards for the rest of this week, with consecutive days of chase potential over the central and southern Plains.

Starting with today, trough/low in lee of the Rockies Front Range over Ern CO is expected to generate some high-based storms later over Ern Colorado and far west of Kansas, the severe potential somewhat limited by meagre moisture/CAPE values - but dew points even in the high 40s/low 50s can produce half-decent storm over the High Plains. Tornado potential looks rather low, so not too sure about SPC's 2% risk.

Tomorrow, the lee trough looks to deepen its circulation across the High Plains and better moisture return over Wern OK and N/NW TX may see some storms develop late afternoon/evening in this area along the dry-line - though severe potential does look limited again.

Thursday seeing a better potential for severe storms with better moisture return and CAPE across Nern TX, central OK and KS and east of dry line that looks to be roughly from Abilene, TX north through Wichita Falls, TX up to around Greensbug, KS where the triple point is modelled. SPC have put a SLIGHT risk for TX/OK/KS:

THERE IS LITTLE DOUBT THAT STRONG SFC HEATING ACROSS SWRN KS...SWD INTO NWRN

TX WILL REINFORCE A WELL DEFINED DRYLINE THAT SHOULD MIX TO NEAR THE

TX/OK BORDER BY PEAK HEATING. THIS FEATURE WILL SERVE AS A FOCUS

FOR SUPERCELL INITIATION AS TEMPERATURES SOAR THROUGH THE UPPER 80S

TO NEAR 90 ALONG THE WIND SHIFT. JUST EAST-NORTH OF THE DRYLINE

HIGHER RH VALUES AND COOLER READINGS SHOULD PROVE FAVORABLE FOR A

THREAT OF ISOLATED TORNADOES GIVEN THAT STRONG DEEP LAYER SHEAR WILL

BE IN PLACE IF CLOUD BASES CAN LOWER AND ROOT INTO 60+ SFC DEW

POINTS.

Friday again looking good, with perhaps better moisture return/CAPE and more favourable shear ... the dryline perhaps setting-up during peak heating a little further east along or just west of the I-35 corridor. SPC have a Day 4 outlook for TX, OK, KS:

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0331 AM CDT TUE MAY 17 2011

VALID 201200Z - 251200Z

...DISCUSSION...

GFS AND ECMWF AGREE THAT UPPER TROUGHING WILL EVENTUALLY SPREAD INTO

THE PLAINS/MS VALLEY...BUT TIMING DIFFERENCES BEGIN TO APPEAR DURING

THE MEDIUM RANGE PERIOD...AS EARLY AS DAY4. GIVEN THE RELUCTANCE OF

THE TROUGH TO ADVECT EWD...AND SHORT RANGE NAM GUIDANCE MORE IN LINE

WITH ECMWF...IT APPEARS THE GFS MAY BE TOO PROGRESSIVE WITH HEIGHT

FALLS ACROSS THE PLAINS INTO THE MID MS VALLEY DAY4. FOR THIS

REASON WILL INTRODUCE A RISK OF ORGANIZED SEVERE THUNDERSTORMS MORE

IN LINE WITH A DELAYED ECMWF. IT/S LIKELY THAT A MARITIME TROPICAL

BOUNDARY LAYER WILL HAVE RETURNED TO THE SRN PLAINS BY LATE WEEK

WITH AT LEAST MODERATE INSTABILITY IN PLACE PRIOR TO LARGE SCALE

FORCING/INTERACTION. IF TIMING OF UPPER TROUGH IS OPTIMIZED WITH

MINIMAL CONVECTIVE INTERFERENCE THEN A SIGNIFICANT SEVERE EVENT MAY

EVOLVE ACROSS THE ERN PLAINS...POSSIBLY EXTENDING INTO PORTIONS OF

THE MS VALLEY BY SATURDAY DEPENDING ON TROUGH PROGRESSION.

..DARROW.. 05/17/2011

So hopefully Tour 2 will have something to shout about and memorable before they head home at the w/e...