Chase 2010 - Day 10 Discussion

[Nick F]

1730z update from the SPC expands the slight risk area further W and SW, so the team may not have to venture far from Witchita, KS - their overnight stay after visiting Greensburg today ... even the Greensburg - Great Bend area of S-central KS maybe be the focal point for initiation with the dry-line triple point moving into this area from SW in the evening. Could be a window for isolated tornadoes too. Will have a look at the charts in a while to see where I would initially target for tomorrow's chase.

- sfc prog for 00z Friday (18z CDT Thurs)

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1227 PM CDT WED MAY 05 2010

VALID 061200Z - 071200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE CNTRL

PLAINS AND MID MS VALLEY...

...SYNOPSIS...

PROGRESSIVE QUASI-ZONAL UPPER FLOW REGIME WILL PERSIST THIS PERIOD.

UPPER TROUGH OVER THE UPPER MS VALLEY WILL MOVE THROUGH THE GREAT

LAKES AND NERN U.S. THEN OFF THE ATLANTIC SEABOARD THURSDAY NIGHT.

UPPER TROUGH OVER THE PACIFIC NW WILL REACH THE NRN AND CNTRL PLAINS

THURSDAY EVENING AND THE MID-UPPER MS VALLEY LATE THURSDAY NIGHT. A

COLD FRONT WILL ACCOMPANY LEAD UPPER TROUGH EWD THROUGH THE GREAT

LAKES...OH VALLEY AND NERN STATES. TRAILING PORTION OF THIS BOUNDARY

WILL DEVELOP NWD INTO KS AS A WARM FRONT AS LEE CYCLOGENESIS

COMMENCES ACROSS WRN KS THURSDAY AFTERNOON. DRYLINE WILL EXTEND FROM

THE SURFACE LOW IN SWRN KS THROUGH WRN OK AND W-CNTRL TX. SHORTWAVE

TROUGH EJECTING INTO THE CNTRL PLAINS WILL PROVIDE IMPETUS FOR A

POLAR FRONT TO ACCELERATE SEWD THROUGH KS OVERNIGHT.

...CNTRL PLAINS THROUGH MID MS VALLEY AREAS...

LOW-LEVEL JET WILL STRENGTHEN ACROSS TX AND OK THURSDAY IN RESPONSE

TO DEVELOPING LEE CYCLONE OVER THE CNTRL HIGH PLAINS. THIS FEATURE

WILL ADVECT MODIFIED CP AIR NWD THROUGH WARM SECTOR WITH DEWPOINTS

IN THE 50S EXPECTED...EXCEPT POSSIBLY LOW 60S IN VICINITY OF

RETREATING WARM FRONT. STRENGTHENING WSWLY FLOW IN THE 3-6 KM LAYER

ACCOMPANYING THE UPPER TROUGH WILL ADVECT AN EML NEWD ABOVE MOIST

AXIS. THESE PROCESSES AND DIABATIC WARMING WILL RESULT IN A

RESERVOIR OF MODERATE INSTABILITY. THE EML WILL BE WARM ENOUGH TO

CAP THE ATMOSPHERE MOST OF THE DAY. INITIAL STORMS MAY DEVELOP

WITHIN AREA OF FOCUSED MESOSCALE FORCING NEAR TRIPLE POINT EAST OF

THE SURFACE LOW ACROSS S-CNTRL KS DURING THE LATE AFTERNOON OR EARLY

EVENING. EFFECTIVE VERTICAL SHEAR NEAR 50 KT WILL SUPPORT SUPERCELLS

WITH VERY LARGE HAIL THE INITIAL PRIMARY THREAT. HODOGRAPH SIZE IN

THE 0-1 KM LAYER WILL INCREASE SUBSTANTIALLY AS THE LOW LEVEL JET

STRENGTHENS DURING THE EVENING RESULTING IN A SMALL WINDOW FOR

ISOLATED TORNADOES BEFORE THE BOUNDARY LAYER DECOUPLES.

HOWEVER...LARGER THAN OPTIMAL BOUNDARY LAYER TEMPERATURE-DEWPOINTS

SPREADS COULD SERVE AS A LIMITING FACTOR FOR A MORE ROBUST TORNADO

THREAT. STORMS WILL LIKELY EXPAND NEWD TOWARD THE MS VALLEY DURING

THE EVENING WITHIN ZONE OF STRENGTHENING ISENTROPIC LIFT ALONG AND

NORTH OF WARM FRONT AS WELL AS ALONG SEWD ADVANCING COLD FRONT WITH

A CONTINUED THREAT FOR ISOLATED LARGE HAIL AND DAMAGING WIND.

...NERN STATES THROUGH MID ATLANTIC...

AN AXIS OF 50S DEWPOINTS WILL ADVECT NWD THROUGH PRE-FRONTAL WARM

SECTOR ACROSS THE MID-ATLANTIC AND NERN STATES.

HOWEVER...PRE-FRONTAL CLOUDS AND ONGOING CONVECTION MAY LIMIT THE

POTENTIAL FOR MORE ROBUST BOUNDARY LAYER DESTABILIZATION BEFORE

FRONTAL PASSAGE. CONVECTION WILL LIKELY REDEVELOP ALONG AND AHEAD OF

THE COLD FRONT OR OUTFLOW BOUNDARIES DURING THE MORNING. STRONG

UNIDIRECTIONAL SHEAR ACCOMPANYING THE SHORTWAVE TROUGH WILL BE

SUPPORTIVE OF ORGANIZED STORMS WITH A THREAT FOR MAINLY ISOLATED

WIND DAMAGE. AT THIS TIME IT APPEARS A RELATIVELY SMALL WINDOW WILL

EXIST TO DESTABILIZE THE ATMOSPHERE PRIOR TO ARRIVAL OF THE

FRONT...AND THIS COULD SERVE AS A LIMING FACTOR. HOWEVER...A SLIGHT

RISK MIGHT BE NEEDED IN DAY 1 OUTLOOKS IF IT BEGINS TO APPEAR THE

ATMOSPHERE WILL DESTABILIZE MORE THAN CURRENTLY ANTICIPATED.

..DIAL.. 05/05/2010

[Tom Lynch]

1730z update from the SPC expands the slight risk area further W and SW, so the team may not have to venture far from Witchita, KS - their overnight stay after visiting Greensburg today ... even the Greensburg - Great Bend area of S-central KS maybe be the focal point for initiation with the dry-line triple point moving into this area from SW in the evening. Could be a window for isolated tornadoes too. Will have a look at the charts in a while to see where I would initially target for tomorrow's chase.

Thanks Nick

I have passed that info onto Paul.

Tom

[Nick F]

Looking at the 12z WRF/NAM model this evening, provisional target area for me would be Pratt, KS. This area sees overlap of highest CAPE and favourable wind fields with good backing of winds towards the surface as cyclone moves in from the SW with warm front/dryline triple point nearing area by 00z Friday (18z CDT),

... also LLJ should crank up from the south just before dark and we have a strong upper level westerly jet aloft across Kansas, combine this with SE/E sfc winds will provide favourable hodographs for rotating storms and tornado potential across this area of S-central KS for a time in the early evening.

12z GFS is further east with the best moisture/faster with ejecting the low and triple point NE ... so this close there are some differences in modelling, so a change in target tomorrow maybe needed with this dynamic set-up...

[Paul Sherman]

Going to wait for the Mornings Models before pulling the Trigger on a Chase Target. But being situated in Wichita gives us great road options in all directions.

I currently am dubious that Mid 60's Dews are going to make it in time for this event, but with a Stationery Warm Front and a Trailing Dryline out west of here then if we can just get the odd Supercell to initiate around 6pm then it could be game on for a short window of about 90 mins or so before Sunset for an Isolated Tornado. The biggest threat tomorrow is going to be Very Large Hail with 3,400jkg of Cape to play with.

Paul S & Team

[dogs32]

good luck guys..hope you get some nice pics

[nsrobins]

A tricky one to call for today but I think there may well be a window of opportunity for structure and possible brief spin-ups between 00Z and 02Z. The stout cap rapidly erodes from west to east and there's just enough moisture ahead of the DL to initiate convection from 23Z, and although the NAM composite doesn't want to know, I think the juxtaposition of warm boundary and DL will be enough to get the parcels to pop. The rotation will be provided by some directional shear in C KS as any cell moves west to east.

Taking timing, cap, cape and DL position (broad bulge) into account, I would be wandering towards Ness City / Dighton by the late afternoon.

[Nick F]

Going to be a day of luck I think, set-up is quite restrictive in that the best available surface moisture doesn't really arrive until evening from the SE behind approaching warm sector over Sern Kansas which looks to remain capped, with elevated storms likely to develop and evolve into an MCS north of the warm front in the evening, especially after dark to the north of the E-W I-70 through Kansas. However, there maybe a small daylight window of opportunity for more discrete surface based supercell(s) to develop invof triple point moving in from the WSW across S-central Kansas in the evening:

... so I would probably target somewhere in the Great Bend - Kinsley area. However, whether the models have got an exact grip on moisture return and track of low centre/triple point will mean this will be a dynamic situation, with the 3 hourly RUC updates the best option to see where storms are most likely to intiate and where the best wind fields will be. Ideally need to be on the NE side of the approaching low from WSW, to get the best wind fields for tornadic potential.

[Tom Lynch]

Going to be a day of luck I think, set-up is quite restrictive in that the best available surface moisture doesn't really arrive until evening from the SE behind approaching warm sector over Sern Kansas which looks to remain capped, with elevated storms likely to develop and evolve into an MCS north of the warm front in the evening, especially after dark to the northof the warm front in the evening, especially after dark, to the north of the E-W I-70 through Kansas. However, there maybe a small daylight window of opportunity for more discrete surface based supercell(s) to develop invof triple point moving in from the WSW across S-central Kansas in the evening:

... so I would probably target somewhere in the Great Bend - Kinsley area. However, whether the models have got an exact grip on moisture return and track of low centre/triple point will mean this will be a dynamic situation, with the 3 hourly RUC updates the best option to see where storms are most likely to intiate and where the best wind fields will be. Ideally need to be on the NE side of the approaching low from WSW, to get the best wind fields for tornadic potential.

Thanks Nick

I agree with you on all counts here and as this may be our last chase day of the tour , we need to ensure that we get the best of what is offered today.

Tom

[Paul Sherman]

Today still not giving any clues on the Models so we are going to head West from our Starting location and position ourselves between the Triple Point and what the Models are showing where they think Initiation will start namely NE Of the Low Pressure. Obviously if Storms dont fire further to the South and West then we will head east of the devloping MCS & Let the Storms over-run our overnight position and try to get some Lightning Photography.

Then it is a journey tomorrow down I-35 Towards the Dallas Area for the changeover day, I really hope we can squeeze one last day of Chasing in for Tour 1 before this tour comes to an end.

Paul S

[Gorky]

There are some promises of some decent chasing if you are to believe the models, up towards NW KS, SW NE. Will be a late show again, but storm motions to the east at a reasonable pace in reasonable terrain could lead to some good lightning late on. The WRF 4km run shows convection supercellular in nature forming with daylight hours to spare, but the NAM and RUC both keep convection away until pretty much dusk. Given that it's the last chase day and it's just a travel day tomorrow, I'd go for a late nighter and follow these storms till you can't chase no more I've not had a deep look, but if I had to pull a chase location out of thin air right now, I'd say somewhere in the region of Phillipsburg, KS...

Good luck all

[dogs32]

there going live now..

Radio check is fine Tom

looks like the team are heading for some discreet cells that might be building in the West and posistioning them selves for later

Edited May 6, 2010 by dogs32

[Nick F]

Bit of fair weather cumulus appearing in the livestream now, as temps head into the high 70F. Dew points still lagging though in the low-mid 50F so quite a spread still. Cumulus fields showing to their north now on vis. satellite:

[MAF]

some nice looking scenery there guys. whats the current conditions? (other than the obvious sunny sky) :lol:

[NL]

Tornado probabilities increased to 5% further east Kansas/Missouri.

ecast Discussion SPC AC 062000

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0300 PM CDT THU MAY 06 2010

VALID 062000Z - 071200Z

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

RIVER VALLEY...

...CENTRAL PLAINS TO MO RIVER VALLEY...

RELATIVELY FEW CHANGES TO PRIOR FORECASTING REASONING/PROBABILITIES.

AS A SUPPLEMENT TO PRIOR DISCUSSION...ASIDE FROM INITIAL

UPSLOPE-AIDED DEVELOPMENT PERHAPS ACROSS NORTHEAST CO/SOUTHWEST

NEB/NORTHWEST KS VICINITY...VARIOUS MESOSCALE NUMERICAL GUIDANCE

INCLUDING THE WRF-NMM AND WRF-HRRR IMPLY THE POSSIBILITY OF TSTM

DEVELOPMENT NEAR THE NORTHWARD RETREATING WARM FRONT ACROSS EASTERN

KS/NEAR I-70 TOWARD/JUST AFTER SUNSET. HAVE INTRODUCED A

NEAR-FRONTAL 5% TORNADO RISK...BUT OTHERWISE SEVERE HAIL/DAMAGING

WINDS WILL BE THE PRIMARY CONCERNS WITH UPSCALE DEVELOPMENT PROBABLE

LATER TONIGHT.

[Tom Lynch]

some nice looking scenery there guys. whats the current conditions? (other than the obvious sunny sky) :lol:

##

Sorry for the delay in replying.

Temps 80s or the about winds south east dewpoints 55f at the last measure. It is just a waiting game. We will just sit and waitn until something crops up

We check more accurate info in a mo.

Tom

[MAF]

##

Sorry for the delay in replying.

Temps 80s or the about winds south east dewpoints 55f at the last measure. It is just a waiting game. We will just sit and waitn until something crops up

We check more accurate info in a mo.

Tom

no probs Tom :lol:

from the look of it then its a glorious day out there. lets hope the waiting is not too long

[Nick F]

18z RUC shows convection breaking just north of I-70 over north central KS, then expanding over Ern KS towards Emporia and Topeka.

Though fear not team, you are under/near a large cumulus field which is thicker towards I-70 to the north around Russell which could break the cap later:

Some good wind fields by 18z over you area, if anything pops looking at the 0-3km SR Helicity charts:

[Tom Lynch]

some nice looking scenery there guys. whats the current conditions? (other than the obvious sunny sky) :lol:

Not 80s, just feels like it because I am sat in the car with the doors closed. Getting bitten by some of Gods little creatures.

Time: 3:15 PM CDT (20:15 UTC) Heat Index: 79.7 F

Pressure: 29.64 in Hg Visibility: 10 Statute Miles

Temperature: 78.8 F Wind from: South (190 deg)

Dewpoint: 57.2 F Wind Speed: 13.8 mph (12 kts)

Relative Humidity: 47.6% Gusting To: 25.3 mph (22 kts)

Clouds: Sky Clear

That any better?

Tom

[MAF]

Not 80s, just feels like it because I am sat in the car with the doors closed. Getting bitten by some of Gods little creatures.

Time: 3:15 PM CDT (20:15 UTC) Heat Index: 79.7 F

Pressure: 29.64 in Hg Visibility: 10 Statute Miles

Temperature: 78.8 F Wind from: South (190 deg)

Dewpoint: 57.2 F Wind Speed: 13.8 mph (12 kts)

Relative Humidity: 47.6% Gusting To: 25.3 mph (22 kts)

Clouds: Sky Clear

That any better?

Tom

thanks.

27°C is a lot better than the 15°C i got here today

as for God's creatures. get some anti-histamine cream

[NL]

MD for Central/Eastern Kansas.

345

ACUS11 KWNS 062046

SWOMCD

SPC MCD 062045

KSZ000-062245-

MESOSCALE DISCUSSION 0487

NWS STORM PREDICTION CENTER NORMAN OK

0345 PM CDT THU MAY 06 2010

AREAS AFFECTED...PARTS OF CNTRL/ERN KS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 062045Z - 062245Z

TRENDS ARE BEING MONITORED FOR AN INCREASING SEVERE THREAT AND THE

POSSIBILITY OF A WW.

CONSIDERABLE UNCERTAINTY STILL EXISTS CONCERNING THE POTENTIAL FOR

CONVECTIVE DEVELOPMENT ACROSS THE CENTRAL PLAINS PRIOR TO 07/00Z.

SURFACE DEW POINTS CONTINUE TO INCREASE SOUTH OF ROUGHLY EAST-WEST

WARM FRONT ACROSS SOUTHERN KANSAS...WHICH APPEARS TO BE SLOWLY

ADVANCING NORTHWARD TO THE EAST OF A DEEP SURFACE LOW. BUT THIS IS

NOT ENOUGH TO OVERCOME INHIBITION ASSOCIATED WITH WARM LOWER/MID

TROPOSPHERIC TEMPERATURES ACROSS THE REGION.

THERE ARE INDICATIONS AMONG THE MODELS THAT A LOW AMPLITUDE WAVE

WITHIN BROADLY CYCLONIC MID-LEVEL FLOW WILL SHIFT EAST OF THE

CENTRAL HIGH PLAINS LATE THIS AFTERNOON...ACCOMPANIED BY A

STRENGTHENING SOUTHERLY 850 MB JET ACROSS CENTRAL/EASTERN OKLAHOMA

AND KANSAS. IT IS POSSIBLE THIS COULD PROVIDE ENOUGH FORCING FOR

UPWARD VERTICAL MOTION...COUPLED WITH MORE RAPID AND FOCUSED

DESTABILIZATION NEAR AND NORTH OF THE WARM FRONT...TO SUPPORT

INITIATION OF AT LEAST ISOLATED STORMS PRIOR TO 00Z.

THIS SEEMS MOST PROBABLE IN AN AREA BOUNDED BY HUTCHINSON/SALINA/

MANHATTAN/EMPORIA...WHERE DEEP LAYER SHEAR IS ALREADY SUPPORTIVE OF

SUPERCELLS. AS CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS CONTINUE TO

ENLARGE...IN THE PRESENCE OF MIXED LAYER/MOST UNSTABLE CAPE

INCREASING TOWARD 2000 J/KG...CONDITIONS WILL BE FAVORABLE FOR

SUPERCELLS.

..KERR.. 05/06/2010

Edited May 6, 2010 by NL

[Nick F]

Team in a good position still, just a waiting game ...

[nsrobins]

I think you're in a pretty good position there, Paul. I thought earlier that Ness City would be Ok and that stands. The cap will erode west to east ahead of the DL bulge and just north of the warm frontal boundary by 00Z. Any cell popping through the lid and shunting east north of Wichita will move into a more favourable environment for rotation and as SPC quite rightly say supercells are likley. You're obs confirm 53 ish dps and these will rise by a few pints by 23Z.

Watch the skies!

NB: BBC exit poll shows a hung parliament with no overall majority (I am at an election party with one eye on the results and the other on the conditions in Kansas!)

[MAF]

whilst you guys are in wal-mart could you get some shopping for me

[John Hanrahan]

whilst you guys are in wal-mart could you get some shopping for me :lol:

And they didnt have Heineken

Just the usual 3.2 % stuff

[MAF]

And they didnt have Heineken

Just the usual 3.2 % stuff

foget that! go with the local stuff... JD and coke with lots of ice

Edited May 6, 2010 by MAF