Central/Western Medium-Long Range Discussion

[jojo762]

00z and 06z GFS produced some truly ridiculous soundings across Oklahoma on Wednesday... Euro shows something drastically different, so nothing to get too excited about *yet.*

[1900hurricane]

Yeah, I'm wary to buy into the recent GFS solutions for next Wednesday, especially with the depicted trough being so different from not just the other solutions, but its own ensemble mean as well. Very few individual ensemble members support the operational solution, so it's not likely the mean is becoming too washed out from dispersance either. That's not to say that it can't be a good severe weather day, but I have my doubts that the last few operational GFS solutions will verify the best for the possible event.

 

 

One day that I may begin to keep an eye on is the following Friday, April 21st. It's about 200 hours out as we stand right now, and anything this far out is a far cry from a guarantee as everyone pretty much knows, but the GEFS, GEPS, and EPS means all show troughs ejecting into the southern plains in this time period.

 

 

 

[jojo762]

SPC already including southern KS and central/eastern OK in a Day-8 outlook for Friday April 21st.

[Indystorm]

Yes, on occasion pattern recognition and parameters are such that you can identify a potential significant event a week out.  It is interesting that the normally conservative SPC would highlight this 7 days out.

[jojo762]

9 minutes ago, Indystorm said:

Yes, on occasion pattern recognition and parameters are such that you can identify a potential significant event a week out.  It is interesting that the normally conservative SPC would highlight this 7 days out.

I was shocked honestly given the degree of model spread in location/timing. But outlook area can/will be adjusted as we progress. 

[WhiteoutWX]

7 minutes ago, jojo762 said:

I was shocked honestly given the degree of model spread in location/timing. But outlook area can/will be adjusted as we progress. 

GFS says Wednesday may have some potential as well. It is further south than the Euro though for the entirety of the middle to end of next week.

[bjc0303]

1 hour ago, WhiteoutWX said:

GFS says Wednesday may have some potential as well. It is further south than the Euro though for the entirety of the middle to end of next week.

12z ECMWF while somewhat north/west for Wednesday suggests a similar level of severe threat.

 

Friday looks weird. CAA regime really ****s with cyclogenesis.

[hlcater]

1 hour ago, bjc0303 said:

12z ECMWF while somewhat north/west for Wednesday suggests a similar level of severe threat.

 

Friday looks weird. CAA regime really ****s with cyclogenesis.

That low up in near Sioux City is the key, that needs to lift north and/or be not nearly as strong with the CAA or else cyclogenesis will probably have a bit rougher of a time. 

[jojo762]

00Z GFS crashes the front from Wednesday's system much further south than any other run... which keeps the warm front much further south on Friday as well, which would suggest that any higher-end potential would be relegated to NE TX/DFW/red river valley instead of the I-35 corridor. Guess we'll see what the euro says. Still a week or so out, so obviously a lot will change and a lot of details have yet to be decided. 

[bjc0303]

Unless the 00z ECMWF is strongly different from the 00z GFS, I'd expect at least a 15% contour added for Fri. GEFS and now operational GFS has trended to a more substantial shortwave given weakening trend on dprog/dt with CAA regime in the wake of initial wave departing, allowing stronger lee-side cyclogenesis to occur as a result. 

 

Current progs have a weakly capped atmosphere by 21z with strong shear in place. Storms (verbatim) would probably organize pretty quickly, posing a tornado threat early. Weak low level lapse rates and increasing inhibition by 00z look to be an issue and we'll have to see how far that warm front truly makes it but trends are very encouraging! Will likely be a very strongly sheared environment.

[okiestormgeek]

A couple days ago I heard a lot of hype about potential severe weather on Friday the 21st here in the southern plains. Have model runs today backed off that? 

[jojo762]

2 hours ago, okiestormgeek said:

A couple days ago I heard a lot of hype about potential severe weather on Friday the 21st here in the southern plains. Have model runs today backed off that? 

Models still generally support severe weather somewhere across the southern plains on Friday. The extent of and location of any potential higher-end threats beyond a slight risk is still TBD. 

[Weatherdemon]

2 hours ago, jojo762 said:

Models still generally support severe weather somewhere across the southern plains on Friday. The extent of and location of any potential higher-end threats beyond a slight risk is still TBD. 

My confidence is low for my neck of the woods but if SC/SE OK looks good I might head down there.

The 27th-29th on the GFS was intriguing for C/E OK.

[jojo762]

21 minutes ago, Weatherdemon said:

My confidence is low for my neck of the woods but if SC/SE OK looks good I might head down there.

The 27th-29th on the GFS was intriguing for C/E OK.

Certainly is. Have to believe there is at least some potential for multiple days of severe weather during that time frame, perhaps a shot at a big-league day with the final (intense) trough. 

Notable that this trough on Friday still has a decent amount of potential given its strength, just a few things going against it right now. 18Z GFS was interesting. 

[bjc0303]

Operational runs don't offer much of a clue as to whether it's going to be active or not. Operational GFS could never show those troughs again.

 

What should be a welcome sight, however, is this:

 

This lends credence to the GFS, and the GEFS/EPS seem to be in very good agreement on that period being particularly active. Also fits the recurring pattern of active end of month into early month. GWO/AAM forecasts also indicate increased svr potential in that time frame. Do we get a bigly stretch? Tough to say obviously, but keep in mind that an active period in late April into early May can prove bad, given favorable interactions of the still-active jet with dewpoints beginning to commonly approach upper 60s and low 70s... 

[jojo762]

7 minutes ago, bjc0303 said:

Operational runs don't offer much of a clue as to whether it's going to be active or not. Operational GFS could never show those troughs again.

 

What should be a welcome sight, however, is this:

 

This lends credence to the GFS, and the GEFS/EPS seem to be in very good agreement on that period being particularly active. Also fits the recurring pattern of active end of month into early month. GWO/AAM forecasts also indicate increased svr potential in that time frame. Do we get a bigly stretch? Tough to say obviously, but keep in mind that an active period in late April into early May can prove bad, given favorable interactions of the still-active jet with dewpoints beginning to commonly approach upper 60s and low 70s... 

Seems like most GEFS members certainly have been keening in on some sort of big-time trough(s) entering the plains sometime in the late April-early may time. Haven't had a Synoptically-obvious big-time severe threat in the plains, that actually turned out to be big, in what seems like forever. Have had several "big" days in recent years, but none were really expected to be as big as they were. 4/14/12 was the last plains tornado-driven high risk, maybe we can change that in the next month and a half...

[bjc0303]

It is encouraging to see EPS/GEFS show mean western troughing through the end of month and early May..essentially the second half of fcst period is mean troughing to our west.

[WhiteoutWX]

28 minutes ago, bjc0303 said:

Operational runs don't offer much of a clue as to whether it's going to be active or not. Operational GFS could never show those troughs again.

 

What should be a welcome sight, however, is this:

 

This lends credence to the GFS, and the GEFS/EPS seem to be in very good agreement on that period being particularly active. Also fits the recurring pattern of active end of month into early month. GWO/AAM forecasts also indicate increased svr potential in that time frame. Do we get a bigly stretch? Tough to say obviously, but keep in mind that an active period in late April into early May can prove bad, given favorable interactions of the still-active jet with dewpoints beginning to commonly approach upper 60s and low 70s... 

I've been following the GFS AAM forecasts the past few weeks. It's consistently been showing a move towards Phase 1/2 space in longer ranges but so far that has yet to materialize. It is encouraging to see the GEFS/EPS in agreement for the time frame you mentioned though. Maybe this time the threat will have legs.

[jojo762]

00Z GFS trended a tad further north with the warm front, yet again, and shows an environment conducive to supercells capable of all severe-hazards from south-central Oklahoma southward into north-central Texas. Now within 100 hours of the event, and model variability continues to be prevalent...

[CGChaser]

8 minutes ago, jojo762 said:

00Z GFS trended a tad further north with the warm front, yet again, and shows an environment conducive to supercells capable of all severe-hazards from south-central Oklahoma southward into north-central Texas. Now within 100 hours of the event, and model variability continues to be prevalent...

Agreed, however I think the general area has been fairly consistent with that being SW/S OK into north-central TX, some minor shifts likely though N/S pending on location of wf.

[WhiteoutWX]

GFS and Euro continue to have large differences in trough placement/orientation for this Friday which has a large impact on surface low and frontal features. SPC has southern half of OK and north Texas outlooked but mentions the model uncertainty. Which model caves first?

[bjc0303]

2 hours ago, WhiteoutWX said:

GFS and Euro continue to have large differences in trough placement/orientation for this Friday which has a large impact on surface low and frontal features. SPC has southern half of OK and north Texas outlooked but mentions the model uncertainty. Which model caves first?

Would think the euro caves. GFS has been *very* consistent.

 

On the GFS.. this would favor discrete tornadic supercells by as early as 21-22z. Rapid storm organization would be likely with ample low-deep layer shear early on in the day. Could be a busy day if the GFS verifies.

[okiestormgeek]

2 minutes ago, bjc0303 said:

Would think the euro caves. GFS has been *very* consistent.

 

On the GFS.. this would favor discrete tornadic supercells by as early as 21-22z. Rapid storm organization would be likely with ample low-deep layer shear early on in the day. Could be a busy day if the GFS verifies.

What region would this be affecting? 

[wildwestpb]

1 hour ago, okiestormgeek said:

What region would this be affecting? 

Currently, SPC has the outlined area for Friday the southern half of Oklahoma (basically I-40 south nearly border to border) and all of North Texas from just west of Vernon TX, over to the ArkLaTex, and just north of DFW.

 

Per the AFDs this morning from both OUN and TSA - they believe the best/most likely threat for severe weather will be around the Red River Valley and to areas south. This will likely change somewhat as we get closer to the event, but this has been a fairly steady forecast from both offices for a few days now. We'll know a little better come tomorrow and Thursday I suppose.

OUN AFD -

As for severe storms, Friday, the impact of the ongoing convection
through the morning hours will have an obvious impact on where, if
any, suitable warm sector will reside and the potential for severe
thunderstorms. At present, given the various solutions, it appears
some recovery may occur along and near the Red River Valley,
including far southern Oklahoma into north Texas, with storms
primarily developing along the front as it advances south/southeast
overnight into early Saturday.

TSA AFD -

The frontal boundary will stall near the Red River Thursday night
and Friday as a potent upper system dives southeast from the
northern Rockies into the southern Plains. The severe weather risk
across our area does not appear overly high (upper low dig,
nothing big rule in place), especially if the favored ECMWF/UKMET
verify, with heavy rainfall and potential flooding being the
greatest concern, particularly across the northern half of our
forecast area. A wide range of temperatures will likely exist
Friday, with areas near the Kansas border struggling to reach 60,
while far southeast Oklahoma near the stalled frontal boundary may
approach 80.

[jojo762]

12Z GFS continues to maintain a significant severe risk from south-central OK southward into northern TX.... current indications from the GFS are for MLCAPE values of 2000-2800J/KG, 0-6KM shear of 60-70kts, and 0-1KM SRH on the order of 300-400m2/s2 across the main threat area by 00Z.

[bjc0303]

Just waiting for the GPS to trend to the euro at this point... but the GFS has been very consistent as has its ensemble

[CGChaser]

12z euro has the wf farther north Friday afternoon. Definite shift north w/ regards to track as well. low placement on 00z run near little rock @06z saturday, 12z run has low ~Tulsa.

[WhiteoutWX]

1 hour ago, CGChaser said:

12z euro has the wf farther north Friday afternoon. Definite shift north w/ regards to track as well. low placement on 00z run near little rock @06z saturday, 12z run has low ~Tulsa.

Looking at 500 mb the 12z Euro and GFS are almost identical at 96 HR. The Euro is maybe a bit further north than the GFS but very close. 

[Superstorm93]

24 minutes ago, WhiteoutWX said:

Looking at 500 mb the 12z Euro and GFS are almost identical at 96 HR. The Euro is maybe a bit further north than the GFS but very close. 

 

 

[bjc0303]

To sum up the EPS and ECMWF for the medium/extended range.... Bigly