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andyhb

Central/Western Medium-Long Range Discussion

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Best way to describe evolution of GFS runs would probably be...wacky. Highly inconsistent and lots of spread among ensemble members. Interested in whether the euro continues its consistency.

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Looks like Tuesday (2/28) is another potential event that fell apart as it got closer, basically nothing now on the models, at least for the plains. This was a theme last year, hopefully it  doesn't become one this year. 

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7 hours ago, jojo762 said:

Looks like Tuesday (2/28) is another potential event that fell apart as it got closer, basically nothing now on the models, at least for the plains. This was a theme last year, hopefully it  doesn't become one this year. 

It's still early in the season. It's not particularly common for events in the Plains or Ohio Valley through about mid-March, aside from outlier outbreaks. Limited moisture is a glaring issue, unless you get a string of anomalously strong surface lows diving north into the Upper Midwest.  

The early signs have been encouraging at the least. While we may quiet down a bit upon finishing up February, I am looking ahead in a cautiously optimistic manner. 

About two months into the year, we've seen the most early season tornadoes since 2008. Even if we flatline for the next two weeks, we'll still be above climo, year-to-date. 

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Yeah, it's nothing really to worry about. 

Might get some western US troughing as we approach spring break, which would be absolutely perfect. euro ensemble indicates retrogressuon of the west us ridging around the middle of march. For March though you need a few days worth of return flow. ..so we will see how that pans out when the pattern inevitably changes. 

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Idk if it's completely dead in the water. 00z ECMWF pulled the dry line back closer to i-35 again.

 

So did the GFS. here is dprog/dt for GFS. 

gfs.sfctd_b.us_c.trend.gif

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1 hour ago, bjc0303 said:

Idk if it's completely dead in the water. 00z ECMWF pulled the dry line back closer to i-35 again.

 

So did the GFS. here is dprog/dt for GFS. 

gfs.sfctd_b.us_c.trend.gif

I'm also not totally convinced this is a done deal. The trend has definitely been for a sharper dryline positioned further west on the GFS. Also, just about every dryline event ends up further west than models have it at this range. I can remember a number of days last year when the GFS had the dryline along or east of 35 and it ended up in western Oklahoma or even the Texas panhandle. 

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43 minutes ago, WhiteoutWX said:

I'm also not totally convinced this is a done deal. The trend has definitely been for a sharper dryline positioned further west on the GFS. Also, just about every dryline event ends up further west than models have it at this range. I can remember a number of days last year when the GFS had the dryline along or east of 35 and it ended up in western Oklahoma or even the Texas panhandle. 

Not sure it is ever that extreme. I would bet on a dry line no father east than I 35 unless flow becomes veered overall like previous model runs suggested 

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15 minutes ago, bjc0303 said:

Not sure it is ever that extreme. I would bet on a dry line no father east than I 35 unless flow becomes veered overall like previous model runs suggested 

I'm not saying the dryline will be that far west this time but there were a number of events with large eastward model biases last year. 

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Seems like a dipole severe event is possible Tuesday with the stronger vort coming through the Four Corners + dryline and then the lead low over the Lakes/OV. Cap does look breakable further SW and if you do get backing (deeper vort leading to stronger lee cyclone/etc.), the shear profiles become rather conducive for tornadic supercells. Deep layer shear is already on the high end across basically all of the warm sector.

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9 minutes ago, andyhb said:

Seems like a dipole severe event is possible Tuesday with the stronger vort coming through the Four Corners + dryline and then the lead low over the Lakes/OV. Cap does look breakable further SW and if you do get backing (deeper vort leading to stronger lee cyclone/etc.), the shear profiles become rather conducive for tornadic supercells. Deep layer shear is already on the high end across basically all of the warm sector.

Key point here is with the jet stream overhead small fluctuations in amplitude,  strength,  etc make a huge difference, hence varying strength and positioning of key features. 

Likewise bulk shear will be high given strong flow aloft. if stronger sfc low becomes forecast or evident... could be in for a show given MLCAPE 1000-2000 likely 

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On the other hand if we get forecast sfc lows closer to 1000 mb the flow will be largely veered and the warm sector will be more in line with what is currently depicted in the day 4-8 outlook.

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SPC has an outlook (15%) for Day-4 Arkansas, Day-5, AL/MS/TN. The GFS has over 1000 J/kg of CAPE at 12z on Wednesday, in Arkansas. Synoptic details will probably change a lot, but that's a lot of CAPE for 12z in the winter.

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43 minutes ago, MattPetrulli said:

Looks like a plains severe threat Monday. Still a lot of details to be ironed out. Dynamically looks like a great system.

Hard to tell. I'm not sold yet that moisture return will be sufficient, but it could be. 

 

The gulf of mexico made it through the brunt of the cold season without any harsh intrusions. In fact it was one of the warmest seasons for the gulf ever I think... I saw an article about the GOMEX temperatures not dropping below a certain value thru winter since some time in the 60s or something...anyway...

 

The NAM and GFS show quite the deep upper level low approaching the west coast by hour 84. The trend with the GFS has been to deepen and amplify the system with each run. the ECMWF 12z deterministic and ensembles did the same, though to a lesser degree. Personally, there probably will be, somewhere, a marginal supercell environment somewhere, probably farther north where colder Temps aloft will reside over modest moisture. If moisture return is sufficient, which would require stronger return flow/longer or weaker frontal passage than currently depicted, then I could see a pretty widespread severe risk over a large portion of the plains. 

 

Finally the GFS for now indicates potential for widespread cloud cover, which would probably kill any potential even with stronger return flow. Next few days will provide more clarity. The shear and dynamics of the system do look impressive. It would help if the system continued its trend to be more amplified with each run. 

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00z Euro might have enough instability for an issue in W IA/NW MO on Monday just eyeballing it. 500-1000 J/kg would probably be enough for some fast moving/low-topped cells with a tornado threat if anything can get going in that highly sheared environment on the western periphery of the LLJ. Might also be worth watching further south down the dryline towards KS/OK although better moisture would certainly be appreciated.

GFS is too fast for the former threat.

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1 hour ago, bjc0303 said:

Although currently an outlier the NAM looks pretty potent for Monday evening across OK and central KS 

Geez... I'd say so. Too bad it probably will not happen. 12Z NAM is about the best case scenario for severe storms/tornado potential that this system has. 

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Just now, jojo762 said:

Geez... I'd say so. Too bad it probably will not happen. 12Z NAM is about the best case scenario for severe storms/tornado potential that this system has. 

Too early to tell. The operational 12z GFS looks awful... but I am more interested in the ensemble forecast, the 12z operational ECMWF, and SREF forecasts. latest SREF doesn't look awful across OK/SE KS 

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Still a long way out, but the GFS hints at a potential midweek, multi-day threat across the plains in mid-March.

Sent from my Pixel XL using Tapatalk

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18 minutes ago, SluggerWx said:

Still a long way out, but the GFS hints at a potential midweek, multi-day threat across the plains in mid-March.

Sent from my Pixel XL using Tapatalk
 

It's been hinting at this for several days now. Has had trouble figuring out exactly what time period it'll occur though. Think it is safe to bet a strong system will be effecting the plains sometime during mid-march, moisture return/quality of course is the biggest question. 

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3 hours ago, SluggerWx said:

Still a long way out, but the GFS hints at a potential midweek, multi-day threat across the plains in mid-March.

Sent from my Pixel XL using Tapatalk
 

Saw that too. ECMWF is harsher. It basically pushes a high amplitude Ridge over the west/central states. 

 

I haven't looked into the ECMWF ensemble, but the GFS ensemble shows support for a multi day severe weather threat next week. interestingly enough the GFS started showing this about when the euro stopped doing so. Looks more like Thursday and/or Friday but I could be mistaken.

 

Edit: 18z GEFS continues to suggest increased severe potential late this upcoming week (most likely Fri-Sat-Sun).

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10 hours ago, bjc0303 said:

Too early to tell. The operational 12z GFS looks awful... but I am more interested in the ensemble forecast, the 12z operational ECMWF, and SREF forecasts. latest SREF doesn't look awful across OK/SE KS 

The NAM has 65-66 degree dew points into SE Oklahoma Monday. My guess is that the SPC will issue a slight risk on Monday. Until a couple of days ago, the GFS runs had basically no CAPE for Monday. But now I think a localized hail/wind threat is possible.

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18 minutes ago, Chinook said:

The NAM has 65-66 degree dew points into SE Oklahoma Monday. My guess is that the SPC will issue a slight risk on Monday. Until a couple of days ago, the GFS runs had basically no CAPE for Monday. But now I think a localized hail/wind threat is possible.

Looks like more than a localized wind/hail threat.

Assuming initiation does happen and that the NAM isn't grossly overdoing moisture... Looks like a nocturnal tornado threat into east OK Monday eve/night. 

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1 hour ago, bjc0303 said:

Looks like more than a localized wind/hail threat.

Assuming initiation does happen and that the NAM isn't grossly overdoing moisture... Looks like a nocturnal tornado threat into east OK Monday eve/night. 

Agree. NAM continues to emphasize a good threat for ne OK and sw MO Monday eve/night with parameters increasing in severity.  NAM did better than the more progressive GFS on the Feb. 27/March 1 system so it certainly bears watching as we get closer. Springfield AFD beginning to express concern.

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1 hour ago, bjc0303 said:

Looks like more than a localized wind/hail threat.

Assuming initiation does happen and that the NAM isn't grossly overdoing moisture... Looks like a nocturnal tornado threat into east OK Monday eve/night. 

Yep. Some pretty nasty soundings coming out of that region on the NAM. Other models are far less enthusiastic for now though so nothing to hang our hats on.

 

 

ZXwirna.png

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4 minutes ago, TropicalAnalystwx13 said:

Yep. Some pretty nasty soundings coming out of that region on the NAM. Other models are far less enthusiastic for now though so nothing to hang our hats on.

 

 

ZXwirna.png

Agreed. Storm mode will also probably preclude sig tor potential, unless open warm sector development is to occur. Not sure this will be the case.  

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Looking past Monday, GEFS continues to suggest increased severe potential late next week... somewhere around Sat or Sunday 

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SPC went with a broad brushed Marginal risk for Monday, which seems like a safe bet right now given wide model variability. Likely will see a slight risk later on. Given the strength of the wind fields, any forecast change in moisture quality/instability can alter the severe storm forecast drastically for any given area. 

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Yeah, GFS has trended some better on instability into east OK with 1000 mlcape.

Still considerable spread among SREF members, as well as deterministic guidance.

 

Looking past Monday, still looks like potential uptick in severe next weekend/early next week. 

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13 hours ago, bjc0303 said:

Yeah, GFS has trended some better on instability into east OK with 1000 mlcape.

Still considerable spread among SREF members, as well as deterministic guidance.

 

Looking past Monday, still looks like potential uptick in severe next weekend/early next week. 

For next weekend/ early next week, the GFS has been hinting at some days that would feature some pretty impressive conditions. Multiple waves coming through before the main dish. GFS has very little consistency with the main system, nonetheless timing is looking like it will be an issue. On a positive note, it does not appear that moisture will be an overwhelming issue, as of now.

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