nrgjeff

Today should mark the beginning of a 7-10 day stretch of surprisingly good storm chasing so late in the season. Thank the Nino to Nina transition, reaching neutral by late spring. Jet stream is active from the Pac NW across the US/Canada border. SPC already has the box out for western Minnesota today. Distinct boundary offers a focal point for severe, perhaps tornadoes on a dominant cell. Wednesday looks like a good upslope day, from the boundary in northwest Kansas north into the upslope flow. Thursday should be active on the warm front in Iowa, but maybe sloppy. Friday could be the day-before-the-day in MT/ND. Saturday should be active with a defined system approaching North Dakota. LLJ responds to upper jet and moisture returns quite well. I would use Thursday to reposition for Friday, after the Wednesday target. One could argue Friday is the repo day if going from Iowa Thursday to ND Saturday. If I were really chasing I would try upslope Wednesday, repo Thursday, and be in MT/ND Friday. Don't forget the passport Fri/Sat. Sun/Mon the Saturday system lumbers northeast into Canada probably becoming meridional. Later next week another system is possible across the far northern US and/or on the Canadian border.

GFS ensembles and CFS weeklies should be available at NCEP or many free models sites. Euro ensembles and Euro weeklies usually require a subscription somewhere. Euro op is starting to show up on a few free sites though.

Both weeklies and some of the 11-15 day ensembles are starting to hint at a new trough in the Rockies. Some have it unseasonably south. Others have things northern Plains and Upper Midwest which is June Nino-ish. Either way a chaser has to like about a third of the way into June. North would be nice with smaller crowds.

Next week looks like some good storm chasing. Note I do not call for a big outbreak, but I see 3-4 chase days out of a 7 day stretch. Rockies trough is forecast to send out shortwaves for several days. Yes, sounds like SPC is teeing up. Sunday starts with short-wave ridging early but some southern stream jet energy pokes out over the Panhandles late. LLJ responds too. If enough moisture can return in time Sunday evening could be an appetizer. Monday and/or Tuesday should have some better moisture and wind shear, plus some surface boundaries to locally enhance SRH. Upper level wind fields are not particularly strong, but likely will be plenty for late May. Quality LLJ is forecast away from contamination. Plus no VBV is forecast. One can be reasonably confident that holds with WSW flow upstairs and open waves. If a stronger wave ejects Monday, then Tuesday could be an in between day. Tough to discern this far out. Wednesday or Thursday could go again. New shortwave is shown coming out sometime the middle of next week. Timing is variable run-to-run but the broad pattern is consistent. Perhaps Friday or Saturday something else comes out. For now I like Sunday-midweek.

Don't forget to check winds upstairs. Look for southwest winds at 500 mb and 200 mb; west is even better at 200 mb. Look for nearly straight south at 850 mb, SSE is even better. I wrote a lot more in the May 7-9 severe thread page 26. At any rate the 12Z GFS in on board with winds, and with low press and fronts in the central Plains. Lots of rain shown before peak heating, but it is days away...

In addition to climo improving for severe after April 15, a couple other reasons to be optimistic are noted. Pacific upstream situation should favor a transition to warmer zonal flow in the US, at first. Some of the weekly models hint a West trough later in April. Need to avoid the tear drop trash and get some real open troughs. Time will tell.

I agree with Andy. Models are probably too pessimistic due to clouds etc. However the system is very dynamic. It should over achieve. Look at the wind fields. SPC is right to go ENH for sure.

Ice storms are stressful at work so I voted no; otherwise, I would have voted light since it is pretty. On days you can get sunshine while ice is still on trees, it is a spectacular treat. Still, the day before was probably stressful at work, lol. Here is a detailed rank of weather for me: 1. Snow in the South - very special 2. Tornado chasing - never being chased 3. Hail, medium size - exciting but not damaging 4. Snow in the North - more routine 5. Sleet, with the hope of lightning 6. Straight line thunderstorm wind esp with good shelfie 7. Warm Sunshine 8. Dust storm - interesting but annoying 9. Heavy hoar frost or rime icing is pretty. 10. Freezing rain can be pretty. Worst weather: Flooding impacts too many lives too much. Low overcast is depressing with no precip.

Also, some model agreement is noted in the 11-15 day for a trough West ridge Midwest pattern. I'm talking end of August and first few days of September. Hints of both upper and low level jets responding is shown in the Plains some of the days. Northern stream staying active through the summer helps the case.

This week is well handled in the short-term thread. After perhaps a relatively quiet 6-10 day, always some little local events in June, things may become more active again the middle of June. MJO is forecast to perk up in Region 4-5 by some models. Others have the MJO going back to sleep. Region 4-5 is favorable for a Pac NW trough. Even the models that put the MJO back to sleep introduce the said trough late in the 11-15 day period. All 3 agree on the feature. Jet stream energy punches into the Pac NW. Downstream ridge is depicted over the Upper Midwest. All of the above is favorable for the northern High Plains. EDIT: June 4 probably needs to be added to the short-term thread dates. 12Z GFS/Euro both paint excellent chase days this Wednesday and Thursday. Moderate speed shear combines with high CAPE and quality low level turning. EML may finally limit junkvection and promote more chasable events.

Ian you are golden. GFS stands for curse words. Euro and Canadian keep warm sector in tact for next weekend. Both their ensemble products maintain the North American pattern into the 11-15. Euro weeklies and CFS maintain into early June. I think you get all that data, but just a reminder everything but a crappy op model is on your side. I'm reluctantly letting this weekend go based on long travel and odds. Tornadoes will verify today and tomorrow, but terrain issues are noted in NE/SD today. Tomorrow target is so diffuse I'm not betting a 700-800 mi drive on anywhere. However for those already out there, tomorrow will verify. Kansas sups may have issues with poor inflow and/or bad hodos. Eastern OK could go on the OFB with excellent shear but terrain could be an issue. Bust activity: Talimena Parkway is a gorgeous scenic drive. Lead up to Memorial Day could end up wet too. However I know this weekend is a mess. There is still hope for next. Much of next week a broad West trough is in place ejecting occasional short-waves. Each time a 250 mb jet comes out the LLJ at 850/925 mb responds. If a main target rainout, upslope would probably verify. It will work out one way or another. Late May climo favors tornadoes. Beyond that a recurving Pacific typhoon could have impacts. However Euro/Canadian ensembles do not echo GFS ens pattern change. Either the typhoon is not strong enough, or it just gets absorbed into a mid-latitude system within the already established buffet line of Pacific systems. Good to go!

Word of caution: Recurving Pacific typhoon, SOI drop, and increasing GLAAM could mix up the pattern. All that said the ensembles may be jumping the gun. Looks good through Memorial Day, even if more upslope than classic.

Yes all 3 ensemble suites hint at a less meridonal upper level jet ahead of Memorial Day. They also show LLJ responses. This coming weekend of May 15-16 will be great; but, if you can't make it the lead-up to Memorial Day looks good too. Why do I have faith in a 10 day forecast? It is late May in the Plains. If all else fails and/or the trough teardrops again, upslope would verify. This is not like forecasting snow in the South. This is peak tornado season in the Plains.

This weekend does have a better trough than last models verbatim; that said, last week was a respectable sequence. Memorial Day could repeat yet again after these. Why all the bickering? State of the season remains strong. First, if the EML fails and/or ATMO gets overturned by morning convection, May climo indeed still favors chasers. One would simply modify target and/or philosophy. Shift south if maintaining OFB/DL reasoning. Shift north for broad upslope flow. Saturday worked out great for both. Second, this sequence less midday rain is forecast. Keep in mind morning rain ending is good for OBFs. That could change, but so far it does not look as messy. If upper winds are straight south and/or veer/back no problem. Just target upslope where one would expect 850 winds to be screaming and quite backed. Finally, the ceiling remains high if the short-wave can come out at the right time and with some southwest (vs south) winds upstairs. Last time never looked high risk at any point, due to teardrop trough, but there it at least a path to another MDT for tornadoes on Saturday. Similar thoughts are valid for the trough leading up to Memorial Day. Don't worry, be happy!

Rest of this week has indeed perked up. Wednesday through Saturday look like a possible sequence. While there may be a less active day Thursday or Friday, not both, Wednesday and Saturday are looking pretty good. Next week may set up again starting around midweek. Currently looks like a little shorter wavelength trough but with a better straight westerly jet stream. Jury is out on strength and low levels. Finally the following week of May 18th all ensembles (GFS, Euro, Canadian) have a new big western trough. Southwest below normal heights signal is consistent. Also the East keeps verifying warmer, which is another plus in the US weather pattern.

Though we have not had a large outbreak, events and even sequences are happening. While the hemispheric weather pattern is far from ideal, it appears to be quite adequate. Could get southern Plains action next week, but need better winds upstairs 500/250 mb. Model 850 and even 925 look okay, but out of sync with what little jet stream energy comes out. I think later weeks will be better. Mid-Atlantic ridge hints at returning the following week after Mother’s Day Midwest trough. Such a ridge was featured 3 weeks ago when the season suddenly woke up with a bang from Kansas to Illinois. Then the Pacific jet stream is shown strengthening out over the ocean early to mid-May. West Pac has been blocky too. Whether a stronger Pac jet stream benefits or hurts depends on how it comes into the US West. Kind of like shuffling the cards though, it certainly brings new hope. Also warm waters off the Baja Peninsula are starting to ease, relative to normal, which could help more West troughs – iff we the atmo responds in time. Concern about northern stream lifting to Canada early is noted, but southern stream is fine. Could get Panhandle magic and High Plains beauties in later weeks. Thoughts on remainder of the Chase Season: The biggest synoptic outbreaks seem to be 15 April to 15 May. Are we at halftime? However those are not necessarily the best chase days due to storm speed, chaser convergence, and one-and-done. May is the peak, a blend of synoptic outbreaks, local set-ups, and perhaps a sequence. We are just in the first quarter. For a chase trip (chasecation) one could argue peak is actually 15 May to 15 June; we are pre-game. After Memorial Day outbreaks trail off, but sequences seem to peak late May. Then in June 1-3 day subtle set-ups can be a chaser dream. Much of the heard is out of time and funds; it is north of the herd bullseye; and, the meteorology can be superb. June offers guaranteed moisture, reasonable storm motion, and little risk of cold front intrusions. Lovely weather is forecast over large areas this weekend. Enjoy it and stay optimistic about stormy weather later in May.

Welcome to the Board! It is a little quiet right now, but will perk up with chances of severe weather. Gardening and Outdoors threads are fairly active though. Enjoy!

Thank you for creating this sub-forum. I'd often post two distinct discussions for west and east of the Apps. Now they can both be posted in their respective sub-forums. It'll be clearer for both. Keep in mind it's perfectly acceptable to post in another sub-forum, long as we match the region. In fact it probably adds value and knowledge. They do that a lot for Northeast storms crossing multiple regions. In spring I live in Central/West due to the severe and since I'm from there. However now the Tennessee Valley is home, and I'm glad we have a sub-forum. Cheers!

Maybe I'm old school, but I still like Unisys Weather for a mix of layperson and met charts. Good jumping off point, especially in the Plains, but useful nationwide is the OU Met page som.ou.edu/wx and no I did not go to OU. If you do not have access to the European model www.meteoblue.com has an approximation I believe. It is a European weather site. Click on North America weather maps and go from there using the tabs at the top of the chart. This is anecdotal only, but I think the clouds/rain is loosely based on European output. Enjoy!