Days 4 to 7 - Discussion

[Nick F]

Been looking at the models over the last hour or so, really quite tough to choose a target area for tomorrow, most likely area will be SE Kansas, but where exactly, I don't think we will decide until we get up tomorrow morning.

Main axis of high theta-e, CAPE anf Td values appears to be just east of the I-35 SE/E of Wichita at 00z Friday (18z Thurs here):

Sfc progs show the dry line arriving on the western side of warm moist air advecting north at 00z Fri too, and will likely, with help of falling heights, initiate convection provided cap erodes:

Still some uncertainties over whether the cap will break, maybe not until 6-7pm, and also on moisture return over SE Kansas, as the models tend to be too bullish with Tds, though the Low-level jet should strengthen overnight advecting wamer Tds north from GoM ...Tds are beginning to recover as moisture returns from TX, 60F Tds begining to appear over south-central OK, slightly further west this warm moist axis than model progs:

I'm thinking now that we will need only to head a little east or SE from Witchita for tomorrow afternoon's risk, the way the warm moist axis is shifting a little further west atm.

This will be Tour 1's 1st Chase day after 3 days of sunshine!

[Paul Sherman]

New Day 1 Outlook just released from the SPC - Looks like we are ideally positioned in Witchita, SPC Worried about the Cap further South and the problem with the CF Overtaking the Dryline, I am sorely tempted to stay put in the Witchita area or points north towards Nebraska, will see what Nick wants to do tomorrow morning, but looks like High Based Supercells will be easier to come by from around 5pm further North!

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1234 AM CDT THU MAY 01 2008

VALID 011200Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE

CNTRL/SRN PLAINS AND MID MS VALLEY...

...CENTRAL/SOUTHERN PLAINS...MID MS VALLEY...

LATEST MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT WITH LEADING

PORTION OF UPPER SPEED MAX DIGGING SEWD ACROSS THE 4-CORNERS REGION

BEFORE EJECTING NEWD ACROSS THE CNTRL PLAINS DURING THE DAYLIGHT

HOURS. THIS LEAD FEATURE WILL LIKELY DRAW INITIAL SFC LOW NWD INTO

NEB BEFORE OCCLUDING OVER SD...WHILE SECONDARY PRESSURE FALLS SHOULD

RESULT IN ANOTHER SFC CYCLONE AHEAD OF ADVANCING COLD FRONT OVER KS

BY PEAK HEATING.

DESPITE SUSTAINED STRONG LLJ ACROSS THE SRN PLAINS BOUNDARY LAYER

MOISTURE IS ONLY NOW BEGINNING TO RETURN IN EARNEST ACROSS THE WRN

GULF OF MEXICO AND SOUTH TX WHERE MID-UPPER 60S SFC DEW POINTS ARE

NOW OBSERVED. SLOW MOISTURE RETURN WILL PROVE SOMEWHAT PROBLEMATIC

FOR DIURNAL THUNDERSTORM DEVELOPMENT ALONG THE DRYLINE OVER OK...BUT

TO A LESSER DEGREE OVER KS WHERE STRONG FORCING WILL ENSURE DEEP

CONVECTION BY 23Z-01Z TIME FRAME.

LATEST THINKING IS DRYLINE WILL MIX TO A POSITION NEAR I-35 ACROSS

KS/OK AS FLOW ATOP THE BOUNDARY LAYER IS INITIALLY SOMEWHAT VEERED.

HOWEVER...PRESSURE FALLS ACROSS KS SHOULD RESULT IN THIS BOUNDARY

BECOMING A BIT MORE CONVERGENT BY SUNSET. AS TEMPERATURES SOAR INTO

THE 80S VERY STEEP LAPSE RATES WILL DEVELOP WITHIN POST DRYLINE

AIRMASS ULTIMATELY REMOVING INHIBITION FOR THOSE PARCELS RESIDING

NEAR DRYLINE/COLD FRONT. IT APPEARS THUNDERSTORMS WILL INITIALLY

DEVELOP ACROSS KS INTO SERN NEB WITH THIS ACTIVITY EXPERIENCING

UPWARD GROWTH/EXPANSION AS STRONG FORCING SPREADS EAST ACROSS THE

PLAINS LATE IN THE PERIOD. INITIAL STORM MODE SHOULD BE HIGH-BASED

SUPERCELLS...THOUGH STORM MERGERS AND FRONTAL FORCING SHOULD ENHANCE

SQUALL LINE POTENTIAL LATE AS CONVECTION SPREADS INTO THE MS VALLEY.

WHILE DRYLINE DEVELOPMENT INTO NRN OK IS POSSIBLE BEFORE

SUNSET...IT APPEARS GREATEST THREAT FOR CONVECTION ACROSS SRN

PORTIONS OF THE OUTLOOK WILL BE ALONG THE COLD FRONT AS IT SURGES

SOUTHEAST DURING THE OVERNIGHT HOURS.

GIVEN THE RETARDED MOISTURE RETURN THE GREATEST SEVERE THREAT SHOULD

BE LARGE HAIL...ESPECIALLY WITH SUPERCELLS ACROSS KS/NEB INTO SWRN

IA AND WRN MO. AS OVERALL CONVECTIVE MODE EVOLVES INTO A SQUALL

LINE THERE MAY BE AN INCREASED RISK OF DAMAGING WINDS DURING THE

OVERNIGHT HOURS.

[pottyprof]

The current 1 day outlook places the team inside the slight risk now.

Current thinking within the area is a 5% chance of tornadoes

A 30% chance of hail..

and a 15% chance of strong winds

[pottyprof]

Upgrade to moderate...

SPC-Day1 Discussion

ACUS01 KWNS 011256

SWODY1

SPC AC 011254

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0754 AM CDT THU MAY 01 2008

VALID 011300Z - 021200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF ERN KS THIS

EVENING INTO TONIGHT...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLNS INTO WRN

AR...

...SYNOPSIS...

STRONG CO UPR LOW EXPECTED TO EDGE SLOWLY E INTO S CNTRL NEB THIS

PERIOD AS 80+ KT MID LVL JET STREAK NOW CROSSING THE SRN GRT BASIN

AND FOUR CORNERS REGION REDEVELOPS E ACROSS OK/SRN KS. AT LWR

LVLS...EXPECT DEEP SFC LOW NOW OVER S CNTRL NEB TO LIFT NE INTO SE

SD AND WEAKEN BY THIS EVENING AS A NEW CENTER FORMS OVER SW/S CNTRL

KS IN RESPONSE TO APPROACHING JET STREAK. THIS LOW SHOULD...IN

TURN...LIFT NNE TO NEAR OMA BY THE END OF THE PERIOD AS ASSOCIATED

COLD FRONT ACCELERATES E/SE TO A WRN MO/NE OK/CNTRL TX LINE BY

FRIDAY MORNING. THE COLD FRONT WILL OVERTAKE DRYLINE IN CNTRL KS

THIS AFTN...OVER OK TONIGHT...AND OVER NE TX EARLY FRIDAY.

...KS INTO LWR MO VLY...

UNCERTAINTIES REGARDING QUALITY AND TIME OF ARRIVAL OF MOISTURE

RETURN...AND TIMING OF UPR LVL VORT MAXIMA...MAKE THIS A MORE

DIFFICULT FCST THAN USUAL FOR SUCH A POTENT KINEMATIC/DYNAMIC SETUP.

REGARDING THE MOISTURE ISSUE...REGIONAL VWP AND PROFILER DATA SHOW

BROAD SSWLY LLJ IN PLACE ACROSS THE SRN HALF OF THE PLNS/MS VLY.

BUT SATELLITE-DERIVED AND GPS PW DATA SHOW THAT LEADING EDGE OF 1

INCH ISOLINE ATTM HAS ADVANCED NWD ONLY TO A TPL/LFK LINE IN E CNTRL

TX. ASSUMING THIS RATE OF MOISTURE RETURN IS MAINTAINED...1 INCH

PWS SHOULD REACH THE I-40 CORRIDOR IN CNTRL OK BY 21Z...AND W CNTRL

MO BY 09Z FRIDAY. IN CONTRAST...PW FIELD FROM THE 00Z ECMWF SHOWS

THE 1 INCH PW ALREADY INTO SRN OK THIS MORNING...WITH VALUES AOA 1

INCH EXPECTED NWD INTO ERN KS/NW MO AND SW IA BY THIS EVENING.

CONSIDERING THE OVERALL PICTURE...AND THE FACT THAT THE 65F SFC

ISODROSOTHERM IS STILL WELL S IN CNTRL TX...BELIEVE THAT THE RICHEST

SFC MOISTURE LIKELY WILL REMAIN S AND E OF ERN KS AND ADJACENT PARTS

OF SE NEB/NW MO/SW IA THROUGH THE PERIOD. IN ADDITION...MUCH OF THE

REGION MAY REMAIN UNDER SLIGHT NVA THROUGH THE DAY IN WAKE OF LEAD

UPR IMPULSE NOW LIFTING N INTO NEB. BUT GIVEN STRENGTHENING

CONVERGENCE/ASCENT DOWNSTREAM FROM DEVELOPING SFC LOW...SUFFICIENT

MOISTURE LIKELY WILL BE AVAILABLE TO SUPPORT SVR STORM DEVELOPMENT

BY VERY LATE TODAY OR EARLY TONIGHT INVOF COLD FRONT AND/OR DRYLINE

FROM ERN KS E AND NE INTO SE NEB/NW MO AND SW IA...ON W SIDE OF

LOW-LVL MOISTURE RETURN.

THE INITIAL STORMS SHOULD BE SUPERCELLS...A FEW OF WHICH MAY BE

HIGH-BASED. INCREASING FRONTAL UPLIFT AND BACKING UPR FLOW SHOULD

FAVOR STORM MERGERS AND SQLN DEVELOPMENT LATER TONIGHT /EARLY FRIDAY

AS THE CONVECTION CONTINUES E INTO MO. STRENGTH OF LOW- TO

DEEP-LAYER SHEAR AND STEEP MID LVL LAPSE RATES SUGGEST POTENTIAL FOR

LARGE HAIL...HIGH WIND AND PERHAPS A COUPLE TORNADOES.

...SRN PLNS INTO WRN AR...

FARTHER S...BROAD AND STRONG EML CAP WILL KEEP ANY DAYTIME SVR

THREAT MUCH MORE CONDITIONAL ALONG DRY LINE FROM S CNTRL KS INTO OK

AND N TX. NEVERTHELESS...ANY ISOLD STORMS THAT DO FORM LATE THIS

AFTN OR EARLY TONIGHT WILL POSE A THREAT FOR VERY LARGE HAIL AND

TORNADOES. THE DRY LINE...AND ASSOCIATED ISOLD SVR THREAT ...MAY

RETREAT A BIT W ACROSS CNTRL OK THIS EVENING IN RESPONSE TO PRESSURE

FALLS AHEAD OF APPROACHING JET STREAK.

PROBABILISTICALLY...THE GREATEST SVR THREAT OVER THE SRN PLNS SHOULD

EVOLVE TONIGHT AS THE ERN KS SQLN DEVELOPS SWD ALONG MERGING COLD

FRONT/DRYLINE INTO ERN OK AND NW AR. EMBEDDED STORMS COULD POSE A

CONTINUING THREAT FOR HIGH WIND/LARGE HAIL AND PERHAPS AN ISOLATED

TORNADO THROUGH 12Z FRIDAY GIVEN INCREASING MOISTURE INFLOW AND

PROGRESSIVE NATURE OF UPR TROUGH.

..CORFIDI/CROSBIE/CARBIN.. 05/01/2008

Tornado risk remains at 5%

Hail risk increased to 45%

Wind risk is up to 30%

[Nick F]

Excellent, MDT area a bit further east than I would put it, but we will try leave here around 10-10.30am and head east of here on the Hwy 54 towards Woodson and Allen Counties area to get in the general area of the MDT risk.

Going to get some breakfast in a minute ... but getting really excited now!

[pottyprof]

Excellent, MDT area a bit further east than I would put it, but we will try leave here around 10-10.30am and head east of here on the Hwy 54 towards Woodson and Allen Counties area to get in the general area of the MDT risk.

Going to get some breakfast in a minute ... but getting really excited now!

Its very possible that it is a little too far east Nick. The risk has back tracked over the last couple of days but if it is too far east, then id say you are due south of the moderate area..

[Nick F]

A second look at the streets and trips suggests maybe that we only need to get a little east of Witchita to get in the MDT area, though the chances are that severe supercells will form outside this area anyway. Can feel the air is more humid today thanks to moisture return, 60F Tds just south of here 63F Tds advecting into SC Oklahoma - so moisture look less of a worry. Very strong surface winds from the south here atm:

The main hurdle this afternoon here will be breaking the cap.

We're currently thinking Emporia for a target now, NE of Witchita.

[chionomaniac]

Morning to those in the USA , afternoon to all here. Good luck on the chase today . Heres hoping you get to see some action.

With the tornado risk being 5% does that mean the chance of any particular storm dropping a tornado or for the area as a whole? Has it ever been 100%?

c

[kold weather]

Yep upgraded to moderate which is not that surprising really given the atmospheric set-up. I've not got much to add to what Nick has said with reagrds to the general set-up though the moisture return doesn't look too bad right now with dew points rising quite readily.

Cap still holding nice and strong though thats to be expected as its still the middle of the morning but the models do take a little while for the cap to erode and the instablity to show. The cap should mean though that any storms that do break through in the afternoon hours will be powerful and fairly discrete at least till the cap weakens even more into the early eveing hours where more widespread storms will form.

[pottyprof]

Should be under clear skies for a while.. Cookin!!!

[Nick F]

Yep, pretty clear skies here:

Just waiting for everyone to get ready and we'll be off within the next hour, we will try and update throughout the day while we are on the road, as we have a card for the internet to pick up a mobile signal, if there is a signal. Otherwise we'll be near wi-fi no doubt for lunch.

Really looking forward to some supercell action!

[Paul Sherman]

As Nick says we are loading up the Cars and the Barons is fired up and ready to go, really looking forward to today, going to sit just east of the Dryline and watch them Towers explode, good thing is me, Nick and Michael Fish are all in agreement as todays target. Will update around lunch or 7-9pm your time!

Paul S & Team

[kold weather]

Cool thats good to hear. i think today isn't that bad to forecast as there is no low level muck to worry about its just going to be a case of waiting for the cap to break which it no doubt will eventually, I think I'm going to watch this quite closely tonight UK time because whilst maybe not record-breakingly severe there are signs that there will be severe supercells present.

Being east of the dryline is a good idea obviously and with the clear skies presently you should get a very impressive veiw of those cells thundering up. Bet you are all excited!

[Stu_London]

Bring it on I say

Had enough acclimatising now - want action!!

[Gorky]

Well, I'm sat in Bartlesville atm about to move North, but not too far. Probably to Independance. I'll reposition again at 2:00pm which should give me a good 3 hours drive before initiation at the very least, giving me targets up past Emporia or back down towards Tulsa. I have a sneaky suspicion that the OK threat has been downplayed and wouldn't be surprissed to end up chasing down there, but atm it is too much of a risk to stay put. It doesn't cost much in petrol in this car if I have to backtrack. I made it from Amarillo to Tulsa on one tank yesterday I'd hate to see your Mileage, Paul

[pottyprof]

Just to give you an idea as to where Nath is..

[NL]

Should be under clear skies for a while.. Cookin!!!

Great high temps to erode that cap, just need the moisture

to return soon. I think Nath could be right and further south into Oklahoma

might not be a bad idea stronger cap down there but temps are pretty good

and any storms that do develop will no doubt be very severe.

[kold weather]

Well obviously the further south you go your playing an ever more risky game with regards to the cap and whether it breaks, I think the chase team out there have sort of gone for the middle ground with regards to that.

[Roger J Smith]

At the moment I like anywhere around Emporia, Topeka, Junction City, Ottawa KS as a risk/opportunity box.

Risk slightly lower south, not much lower north.

I think the team(s) will bag later today, storms are not likely to be racing but should track northeast once on the ground.

Seem to remember a very similar set-up in 1991 with tornadoes crossing the interstate highway near Emporia (late April).

Maybe you've seen the videos, people huddled under an overpass as the tornadoes came through.

Risk assessment from me is F3 at 21-22z between Emporia and Topeka. Good luck, I'm watching from now on.

[pottyprof]

Latest Outlook discussion

SPC AC 011623

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1123 AM CDT THU MAY 01 2008

VALID 011630Z - 021200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER SERN KS...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE

SRN/CENTRAL PLAINS...

...SYNOPSIS...

STRONG SPRING UPPER SYSTEM WILL SPREAD EWD ACROSS THE HIGH PLAINS

THROUGH THE PERIOD...WITH ASSOCIATED ENHANCED MID/UPPER LEVEL WIND

FIELDS SPREADING ACROSS MUCH OF THE CENTRAL PLAINS. MID MORNING

SURFACE ANALYSES INDICATE SURFACE LOW OVER CENTRAL NEB WHICH WILL

DEEPEN SOME AS IT LIFTS SLOWLY NWD THROUGH THE DAY. AS THIS

OCCURS...DEEP MIXING WITHIN DRY TROPOSPHERE AND DOWNWARD MIXING OF

STRONG SWLY FLOW ALOFT WILL ALLOW DRYLINE TO DEVELOP EWD ACROSS A

LARGE PART OF SERN NEB/NERN KS...TRAILING SSWWD INTO CENTRAL OK BY

LATE THIS AFTERNOON. MAIN NEGATIVE FACTOR FOR WIDESPREAD AND/OR

SIGNIFICANT SEVERE THUNDERSTORMS ACROSS A LARGE AREA REMAINS THE

LIMITED MOISTURE AND STRONG CAPPING. MOISTURE RETURN HAS NOT BEEN

HELPED THUS FAR BY STRONG SWLY LLJ EXTENDING FROM ERN TX ACROSS THE

MID MS RIVER VALLEY. HOWEVER...SECONDARY SLY LLJ IS FORECAST TO

DEVELOP LATE IN THE DAY/OVERNIGHT OVER ERN OK IN RESPONSE TO MAIN

ENERGY EJECTING EWD ACROSS THE PLAINS LATE IN THE PERIOD.

REGARDLESS...INTENSE SYSTEM AND ASSOCIATED LARGE SCALE ASCENT WILL

INCREASE SEVERE THUNDERSTORM THREAT THROUGH THE LATTER HALF OF THE

PERIOD AS STRONG SURFACE COLD FRONT OVERTAKES DRY LINE. PRIOR TO

THIS OCCURRING THIS EVENING...12Z GFS AND NAM BOTH FAVOR BACKING

WINDS WITHIN THE WARM SECTOR OVER ERN OK/SERN KS AND A SLIGHT NWWD

SHIFT TO THE DRY LINE INTO MORE OF S-CENTRAL KS/N-CENTRAL OK BETWEEN

00-03Z AS SURFACE LOW DEVELOPS IN RESPONSE TO APPROACH OF MAIN

IMPULSE.

...LOWER MO RIVER VALLEY INTO OK/WRN AR/WRN MO...

DIURNAL DEVELOPMENT ALONG DRY LINE WILL REMAIN CONDITIONAL DUE TO

FACTORS LISTED ABOVE. HOWEVER...STRONG HEATING AND CONTINUED INFLUX

OF LOWER 60S SURFACE DEW POINTS WILL LIKELY GREATLY WEAKEN CAP FROM

FAR NERN KS ACROSS SERN KS/FAR NRN OK THIS AFTERNOON. SHOULD EVEN

ONE OR TWO STORMS FIRE DURING THE AFTERNOON/EARLY EVENING ACROSS

THIS REGION...THEY COULD EASILY EVOLVE INTO LONG-LIVED SUPERCELLS

GIVEN MLCAPE AOA 2500 J/KG AND 40-50 KT DEEP LAYER SHEAR. COVERAGE

OF STORMS WILL INCREASE THROUGH THE EVENING...WHICH WILL ALSO EVOLVE

AS SUPERCELLS AND LINES/BOW ECHOES AS FRONT OVERCOMES CAPPING. THIS

ACTIVITY WILL EXPAND SWD AS STORMS SHIFT GENERALLY EWD ACROSS ERN

KS/ERN OK/WRN MO/WRN AR THROUGH THE NIGHT. VERY STEEP LAPSE RATES

WILL FAVOR LARGE HAIL AND DAMAGING WINDS...ALTHOUGH TORNADOES CAN

NOT BE RULED OUT WITH THE OVERNIGHT STORMS GIVEN VERY STRONG LOWER

AND DEEP LAYER SHEAR IN PLACE.

...MID MO RIVER VALLEY...

STRONG SURFACE PRESSURE FALLS WILL SPREAD NWD TOWARDS FAR SERN

SD/NERN NEB THROUGH THE DAY AHEAD OF APPROACHING LOW CENTER. DEEP

ASCENT AND WEAKENING CAP AS AFTERNOON TEMPERATURES RISE INTO THE 70S

SHOULD SUPPORT THUNDERSTORMS WITHIN WARM SECTOR OVER THIS REGION.

LOW LEVEL SHEAR WILL BE ENHANCED FROM ESELY SURFACE WINDS AND EXPECT

A FEW SUPERCELLS WILL DEVELOP WITH THREATS OF LARGE HAIL AND

ISOLATED TORNADOES INTO THE EARLY EVENING. STORMS SHOULD EVOLVE

ALONG THE FRONT AND MAINTAIN A RISK OF SEVERE EWD ACROSS FAR ERN NEB

AND INTO WRN IA DURING THE EVENING PRIOR TO STORMS SHIFTING EAST OF

GREATER INSTABILITY AXIS.

..EVANS/GRAMS.. 05/01/2008

[Gorky]

If you want to follow me, I'm on spotter network now. These are the links to the place files for the following apps. I know most won't have GRLevelx or StormLab, but google Earth is free so try it out and let me know if you can see me on the map

GRLevelX Place File: http://www.spotternetwork.org/feeds/grlevelx.txt

StormLab Position File: http://www.spotternetwork.org/feeds/stormlab.txt

Google Earth NetworkLink File: http://www.spotternetwork.org/feeds/earth.kml

Also, I see the moderate risk is a little further south and I am now in it here in Independance. Yay!

Big moderate risk for tomorrow, which I am planning to play. Hope to get over to NE Arkansas after an earlyish start if posible.

[dallas]

If you want to follow me, I'm on spotter network now. These are the links to the place files for the following apps. I know most won't have GRLevelx or StormLab, but google Earth is free so try it out and let me know if you can see me on the map

GRLevelX Place File: http://www.spotternetwork.org/feeds/grlevelx.txt

StormLab Position File: http://www.spotternetwork.org/feeds/stormlab.txt

Google Earth NetworkLink File: http://www.spotternetwork.org/feeds/earth.kml

Also, I see the moderate risk is a little further south and I am now in it here in Independance. Yay!

Big moderate risk for tomorrow, which I am planning to play. Hope to get over to NE Arkansas after an earlyish start if posible.

Hi Gorky, have you a spotter number, on the site now and there are green or red icons with numbers,

Good luck

[Roger J Smith]

J-field analysis made possible by developing IR signatures on dry line nw OK into s/c KS, peaks 01-03z near Emporia KS.

I have the feeling that this severe storm episode will initiate rather slowly after 21z and explode around 23z as J-field elements reach triple-overtake at 03z, this likely to be between Emporia and Missouri border. Given daylight considerations still think Emporia is about the best place to be at this time, 20 SE Emporia my current estimate of tornadic peak potential at 0130z.

[kold weather]

Cool good to hear that bristolwx, whats the weather like, is there any signs of cumulus development yet, the Sat.imagery showing just the first hints of cumulus development at least over OK right now and the latest soundings show that whilst there is still a cap it is starting to weaken a little now.

Another balloon is going up very shortly, I'd advise to watch out for that and see how the cap is doing, hopefully it will have decayed yet further.

[pottyprof]

Cloud tops starting to cool nicely..

Latest discussion

SPC-Day1 Discussion

ACUS01 KWNS 012001

SWODY1

SPC AC 011958

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0258 PM CDT THU MAY 01 2008

VALID 012000Z - 021200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF ERN KS AND INTO

FAR W CENTRAL MO AND A SMALL PORTION OF NERN OK...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID MO VALLEY SWD INTO

ERN OK/WRN AR...

...NERN KS/WRN MO SWD INTO OK/WRN AR...

DRYLINE CONTINUES SHIFTING EWD ACROSS OK/KS...WHILE COLD FRONT

PROGRESSES SEWD ACROSS NRN AND WRN KS. WARM SECTOR AHEAD OF THE

DRYLINE REMAINS MARGINALLY MOIST...WITH DEWPOINTS IN THE UPPER 50S

TO LOW 60S FROM ERN KS SWD INTO CENTRAL AND ERN OK.

DESPITE THE SOMEWHAT LIMITED NATURE OF THE BOUNDARY-LAYER

MOISTURE...VERY STEEP LAPSE RATES ALOFT PERSIST -- WITH SUBSTANTIAL

CAPE INDICATED ABOVE THE LOW-LEVEL CAP. BOUNDARY-LAYER

HEATING/MIXING HAS HELPED TO WEAKEN THE LOW-LEVEL CAP -- PER 20Z

NORMAN OK RAOB -- WHICH COMBINED WITH NEW 12Z HI-RES GUIDANCE

SUGGESTS THAT ISOLATED STORMS MAY DEVELOP ACROSS PARTS OF OK. MORE

WIDESPREAD CONVECTION THOUGH IS STILL ANTICIPATED FURTHER N -- FROM

NRN OK NEWD ACROSS ERN KS -- AS COLD FRONT OVERTAKES THE DRYLINE

LATE THIS AFTERNOON AND THIS EVENING.

THOUGH BOUNDARY-LAYER FLOW REMAINS SOMEWHAT VEERED/SSWLY ACROSS MOST

OF THE WARM SECTOR ATTM...MODELS SUGGEST THAT LOW-LEVEL FLOW SHOULD

BACK FROM CENTRAL OK NWD INTO ERN KS AS SURFACE LOW DEVELOPS ALONG

SEWD-MOVING FRONT OVER WRN OK THIS EVENING. RESULTING INCREASE IN

LOW-LEVEL SHEAR SUGGESTS THAT ISOLATED TORNADOES WILL BE

POSSIBLE...THOUGH GREATER SEVERE THREAT SHOULD REMAIN IN THE FORM OF

VERY LARGE HAIL AND DAMAGING WINDS.

OVERNIGHT...STORM ORGANIZATION SHOULD BECOME MORE LINEAR AS COLD

FRONT PROGRESSES SEWD ACROSS THE REGION. POTENTIAL FOR DAMAGING

WINDS SHOULD THEREFORE MAXIMIZE LATER THIS EVENING FROM ERN KS/NERN

OK INTO WRN MO/NWRN AR.

...MID MO VALLEY REGION...

SELY LOW-LEVEL FLOW AND A NARROW MOIST AXIS ARE INDICATED NEAR AND

JUST E OF THE ERN NEB/WRN IA BORDER ATTM...WITH LIMITED

HEATING/DESTABILIZATION ONGOING E OF THE NERN NEB SURFACE LOW. THIS

LOW FORECAST TO LINGER ACROSS THIS AREA INTO THIS EVENING...AND

SHOULD OCCLUDE WITH TIME AS COLD FRONT SHIFTS SEWD. NEAR AND JUST E

OF THE OCCLUSION...SELY FLOW AND PERSISTENT MOIST AXIS COMBINED WITH

THE SLOW APPROACH OF THE UPPER LOW FROM THE W WILL LIKELY RESULT IN

THE DEVELOPMENT OF THUNDERSTORMS -- FROM SERN SD SSEWD INTO ERN

NEB/WRN IA. ALONG WITH THE POTENTIAL FOR HAIL AND ISOLATED SEVERE

GUSTS...ENHANCED LOW-LEVEL SHEAR SUGGESTS THE POTENTIAL FOR ISOLATED

TORNADOES -- MAINLY LATE THIS AFTERNOON THROUGH MID-EVENING.

..GOSS/KIS.. 05/01/2008

Risk map