11/5/08 FCST: IA/MO/AR/E. KS

[Greg McLaughlin]

Based on current models, I am not sure how one would be concerned with initiation after dark. The NAM and GFS both have precip broken out by 00z. Considering the placement of the mid/upper jets and pva I would assume convection would be going before dark. Now if we get supercells by late afternoon we might now get tornadoes until right after sunset....assuming there is even a risk of tornadoes.

Concerning moisture, I am a little pessimistic about moisture return considering current surface obs have some mid-upper 50s Tdps in the GOM. Its not like the GOM is loaded. Meager moisture will be a concern for the southern target, but not as much of a concern if you get a cold-core setup way up north.

 

[Scott Lincoln]

Based on current models, I am not sure how one would be concerned with initiation after dark. The NAM and GFS both have precip broken out by 00z.

Well it is November. Sunset is from 5:00pm-5:15pm now in eastern Kansas/Nebraska and Iowa/Missouri.

 

[Mike Smith]

Sunset in ICT on Wednesday = 5:27pm

 

[Robert Rohloff]

Well it might bust however gas is $1.80 and droping in OK, it is time to get out for a drive.....might get wildfire footage if all else fails. Heading west and north towards Ponca City and start out there.

Looks like a night event in this area at this point

 

[Greg McLaughlin]

Sunset is at 5:30pm and 00z is at 6pm. If the models are showing QPF by
00z then that likely means storms have fired at least an hour or two before dark. I think things get going sometime between 2-4pm. The latest runs of the NAM and GFS have precip breaking out by 1pm.

 

[Mike Hollingshead]

Cap starts going bye bye really early, at least according to the NAM. I wouldn't think darkness would be an issue either. I've thought that plenty of times before though and been very wrong, lol.

http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=045&STATIONID=ksln

Cap very gone at Salina by 21z/3pm. It's gone even before that to the west, and of course north.

http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=042&STATIONID=kear
Kearney at noon.

Enid and OKC gone by 3pm as well.

 

[Brandon Ivey]

The last two or three WRF runs have been pretty consistent on developing a target near the Kansas/Oklahoma border on Wednesday. It looks like this system won't really become a cold core low until it moves into the Midwest. GFS did pretty good though, about a day fast, as usual. I think the I-35 coridor from Wichita to Oklahoma City, currently looks good for Wednesday afternoon. The moisture gradient along the dryline will be the sharpest along the KS/OK border with dewpoints approaching 60 to be expected. The forecast soundings from KICT and KOUN look really good by Wednesday evening. 0-3km CAPE values are forecast to range from 63 at Norman to 176! at Wichita. 0-1km SRH should be around 300 with 0-6km shear of 50-55kts and overall CAPE values of 1,000-1,500. Everything is looking good for supercells to develop along the dryline with a few tornadoes possible. The cold front will help everything become linear during the evening as it overtakes the dryline.

 

[Andrew Ryan]

The 0z NAM still paints a better picture than the GFS. I agree with the target around the OK/KS border. The NAM progs CAPE values aoa 1500 at 21z and just about the same as what has been said before. I agree that moisture is still a problem. But dewpoints of 60F+ are slowly making there way north from the gulf. I don't think it's hard to imagine dews near 60 by Wednesday afternoon/evening. But as always, time will tell.

 

[Chad Cowan]

This is my preliminary target map, using the 03/12z model suite and 21z SREF as main guidance and refined with the 0z runs. Note that this map is my forecast for tornadoes only and not general severe weather which will extend well east into the night. The GFS has been unsurprisingly more progressive with the trough and subsequent sfc features. A quick glance at the ensemble members shows the Operational GFS as the progressive outlier (Black line), so this fcst will lean towards a blend of the slower NAM and Euro.

I am not convinced the moisture return will be anything near what the 0z NAM is advertising, with 60 dews up into NE. In fact, I wouldn't be surprised to see the 60 degree isodrosotherm not make it into OK on Wednesday. The SW low level flow prior to the event will not favor deep, quality moisture return- but given a narrow tongue of mid-upper 50 dps, the seasonably cold temps aloft and unseasonably warm temps at the sfc, instability will be sufficient for supercells and tornadoes as far north as the sfc low in SD. Hodographs will enlarge throughout the afternoon as the LLJ backs and strengthens with time across the warm sector. This will be vital to the low-level turning in an otherwise unidirectional flow. I agree with Brian Stertz that we could see some LEWPs/embedded sups after everything goes linear.

I am favoring the southern target ATTM for a few reasons. First of all there is the potential for early-mid day convection in nrn-KS and NE as the strong forcing arrives a tad early. This could kill any instability, but the screaming storm motions up there would quickly take this convection away from the initiating boundary. Secondly there is the issue of the cold front and how much it will push east during daylight potentially mashing potential supercells into a congealed mess. Depending on which model to believe, the CF won't undercut the dryline until after dark in the southern target. Lastly, storm motions in the northern target under the 70+kt H5 jet streak will not be fun to chase. I miss spring.

 

[Michael O'Keeffe]

Wow moisture looks impressive now! Just checked the latest surface obs and dews are already in the mid-upper 50s across much of Oklahoma with low 60s right on their tail near the Red River. The moisture "problem" appears to be diminishing as winds are expected to increase through day across OK and KS.

 

[Paul Knightley]

A stout upper trough is forecast to dig in from the NW over the next 24-36 hours, inducing lee cyclongenesis and pulling Gulf moisture northward as a result. However, the moisture does not look too high, around 13-15C dewpoints, perhaps a 16C in N OK/S KS. A cold front/dryline intersection should form around about DDC by around 18Z, and then sharpen by 21Z/00Z, and being located (if you believe ECMWF) in a triangle bounded by DDC, GBD and P28. Storms would want to form close to and east of this, making the corridor from OKC to Salina a target area, although the more northern area would be overtaken with the cold front. However, further to the south, storms may not fire until close to or after dark, with a risk of some evening tornadoes for NE OK/SE & E KS. I think I'd be in Wichita for the morning, and then see what happens thereafter, with a tendancy towards Salina.

Whilst I think some probability exists for storms further east, I suspect it may be dark by then, so I'd hold to the west.

As always away from vacation time in May, this is all just practice on my part!

 

[Chad Cowan]

Wow moisture looks impressive now! Just checked the latest surface obs and dews are already in the mid-upper 50s across much of Oklahoma with low 60s right on their tail near the Red River. The moisture "problem" appears to be diminishing as winds are expected to increase through day across OK and KS.

I wouldn't be too quick to write off the moisture concerns for tomorrow, Mike. This is the initial northward moisture surge in response to the lee cyclogenesis that unfortunately gets 'pinched off' thanks to the anticyclonic flow over the southeast. Note the sub-50 dp sfc obs circled in red that will mix westward. This current moisture surge will be good for those targeting the northern Plains tomorrow.

04/16z sfc obs on left, 04/12z WRF 24hr dps on right

 

[Andrew Stoller]

Is anyone else worried that there is a lack of backing to the surface winds basically everywhere along the dryline? Looking at forecast skew Ts, it does seem to improve the further south you go. Ponca City looked the best from all the ones I looked at by 21Z. The winds also back more closer/east of the surface low, say by Wayne, NE by 00Z, but that far north, the 500 mb winds are more out of the south, so you basically get less degree of turning between surface and 500mb compared to the southern Target area. Lack of a backing component with the cold front really swooping in by 00z is my only concern; everything else looks great.

 

[Skip Talbot]

Forecasted effective SR helicity values over 300 in southern Kansas are more than enough to support discrete supercells and tornadoes. Thanks to the veering midlevel winds, we don't need completely backed surface winds for good directional sheer.

 

[Greg McLaughlin]

Right now I like the area between Wichita and Ponca City. I will be playing close attention tomorrow to any moisture tongue and try to be on the nose of it.