Possible Severe Event - 4/30 to 5/3

[Beam]

ZCZC SPCSWOD48 ALL
ACUS48 KWNS 260852
SPC AC 260852

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0352 AM CDT SAT APR 26 2008

VALID 291200Z - 041200Z

...DISCUSSION...
LARGE CYCLONE FCST TO EVOLVE OVER NWRN CONUS DURING DAY 4-5/29TH-1ST
TIME FRAME...INDUCING LEE TROUGHING AND EVENTUAL CYCLOGENESIS OVER
GREAT PLAINS. GEN PATTERN INDICATES MULTI-DAY SVR POSSIBILITIES
ALONG/E OF DRYLINE AND NEAR AND S OF WARM FRONT BEGINNING
DAY-5...THOUGH IMPORTANT DETAILS SUCH AS EML-RELATED CINH WILL BE
IMPORTANT FACTOR ESPECIALLY DURING FIRST DAY OR TWO OF THIS
SCENARIO. ECMWF -- ON AVERAGE THE MOST RELIABLE MODEL FOR THIS TIME
FRAME -- APPEARS TO BE SUBSTANTIAL OUTLIER COMPARED TO
UKMET/SPECTRAL AND ALL MREF MEMBERS WITH RESPECT TO MUCH MORE RAPID
AND SELY EJECTION OF PRIMARY SHORTWAVE FROM BASE OF NWRN CONUS
CYCLONE. THIS ALSO IS INCONSISTENT WITH SOME OF ITS OWN PREVIOUS
RUNS. THEREFORE WILL DOWNPLAY ECMWF FOR THIS FCST CYCLE AND WEIGH
OUTLOOK TOWARD MREF CONSENSUS. CONSIDERABLE LATITUDINAL VARIATION
EXISTS WITH BOTH MAGNITUDE/QUALITY OF MOISTURE RETURN AND PLACEMENT
OF DEEPENING SFC CYCLONE DAY-5/30TH-1ST...AMONGST MREF AND
SPECTRAL/UK RUNS. HOWEVER...STG AGREEMENT IN EXISTENCE OF THIS
LOW...AS WELL AS IN FAVORABLE MOISTENING LATE DAY-5 THROUGH
DAY-7/2ND-3RD...ENGENDERS HIGH CONFIDENCE IN WELL-ORGANIZED SVR
POSSIBLY INCLUDING AN OUTBREAK...AND COMPELS INTRODUCTION OF
CATEGORICAL OUTLOOKS. THESE AREAS ARE HIGHLY GENERALIZED AND
SUBJECT TO CONSIDERABLE SPATIAL REVISION AS OUTLOOK PERIODS DRAW
CLOSER.

..EDWARDS.. 04/26/2008

I think this is the boldest call on a Day 4-8 outlook I've seen. Obviously, things are still rough this far out, but we could be looking at a multi-day severe weather event over the Central Plains starting Wednesday night or Thursday and continuing through Saturday. Climatology certainly favors the beginning of May in this part of the country with regards to violent weather.

After the semi-busts we've been having here in Eastern MO this month, I'm keeping my enthusiasm in check. Still, if everything holds up, May could be off to a very interesting start.

[Tampa Bay Hurricane]

Some intense activity it looks like there. Watch out!

[RL3AO]

After the debacle on April 10, I'm not sure what to think of this.

[wx247]

The most recent outlooks from the SPC are much more tame, although I do think there are some stormy days ahead. Things will be much more in focus within the next 48 hours or so regarding the beginning of this active period.

[cheezyWXguy]

although theres no longer a day 6 or7 outlook, there is a day five, which contains a good part of the southern plains, including my area (yes!). They seem to have at least some confidence in this forecast up to day 5, although rain chances appear low attm. well have to see.

[wx247]

I am surprised that no one is still talking about this. Tomorrow could be a busy day into the night depending on moisture return setup. Thoughts?

[KWT]

Yep and the good thing is the jet streak isn't quite as insane as the earlym April set-up, I tend to find such set-ups like the one tomorrow often throw up some surprises, still got a strong jet streak esp at lower levels and decent instablity with Cape upwards of 2000 in some places.

[Ed Mahmoud]

If the Euro is correct, the real severe event Central and Southern Plains gets started Monday (Cinco de Mayo) and really cranks Tuesday.






Now, Wednesday it may get closer to Houston, and Euro 850 mb winds from South, even Southeast, suggesting less cap than has been the case this Spring in South Texas. And we need the rain.

But the real action is still a little farther North.




Can't look up CAPE, or check intervals less than 12 hours anywhere I can think of, free of charge, on Euro, but when one has a decent upper low, and decent low level jet, than I have found that to be a reasonable indicator of possible severe weather.

[RL3AO]

Moderate risk (for hail) in eastern Kansas.

[snoopj]

Yuck. Hail. Hatched and over my area.

--snoopj

[Ed Mahmoud]

0Z Euro is over 2 days slower than the 12Z Euro in moving out the trough. Making any guesses as to severe when the model changes so sharply between runs seems pointless.

[simplykristi]

Yeah we are on the edge of moderate risk here in KC. Some teen actually cheered about it on a local station's weather blog and I got mad about it.

Kristi

[KWT]

Today is still looking interesting, some good shear levels thanks to the jet streak and some decent instablity. Moisture returns looks good enough to warrant the upgrade to moderate though the cap is still maybe an issue.

[Ed Mahmoud]

Yeah we are on the edge of moderate risk here in KC. Some teen actually cheered about it on a local station's weather blog and I got mad about it.

Kristi

My brother lives in Lee's Summit.


I e-mailed him the SPC hail probability map.


May not get the surface moisture for much tornado action. Of course, hail tends to produce more widespread (though nowhere near as severe damage) as tornadoes, and while I suppose I could live with a few dings on the sheet-metal, automotive glass and home roof repair cost money.

I will say, re: the tornado threat, two hours ago the 1" PW line was South of Dallas, and nowhere near Oklahoma or Kansas. Look now.

[KWT]

Yeah thats the uncertainty Ed though the moisture returns seems to be a little better then the models were suggesting a few days ago, whether it'll be enough we will have to wait and see.

Nice clear skies presently in the risk zone so when the convection goes up should get some pretty good veiws.

[Ed Mahmoud]

Yeah thats the uncertainty Ed though the moisture returns seems to be a little better then the models were suggesting a few days ago, whether it'll be enough we will have to wait and see.

Nice clear skies presently in the risk zone so when the convection goes up should get some pretty good veiws.

I have watched a few documentaries about tornado tours in the Plains, and it always seems like a few British folks come along for the fun. Must be a rather expensive vacation, er, holiday, to come all the way to Kansas or Oklahoma, but I'd guess the falling dollar might make American visits a good value this year.

[KWT]

Well I'm not there but the website I'm a host at has a tour out there presently, with a famous met in the UK anyway coming along for the ride (Micheal Fish). I'm keeping a very close eye though on everything esp as they will be chasing today.

[Ed Mahmoud]

Being Texas centric, I am looking at DFW area and points North, where the cap is unlikely to break, (7 am CINH was -450 J/Kg, and GFS forecast 7 pm CDT inhibition around -100 J/Kg), but late afternoon CAPE should be between 2500 and 3000 Joules/Kg, morning helicity was 400 m^2/s^2, and forecast values remain near 300 J/Kg, and the low clouds are mixing out now.

So, on the odd chance the cap breaks somewhere, very impressive storms would result.





Hope we get 18Z soundings from FWD, OUN and TOP.

[KWT]

Well yeah over Texas the cap will probably hold but obviously further north over OK/KS looks likee the cap will slowly erode away during the afternoon, though hopefully not completely go so we can keep some seperation of the cells.

[Ed Mahmoud]

BBC page found on Google says Mr. Fish is famous for saying a hurricane wasn't headed for the UK. Technically correct, but a gale center with hurricane force gusts apparently did hit the next day, back in 1987. Mr Fish claims he was responding to a woman calling about a Florida vacation, and he did advise of strong winds.-