TWISTEX Status for Wedneday: Go; ISU, MN, Denver all go

**This is the 3^rd post for the day and another one is possible later this evening.

Severe weather outlook...Forecast discussion synopsis from...Rapid City (UNR)...Aberdeen (ABR)... Sioux Falls (FSD)...Des Moines (DMX)...Davenport (DVN)...Omaha (OAX)...North Platte (LBF)...Bismarck (BIS)...

...Wednesday...

Afternoon WFO forecast discussions are flowing in. The cap is hit upon again by numerous forecasting offices, and they too believe convection will be held down until late afternoon/early evening (FSD: 22-23Z). From discussion, two areas will be likely for the cap to be broken first—near the triple point in central SD and over central/north central NE. I favor triple point as it will likely offer more dynamics to break progged 200-300J/kg CIN.

...Triple point...

Given discussions, triple point will offer the best chance for cap to broken. However, both UNR and ABR only cite “isolated tornado” risk. I'm not sure exactly why because instability and shear are fantastic. Perhaps the dewpoint depression (ABR at 21Z shows about 15 dewpoint depression) or convection being held off until late afternoon/early evening could be the reason for less tornado potential.

...Dryline...

If dryline mixes out and can break the cap, this may be the better chance for tornadoes as storms will explode and may remain fairly isolated. This will allow for good inflow into the storm and may keep them from going HP. After sunset, storms will congeal into a line of a squall line. Only concern here is if storms break the cap further south where 700mb temps are forecasted 14-16 (14-16 is unbreakable), then a whole bunch of storms may go up further north.

...Thursday...

DVN has some potent wording in their discussion. A large MCS will move through eastern IA/WI/IL Thursday afternoon/evening with damaging winds and hail being the main threat. Isolated tornadoes may occur with early convection in the period as flow isn't nearly as unidirectional. Even in the afternoon with this powerful system, if unidirectional flow can be backed in localized areas, isolated tornado threat may continue into late afternoon/early evening. I have not seen a mention of it yet anywhere, but a derecho (long lived and widespread wind event) is possible across eastern 1/3 of IA into WI and IL Thursday evening/Friday morning. Derecho parameter from latest 15z SREF shows a value of 6 across much of eastern IA at 21z/4PM and more spotty by 08/00Z /Thurs. 7PM/. I've been trying to find out what a “good” value for derecho parameter is and have come across greater than 2. If anyone knows something more definitive, please leave a comment or email me as I'd be interested.

TWISTEX Status for Tuesday: No-Go
TWISTEX Status for Wednesday: Go; ISU, MN, Denver all go

**For those who use theweathergun.com pages, they now have added some of the SREF (all the products you find on NCEP, not all the parameters from SPC) and the hurricane WRF. Also, NCEP NAM simulated radar has been added.

**Thanks to Jake and Chris for forecasting input.

Severe weather outlook...9Z SREF; 12Z GFS/NAM/WRF-NMM/WRF-ARW; 18Z RUC ...

...Short term...Wednesday...

Updated day 2 outlook has shifted moderate risk north and west removing any part of IA and KS from threat. Southern half of ND, most of SD, and central and northeast NE are in the moderate risk for severe weather with a possible significant outbreak of storms.

Keys for tomorrow will be moisture supply and cap. Currently, 60 Td (dewpoints) are in AR and south of I-40 in OK. 13Km RUC (Rapid Update Cycle) model is fairly close to current 60 dewpoint line, although maybe a little too far north with northern edge of 60 dewpoints. However, they are forecasted to quickly spread northward tomorrow by 18Z into SD with strong surface winds between 20-30kts. I think moisture will be able to make it up as long as southerly flow returns overnight (6Z from RUC) and as strong as forecasted.

Cap may be the biggest inhibitor tomorrow. Numerous WFOs in NE and SD are calling the cap the big if. OAX calls tomorrow “all or nothing.” And I think they have it on the money. Cap/CIN will not allow for storms to fire early, likely not before 21-22Z time frame. Question is if cap will be able to broken after peak heating of the day. If you like the WRF, you don't anymore. 12Z WRF-NMM and WRF-ARW graphics show no precipitation until after 0Z, and then spreads in some precip from the west into western SD. Obviously, grid-spacing of the model could potentially hide isolated storms, but there is no formation of any sort of MCS line after dark that I am anticipating. I will be watching this tomorrow and see how it verifies. However, looks like triple point in central SD will be main focus for any development/cap breaking.

Otherwise, other severe weather indicators look great! LIs will drop to -8 around 07/00Z with leading edge from Wagner, SD to Lake Oahe, SD. 3000 J/kg of CAPE also poking up into towards ABR and basically covering eastern SD, eastern NE, and central KS. This seems to be in line with 12Z NAM ABR BUFKIT sounding showing 3300J/kg and LIs around -8. Other severe weather indicies from ABR (SWEAT, EHI) all look good for supercells with only BRN more favorable for multicell type storms. Hodograph for ABR is not outstanding as it does not have the smooth curve, yet helicity values are still decent for supercells.

It has come to my attention that Justin Gehrts /ISU student/ has posted TWISTEX summaries on his blog. He was in M2 during May 22-24, 2007 TWISTEX. So, in my May 22, 2007 summary, when I wrote, "Since I was in M3, all I know M1/M2 were doing was trying to sample the RFD region of the storm..." This means if you go to Justin's blog, you'll likely be able to find out more of what M1/M2 were doing.

So, since Justin has been sending people over my direction, I'll send you his direction.

http://www.justingehrts.com/blog

or if you have RSS feeds

feed://www.justingehrts.com/blog/feed

A moderate risk is in place for day 2/Thursday across the eastern 2/3rds of SD and NE, southern ND, NW IA, SW MN, and north central KS. The moderate risk has been pushed slighly further west and extended slightly north to south. Back to back, and now the 5th, moderate risk on day 3 has been issued over the SE MN, eastern IA, NE MO, NW IL, WI and U.P. of MI.

For Wednesday, WFOs in SD and NE are playing up the cap quite a bit. This is likely not overdone as forecasters think the cap will hold convection til late afternoon (22Z?/5PM) or early evening.

Longer discussion will come early this afternoon...

TWISTEX Status for Monday: No-Go
TWISTEX Status for Tuesday: No-Go
TWISTEX *Unofficial* Status for Wednesday: Go; ISU, MN, Denver teams all go

Severe weather discussion…Short-Term (Wednesday)…00Z NAM/GFS…
00Z/08 (Wed 7PM) ABR sounding shows CAPE over 4000J/kg, helicity of 200+m2/s2, EHI of 4.4 (EHI is severe weather paramter; favorable for tornadoes), BRN of 86 (another severe weather parameter indicates more of a line of storms). Similar soundings at Mitchell (MKE) and Yankton (YKN). Overall, soundings look very impressive with backed winds. While there is inhibition, SPC/WFO (weather forecast offices) feel confident dynamics will break cap.

Both the NAM and GFS have has weakened the low slightly and have the low tracking a bit further south and southeast, respectively.

…Long Term…Friday-Sunday

Low over eastern Dakotas Thursday morning rapidly moves off to the NE into Canada by Thursday evening. Trailing cold front from U.P. of MI down towards Saint Louis will spark make primary threat wind and hail, although with this potent system can’t rule out scattered tornadoes. 18Z sounding for Davenport shows cold front through (or very close). Shear is mostly unidirectional out of SW.

By Saturday morning, cold front is in the OH River Valley, although becomes stalled back as it strectches back through MO/SE KS/NW OK into panhandle of TX. It is likely storms will fire along this stationary/perhaps warm front each of these days as small shortwaves move out. The most impressive shortwave is Saturday evening into Sunday. Also, dryline in TX just hangs out in the western part of the state so isolated supercell are possible. KS/OK border appears under the bullseye for severe weather Friday/Saturday and again into Sunday including panhandles of OK/TX as well. This is broad and general, and I leaned upon SPC/GFS for areas highlighted.

---End weather discussion---

I would stay up for day 2 outlook, but my eyes are tired. If day 2 is high risk, it will be only the second time. I spent too much time at the computer today, and not all weather related, although definitely have looked at a lot of data. It feels good to actually be able to apply something I learned from classes.
--------
Prayer Requests:
• Continue to pray for Patricia, Darlene, and Andrew (not me)
•Pray for safe travel as folks for Denver will be likely heading out to pre-deploy Tuesday evening. ISU crew will likely be heading out Wednesday early morning. Pray for safe travel for all folks involved.
• Wednesday looks to be a major severe weather outbreak. While no one on this Earth knows for certain what will transpire in the next few days, pray that God would bless the meteorologists with awareness of dangerous and/or life threatening storms so as to be able to give those in the path plenty of time to seek shelter. Pray for the safety of those that may be affected by any storm, and those who may be required in rescue operations.
• If you have a prayer request, feel free to email me.
--------
Views expressed are solely those of the author, Andrew Ansorge, and may not represent the views of National Geographic and their crew, Iowa State University and the Iowa Board of Regents, Tim Samaras and his crew, other Iowa State University students, or other TWISTEX members.

TWISTEX Status for Monday: No-Go
TWISTEX Status for Tuesday: No-Go

Day 3 moderate risk of severe storms. This has only occurred 3 times previously:
June 10, 2005,
January 2, 2006
April 24, 2007.

Storm Reports from those days:

June 10, 2005
January 2, 2006
April 24, 2007

Severe weather discussion...focused on Wednesday using 9Z SREF...
While the dryline is still shown to progress into western KS/OK/panhandle of TX, the warm front is likely where the main action will be. Storms that do fire on the dryline will be isolated, but this isolation may allow supercells to develop, although Goodland (GLD) and Dodge City (DDC) do not show good directional shear.

Reason why action will be along warm front is likely a contribution of 700mb temps above 13-14C (unbreakable cap), in the area near the dryline. However, as you work yourself northward into SD/NE, cap is on the edge of breakable across northeastern NE/eastern SD. CAPE values though are huge with 4000J/kg by the 9Z SREF and perhaps 6000J/kg by the 18Z NAM. LI values of -9 across north central NE by 00Z with -6 across all of eastern NE/SD by 21Z is outstanding. Lapse rate are high (8-10C/km) with severe weather parameters (CravenBrooks, sig tornado) showing high values. Helcity is present as well at both 0-1km and 0-3km and favorable, albeit a bit east of the best CAPE/CIN/LI gradients.

Only threats for no storms are 700mb cap and moisture supply. SPC sees no problem in dewpoints being advected northward up into NE/SD by Wednesday afternoon. WRF-NMM (NAM) show mid to upper 60 dewpoints surging up to Aberdeen (ABR) and between Hwy 83 and I29 in SD at 18Z. 70 dewpoints are forecasted by 00Z in the same area. Dewpoint depressions do not appear to be too large, allowing for possible tornado development. Soundings for ABR and Omaha (OMA) at 18Z Wednesday show good speed and directional shear.

Overall, day 3 moderate risk has me pleased, especially with wording “TORNADOES ARE ALSO ANTICIPATED -- WITH A FEWSIGNIFICANT/LONG-TRACK TORNADOES POSSIBLE.” Sioux Falls (FSD) and Omaha (OAX) discussions talk about an outbreak of severe weather as well. Wednesday will need to be carefully watched as severe weather indicies/outlooks look impressive along with the strong developing low moving through the Dakota.

Looking into Thursday...Data overload. Honestly, I have looked at enough data for this morning/afternoon. Possible update briefly on Wednesday later this evening, but will try to focus on Thursday-Saturday outlook.
------------------
Views expressed are solely those of the author, Andrew Ansorge, and may not represent the views of National Geographic and their crew, Iowa State University and the Iowa Board of Regents, Tim Samaras and his crew, other Iowa State University students, or other TWISTEX members.

TWISTEX Status for Sunday: No-Go
TWISTEX Status for Monday: No-Go

Severe weather outlook:

Latest GFS and HPC analysis have come to a compromise and are in much better agreement than yesterday. Low will drop down on the Rockies and rapidly strengthening as it progressing through SD Wednesday evening into Thursday morning. GFS has a low center of 976mb while HPC only goes down to 984mb, but hey, what's a few millibars between friends? In any regard, that difference may work out in time, but the track of the low and the strengthening of the low are in agreement. A negatively tilted trough at 500mb backs up this strengthening low at the surface.

Monday and Tuesday will offer up mostly hail and wind threats; although as always isolated tornadoes cannot be ruled out. Late Tuesday/early Wednesday morning would offer up a better atmosphere as southerly flow pumping up Gulf moisture returns; however, still feel that Wednesday morning will be earliest moisture will really start to stream northward.

Dryline still looks poised to move out into western KS/OK/TX Wednesday afternoon and may even stretch into far SW NE. A warm front will be planted across western NE/eastern KS. Wednesday’s target would be best along either dryline or warm front, although I favor the dryline at this time. I didn’t look at any SREF runs today so opinion may change tomorrow, but concern is whether moisture will make it up into NE by Wednesday afternoon. GFS is producing precipitation over western NE, but at its coarse resolution it wouldn’t pick up on isolated convection along the dryline. Not to mention that the GFS uses the Betts-Miller-Janjic convective scheme, but I’ll stop before I digress any further (convective scheme=my Sunday’s time with research)

Thursday has the dryline slashed back down into TX. Typically, I would favor a dryline over a cold front, but for an odd reason I think staying north with the cold front may be the better choice. That’s my gut feeling. Model-based feeling is that the dryline will offer up the best tornado chances. Topeka (TOP) 12Z sounding Thursday morning shows slight veering of winds from surface to 850mb, then fairly unidirectional flow above 850mb. Del Rio (DRT), TX sounding for same time period looks more favorable for directional as winds are backed as the surface, but is removed from upper-level winds (lacks speed shear). Best area to set up would be in western OK/just east of TX panhandle in northern TX. Definitely will have a better feel for Thursday after 12Z NAM/3Z SREF runs are in tomorrow morning.

Friday and Saturday feature another, yet less potent, negatively tilted 500mb trough moving through the Upper Midwest as cold front stalls out around the OK/KS border back east through MO and the OH River Valley. Best target for possible severe weather would be a general southern KS/northern OK area at this time, but have focused more on near-term threat and will evaluate as time progresses.

Overall, this TWISTEX deployment is similar to the one a few weeks ago as we were in KS one day, then dropped down into TX the next.

---------End severe weather discussion---------

Today was more relaxed than yesterday, although the paper is completed and will be sent for revisions. The hardest part I find is the results and conclusions sections. After performing research for whatever the period, you find that you have many, many results. It is difficult to narrow all the results you have down to just a few that would be the most beneficial to your audience. This is because every result to you is the most important thing ever (maybe that is just my take).

Conclusions are not any easier to write. You don’t want to overstep your results and try to draw or make a leap to a conclusion. In the same regard, you don’t want to undercut yourself by making weak statements as then your paper doesn’t finish strongly and perhaps leaves your audience wondering about your credibility.

In the end, both these sections for me take the longest. They have to be written in a manner that is clear and concise and gives the reader a complete understanding of your topic with some points to take as they leave their reading chair.

Prayer Request:
• Continue to pray for Patricia, Darlene, and Andrew (not me)
•TWISTEX will likely be getting called up to depart early Wednesday morning (assuming target isn’t too much further west or south as 7AM departure was cutting it close to western KS). Pray for safe travel as folks from ISU, Denver, Minnesota, and even Germany travel
• If you have a prayer request, feel free to email me.
------------------
Views expressed are solely those of the author, Andrew Ansorge, and may not represent the views of National Geographic and their crew, Iowa State University and the Iowa Board of Regents, Tim Samaras and his crew, other Iowa State University students, or other TWISTEX members.

TWISTEX Status for Saturday: No-Go
TWISTEX Status for Sunday: No-Go

Severe weather outlook:

Severe weather threat in the northern Plains never materialized today, although dewpoints were in line with this morning's SREF run (low to mid 60s) along Lake Michigan. A few hail and wind reports though in eastern MN.

15Z SREF has LIs most favorable down in TX the next few days with moist air (dewpoints mid to upper 60s) in place. Dewpoints in the low to mid 60s try to surge northward up to the I40 corridor over the weekend, but I think the juicy air will be kept down in TX along with severe threat (primarily hail/wind, isolated tornado). Tuesday afternoon, according to the SREF, is when dewpoints in the mid 60s stream into OK. 00Z GFS and NAM show Gulf moisture being pulled back northward later in the day Wednesday up in to eastern OK/KS and I tend to lean towards these models over SREF at this time. CAPE/helicity don't look outstanding, but a bit early to worry about lack of these ingredients. It appears late Tuesday at the very earliest would be when the severe chances begin to increase as northwesterly flow diminishes and southerly flow begins to take over.

A still impressive low (not as impressive in latest GFS run) is progged to cut through the Dakotas and Minnesota mid to late week. A dryline will likely mix out into western KS/OK/TX Wednesday and Thursday. I'd like to say more about the dryline and potential intersection of cold front/dryline, but confidence is not high as HPC analysis/GFS are not agreeing on low position/track. Nonetheless, mid to late next week likely offers best chance of severe weather, including tornadoes. After Thursday, severe threat seems to focus on the cold front with tornado threat appearing to diminish as low tracks NE in Canada trailing a cold front through the OH River Valley.

-----
A surprisingly productive Saturday. The poster is completed and will send it off for comments/suggestions/questions. Since this is my third poster, there isn't a lot of work involved as it is basically modifying the text and figures to the new research. However, formatting takes an incredible amount of time. The written paper has come a long ways today, which I had not expected at all. Yet, I know from experience that writing tends to take longer than you anticipate. In other news, installed a water feature in the backyard, bid and won a new weather station to replace the old Heathkit (display has been broken), and if not obvious from above I also had a little time to look at the weather.

Odd item today was an email I received today from ISU saying I owe them money. How much? One dollar.

Prayer Requests:
Patricia, Darlene, Andrew (not me)...I was visited by these Jehovah Witness' earlier this week. They talked a lot about fear and hope, but I never heard a lot about Jesus. Pray that God would open their eyes to their false teaching, that they would see that salvation is not obtained by good works, but by faith in Jesus Christ.

TWISTEX Status for Friday: No-Go
TWISTEX Status for Saturday: No-Go

The severe weather for today was expected, but not quite what I had posted last evening. While I was anticipating a brief tornado or two in the upper Midwest, there were 15 while there were none in Texas (2 in FL with Tropical Storm Barry). Only activity today in SL was a weak shower dancing through Storm Lake shortly after 6:30 this evening.

In any regard, next week continues to look promising with Gulf moisture being pulled up at the earliest late Tuesday evening/Wednesday morning according to the GFS. Monday doesn't look to be a great tornado threat (I'll likely eat these words) as winds aloft are shown out of the northwest. Tuesday morning into evening offers a vorticity maximum moving SE through TX, which might provide for some lift for some storms.

However, an impressive low swings through the Dakotas and Minnesota Wednesday through Friday, which would bring a cold front through the upper Midwest with a dryline likely across western KS/OK/TX during same time frame. This is likely the best time frame for severe weather as a negatively tilted trough moves in at 500 from the West Coast with the moisture conveyor belt up and running. This all based off 00Z GFS and will be interesting to view NAM/SREF data as it begins to enter into middle of next week tomorrow.

On tap for my Saturday (besides sleeping and looking at some weather data later today) is finishing up work on a poster for a weather conference later this month. Also, need to wrap up the text version of same research, although I'm not sure if I can do that all in one day.

Prayer Request:
While I am removing Greensburg from the requests, they still need our prayers as they are still cleaning up the town and residents are likely still picking up pieces.

Current Date/Time: May 31, 2007, 11:13PM
My Current Location: Storm Lake, IA

First model runs of June are in! The joy!

The low that has been plaguing the northern Plains with instability showers and thunderstorms the last few days has decided to stay for the weekend. It appears the end of this short work week will end on a soggy note, but the upper low will depart by Monday.

Tomorrow’s severe weather for the upper Midwest will be mostly a hail and wind threat (Iowa) as a line of storms rumbles through, but down in the Southern Plains, isolated tornadoes cannot be ruled out along the dryline and the triple point (cold front/dryline/outflow boundary)

Next TWISTEX deployment will likely be middle of next week as strong negatively tilted trough kicks out into the Plains. Surface features at this time don’t look outstanding though as the cold front that will push through the Midwest this weekend will still be draped across the South and the East on Tuesday with reinforcing cold front dropping South into the Northern Plains. The concern here is what will be the return of Gulf moisture with a forecasted developing low over the Rockies next Wednesday.

Wednesday’s Results: None

TWISTEX Status for Thursday: No-Go
TWISTEX Status for Friday: No-Go

Prayer Requests:
• Please continue to pray for the residents affected by the early May tornadoes, including Greensburg, KS.
--------
Views expressed are solely those of the author, Andrew Ansorge, and may not represent the views of National Geographic and their crew, Iowa State University and the Iowa Board of Regents, Tim Samaras and his crew, other Iowa State University students, or other TWISTEX members.