Central/Western Medium-Long Range Discussion

[jojo762]

Surprised by the lack of talk regarding early next week and into early May. Obviously some spread on the ensembles and amongst the global OPs, but early May looks active fellas. 

[Weatherdemon]

1 hour ago, jojo762 said:

Surprised by the lack of talk regarding early next week and into early May. Obviously some spread on the ensembles and amongst the global OPs, but early May looks active fellas. 

Felt a twinge if hope reviewing models today

[WhiteoutWX]

No one wants to jinx it given the past few years...

[nrgjeff]

ECMWF verbatim May 4 will be Bennington 4.0 but it's Day 10. EPS and GFS keep the train rolling in the 11-15 day. Weekly models (no skill after week 3) have more action the rest of May. MJO and AAM trends are forecast to be friendly. We'll see.

One example of nice real data is Japan's Himawari satellite loop. West Pac convection is starting to lose influence as the Indian Ocean flares up. Buffet line of mid-latitude systems is noted from East Asia across the Pacific Ocean.

[SluggerWx]

Next weekend and into the week of 5/20 continue to show promise for the last few days on the GFS.

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[jojo762]

1 hour ago, SluggerWx said:

Next weekend and into the week of 5/20 continue to show promise for the last few days on the GFS.

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And on the CFS, GEFS, and EPS as well. Numerous different "types" of severe setups being shown, which I suppose is typical for late May anyways. 

Either way, mean S/W flow for a few/several days + favorably progged moisture trajectories = at least several quality chase days somewhere across the Plains. 

[nrgjeff]

The period from May 17/18-ish for 7-10 days looks very active in the Plains. This 500 mb chart forecast is accompanied by strengthening upper level jet stream from the WSW and LLJ response most days from the straight south. Tee. It. Up!

[DanLarsen34]

I’m a little surprised this forum has been quiet. The long-range models are suggesting we could be looking at the most active stretch of severe weather we’ve had since 2011. 

Right now, the models are depicting several days of favorable flow across the plains from May 19-26 with ample moisture and instability.

Obviously, there’s still a ways to go, but I’ve seen some of the most reserved meteorologists I know starting to highlight this period as potentially being a May 2003 or May 2008 sequence if everything comes together. 

[WhiteoutWX]

I think the models have consistently shown an overall favorable pattern but have been jumping around regarding the ceiling of the period. Could be something great or could be something more along “average” climo for this time of year. Depends on how the trough orientation sets up and the individual waves eject out into the plains. Models have occasionally shown some blockiness over the eastern US as well which could complicate the setup some. Still far enough out that I’m just in a wait and see mode. 

[jojo762]

Wouldn’t be totally surprised to see the SPC delineate an area for Saturday (May 18) in the next D4-8 outlook. Looks pretty promising on the euro and GFS. Given what models show now, would certainly expect a higher-end ceiling. 

[nrgjeff]

Indeed SPC started with Friday (Sunday Day 4-8). Looks like they left Saturday for post-MCS meso-scale details. Friday could be more active up on the WF. I'm afraid dews are not high enough on the DL; but, anything can happen on the High Plains.

More importantly, it appears we have reeled in the weeklies and ensembles into the Day 5-7 forecast. That's an accomplishment compared to the last few years. Remember the epic flip last year? A perfect pattern out weeks 3-4 turned into trash by week 2. Not this year!

Complex signals add confidence to model forecasts. Pacific jet extension will set the table. Then a +AAO and -NAO combo this time of year actually helps keep a west trough and systems going through the Plains. NAO is not the same animal as back in April. +AAO helps avoid that awful GL trough no longer progged. Boundary layer moisture has improved the last few runs, not a surprise really.

This weekend should be just the start of an active 7-10 day period, perhaps as long as two weeks. It's on!

[WhiteoutWX]

GFS and ECM still have large differences regarding the trough amplitude in the Fri-Sun period. One (GFS) being much more low amplitude/zonal mid level flow while the other has much more meridonial flow over the plains as the trough ejects. I think for me the GFS would be preferred for more discrete activity and also would have a better shot at a multi-day threat. We know meridonial flow often gets messy. Either model would imply at least one good day during the period though. After that we may have a couple day break before trough reloads to the west.

Also, GFS is showing the dryline getting pretty far east into Oklahoma and I would almost guarantee it verifies further to the west, which would bring it underneath more favorable wind fields than currently progged. Something to keep in mind. 

[jojo762]

As far as mid-long-range forecasting goes for chasers and enthusiasts, mid/late May this go-around looks potentially epic for just about anyone who enjoys severe weather. Multiple large troughs (leading to potentially BIG days, and also allowing for surprise "the day before the day" type events.) 

Opportunities for severe weather appear to start this coming friday as the western CONUS trough begins to eject into a richly moist and unstable western/central plains atmosphere characterized by mid to upper 60s dewpoints and steep mid-level lapse rates, producing CAPE profiles upwards of 3000+ J/KG. Timing of the wave will be critical to how friday evolves. Given an amply strong low-level jet of 40-60kts (and 30-40kts by as early as 21Z), and favorably timed wave on the models, friday seems to have obvious severe weather and tornado potential.

Likewise, how Saturday evolves is heavily dependent on several factors: 1. Wave timing (and orientation), 2. convective evolution of previous day, 3. the potential for early-day convection that could washout the atmosphere. If the wave slows down a few hours (which would likely mean somewhat mitigated potential for Friday), Saturday has big time potential written all over it. 

Sunday appears to be a lull day explicitly on the globals *as of now* which could change as the trough evolves throughout the next few days... Followed by potentially a day or two more of significant severe weather potential into the week of the 20th.

 

Important to not get too bogged down into too many details or specific model runs this far out, just watch for trends. Stay tuned.

[Indystorm]

The ERTAF researchers are talking about the period from May 19-25 in tonight's outlook as being synoptically similar to historically significant May tornado outbreaks.

[jojo762]

14 minutes ago, Indystorm said:

The ERTAF researchers are talking about the period from May 19-25 in tonight's outlook as being synoptically similar to historically significant May tornado outbreaks.

http://atlas.niu.edu/ertaf/

For those who might wonder what he is referring to: 

Forecast Discussion: The long advertised "forecast of opportunity" has now entered the ERTAF week 2 forecast period. We will continue our week 3 forecast of AA for week 2, with all signals in the analog and dynamic solutions suggesting a rather robust 5-day period of severe convective storms centered on 20 May. In fact, the latest 00 and 12z suites of GEFS dynamic solutions suggest this period maintains a 1+ sigma STDA for 12z-12z sum of CONUS supercell composite parameter for the duration of this 5-day period. While mesoscale details for tornado favorability cannot be clearly determined at this time, the synoptic scale will be supportive of a regime analogous to historical significant tornadoes in May.

For week 3, we see many signals that this week 2 AA period could re-load after some breaks between systems emerging on the west coast. Thus, signs would point to at least an 'A' period for week 3, but we will maintain low confidence at this time and upgrade next week if needed.  

Forecasters:   Gensini, Gold,  Sirvatka

[nrgjeff]

Chasers rejoice; the GL trough is even weaker and less important now! Friday it now appears ample moisture will be up on the dry line. Low level winds are backed a bit. Uppers are SSW to SW, and probably enough turning with height. 

Saturday remains TBD based on mesoscale factors. Upper winds get a little meridional in the Plains. However if an outflow gets down to Texas, winds show more turning upstairs on the ECMWF. I'm not sure whether to hope for that though. Texas tends to be messy.

Sunday could be a break. Might need a rest and or reposition day.

Monday through Wednesday I figure two more chase days. I doubt all 3, but who knows. Looks like another trough comes out Monday; placement is TBD between Iowa and Kansas. Tuesday or Wednesday looks like another. Models still sorting out which, and there is a slight chance all 3 days go.

[OUGrad05]

15 hours ago, jojo762 said:

As far as mid-long-range forecasting goes for chasers and enthusiasts, mid/late May this go-around looks potentially epic for just about anyone who enjoys severe weather. Multiple large troughs (leading to potentially BIG days, and also allowing for surprise "the day before the day" type events.) 

Opportunities for severe weather appear to start this coming friday as the western CONUS trough begins to eject into a richly moist and unstable western/central plains atmosphere characterized by mid to upper 60s dewpoints and steep mid-level lapse rates, producing CAPE profiles upwards of 3000+ J/KG. Timing of the wave will be critical to how friday evolves. Given an amply strong low-level jet of 40-60kts (and 30-40kts by as early as 21Z), and favorably timed wave on the models, friday seems to have obvious severe weather and tornado potential.

Likewise, how Saturday evolves is heavily dependent on several factors: 1. Wave timing (and orientation), 2. convective evolution of previous day, 3. the potential for early-day convection that could washout the atmosphere. If the wave slows down a few hours (which would likely mean somewhat mitigated potential for Friday), Saturday has big time potential written all over it. 

Sunday appears to be a lull day explicitly on the globals *as of now* which could change as the trough evolves throughout the next few days... Followed by potentially a day or two more of significant severe weather potential into the week of the 20th.

 

Important to not get too bogged down into too many details or specific model runs this far out, just watch for trends. Stay tuned.

You may be able to update that avatar pic sir!  Take April 14th down and go with something else :)

I agree not to get too hung up on any one model run, look at the broader trends.  

I do think its interesting that you think Sunday could be a lullday.  I hope so since I have significant family obligations that day, but I'm not sold that's the case.  In fact, I think it has rather high end potential S of I70 and along and east of 35 at this point.  Hope you're right in this case sir.  

[cheese007]

D6 risk contour added

[jojo762]

As Jeff mentioned next week looks really good. GFS and Euro have had some **remarkable** outputs for Monday or Tuesday next week, like 80kt at 500mb atop massive CAPE and intense LLJ remarkable...(but honestly you should expect it with a seasonally anomalous trough like this)... Still jumping around a bit as to which day will be better. Not sure how much value you should put into outputs like that at Day 7-9 range, likewise its still enough for SPC to mention something about D9 in their outlooks. 

This weekend *could* be an appetizer for whats to come. As of now, definitely plan on making the 4+ hour drive out to WC/W KS for Friday. 

[jojo762]

00Z GFS continues the general idea that Friday could be a big day, followed by a conditionally chaseable day on Saturday, with a lull on Sunday followed by a potential big-league severe weather setup on Monday. 

[OUGrad05]

On 5/12/2019 at 6:26 PM, jojo762 said:

As far as mid-long-range forecasting goes for chasers and enthusiasts, mid/late May this go-around looks potentially epic for just about anyone who enjoys severe weather. Multiple large troughs (leading to potentially BIG days, and also allowing for surprise "the day before the day" type events.) 

Opportunities for severe weather appear to start this coming friday as the western CONUS trough begins to eject into a richly moist and unstable western/central plains atmosphere characterized by mid to upper 60s dewpoints and steep mid-level lapse rates, producing CAPE profiles upwards of 3000+ J/KG. Timing of the wave will be critical to how friday evolves. Given an amply strong low-level jet of 40-60kts (and 30-40kts by as early as 21Z), and favorably timed wave on the models, friday seems to have obvious severe weather and tornado potential.

Likewise, how Saturday evolves is heavily dependent on several factors: 1. Wave timing (and orientation), 2. convective evolution of previous day, 3. the potential for early-day convection that could washout the atmosphere. If the wave slows down a few hours (which would likely mean somewhat mitigated potential for Friday), Saturday has big time potential written all over it. 

Sunday appears to be a lull day explicitly on the globals *as of now* which could change as the trough evolves throughout the next few days... Followed by potentially a day or two more of significant severe weather potential into the week of the 20th.

 

Important to not get too bogged down into too many details or specific model runs this far out, just watch for trends. Stay tuned.

Good call on Sunday, I'm now onboard with your position that it appears to be further east and not something I'm going to chase.  

[OUGrad05]

SPC now has an enhanced risk in the Eastern TX Panhandle, Western OK and W/C Kansas and into Central Nebraska.  I'm not super impressed with the shear profiles on the GFS at this point, CAPE will be more than adequate to support big hailers.  Plenty of time for GFS to come around a bit on the shear.  It's adequate no doubt but not great.  Euro looks more impressive.  

Monday and Tuesday of next week look positively crazy.

 

[StormChazer]

Day 8 risk on the SPC. Don’t see that too often.

[pbrussell]

Time to get out the 1995 fully loaded red dodge truck with liability only insurance.

also probably time to make a dedicated thread 

[JMT417]

3 minutes ago, pbrussell said:

Time to get out the 1995 fully loaded red dodge truck with liability only insurance.

also probably time to make a dedicated thread 

Yep and Yep

[yoda]

52 minutes ago, StormChazer said:

Day 8 risk on the SPC. Don’t see that too often.

There's a risk each day as well... don't see that at all before either I believe.  I think this is like the 3rd time ever SPC has had a Day 8 risk?

[cheese007]

Tomorrow marks two years since the last high-risk day. Wonder if we'll break the streak in the next couple weeks or go for a record-long streak in 20? 

[CheeselandSkies]

12 hours ago, cheese007 said:

Tomorrow marks two years since the last high-risk day. Wonder if we'll break the streak in the next couple weeks or go for a record-long streak in 20? 

If Monday holds serve from the 00Z suite, I suspect it will break the streak.

[CheeselandSkies]

Which it did...and largely busted as we know.

If Monday holds serve from the 00Z suite, I suspect it will break the streak.

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[MNstorms]

Monday is a day to keep a look at imo. 6 days out and the models are in decent agreement it seems.