State of the Chase Season: 2019

Jeff House

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Jun 1, 2008
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ECMWF ensembles and Weeklies look fine mid May. The 11-15 day does not show classic southwest flow. However it does not show death ridge or SE trough either. Systems are forecast per 500 mb spaghetti plots and surface lows from individual members. Flow is choppy somewhat zonal, not bad mid-May. ERTAF might nail it with Average. Note the climo is good.

Weeklies go on to keep it active the week of May 13. CFS Dashboard (Chiclets) want to get things going around May 12 again, this after the week 2 action shown. Much of it has issues because it's not classic southwest flow outbreak. However in mid-May one has to think tornadoes will happen. Especially by May 15 climo ramps up; so, it only takes an average pattern to be good.
 
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Jun 3, 2009
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Stuttgart, Germany
One week out until we arrive. With the latest GFS 12Z run coming in, I am getting increasingly confident that we will at least not see a stout blocking pattern. It seems that the gulf remains open and there in no crashing coldfront in sight atm. Everything else remains to be seen in the next couple of days.
 
Dec 21, 2006
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Sugar Grove
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I think the NHEM pattern is coming together for a pretty outstanding May for severe convective storms in the US (especially in comparison to the last few years!). While the first two weeks should see activity biased to the southern Plains, large areas of negative OLR anomalies have been showing up due to twin hemisphere cyclones since ~ April 20th. Should this turn into an active MJO and propagate across the Maritime Continent, it would have mouth watering for the back half of May. I am assuming we will introduce a week 3 'AA' via ERTAF this coming Sunday...
 
Thanks for your thoughts, Victor. We look at the MJO (and many other things, of course!) for our long-range forecasting operations and have been following the development of this MJO episode closely. There are suggestions of moving towards Phase 2 by mid-late May, which some studies have indicated a significantly higher chance of violent tornado outbreaks.
 
Jun 3, 2009
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Stuttgart, Germany
Ok, I guess I need to take back that "no crashing coldfront" part because the models now persistantly see one pushing the good air back to the TX coast line. Seems like a slow start to our chasecation. But well, first chase day is still 6 days out so this is not carved in stone just yet.
 
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Jan 14, 2011
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Still in standby mode here with no sign of an impetus for my departure to the Plains. Models are having trouble locking in on a pattern. The trend has been for an active southern stream similar to what we saw in April. If that comes to pass, it won't be dead, but most action will be well south of the Red River in less than ideal terrain. At least that cold front next week isn't shown going all the way to the Yucatan - yet.
 
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Warren Faidley

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May 7, 2006
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Yes, this constant pattern "flip-flopping" is not impressing me -- GFS, ECMWF, etc. The NCEP Ensemble is pretty solid until about May 10. It's still way too early to say either way, although I'm starting to think plan X33 (Northeastern Colorado chase year) could be a reality, unless the moisture gets pushed to the Equator... then it's plan H33 (hurricane season). :rolleyes:

Edit. After a momentary loss of consciousness, the 18z GFS has swung back to keeping the moisture in place for the mid+ May period.
 
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Jeff House

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Some 11-15 day concerns are noted. So it might be slow after next week, but I don't think over.

The 16-20 day, perhaps sooner, a new trough may enter the West. CFS shows more southern stream. ECMWF ensemble and weeklies have the new trough as early as May 17, give or take.

With an active Pacific jet, no reason to doubt a new trough. Some -AO worries are noted though. Maybe no big Plains outbreak, but I expect mid-late May chase days.
 
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Apr 24, 2015
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Grand Rapids, Michigan
Yes, this constant pattern "flip-flopping" is not impressing me -- GFS, ECMWF, etc. The NCEP Ensemble is pretty solid until about May 10. It's still way too early to say either way, although I'm starting to think plan X33 (Northeastern Colorado chase year) could be a reality, unless the moisture gets pushed to the Equator... then it's plan H33 (hurricane season). :rolleyes:

Edit. After a momentary loss of consciousness, the 18z GFS has swung back to keeping the moisture in place for the mid+ May period.
This confluent jet pattern over the wester CONUS is just making the future evolution of the pattern over the east super sensitive to initial conditions. Strong zonal 850hpa baroclinicity but very ill-defined jet pattern upstream just spells low forecast skill it seems. Can only pray that closed SE low dragging northerlies to the Gulf doesn’t appear again in later runs. I get spooked when both the GFS and ECMWF happen to show it on the same run.
 
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Apr 24, 2015
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Grand Rapids, Michigan
Hopefully once the pesky East Pacific ridge breaks down there will be better predictability in the 5-8 day range. There's no hint of it happening before the 12th or so. The period between now and then is anyone's guess sadly. Forecast skill is so low due to the current pattern.
 
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Apr 23, 2016
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Cedar Rapids, IA
The supposed pattern change keeps getting pushed back. :(
I've found this to almost always be the case whenever a specific pattern change(either positive or negative) is modeled in the longer range(3-5+ weeks). In almost every case, models are too zealous in breaking down the current pattern, which holds on longer than anticipated. Usually, the advertised long range pattern change comes at some point, but just in a smaller degree and later than was initially modeled (Unfortunately, I don't really know why this is the case, but have noticed that it often is). These pattern changes can also be staggered for eternity and eventually disappear(a la 2018). Though I agree with the majority in thinking that the show starts when we get that Pacific jet extension ---> I'm optimistic for mid/late May.
 

Kai-Asle

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Mar 17, 2006
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We will be flying to Denver May 8th and have 14 days net for chasing. SPC is now mentioning the possibility of zonal flow through next weekend. I hope we will see a return to western troughing by the time we arrive. By Thursday next week I might start to believe what GFS and ECMWF show for the time of our arrival.
Hi, Jörg.
We will fly in from Denmark on May 15th. Hope to see you out there. Who are you chasing with this year?
Kai-Asle
 
Jun 3, 2009
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Stuttgart, Germany
Hi Kai-Asle,

great to hear. I envy you a little bit for that later start date. We can´t shift unfortunately.

The models are in generally good agreement that this coldfront will stall somewhere off or at the TX coast on Friday. Let´s hope for a quick recovery after that. Next week seems to look better for us.
 

Jeff House

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Jun 1, 2008
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The period starting May 15 or 16 going through May 20-22 continues to have great potential. I'm skipping over this week, which will now be handled mostly in the Target Area.

New Indian Ocean convection is going, not a tropical cyclone for once. Looking for it to push out across the Maritime Continent. Chasers hope this creates a jet extension then retraction; and, around May 15-16 a new West trough. Complicated forecast though as West Pacific convection will probably keep the southern stream going too.

By the second half of May moisture can recover much faster even in spite of southern stream shenanigans. Unlike last year, the Plains is quite moist too. Finally both sets of Ensembles support the new trough idea.
 

Jeff House

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The 11-15 day forecast looks excellent this morning. Some GL troughing is noted, probably due to West Pac. However, the IO induced jet extension is on track. Should favor the Southwest trough as well. So, by late May we don't stress over GL troughs. We chase Southwest troughs coming into the Plains. I'm feeling great about May 17+.
 

Dean Baron

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Sep 25, 2006
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It looks like people's prediction of a more active second half of May might be coming true. Finally starting to see some big potential towards the end of the GFS's range (albeit still a long ways out) starting around the 17th. Looks like the jet stream could still be digging out of the SW beyond the GFS's range. If this actually verifies, it could be a very active end to the month. A long ways out so it's hard to get too excited, but when trying to plan a multi day trip it is encouraging to see some signs of life finally in the deterministic models.
 
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Oct 10, 2004
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Madison, WI
The 11-15 day forecast looks excellent this morning. Some GL troughing is noted, probably due to West Pac. However, the IO induced jet extension is on track. Should favor the Southwest trough as well. So, by late May we don't stress over GL troughs. We chase Southwest troughs coming into the Plains. I'm feeling great about May 17+.
You do if you live in the GL and would like it to not be 50s and showery when it's almost June...and would also like some local/regional setups to chase.
 
Apr 24, 2015
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Grand Rapids, Michigan
You do if you live in the GL and would like it to not be 50s and showery when it's almost June...and would also like some local/regional setups to chase.
Might have to wait for a La Nina spring for that. :( Good instability in the southern GL is hard to come by without a strong SE ridge. Gulf-Coast riding mega-MCS always does a number on instability east of the Mississippi. By late June we can generate good instability locally over the corn belt, but by then you have to prey the dynamics haven't gone to shit.
 

Todd Lemery

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Jun 2, 2014
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GFS and CFS are coming into agreement on the 17th-22nd period. There’s enough moisture returning from the gulf and the 500 and 850 winds come to life, especially starting the 19th. A couple of lows sliding through during that time period equals smiles. I did notice relatively uncapped air in the middle of the period, but it’s starting to look up.