bjc0303 Posted March 11, 2018 Share Posted March 11, 2018 GFS certainly coming in more potent. It slows down the progression of the pattern and amplifies the upper level trough as it ejects, which is leading to these really strong low systems. Interesting development. Link to comment Share on other sites More sharing options...
Radtechwxman Posted March 11, 2018 Share Posted March 11, 2018 Yea gfs is crazy. Powerhouse system is nearly stationary for days cuz of the strong blocking downstream. Would like to see a little more progression and less blocking. But overall this will def bring some chase days if gfs verifies. Ample moisture and very strong jet dynamics Link to comment Share on other sites More sharing options...
Jim Martin Posted March 11, 2018 Share Posted March 11, 2018 From last night in Southeast Arkansas... 0221 300 PINE BLUFF JEFFERSON AR 3423 9200 MAXIMUM HAIL SIZE MEASURED WAS 3.50 INCHES. (LZK) Link to comment Share on other sites More sharing options...
jojo762 Posted March 11, 2018 Share Posted March 11, 2018 Euro looks pretty potent for next weekend as well. Frivolous to get into much detail, but looks fairly promising for a day or two of solid severe chances somewhere across the central/southern plains. Link to comment Share on other sites More sharing options...
bjc0303 Posted March 11, 2018 Share Posted March 11, 2018 Pretty impressive agreement between ECMWF, CMC, and GFS. Differ on amplitude and timing, but the general consensus shows a severe weather event over the same general area for Sunday. Impressive for a week out. Not sure who is more potent: the GFS or the ECMWF. GFS more unstable, ECMWF by far the stronger between the two wrt shear profiles. 70 knot deep layer shear and 35-45 knot 0-1km shear on the ECMWF. Definitely one to watch, and one that has some synoptic backing for sure. Would think the dry line sets up along I-35 if things hold, but with how strong the synoptics are it could push near Tulsa. Seems to me that this is a pattern offering higher predictability. It doesn't seem like there is much to offer in terms of downstream/eastern amplification. The GEFS 6-8 day analogue forecast: At least 10 Svr reports At least 1 tornado At least 1 sig tor. Seems to me that models should have a good handle on this one. 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 11, 2018 Share Posted March 11, 2018 Way too early to take seriously, but 12Z GFS also has a nice little event in IA/MO for Saturday the 24th. That's the 2nd run in a row that suggests another potent system 5-7 days after the first. Link to comment Share on other sites More sharing options...
monsoonman1 Posted March 12, 2018 Share Posted March 12, 2018 12z GFS has trough after trough swinging through the middle of the country from this weekend on, which is about all we can ask for right now. 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 12, 2018 Share Posted March 12, 2018 12 minutes ago, monsoonman1 said: 12z GFS has trough after trough swinging through the middle of the country from this weekend on, which is about all we can ask for right now. I'd say a tad earlier in the season than ideal for such an active pattern. Much like last year, might run into a problem with not enough moisture recovery between systems, although as it stands right now (one system next Sunday-Monday and then another the following Friday-Saturday) it shouldn't be as much of an issue. I know I've said it before, but it sure would be nice to get a look like that from late April through May one of these years. One thing that the last few years have taught me is that with any given early season setup, actual dewpoint value doesn't matter as much as long as LCL is not too high (not too much of a difference between dewpoint and temperature) and the upper levels are sufficiently cold. The setups in late March-early April '17 that underwhelmed had other issues besides moisture. You get ideal shear profiles and cold upper levels, and marginal-looking surfaced T/Td can get the job done (3/15/16, 2/28/17). 1 Link to comment Share on other sites More sharing options...
bjc0303 Posted March 12, 2018 Share Posted March 12, 2018 Patterns don’t get used up. An active march pattern says nothing of what April and May will bring. Could be a year where the base state is active, or reverse. Link to comment Share on other sites More sharing options...
WhiteoutWX Posted March 12, 2018 Share Posted March 12, 2018 Just no July like ridging in April this year. Almost the entire month of April last year was wasted due to substantial ridging over the Rockies and Plains with the jet stream up in Canada at times IIRC. 1 Link to comment Share on other sites More sharing options...
Chinook Posted March 12, 2018 Share Posted March 12, 2018 I was searching around on Youtube and I found a very good lecture series about tornado forecasting done by Rich Thompson of the SPC. Hopefully this link will take you to the whole playlist, including 9 lectures. Link to comment Share on other sites More sharing options...
Quincy Posted March 12, 2018 Share Posted March 12, 2018 4 hours ago, CheeselandSkies said: I'd say a tad earlier in the season than ideal for such an active pattern. Much like last year, might run into a problem with not enough moisture recovery between systems, although as it stands right now (one system next Sunday-Monday and then another the following Friday-Saturday) it shouldn't be as much of an issue. I know I've said it before, but it sure would be nice to get a look like that from late April through May one of these years. One thing that the last few years have taught me is that with any given early season setup, actual dewpoint value doesn't matter as much as long as LCL is not too high (not too much of a difference between dewpoint and temperature) and the upper levels are sufficiently cold. The setups in late March-early April '17 that underwhelmed had other issues besides moisture. You get ideal shear profiles and cold upper levels, and marginal-looking surfaced T/Td can get the job done (3/15/16, 2/28/17). I don't know about moisture recovery not being an issue with the upcoming systems. The 12z Euro looks awful tame now with 60F dews staying south of the Red River on Sunday and struggling to reach into Arkansas on Monday. The overall pattern is too messy, especially for March, given such a large trough over eastern North America. With relatively small systems reoccurring in a fast-flow pattern, there isn't much reason to believe there will be substantial moisture recovery. More of a robust south/southeasterly wind trajectory over the southern Plains/lower Mississippi Valley is needed than what is progged with the expected pattern. If it was later in the season, it wouldn't take as much to moisten the warm sector, but we're only in mid-March and next week doesn't look too promising. I wouldn't be overly concerned though, as it is barely meteorological spring and not even the spring equinox yet. I wouldn't rule out some spotty severe next week and maybe the evolution of one or two of the systems will improve, but it definitely does not look like an outbreak setup and doesn't even look like a scenario for anything impressive for mid-March standards. Link to comment Share on other sites More sharing options...
bjc0303 Posted March 12, 2018 Share Posted March 12, 2018 Yeah, the evolution of the wave has degraded significantly and the moisture return and associated surface evolution just looks like... uh.. garbage. The numerous vorticity maxima weakening return flow big time. 1 Link to comment Share on other sites More sharing options...
andyhb Posted March 13, 2018 Author Share Posted March 13, 2018 The 500 mb height gradient across the SW is total garbage for this weekend especially on the Euro and the most recent 18z GFS. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 13, 2018 Share Posted March 13, 2018 1 Link to comment Share on other sites More sharing options...
WhiteoutWX Posted March 13, 2018 Share Posted March 13, 2018 Until this blocking pattern over eastern North America breaks down I’m not excited about early season severe in the Plains. Moisture will continually be a problem in that setup with a trough parked on the east coast and northerly flow over the gulf. GFS has hints of the blocking holding on all the way to the end of the run, so we’ll see. I’m highly skeptical of the ERTAF forecast for above normal tornado activity in the southern plains and Midwest for next week. Link to comment Share on other sites More sharing options...
monsoonman1 Posted March 14, 2018 Share Posted March 14, 2018 Day 3 slight risk issued for SE AR/NE LA/west MS with few tornadoes possible. Also mention of a cold-core type threat in east KS, which I've had my eye on for a few days. Sent from my SM-G920V using Tapatalk Link to comment Share on other sites More sharing options...
Radtechwxman Posted March 14, 2018 Share Posted March 14, 2018 I saw NAO is suppose to stay negative through at least next week so looking like that eastern trough will hold. Nor'easter galore. Heck by this time last yr I already saw several nice tornadoes Link to comment Share on other sites More sharing options...
monsoonman1 Posted March 14, 2018 Share Posted March 14, 2018 Sunday looks at least somewhat intriguing for OK/TX on last night's Euro.Sent from my SM-G920V using Tapatalk Link to comment Share on other sites More sharing options...
garfan Posted March 14, 2018 Share Posted March 14, 2018 The 18Z GFS for Sunday looks more interesting than previous runs. Link to comment Share on other sites More sharing options...
WhiteoutWX Posted March 15, 2018 Share Posted March 15, 2018 00z Euro and 12z NAM looking a little better for Sunday. Moisture return at this point is marginal but the trend with the surface low and upper wave has improved the shear profiles. Definitely time for it to trend better. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 20, 2018 Share Posted March 20, 2018 Recent GFS runs would support some degree of severe threat in the southern/central Plains next Sunday, the 25th. Warm sector SRH and EHI took a big jump from the 00z to the 06z run, popping some impressive analogs. Remains to be seen if it has legs, but it's the next thing to watch. Link to comment Share on other sites More sharing options...
WhiteoutWX Posted March 20, 2018 Share Posted March 20, 2018 45 minutes ago, CheeselandSkies said: Recent GFS runs would support some degree of severe threat in the southern/central Plains next Sunday, the 25th. Warm sector SRH and EHI took a big jump from the 00z to the 06z run, popping some impressive analogs. Remains to be seen if it has legs, but it's the next thing to watch. Something to watch, although the GFS has been wildly inconsistent on placement/magnitude of potential threats (to be expected from this range I guess). Euro is slower with the trough and would shift any potential focus to Monday and beyond. ETA: On closer inspection even with the slower trough the Euro would still imply at least some severe threat in Texas/southern Oklahoma for Sunday. 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 20, 2018 Share Posted March 20, 2018 12Z GFS solution still maintains a fairly robust severe threat for next Sunday along the I-35 corridor in OK/southern KS. Although, it is rather disconcerting to see the surface low and its associated warm sector basically get crushed between one cold air mass to its east and another to its northwest, instead of continuing to deepen as it lifts towards the upper Midwest on Monday. Link to comment Share on other sites More sharing options...
bjc0303 Posted March 21, 2018 Share Posted March 21, 2018 7 hours ago, CheeselandSkies said: 12Z GFS solution still maintains a fairly robust severe threat for next Sunday along the I-35 corridor in OK/southern KS. Although, it is rather disconcerting to see the surface low and its associated warm sector basically get crushed between one cold air mass to its east and another to its northwest, instead of continuing to deepen as it lifts towards the upper Midwest on Monday. Unfortunately I am most confident in that massive northeastern ridging, given model forecasts and the continuing effects of the Feb SSW. But even so, the GFS and its ensemble do paint an elevated severe risk day. I can’t help but be in love with the GFS ensemble mean for Sunday. The Euro is a different story. We will see - I am not confident the GFS will win here, but I do like the look of the ensemble mean. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 21, 2018 Share Posted March 21, 2018 32 minutes ago, bjc0303 said: Unfortunately I am most confident in that massive northeastern ridging, given model forecasts and the continuing effects of the Feb SSW. But even so, the GFS and its ensemble do paint an elevated severe risk day. I can’t help but be in love with the GFS ensemble mean for Sunday. The Euro is a different story. We will see - I am not confident the GFS will win here, but I do like the look of the ensemble mean. Ugh. WHEN is it going to wane? Link to comment Share on other sites More sharing options...
bjc0303 Posted March 21, 2018 Share Posted March 21, 2018 56 minutes ago, CheeselandSkies said: Ugh. WHEN is it going to wane? I’ve heard that the effects of the SSW could last until late April. Link to comment Share on other sites More sharing options...
jojo762 Posted March 21, 2018 Share Posted March 21, 2018 Given the differences between the GFS and euro it's a fairly low confidence forecast for now. But even the euro would feature a couple days of at least slight-risk caliber severe chances, obviously with various caveats and conditions. Whereas the GFS shows a fairly robust, but imperfect, setup along the "classic" I-35 corridor on sunday. Link to comment Share on other sites More sharing options...
bjc0303 Posted March 21, 2018 Share Posted March 21, 2018 00z euro has taken a dramatic step towards the GFS in my opinion. Similar boundary/low placement and everything for Sunday. GFS ensemble is really locking in on Sunday and with Euro agreement I’d say there’s a chance at a broad 15% day 5 for west OK. Euro slightly less on moisture but looks to be higher on 0-1 km bulk shear and instability which is the most interesting bit Edit: I’d have to analyze the ECMWF ensemble before making a definitive statement there. 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 21, 2018 Share Posted March 21, 2018 I’ve heard that the effects of the SSW could last until late April. Yuck. Shades of 2014, except with less snow and thus a looming drought in the mix. Fun. Sent from my SM-G955U using Tapatalk Link to comment Share on other sites More sharing options...
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