Chase 2010 - Day 3 Discussion

[Paul Sherman]

Thursday April 29th should be Tour 1's first shot at Chasing. Current thinking is to head out around 9am and head North on I-35 Through OK City and cross the Kansas Border, after moving through Wichita we are looking to set up in an area from Topeka towards Hiawatha and maybe even Falls City (Nebraska) This should take us around 5 1/2 hours to get into the Target Area as the Models stand atm. Of course this is subject to change if the Models shift massively overnight.

Not an easy chase tomorrow as we have the Problem of the Cold Front racing into any Supercell that can form early and turning these Storms into a SE Moving Linear Squall Line. So getting onto the Storm early is a must for Tornadogenesis before it all lines out, I cant see the Cap breaking further South until Dusk or even 10-11pm. We also have to keep 1 eye on Fridays Risk and may even have to cut at least 1/3 of the Mileage out Thursday Night to have an even chance of the Target area for Friday. Hopefully we can get far enough in front of the CF And let it run over the Hotel in the early hours.

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DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1230 PM CDT WED APR 28 2010

VALID 291200Z - 301200Z

...THERE IS A SLGT RISK OF SVR TSTMS THU ACROSS THE CENTRAL PLAINS

INTO THE UPPER MISSISSIPPI VALLEY...

...SYNOPSIS...

MODELS INDICATE THAT AMPLIFICATION WITHIN THE STRONG POLAR JET

EXTENDING ACROSS THE LENGTH OF THE PACIFIC THROUGH THE WESTERN U.S.

WILL CONTINUE DURING THIS FORECAST PERIOD. THIS APPEARS LIKELY TO

BE MOST PRONOUNCED WITHIN AN UPPER RIDGE BUILDING WEST OF THE

PACIFIC COAST. THE LARGE-SCALE DOWNSTREAM TROUGH IS EXPECTED TO BE

SLOW TO DEVELOP EASTWARD OUT OF THE WESTERN STATES ...WITH A SERIES

OF STRONG EMBEDDED SHORT WAVE IMPULSES CONTINUING TO DIG THROUGH ITS

WESTERN/SOUTHERN PERIPHERY...ALONG THE PACIFIC COAST INTO THE

SOUTHERN U.S./NORTHERN MEXICAN PLATEAU REGION.

HOWEVER...A COUPLE OF PERTURBATIONS WILL LIFT OUT AND EAST OF THE

BASE OF THE TROUGH...CONTRIBUTING TO STRENGTHENING CYCLONIC...

INCREASINGLY MERIDIONAL...FLOW THROUGH THE PLAINS AND UPPER

MISSISSIPPI VALLEY REGION. AS THIS OCCURS...A CLOSED LOW EMBEDDED

WITHIN THE LARGER-SCALE TROUGH IS PROGGED TO SHIFT SLOWLY EASTWARD

THROUGH THE NORTHERN PLAINS...ACCOMPANIED BY THE PRIMARY CYCLONE

EMBEDDED WITHIN A DEEP SURFACE TROUGH ENCOMPASSING MUCH OF THE

PLAINS. A BROAD STRONG SOUTHERLY LOW-LEVEL JET WILL PERSIST FROM

THE SOUTHERN PLAINS THROUGH THE UPPER MISSISSIPPI VALLEY...WITH

SOUTHWARD DEVELOPMENT INTO THE WESTERN GULF OF MEXICO

PROGGED...WHICH SHOULD CONTRIBUTE TO THE BEGINNING OF A MORE RAPID

AND SUBSTANTIVE RETURN FLOW OF MOISTURE TO THE WARM SECTOR OF THE

PLAINS CYCLONE. LATEST SREF GUIDANCE AND OBSERVATIONAL DATA SUGGEST

THAT INLAND RETURN OF 65-70F+ SURFACE DEW POINTS MAY NOT OCCUR UNTIL

VERY LATE THURSDAY INTO FRIDAY...BUT AT LEAST A NARROW AXIS OF LOWER

60S DEW POINTS IS EXPECTED TO CONTRIBUTE TO DESTABILIZATION THURSDAY

NEAR A SOUTHEASTWARD ADVANCING COLD FRONT ACROSS THE UPPER

MISSISSIPPI VALLEY INTO THE MID MISSOURI VALLEY...AND THE DRY LINE

ACROSS THE CENTRAL/SOUTHERN PLAINS.

GIVEN STILL SOMEWHAT MODEST LOW-LEVEL MOISTENING...A VERY WARM

ELEVATED MIXED LAYER ADVECTING NORTHEASTWARD OFF THE ROCKIES/

PLATEAU REGION MAY INHIBIT CONVECTIVE DEVELOPMENT THROUGH MUCH OF

THE PERIOD ACROSS THE SOUTHERN PLAINS. BUT...THE EVOLVING PATTERN

IS EXPECTED TO BECOME SUPPORTIVE OF CONSIDERABLE THUNDERSTORM

ACTIVITY ACROSS PARTS OF THE CENTRAL PLAINS/MID MISSOURI VALLEY INTO

THE UPPER GREAT LAKES REGION...SOME OF WHICH LIKELY WILL BE SEVERE.

...PLAINS/MISSISSIPPI VALLEY...

IDEA OF PRIOR OUTLOOK LOOKS GENERALLY ON TRACK...BUT CATEGORICAL AND

OUTLOOK LINES HAVE BEEN ADJUSTED TO ACCOUNT FOR MODEL

VARIABILITY...AND A BIT GREATER UNCERTAINTY CONCERNING THE PLACEMENT

OF FEATURES EXPECTED TO SUPPORT STORM INITIATION. SEVERE THREAT HAS

BEEN EXTENDED NORTHWARD ACROSS MINNESOTA/ WISCONSIN...IN CLOSER

PROXIMITY TO THE PRIMARY SURFACE CYCLONE...BUT STORM DEVELOPMENT

REMAINS MOST CERTAIN ALONG FRONTAL ZONE TO THE SOUTH AND

WEST...ACROSS EASTERN NEBRASKA INTO IOWA...AIDED BY FORCING

ASSOCIATED WITH A MID-LEVEL JET STREAK NOSING ACROSS THE REGION

DURING THE LATE AFTERNOON AND EVENING HOURS.

MODERATE INSTABILITY CHARACTERIZED BY CAPE OF 1000-2000 J/KG...

COUPLED 40-50+ KT SOUTHWESTERLY DEEP LAYER MEAN FLOW AND STRONG

SHEAR...WILL BE FAVORABLE FOR THE DEVELOPMENT OF SUPERCELLS

TRANSITIONING TO UPSCALE GROWTH INTO ONE OR MORE QUASI-LINEAR

CONVECTIVE SYSTEMS. GIVEN A MOIST BOUNDARY LAYER...SIZABLE

CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS WILL BE SUPPORTIVE OF TORNADIC

POTENTIAL...IN ADDITION TO LARGE HAIL...IN EARLY ACTIVITY...BEFORE

DAMAGING WINDS BECOME THE MORE PREDOMINANT THREAT DURING THE EVENING

HOURS. FAST STORM MOTIONS MAY ALLOW THE SEVERE THREAT TO DEVELOP

CONSIDERABLY EAST OF THE RELATIVELY NARROW LATE AFTERNOON/EARLY

EVENING INSTABILITY AXIS...BEFORE CONVECTION WEAKENS THURSDAY NIGHT.

ACROSS THE CENTRAL/SOUTH CENTRAL PLAINS...STRONGER INHIBITION/

WEAKER FORCING WILL LIKELY YIELD MORE SPARSE CONVECTIVE COVERAGE

...BUT THE ENVIRONMENT WILL BE FAVORABLE FOR ISOLATED SUPERCELL

DEVELOPMENT. DESPITE RATHER LARGE CLOCKWISE CURVED LOW-LEVEL

HODOGRAPHS...SIZABLE LOW-LEVEL/SUB CLOUD TEMPERATURE/DEW POINT

SPREADS MAY MITIGATE TORNADIC POTENTIAL.

[MAF]

was just reading the SPC forecast Paul and agree that you are probably heading on the right direction. lets hope the probabilities for the area increase eh

[Nick F]

Yes, a good idea to head north into central Kansas where the cap is much more likely to break than further south over N-central OK, where a stouter EML is likely. A look at the WRF CINH prog for 00z Friday (18z CDT) shows the cap almost completely eroded north of Witchita:

Trick will be to get on any discrete cells ahead of the cold front which moves in by midnight CDT across central Kansas, which will tend to turn storms into a linear MCS:

There maybe an opportunity to take advantage of the dry-line moving in from the west before it retreats/overrun by the cold front.

I'd fancy heading north of Wichita, KS up towards Salina, maybe heading over to Hutchinson perhaps.

Long haul for tomorrow to get in position for tomorrow's risk, with best area that is both in chaseable terrain and has best severe kinematics being in eastern Arkansas.

[SpringStorms]

I can't believe you're already going to be in my "neck of the woods" I hope the severe threat doesn't move North to Omaha. I grew up in FC and worked for 15 yrs in Hiawatha KS. I remember leaving work often for a tornado threat.

I live in Omaha now, which is hopefully North of this severe weather threat. I prefer to come here and read of your successes in say...Texas or Oklahoma.

I didn't agree that this was going to be a bad year for weather...the South East is just having weather they usually get in Feb. I wonder if that moves the threat into even later in the year???

Welcome to the Storm chase teams to the USA.

Good hunting...as long as it's well South of my back yard! Lol

I wish everyone at least an F3...same as above!

Karen

Omaha Nebraska

[dogs32]

good luck everyone...wishing you all a lovely Tornado across the road in front of you at safe distance....plenty of pics and vids.. :blush:

[Cloud]

The drive from Dallas to Topeka is massive and I would be on the road by 7am! Maybe though you drive faster than me!

Good luck with your chasing tour.

[Paul]

Hi Nzstorm, they're in oklahoma currently, so not such a big drive

[Guest North Sea Snow Convection]

I can't believe you're already going to be in my "neck of the woods" I hope the severe threat doesn't move North to Omaha. I grew up in FC and worked for 15 yrs in Hiawatha KS. I remember leaving work often for a tornado threat.

I live in Omaha now, which is hopefully North of this severe weather threat. I prefer to come here and read of your successes in say...Texas or Oklahoma.

I didn't agree that this was going to be a bad year for weather...the South East is just having weather they usually get in Feb. I wonder if that moves the threat into even later in the year???

Welcome to the Storm chase teams to the USA.

Good hunting...as long as it's well South of my back yard! Lol

I wish everyone at least an F3...same as above!

Karen

Omaha Nebraska

Hi Karen

Yes, safe watching from a long distance must be infinitely preferable for you!

Storm chase groups are vital in these set-ups in terms of being on the scene and helping give advice and warnings for these storms. And in the event of trouble they can provide a lot of help to people in storm damage areas. The Yazoo tornado event last weekend is one such case in point with the storm chasers on the scene there - in a part of the country where terrain is not easy with a lot of trees. Which can put their own safety at risk too.

[nsrobins]

Paul and team

If you find it useful I'll try to post my own thoughts every lunchtime on the day's prospects so you have them to add to your breakfast briefing. Please feel free to ignore everything I say though

06 NAM

This is one of those days when you have to gamble on the cap. Yes by all means go North into central KS where CIN decays early and you're likely to see something, but what you'll end up with could be just soggy mush. I might be more tempted to sit on the OK/KS border (with Friday's trip in mind). Stout CIN of > -400 around 21Z looks like it might be quickly eroded in response to a pulse in an area between Kiowa and Medicine Lodge on the 281. Initiation from 22Z with adequate moisture should put discrete cells ahead of the could front and move these into what looks like up to 400 SRH with shear increasing towards 00Z.

The trip east into AR won't seem as daunting from here and who knows, the gamble might work.

[kold weather]

A tough call, the cap is indeed more stout further south but the profiles are pretty explosive down there...but I tihkn your right not to really bother down there as the cap probably won't break right until the late eveing hours and I'd imagine convection further north will kick off earlier then that.

As the others have said, the biggest problem further north is there will likely not be a huge window for tornadic develop until it all becomes a linear windy Squall line and I wouldn't totally rule out the development of a derecho as the front catches up.

Still I'm expecting this to be upgraded to a moderate risk, conditions look good for some tornadoes, its just where these happen thats the key of course!

[Gorky]

I'd probably start around Ellsworth if I was chasing today. Pretty central, and it appears most models show something popping here. I'd keep a very close eye on the spc mesoanalysis page though and see if trends are pointing towards something forming further south. It's much easier to be north of your target and drop south than play catch up!

Teh NAM has slowed things down from what I was looking at yesterday, so tomorrows threat may be west enough to be in chasable terrain down south. Definately a day where you'll need to be reactive to the models!

[Nick F]

Yes, I'd target that sort of area too Nathan, Hutchinson up to Ellsworth ... I think Topeka or Hiawatha would be too far NE/E and would not benefit from the dry-line. Still waiting for the 12z RUC, but the 09z RUC for 21z (3pm CDT) suggests moisture/CAPE tending to pool over this area just ahead of a dry-line bulge moving in from the west:

Also winds look to back nicely as the low and dry-line approaches in from the west in this area, increasing tornado potential.

This area most likely to see a discrete supercell to fire before the cold front arrives.

[Paul Sherman]

Thanks for thoughts guys it is appreciated! 7am over here so just pouring over the new models myself and agree now that further S & W From NE Kansas looks do-able. Also as Nathan says the storm motions should move them towards us and being North of them is always a good thing (Remember the Greensburg day and the LP Supercell we cut down in 40 mins etc) We will also be keeping an eye out for Tomorrow's risk on the Models as they are bigging Friday up big time out here for a Tornado Outbreak.

Will still be on the road by 9am though as this gives us a nice leisurely drive and a few pit stops for Gas and Lunch etc

Regards

Paul S

[Gorky]

The WRF models show the following at 6pm US time . Not much interesting south of Nebraska... though convection is trying to form in Kansas...

By midnight US time, convection is properly firing further south, but it's still showing nothing for OK.

If you are further south, it's gonna be a late night I guess, which might not be ideal with a long trek tomorrow! Still This model seems to be indicating that things will stay quasilinear and not full blown squall line through kansas so there could be some good chasing to have. It just seems to take until dusk for the Kansas convection to finally root...

[John Hanrahan]

Todays briefing here....

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

[dogs32]

just seen the video of pAT*...SORRY this spanish keyboard is crap/....lol at video.....histerics.. burst out laughing/..

will try to watch tonihjt in nhotel lobby...

good luck guys...cying cant be there.....moderate risk here with sangria..

go get them stay safe..mates

excuse my spelling..keyboard is spanish and rubbisdg

[Andy Bown]

Will still be on the road by 9am though as this gives us a nice leisurely drive and a few pit stops for Gas and Lunch etc

One of which is happening as I watch the live stream for the first time this year LOL LOL!

[Cookie]

Todays briefing here....

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

I try to watch but it keeps crashing on that advert

[Nick F]

Great clarity on the live feed. Not a cloud in the sky, so will be great seeing the first cumulus bubble up and then hopefully see a supercell explode with clear skies around it. Though could be a late show if the latest SPC update is anything to go by.

[nsrobins]

RUC 15Z

I still want to be on the far south of the updated Slight risk area for the reasons I stated earlier, as I think the best window of opportunity for tornadic sups will exist with any tail ender that develops on the lesser of the two DL bulges, as the cap erodes around the 22Z mark.

I may have to hang on and watch things develop further North but sitting patiently around Harper/Medicine Lodge may deliver an hour of high-end action as the evening develops.

May be wrong - and been wrong before of course!

Great feed by the way and it looks as hot as the obs say it is.

[dogs32]

great live stream in Majorca..perfect clear picture...well done

lots of drop out's but I THINK thats becasue Im in a resturant with low band frequency.....but the picture is superb!!

[kold weather]

Great clarity on the live feed. Not a cloud in the sky, so will be great seeing the first cumulus bubble up and then hopefully see a supercell explode with clear skies around it. Though could be a late show if the latest SPC update is anything to go by.

Yep you can see exactly what is going on in the sky at the moment with the live feed, its superb. It'll be interesting to see when things finally go up on the live stream thats for sure. I'm thinking today looks like a classic eveing set-up where Paul and the team are heading, further south and I think as the models are showing, we aren't going to get anything really before sunset.

[Nick F]

A look at the 15z RUC shows a nice bullsseye of high CAPE around and just west of Salina, where the team are currently heading, Td (dew point) chart shows moisture pooling just ahead of of a dry-line bulge to the west (dry air shown by black) creating the large CAPE values:

some good 0-1 and 0-3km SR Helicity values in this area too, which will enhance chance of rotating storms and potential for a tornado:

Limiting factor will be the cap in this area, though signs of it eroding at 6pm, not keen to break out precip until 9pm and to the north:

12z WRF showing some convective ppn though developing by 6pm, by 9pm large upscale of ppn to the north with arrival of cold front:

[Aunt Sally]

Hi,

I am watching the live streaming and the picture and streaming is brilliant. The day looks great and I'll be able to see when the storm starts to bubble up.

I enjoyed the 'meet the team' video - Tom does look like Brucie

Tammy

[Roger J Smith]

My mid-day update continues to feature explosive potential 01-03z in nw OK and s/c KS. Further north also looks good but would watch for a break induced by wave formation in e/c Colorado so that eventual development likely to consist of one line of severe storms in e NE and n/c KS, and another from about Liberal KS sw into TX panhandle, racing northeast. This sets up two different storm chase scenarios and it seems like between the NW team and NSR, these two are both covered.

In the southern case explosive potential is being confirmed by unusually strong westerly surface winds across all of NM and extensive cloud formation along developing cold front from north of Pueblo CO into ne NM. Although dry line is likely to become focus of major severe outbreak later, cold front pushing from behind will be the trigger. Noting also 110 kt winds in base of trough w Arizona at 12z. Low sfc pressure readings in CO low another signal for strong severe activity to the southeast of this feature. Note that the activity further north is more dependent on low in SD and that there is likely to be a wave cancellation gap in some part of central KS at least for the daylight portion of this event.

So anyway good luck to both NW team and NSR, it's the usual balancing act between timing certainty and intensity potential. But I think the bullseye for daylight severe conditions will be near Alva OK northeast to Kiowa on KS-OK border in the south, and between Marysville and Clay Center KS in the north (possibly as far northeast as Falls City NE).

Since I like the southern theatre potential more in this case, the intensity forecast is for there, I'm hoping this will verify before sunset. Possible F3 tornado, supercells to 55k ft, wind gusts to 90 mph and 2-3 inch hail. The northern batch may not be this severe but remnants of this southern activity will merge around 04z in e/c KS and so it could be a violent evening across much of KS (and n OK). Expect rapid development around Canadian TX to Woodward OK around 00z-01z (that being 7-8 pm CDT). Max intensity of this system is unfortunately scheduled for about 03-04z which would be 10-11 pm CDT. At that time the most severe storms would likely be near Medicine Lodge to Hutchinson KS.