5/27/06 FCST: MN/ND/MT

NAM, GFS, and GEM pretty similar with the potential set-up for Saturday. Some uncertainty as to how Friday night evolves into Sat. LLJ will crank up overnight and convection is likely to develop in ND and spread east. NAM and GEM have a nice H70 shortwave cruising into MN via southwest flow. The GEM is most agressive with developing convection with this feature. NAM and GEM part ways a bit Sat morning but both of them along with the GFS maintain an H70 wave in central MN during the afternoon. CAPE, shear (below H50), and resultant EHI look phenonenal if storms can break the cap/become surface based during the afternoon. NAM is the most bullish on this. Various NWS AFDs are not buying into this scenario by letting the cap win. H70 temps will be hovering between +9 and +12 which is not unbreakable and may actually be preferred as storms would have a better chance of being discreet. The real death cap for MN looks to hold off until Sunday. Flow above H50 is less than ideal so one one need to be an early arrival or hope for backbuilding. Perhaps a 'stealth' tornado set-up which happens up here frequently enough to not ignore the possibility.

Storms are likely to fire in Montana during the afternoon. A few supercells are possible given northeasterly upslope flow with impressive upper level wind field. Storms should congeal into an MCS which would plow through portions of ND during the evening and overnight. Some storms may fire up along the surface boundary snaking across central ND during the afternoon. No shortage of backed low level flow and instability with this boundary. Still a cap here and upper flow is is unimpressive (upper flow now looks a bit better on the 12z NAM)... After all that we'll see what boundaries are sitting around for Sunday.
 
It's actually looking more conducive as the 06z wants to convect by 21z this afternoon along the surface boundary. Capping has been getting weaker and weaker on subsequent runs, but the H70 temps are still ranging from 9 to 12'C... CINH on forecast soundings is, however, looking better with smaller values. Instability and shear won't be issues at all with this setup with EHI's at 6+ over some areas and CAPE's well over 3000 J/KG. As Justin has pointed out the cap will likely make or break this event, but it could certainly turn out to be a fun day around the area.

I'm pretty much a go today, after an extended morning nap, of course. I have to work this evening, so I won't be able to go far, but even so, the 06z NAM is providing a window of opportunity, so I'm going to take advantage of that. As of now, I'm planning on a target of near Gilby or possibly a point somewhat further westward where deep-layer shear looks slightly better.

Interesting too, to see that the SPC has a 10% hatched area for TOR probs for the area just NE of the surface low... right about in the area I was looking. An interesting (and possibly volatile) situation for this time of year in these parts!
 
TARGET: MINOT, ND TIME OF DEPARTURE: 7 AM In North Platte, NE this morning after a nice stormy day yesterday. Sampled storms at Salina (am), Limon (pm) and Hill City. Frequent lightning till midnight. Will head north all day on Rt. 83 and probably stay in Bismark, ND tonight. Concerned about linear forcing today, but at least there should be storms along the slow moving front. TM
 
This morning's RUC isn't making things any easier, refusing to give us precip up north but instead suggesting that western MN will be the only place experiencing storms before dark. The NAM does not agree, holding off until 00z in central and southern ND. The GFS still holds to north central ND.

I see an interesting faint east-west OFB on radar sinking south in far eastern ND that bears watching. Other than that, no obvious boundaries.

The current widespread dewpoints of only 55-59F across ND, SD and MN are the most troubling thing so far.
 
This morning's RUC isn't making things any easier, refusing to give us precip up north but instead suggesting that western MN will be the only place experiencing storms before dark. The NAM does not agree, holding off until 00z in central and southern ND. The GFS still holds to north central ND.

I see an interesting faint east-west OFB on radar sinking south in far eastern ND that bears watching. Other than that, no obvious boundaries.

The current widespread dewpoints of only 55-59F across ND, SD and MN are the most troubling thing so far.
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Looks like 60-64 right now in Minnesota. not much mention 'officially' of severe wx there yet, but the 09Z
RUC has convection breaking out by 21Z, along with some pretty impressive parmeters. will be interesting
to see what the models do with this mornings upper air data. MPX is 9 deg at 700 this morn.
 
Currently mid-upper 50F tds across central and eastern ND... http://www.rap.ucar.edu/weather/surface/20..._metars_pir.gif . At any rate, the NAM and RUC both show a favorable thermodynamic environment across ND late this afternoon. The NAM forecasts widespread 4500-6000j/kg of surface-based CAPE, but that is based on ~65-68 tds, which the NAM rapidly advects northward through the afternoon, which strongly destabilizes the lower levels (with insolation likely occuring across the area once the clouds move/mix out) and eroding negative buoyancy. The NAM also shows strong 0-6km deep-layer shear developing across northern ND by 00z -- e.g. 40-45kts -- which could support organized supercells. I don't see why we can't get a solid ~4000j/kg of sbCAPE by the afternoon in portions of ND, assuming we do see 62-65 tds, and given the favorable low-level parcel trajectories -- this is quite possible.

At any rate, I'm currently in Aberdeen at the Comfort Inn... I'll probably head north towards Harvey and Devil's Lake within the next hour or so, which is only a 4hr drive from here. I think the potential for a tornadic supercell or two today in central and northern ND looks pretty good.
 
I'll likely be keeping an eye on parts Iowa later today. Midlevel flow is stronger according to profilers than was shown in the model forecasts, though morning RUC seems to be getting a better handle on that. This should allow sufficent deep layer shear for storm organization over section of southern MN, western WI, and northeastern IA later today with potentially favorable low-level parameters. Biggest holdup I see right now is whether ongoing convection in southern IA will weaken and allow OB to shift north under better midlevel flow. RUC does not seem to be treating ongoing convection well - so little faith there. Morning NAM seems to have this a little better actually - and it shows a rather interesting environment coming together by this afternoon. SPC doesn't seem on board with this yet - but maybe they are not as impressed with the potential.
 
I guess I'm going to try for an outiside chance at something near Rapid City SD. Ruc, ETA, and last night's WRF all want something to go there. I figure the 700 temps aren't any worse than they were here yesterday. Ruc has a 981 sfc low to the west of there with backed sfc flow backing up the Black Hills. Add in high temps and maybe, just maybe something to call a storm. Not hoping for a lot, but those days often seem to offer the best displays(or no convection at all, lol.....which I'm not sure I've had a complete clear sky bust yet..hmmm).

Good luck to those out today. I'd be sure to call ahead for your motel rooms if you aren't already. Super 8 south of Hill City(forget the town name) was full at 8 last night. I called Colby and they had a couple. I get here and they were full.
 
I'm not sure where I'm going to head, if I even leave this afternoon... Dewpoints are already up to 61 here in GFK and SBCAPE's continue to rise according to the latest mesoanalysis. The 12z NAM wants to convect things just before 00z and also weakens the capping from the far northeast down towards Bismark. Ideally, I'd love to be sitting on the stalled out surface front, pretty much where this surface vorticity corridor is indicated on the mesoanalysis... But, I won't be able to do much driving today.

Main question for me is, whether to stick around here in GFK and wait for things to come to me, or to travel west-southwest to be in better position for possible initiation. If I do travel, my initial target will be near Cooperstown, possibly as far west as Carrington. I'm gonna have to be choosy (unfortunately) so I'll have to monitor radar/satellite trends and leave as soon as I see any CU fields building. I have a fairly narrow window to chase today... so we'll see how it goes.

Good luck to those out there, today!

By the way, if anyone is within range, the Grand Forks skywarn/ares net (it should be up this afternoon) can be found on 146.34 or 146.94 MHz.
 
Good to see updates on the situation in ND. Way underrated chasing up there. I was also glad to see Matt mention the frequency for the Grand Forks SKYWARN operations. It's always good to know which frequencies are actually in operation (things can change from time to time). Just to clarify a little bit, the frequency to listen for would be *146.94*. That frequency is the output of the repeater, and that's the one you would hear from perhaps a 50-100 mile radius. 146.34 will disappoint as that's the repeater input frequency and the only way you'll hear anything there is if you're within 5-15 miles of the station actually transmitting. The repeater does all the heavy lifting, as it were.

I'm sure this link has been passed along plenty of times here, but I'm going to do it again, because it will probably help someone out right now. Here's a great resource: http://www.caps.ou.edu/~kbrews/spotfreq/ That link has SKYWARN frequencies for the entire US, and it's been updated as of this month.

I realize this isn't a forecast, but it's directly related to good info Matt passed along and I hope it doesn't ruffle anyone's feathers.
 
I noticed nobody is talking about Wisconsin and Minnesota tornado potential today,
but some about Iowa.

Current and forecast shear profile with mid level winds of 40 to 50kts from the
sw to west undercutting south winds with dewpoints 65 to 70, and high CAPE
4000-5000 J/Kg should be enough for some tornados this afternoon from parts
of northeastern IA, southeastern MN, and western WI.

Blue River Profiler looks impressive!
http://www.rap.ucar.edu/weather/upper/blr_wp.gif
 
The stage seems to be set for an active evening of severe weather across parts of North Dakota, with the potential for a few tornadoes likely looming. The surface boundary only slowly continues to creep along, with almost little movement with this feature that is draped from the Canadian border back southwest to just beyond Garrison and to the west of Hettinger. One would expect that it will continue to remain almost stationary with it paralleling upper level flow and little in the way of pressure falls or rises associated with the system the last few hours. Thus initiation should take place somewhere along where the boundary has set up shop presently, but when is the big question, with capping likely holding for a while yet. There was an 18Z sounding out of Bismarck today and it showed, not surprisingly, healthy instability courtesy of steep mid level lapse rates, but with a fairly stout cap to boot. The sounding had some -200 J/KG of MLCIN at that time and for what it's worth, the convective temp from the sounding was 96 degrees. That said, low level moisture continues to increase with lower 60s dewpoints now overspreading much of the warm sector with lots of insolation helping to eat away at the inhibition. One would think that while it may take some time, convergence along our front combined with this heating and increasing boundary layer moisture should weaken the cap for convective initiation. I would think that this could occur close to 23Z, although the RUC model begins convection around 21Z in the Harvey and Devil's Lake areas. The NAM (which remains overly enthusiastic with low level moisture) waits until the 00-03Z timeframe to develop convection.

Where initiation takes place is a good question. The cap is weaker in the Devil's Lake/Harvey area of north central and into northeastern ND, so we may see some growth here toward late afternoon, but in the same token strong heating in northern SD and southern ND may allow high based convection to take off and move northeastward, rooting in the boundary layer in south central ND toward evening, as well.

The prospect for some very large hail is huge as this is a great setup for that very thing around these parts. The 18Z BIS sounding showed only 6kts of 0-1km shear so the tornado threat is somewhat questionable, but we've seen backing winds since that time. There should be sufficient deep layer shear for supercells along and west of the front, and likely enough low level helicity in that area for isolated tornadoes. LCL's too are favorable for these parts. I do like the increasing dewpoints and backed flow, and the fact that the 19Z RUC analysis has 3km VGP's of 0.3 just to the west of BIS. I think this area may be another one to watch come evening and that output concurs.

All in all...it should be a good show. The WFO at Bismarck would greatly appreciate any and all real-time or delayed reports from everyone venturing these parts this afternoon. If you have the time and means, the spotter number is 1-800-247-0212.

P.S. Many rest areas in ND have wireless access, especially those along I-94. Be sure to check them out if you're looking for a good data stop.
 
Murphy strikes again! I had intended to start a 4 or 5 day mini-chasecation this morning, but a minor household emergency took priority. So, with that now taken care of and peace restored, I can return my attention to the weather, or lack there of. My initial target of ND is way out of reach, as is my secondary target of ne IA, so I’ll probably just sit today out and regroup for tomorrow. As this day continues to unfold, I am liking ne IA better all the time. With the earlier convection out of the way things are heating up in a hurry. There appears to be an out flow boundary left in the area, as well as decent LCL & LCF heights. A mid-level short wave and jet streak will help with forcing around 21z. The negative is that the area will be in the right entry region rather than the left exit, but things could be worse. My virtual target will be somewhere about 50 miles east of Mason City, IA. Good luck to all today and I’ll look to catch-up tomorrow.
 
Sitting in Jamestown ND with Joel Ewing. Watching convection on sat loop starting to fire up near Bismarck. SPC issued a watch box. Not ready to move yet. Hope we'll have a NOW thread going in a little while. I think we might have a party.

db
 
"I noticed nobody is talking about Wisconsin and Minnesota tornado potential today,
but some about Iowa. "

Not saying the wind profile is horrid - but there doesn't appear to be anything that screams tornado. MKX/GRB/LOT all issued TOR's on storms with fairly weak rotation and so far no reports that I can see...
 
Not saying the wind profile is horrid - but there doesn't appear to be anything that screams tornado. MKX/GRB/LOT all issued TOR's on storms with fairly weak rotation and so far no reports that I can see...
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As opposed to the 'rock star' environment in North Dakota? I think I'd take the marginal supercell in northern IL over what the envinronment in ND is dishing out right now. If the SPC graphics aren't totally out to lunch, effective shear on the warm side of the boundary in ND is maybe 30 knts, and storms there seem to have the appearance of that type of environment. If you are into parameters, the 6 pm mesoanalysis graphic has a STP of 4 in WI with CIN of -25 or less vs. STP of 2 in ND with CIN of -200. Given the former is also overlayed with 55 knts of effective shear , as well as some convective development in the area, - I don't see any real problem if folks wanted to talk about it. SPC may not be impressed, but maybe the atmosphere will feel differently. Could be, and probably is, that those graphics are out to lunch, but it just seems no worse for discussion.

Glen
 
"I noticed nobody is talking about Wisconsin and Minnesota tornado potential today,
but some about Iowa. "

Not saying the wind profile is horrid - but there doesn't appear to be anything that screams tornado. MKX/GRB/LOT all issued TOR's on storms with fairly weak rotation and so far no reports that I can see...
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I was talking about the tornado potential, not a nowcast. The sfc to mid level shear was
very good with high CAPE. The atmosphere rarely screams tornado, other than the rare
tornado outbreaks, and I was just noting the possibility.

The NWS rarely issues tornado warnings for weak rotation, so I would definately re-think
that one. :)
 
I watched those storms as they were warned and was very surprised... Rotation was on the order of 30kts, which by any definition is very weak. Not even wind damage was reported from the cells, so my interp stands ;>

What I'm saying is that rotational shear was nothing that would get me excited, speed shear usually doesn't do much for me unless it's extreme and/or combined with a very fat CAPE (which wasn't the case today.)
 
I watched those storms as they were warned and was very surprised... Rotation was on the order of 30kts, which by any definition is very weak. Not even wind damage was reported from the cells, so my interp stands ;>

What I'm saying is that rotational shear was nothing that would get me excited, speed shear usually doesn't do much for me unless it's extreme and/or combined with a very fat CAPE (which wasn't the case today.)
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Not to argue, but rotation at that elevation and distance from the radar would be enough to
suggest stronger rotation toward the ground along with a hook echo. Also what you are
seeing as rotation on secondary sources may not be the same as what the NWS see on the
screen. Plus the NWS can, on the fly, switch the storm motion vector, to see the rotation better
at his screen for better Storm Relative motion and rotation that does not show on your views.

I bet they were using other radars around the area and making a best guess. Point being the NWS
(that I work for) does not normally go with a Tornado warning with only "weak" rotation.

If you want to discuss this further please email me directly.
 
"but rotation at that elevation and distance from the radar would be enough to suggest stronger rotation toward the ground along with a hook echo."

I saw no hook echo, and the storm wasn't that far away from the radar locations.

"Also what you are seeing as rotation on secondary sources"

Not sure I understand what "secondary sources" are - I use Level II data which is the exact same data NWS uses (plus AE allows for volume display which NWS offices do not have ready access to.)

"Plus the NWS can, on the fly, switch the storm motion vector, to see the rotation better"

And so can AE.

"I bet they were using other radars around the area and making a best guess."

And so was I.

"Point being the NWS (that I work for) does not normally go with a Tornado warning with only "weak" rotation."

I think that sort of statement is not valid since many offices have different policies. My interpretation of the data was that rotation was incredibly weak, there were no boundaries anywhere in the vicinity on radar or satellite that could add a "local" rotation factor, and the environment really didn't support tornadoes.

And none were reported in the 3 warnings that I was referring to, not even wind damage ;>

"If you want to discuss this further please email me directly."

That was good - just making sure people are aware that you don't have to be sitting inside a NWS office to be able to analyze radar as good (or better than) a NWS met, since they don't have access to all the tools we do in the private sector.

- Rob
 
I don't find any of this "on-topic." Let's either get back to the forecast aspect to what's actually going on in ND, MN, or MT. If you want to discuss what's going on in Wisconsin or radar interpretation, either start a new thread, or move this over to the "Weather and Chasing" forum.

...my opinion, anyway.
 
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