brettjrob Posted May 27, 2012 Share Posted May 27, 2012 Anyone still for the strong tornado threat tomorrow? SPC has dropped that kind of wording now and parameters aren't exactly crazy tomorrow. At least the NAM is coming back around on reasonable moisture, now painting 65-68 F dew points near and ahead of the triple point. The setup is far from spectacular, and most years in late May these would be dime-a-dozen in between the "real" setups. Still, it's something, and probably has a shot of impressing beyond expectations (e.g., a strong tornado or two in NW KS or SC NE). With another unseasonably-quiet pattern progged for the medium range, I have a hunch the atmosphere may try to compensate and keep the May tornado count from being too anomalously low. Link to comment Share on other sites More sharing options...
thewxmann Posted May 27, 2012 Share Posted May 27, 2012 Yesterday had a hell of a lot more going for it then you're giving it credit for. Yeah, 700mb T wasn't ideal, but given the rest of the atmospheric profile, it was just fine. The triple point was very well-defined yesterday and featured very strong sfc convergence, especially because a slight bulge in the dryline had developed by about 2100 UTC just south of it. Add in that the warm front was parallel to right-turning storm motions and you had a recipe for what evolved evident hours in advance. The triple point made yesterday what it was, no doubt. I'll give it that. It was evident early on that the TP would be the sweet spot yesterday. But man, that 500mb map from yesterday. It's usually a capped look. H7 T's were not only high, they were increasing with time. Heights were neutral-rising. It's not hard imagining a bust if convergence was slightly weaker, if boundary layer temperatures and/or moisture were just slightly lower, or if a fortuitous impulse was not there. These things are always borderline. Link to comment Share on other sites More sharing options...
thewxmann Posted May 27, 2012 Share Posted May 27, 2012 BTW, NW of Lacrosse is EF2, as is Russell. A satellite tornado went right through Lacrosse and that has been rated EF1. Link to comment Share on other sites More sharing options...
brettjrob Posted May 27, 2012 Share Posted May 27, 2012 This isn't a great photo, especially thanks to the bastard who dared drive down the main drag with his lights on , but just to give an idea of what the RSL tornado looked like at ropeout: I would estimate it stretched at least 2-3 miles in the horizontal, snaking high over I-70 (and oblivious drivers, no doubt) in this shot. I'm facing SSE. The tornado crossed US-281 about 1.5 S of I-70, and it looked like the funnel met cloud base ~a mile N of the interstate. Link to comment Share on other sites More sharing options...
JoMo Posted May 27, 2012 Share Posted May 27, 2012 That was a really long rope. Link to comment Share on other sites More sharing options...
brettjrob Posted May 27, 2012 Share Posted May 27, 2012 Regarding tomorrow: the more I look at it, the more I feel this might well be the best Plains chase day of the month, on paper. (Granted, if the Rush Co. storm yesterday had gone bonkers during daylight, I wouldn't be saying that). The one glaring question is how quickly and badly moisture will mix out near the triple point. There's going to be a transition to linear mode during the evening at some point, but even a two-hour window of discrete supercells during the 21z-00z period could squeeze out some nice results. Deep-layer shear, including directional, is very nice for late May. Low-level shear may be underestimated if winds back more than explicitly modeled near the triple point, which seems a good bet. Initiation is not really a concern, for once, as the trough axis finally clears the Continental Divide. It will all come down to T/Td obs during the afternoon. I'm honing on a box bounded by WaKeeney-Beaver City-Red Cloud-Russell. If 3-4pm obs there are in the ballpark of, say, 86/67, I'll be quite optimistic. If they're more like 93/64, as the RAP would suggest, it will be a much tougher sell. Link to comment Share on other sites More sharing options...
Minnesota Meso Posted May 27, 2012 Share Posted May 27, 2012 Wondering what the SPC will do for tomorrow, stay with a slight risk, or upgrade it to Moderate risk here in MN. My best guess is to stay with Slight risk, tornado risk looks no better 15%, but either the hail or wind, if not both will go 30% hatched IMO. If they see a chance of 45% hatched for wind or hail it could go to Moderate, but I think both we stay in the 30% hatched thus leading to a high end slight risk area. Anyone have any thoughts? Link to comment Share on other sites More sharing options...
Buckeye05 Posted May 27, 2012 Share Posted May 27, 2012 Wondering what the SPC will do for tomorrow, stay with a slight risk, or upgrade it to Moderate risk here in MN. My best guess is to stay with Slight risk, tornado risk looks no better 15%, but either the hail or wind, if not both will go 30% hatched IMO. If they see a chance of 45% hatched for wind or hail it could go to Moderate, but I think both we stay in the 30% hatched thus leading to a high end slight risk area. Anyone have any thoughts? I think they could bump it to MDT judging by wind and hail potential. Tornado threat looks pretty marginal though. However I am wondering if the storms moving though MN right now could leave boundaries and enhance the tornado potential there a bit. April 3 went from 2% day to a significant event due to that sort of thing. Probably just wishcasting at this point though. Link to comment Share on other sites More sharing options...
Minnesota Meso Posted May 27, 2012 Share Posted May 27, 2012 I think they could bump it to MDT judging by wind and hail potential. Tornado threat looks pretty marginal though. However I am wondering if the storms moving though MN right now could leave boundaries and enhance the potential there a bit. April 3 went from 2% day to a significant event due to that sort of thing. Probably just wishcasting at this point though. Really to be honest with you, I think the tornado threat could be real, but what really concerns me is a widespread wind event here in the metro, most places have seen between 4" to 8" of rain the last few days, a wide spread strong wind event could lend itself to many mature trees coming down on homes, cars..etc...Either way the result could be nasty. Link to comment Share on other sites More sharing options...
andyhb Posted May 27, 2012 Share Posted May 27, 2012 Not sure if the RAP is overdone, but the latest runs have an uncapped and large area of 3000-4000+ J/kg of CAPE across MN and WI by 18z tomorrow...impressive... Link to comment Share on other sites More sharing options...
andyhb Posted May 27, 2012 Share Posted May 27, 2012 They went MDT... Snippet from discussion: SUBSTANTIAL SEVERE WEATHER POTENTIAL IS FORECAST TO EVOLVE THIS AFTERNOON -- FOCUSED ON THE CENTRAL PLAINS REGION -- AS A SHORT-WAVE TROUGH/VORT MAX ON THE SERN FRINGE OF THE LARGER-SCALE UPPER SYSTEM EJECTS EWD. AS THE PRE-FRONTAL WARM SECTOR DESTABILIZES -- BECOMING MODERATELY UNSTABLE DURING THE AFTERNOON...EXPECT THE APPROACH OF THE UPPER SYSTEM TO AID IN WEAKENING THE CAP -- AND EVENTUALLY SUPPORTING ROBUST STORM DEVELOPMENT. WHILE STORMS SHOULD DEVELOP ALONG THE FRONT FROM THE UPPER MS VALLEY SWD -- ACCOMPANIED BY POTENTIAL FOR LARGE HAIL AND DAMAGING WINDS...THE MOST CONCENTRATED THREAT APPEARS TO EXIST INVOF A WEAK SURFACE LOW PROGGED TO MOVE ACROSS KS/SRN NEB DURING THE AFTERNOON. HERE...50 TO 60 KT SWLY MID-LEVEL FLOW SPREADING ATOP LOW-LEVEL SLYS WILL RESULT IN SHEAR VERY FAVORABLE FOR SUPERCELLS -- AND RESULTING POTENTIAL FOR VERY LARGE HAIL AND DAMAGING WINDS. WHILE A FAIRLY DEEP BOUNDARY LAYER AND 20 C OR MORE SURFACE DEWPOINT DEPRESSIONS EXPECTED...TORNADO THREAT SHOULD REMAIN LIMITED OVER MOST OF THE AREA...THOUGH A COUPLE OF TORNADOES WILL ALSO BE POSSIBLE IN PROXIMITY TO THE AFOREMENTIONED SURFACE LOW -- I.E. ACROSS PARTS OF NEB AND KS. Link to comment Share on other sites More sharing options...
Minnesota Meso Posted May 27, 2012 Share Posted May 27, 2012 Not sure if the RAP is overdone, but the latest runs have an uncapped and large area of 3000-4000+ J/kg of CAPE across MN and WI by 18z tomorrow...impressive... I did not research it, but I think the Nam showed precip in the warm sector at 21z just north of the TC metro Link to comment Share on other sites More sharing options...
Minnesota Meso Posted May 27, 2012 Share Posted May 27, 2012 45% hatched hail Wow that equates to the Moderate outlook Link to comment Share on other sites More sharing options...
MnWeatherman Posted May 27, 2012 Share Posted May 27, 2012 Well, today was a disappointment. Decided to sit and wait at freeman, SD for most of the day. I'm starting to get burnt by all these busts... Crossing my fingers for tomorrow. Link to comment Share on other sites More sharing options...
mnchaser Posted May 27, 2012 Share Posted May 27, 2012 Well, today was a disappointment. Decided to sit and wait at freeman, SD for most of the day. I'm starting to get burnt by all these busts... Crossing my fingers for tomorrow. It is getting kinda outta control! We played it safe going into it knowing there was a strong cap we left later on trying not to repeat a 5-5-12 day all over again! Got to about Worthington sat for awhile to ponder the data and realized things were looking pretty slim..turned around and went home. It was kinda comical when that marginal cell went up in Nebraska and seeing all the chasers on SpotterNetwork rush to it lol. Tomorrow looks bleak up here, North Central Kansas looks to have the best shot of anything tornadic today. Link to comment Share on other sites More sharing options...
MnWeatherman Posted May 27, 2012 Share Posted May 27, 2012 It is getting kinda outta control! We played it safe going into it knowing there was a strong cap we left later on trying not to repeat a 5-5-12 day all over again! Got to about Worthington sat for awhile to ponder the data and realized things were looking pretty slim..turned around and went home. It was kinda comical when that marginal cell went up in Nebraska and seeing all the chasers on SpotterNetwork rush to it lol. Tomorrow looks bleak up here, North Central Kansas looks to have the best shot of anything tornadic today. Also saw that, lol. Thought about going for it, if it were to get stronger, but died off after awhile. 4km WRF-NMM popping up cells just west of me. Seems plausible given the rapid erosion of the cap and nearby triple point. Link to comment Share on other sites More sharing options...
Indystorm Posted May 27, 2012 Share Posted May 27, 2012 It seems strange that there is a moderate risk but no public outlook at least as of 8 a.m. CDT. Link to comment Share on other sites More sharing options...
jpeters3 Posted May 27, 2012 Share Posted May 27, 2012 It seems strange that there is a moderate risk but no public outlook at least as of 8 a.m. CDT. uh, it came out at 755am CDT... Link to comment Share on other sites More sharing options...
Indystorm Posted May 27, 2012 Share Posted May 27, 2012 uh, it came out at 755am CDT... Maybe it is just my computer but I don't see the public svr wx outlook on the main SPC weather page as is usually the case in situations like this or a multi media briefing. I thought they would be issued for all moderate risks. Link to comment Share on other sites More sharing options...
Jim Martin Posted May 27, 2012 Share Posted May 27, 2012 We go from not much from 22z today... To explosive development one hour later. Should be an interesting day in the moderate risk area. Link to comment Share on other sites More sharing options...
brettjrob Posted May 27, 2012 Share Posted May 27, 2012 Well, the RAP is absolutely brutal with mixing this afternoon in the MDT risk area, and would render what I said last night laughable. I did a quick comparison between its 9-12 hr. forecasts from yesterday morning and the sfc obs, and found that it did have a dry bias over parts of OK/KS centered on the I-35 corridor. I would bet that it's over-mixing things over a decent chunk of the pre-dryline environment today, but by how much? Even a compromise between the widespread 55-60 F Td's on the RAP vs. 65-68 F on the NAM would yield values too low to get excited about tornado potential, given 88-93 F temps. Another concern is that the otherwise-primed target area is a bit west of where short-term modeling has consistently over-mixed the BL this year, so I can envision the 21z surface map showing mid 60s at SLN and CNK, but only upper 50s farther west where initiation will occur. The 12z OUN/FWD soundings aren't exactly encouraging regarding moisture quality an depth, either. I'm having trouble getting myself out the door as of now, and may hold off another hour or two to see if any improvements are afoot then. Link to comment Share on other sites More sharing options...
Superstorm93 Posted May 27, 2012 Share Posted May 27, 2012 Should quiet the MN folks for a while... Link to comment Share on other sites More sharing options...
Buckeye05 Posted May 27, 2012 Share Posted May 27, 2012 Dewpoints are depressing this afternoon. High bust potential today imo. Link to comment Share on other sites More sharing options...
mnchaser Posted May 27, 2012 Share Posted May 27, 2012 Dewpoints are depressing this afternoon. High bust potential today imo. They are much better up here in MN, Glad everyone opted for a Nebraska and Kansas target, I'm going to be all alone up here! Link to comment Share on other sites More sharing options...
Minnesota Meso Posted May 27, 2012 Share Posted May 27, 2012 They are much better up here in MN, Glad everyone opted for a Nebraska and Kansas target, I'm going to be all alone up here! 81 over 72 here in the northern TC metro Link to comment Share on other sites More sharing options...
tornadotony Posted May 27, 2012 Share Posted May 27, 2012 Dewpoints are depressing this afternoon. High bust potential today imo. Not for hail and wind so much, which, mind you, is what the moderate risk is for... Link to comment Share on other sites More sharing options...
Minnesota Meso Posted May 27, 2012 Share Posted May 27, 2012 cloud tops west of the twin cities have been as high as 28k ft, currently they are around 25, having a hard time breaking the cap, but when the cold front starts to approach the cap should weaken rapidly. VWP's out of MPX show calm winds above 12k, that should change in the next hour or two. Surface winds currently ssw, I would like to see those come around to sse, but may not happen, wind profiles out of FSD are very unidirectional out of the sw. Link to comment Share on other sites More sharing options...
David Reimer Posted May 27, 2012 Share Posted May 27, 2012 Dewpoints are depressing this afternoon. High bust potential today imo. Not good for tornadoes, excellent for monster hail and strong bow echos. I'm targeting Pratt, KS Link to comment Share on other sites More sharing options...
baroclinic_instability Posted May 27, 2012 Share Posted May 27, 2012 The speed max is just ejecting into SE Colorado High Plains...shows up nicely on WV. Should begin to see that secondary lee low tighten up farther S across KS...as well as the low level flow to back to southerly across eastern NE soon. Not sure how big if a hail show we are looking at...shear vector parallel to front and a surging front late would suggest this turns into a line shortly after initiation. I could see more of a wind threat if anything with large hail early...especially given the relatively deep inverted Vs. MN flood threat looks legit...especially with the copious rainfall the past week. Link to comment Share on other sites More sharing options...
MnWeatherman Posted May 27, 2012 Share Posted May 27, 2012 Convective plume in west-central MN, right along the triple point. The temp is in upper 70s, with upper 60s dew points, with a few 70° readings. This area, IMO, seems like the only spot that may produce tornadoes in all the 5% area... once initiation starts. Link to comment Share on other sites More sharing options...
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