One of the ways we arrive at a Forecast

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By KSStorm Media

(Note: This post originally appeared May 10,2014. Updated March 11, 2018)
I know we reach several levels of weather interest through our postings, so I thought I’d do one solidly pointed at weather geeks…a post of the full chat transcript of Scott and Matt’s discussion this morning (which took 90 minutes) on the risks, models and eventually the target box for May 11, 2014. Note: the model graphics linked in the chat are not current. The links we were using are overwritten with each model run.

tl;dr version: good chance for large hail and a few tornadoes in a box Matt will identify in the outlook. (Ed.: due to site changes in the past 4 years, the resulting Outlook was not preserved)

(03:04:38) Scott: Hey there. I have yet to do model scans…why don’t we chat in about 15 minutes?
(03:05:31) Matt: Sounds good.
(03:34:11) Scott: Okay…GFS. are you seeing a chance for 2 rounds in Wichita? GFS STP for 12z: Craven for 12z New STP for 0z Craven for 0z
(03:35:21) Scott: puts a bullseye on Woodward at 0z; new STP for that hour does, too.
(03:36:19) Matt: I think the tornado threat is increasing in an area of KS/OK from US 50 to I-40 Sunday evening and night.
(03:36:45) Matt: Given the shear, could even see a cyclic, long-tracked tornado.
(03:36:45) Scott: 4000 SBCAPE just S of ICT
(03:37:22) Matt: NAM in the same ballpark, 4200-4500 j/Kg CAPE
(03:37:52) Matt: As for two rounds, I don’t see that right now. We will likely be capped after 06z Sunday.
(03:38:22) Matt: Our window here looks to be between 8p-1a for storms as that moisture surges west.
(03:39:01) Scott: It was surprising to see the values on the Earl’s graphics, that’s why I said something. I’m having browser caching problems and not getting as efficient a picture as I’d wanted to.
(03:39:16) Scott: What models are you leaning on in this round?
(03:40:37) Matt: yeah they are impressive. I’m leaning with the combo of the NAM/Euro. Thought the GFS wants to crash the front through central Kansas faster…thats something that will need to be watched, but not a scenario I’m buying at the moment.
(03:41:05) Matt: both NAM/Euro keeps the front held back in response to the low deepening in the E TX Phdl.
(03:41:08) Scott: Just scanned through Sim Reflectvity on NAM, which paints a tail-end charlie situation for ICT near o3z
(03:41:53) Matt: yeah…the 4KM NAM has a nasty line of supercells out there beginning at 21z
(03:42:33) Scott: 1.3″ PW, up to 1.8 west of Salina,,,
(03:43:44) Matt: yeah…we are finally going to have moisture to work with.
(03:43:48) Scott: (I’m working in NAM right now…) 850 winds seem a bit veered for my liking. they aren’t southeast anywhere a 0z
(03:45:06) Scott: Weak shortwave at 700mb — west of OMA to about SPS
(03:46:44) Scott: That shows up in 700 temps, too…either side of it 700 temps are 4 degrees cooler than away from it….and into the 8C range, which is certainly breakable by now, usually.
(03:48:17) Scott: Looks like max 500 wind is about 3 hours upstream at 0z, flow is divergent.
(03:49:01) Scott: There’s a pocket of 120kt wind at 250, right at the leading edge of the 500 speed max.
(03:49:25) Matt: thats at 7pm SUN?
(03:49:43) Scott: Yes. Viewing NAM from COD via Skip talbot
(03:50:54) Scott: I-135 corridor MUCAPe 3500, narrow region of no capping…just in front of the 700mb shortwave.
(03:51:14) Matt: that makes sense
(03:51:54) Scott: kict forecast skew-t does not back the surface wind, thouh…it’s still from the south.
(03:52:27) Matt: yeah…you’d think that in response to the low to the southwest of us, that the flow would be more backed,.
(03:53:03) Scott: Doesn’t seem to be, at least north of the Red River.
(03:53:14) Matt: interesting
(03:54:47) Matt: that’s probably gonna be what gets us…is the flow not being backed more.
(03:55:35) Matt: Still though, looking at this…it wouldn’t take much in the storm environment to get it backed.
(03:55:36) Scott: Yeah, GFS has best backing I’ve seen foo far (haven’t looked at Euro), but the upper fields are out of sync.
(03:55:41) Matt: yeah
(03:56:29) Matt: then there’s this for posterity
(03:58:07) Scott: Yeah, go back to that 0z sounding and move it 3 hours later. A tiny bit of surface backing as Sim reflectivity paints the tail end charlie. Looping hodo, but not terribly long and it’s about 15 degrees too far clockwise for my liking.
(03:59:03) Scott: Hadn’t been to SREF, that was my next stop.
(03:59:19) Scott: 45% chance Hutchinson to Clay Center.
(03:59:28) Scott: at 03z
(03:59:30) Matt: yep….just getting ready to say that
(04:01:01) Scott: ICT sitting on edge of a 90% prob of Craven/Brooks SigSev >40000 from 0z-03z
(04:02:38) Scott: 70% SigSev >60,000 @0z. Tiny 70% SigSev > 60000 at p28 @03z
(04:02:51) Matt: wow
(04:04:20) Scott: BUT…SigTor >5 movs through the area too early…between 12z and 18z
(04:06:32) Matt: the SREF has a bubble of >6 SIG Tor moving through S KS from 00z-06z
(04:07:40) Scott: Yeah…mostly 03-06z
(04:07:48) Matt: yeah
(04:09:07) Scott: I’m satisfied with moisture this go-round. 65+ in the eastern half of the state starting at 15z. (SREF)
(04:09:15) Scott: That oughta cook into some instability.
(04:09:27) Matt: yeah it will…SREF paints 4k+ CAPE.
(04:11:02) Matt: I’m thinking the area with the highest tornado threat is in the US 50 to I-40 corridor in the 00-06z time frame, concur?
(04:11:21) Scott: Looks like highest Prob MUCAPE >3k is at 21z GBD to WWL to SLN/HUT/P28
(04:12:17) Scott: I’d agree with that, but I’ve been focusing on KS. thinking the triple point play or tail-end charlie are the best solution for my goals
(04:12:29) Matt: gotcha
(04:12:40) Scott: I’d confine those to the space between US-50 and US-60
(04:12:56) Scott: TP on the south edge, Charlie in the center.
(04:13:12) Matt: ok
(04:13:19) Scott: Do you agree?
(04:13:36) Matt: yeah I do…40 maybe too far south,
(04:13:55) Scott: I still need to scan Euro.
(04:15:30) Scott: Dew Point depressions: what values are we looking for in a tor forecast?
(04:16:19) Matt: generally less than 15 degrees between temp and dewpoint.
(04:17:59) Scott: Ok, Euro paints 15 from DDC to p28; 10 from Kinsley to Ellsworth to Hutch
(04:18:06) Matt: nice
(04:19:12) Scott: Euro puts good backed surface winds in the 183/50 corridor at 0z
(04:19:51) Scott: 850 winds also backed N of DDC
(04:20:12) Scott: 50kt bubble over the area of backed surface winds.
(04:20:21) Matt: whoa….
(04:21:40) Scott: 700mb is 40kt over most of the state; a bubble of 50in Harper/Sumner/Cowley, and another just upstream of the DDC-area bubble at 500 — Gage to Woodward or so.
(04:21:57) Matt: that would jive because the euro breaks out a supercell in the 183/50 corridor at 00z
(04:22:19) Matt: so we have a good wind fields…the 850 get into the 60-70 kt range after sundown in S KS
(04:23:13) Scott: That’d be right at the leading edge of the 700 10-12C line. 12c to the SW of the line, the Sup would be in 10c air…a little warm for my liking, but lower levels appear to have the forcing.
(04:24:50) Scott: Best surface shear under the sup near Larned/Kinsley, but 70kt 0-6 bulk shear is northwest of that, not on top of it.
(04:25:39) Scott: None of the slices look good for shear except surface-850.
(04:25:55) Matt: this is at 00z?
(04:26:07) Scott: …in the area we’ve been discussing. Nice values, but they are significantly displaced from the storm.. Yes, 0z
(04:26:46) Matt: the Euro is a tad slow with moving the storm system bodily in this run…slowed it down since last night.
(04:28:21) Scott: 2500 CAPE under no CIN. LCL heights good, around 500…but 1500 LCLs are coming in fast from the SW…at 0z they are in the US 500/US 283 corridor.
(04:29:21) Matt: thats the dry punch coming in
(04:30:51) Scott: Shear gets really uncoordinated at 06z. Huge o-3km in central KS, best 0-1km in eastern KS. Guess that’s indicative of hailers by that time.
(04:31:23) Matt: yeah it would be…or line segments
(04:33:53) Scott: SO, based on a blend of the NAM/GFS/Euro/SREF, looks to me like the box is U183 (maybe 283) to I-135, U50 to U60, 0z in the west, 3-4z in the east. Best TOR in the U56 to U160 corridor….maybe as far west as Kinsley early, but east of Pratt for storms on the effective WF. Need to watch storms coming out of the Woodward to Alva area up to 3z for carrying TOR risk into Harper/Sumner/Sedgwick.
(04:34:54) Matt: that jives with my thinking as well.
(04:35:18) Scott: Best hail risk U281 to I-135, north of 54, after sunset?
(04:36:16) Matt: yeah but keep in mind the front will be sagging south as well.
(04:36:40) Matt: for sure during daylight hrs W of K-14.
(04:37:06) Scott: Ok, guess I missed that. I thought north of the TP we were looking at a more ENE line, with a more easterly motion of the whole system than a southeasterly motion.
(04:37:50) Matt: yeah you’re right…
(04:37:57) Matt: I’m getting tired lol
(04:38:45) Matt: I have the timeframe for severe from 3p Sun to 3a Monday
(04:39:31) Matt: by then thinking we could actually be looking at heavy rain being the main threat.



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