CryHavoc Posted December 7, 2022 Share Posted December 7, 2022 Yet another wave pushing in with a high degree of model consensus this far out means we're once again seeing a 15% region introduced on day 6 and day 7. Day 7's outlook is notably large, covering nearly all of Arkansas, most of Louisiana, and the W half of MS. Has to be one of the largest day 7 regions I've ever seen issued. 1 Link to comment Share on other sites More sharing options...
CryHavoc Posted December 7, 2022 Author Share Posted December 7, 2022 Of note, I believe that these are also the 1st and 2nd day 7 outlooks ever issued with 15% for the month of December. A lot could still change, but this is ominous nonetheless. 1 Link to comment Share on other sites More sharing options...
CryHavoc Posted December 7, 2022 Author Share Posted December 7, 2022 ...DISCUSSION... A increase in divergence of solutions amongst medium-range models, and an increase in ensemble spread, is noted as compared to 24 hours prior, along with a general slowing of the advance of the western U.S. trough. In general, models forecast a very gradual amplification of the flow field Days 4-5 and into Day 6, as short-wave energy digs south-southeastward in the vicinity of the western North America Coast Day 4/Saturday, and then begins to pivot a bit more southeastward into the western U.S. Day 5/Sunday. On Day 6/Monday, a more eastward advance of a large closed low will commence, with pronounced height falls reaching the central and southern Plains -- particularly through the evening/overnight hours. This eastward advance appears likely to be accompanied by strong central High Plains cyclogenesis, with a cold front to advance into (GFS) or across (ECMWF) the southern Plains region through the second half of the period. Based on this current pace of advance of the synoptic features, most of the severe risk Monday would appear to exist after dark, spreading across parts of eastern Oklahoma and North Texas, and possibly (per the ECMWF) into western Arkansas. Given favorable northward advection of high theta-e air, and very strong deep-layer shear, all-hazards severe potential would be expected. Continued advance, and additional deepening, of the upper low is expected Tuesday/Day 7, with the surface low progged to occlude over the central Plains and a cold front to sweep eastward to the Mid Mississippi Valley region after dark. With a moist warm sector likely to reside across East Texas/Arkansas/Louisiana in this scenario, and given the very strong wind field accompanying the intensifying synoptic features, all-hazards severe risk including tornado potential would exist. By Day 8, model differences increase, casting additional uncertainty into the forecast. With that said, it does appear that much more limited moisture/instability will exist ahead of the system -- in part due to a strong antecedent ridge of surface high pressure. As such, a diminished severe risk would appear to exist for Day 8. ..Goss.. 12/07/2022 1 Link to comment Share on other sites More sharing options...
METALSTORM Posted December 7, 2022 Share Posted December 7, 2022 Seen more than 1 forecast mentioning the possibility extending to the mid MS Valley. LSX mentioned the possibility in their morning forecast discussion. Quite a ways away. Interesting to see if/how this shifts in the coming days. Link to comment Share on other sites More sharing options...
Amped Posted December 7, 2022 Share Posted December 7, 2022 Hopefully not a repeat of last December. 1 Link to comment Share on other sites More sharing options...
Santa Clause Posted December 7, 2022 Share Posted December 7, 2022 Looks promising Link to comment Share on other sites More sharing options...
Amped Posted December 8, 2022 Share Posted December 8, 2022 8 hours ago, METALSTORM said: Seen more than 1 forecast mentioning the possibility extending to the mid MS Valley. LSX mentioned the possibility in their morning forecast discussion. Quite a ways away. Interesting to see if/how this shifts in the coming days. 00z gfs supports that idea. CMC is pretty similar. This is a nasty setup in a unique pattern. Wouldn't be surprised if it extended east into GA also. 1 Link to comment Share on other sites More sharing options...
CryHavoc Posted December 8, 2022 Author Share Posted December 8, 2022 Monday still looks like an active overnight event, but models are starting to come into agreement that Tuesday looks like an increasingly concerning day of potential. SPC has just issued a 30% day 6 watch. Link to comment Share on other sites More sharing options...
CryHavoc Posted December 8, 2022 Author Share Posted December 8, 2022 ...DISCUSSION... Medium-range models appear to remain solidly consistent -- both in terms of similarity with each other in the most recent run, and also with other, previous runs over the prior 48 hours -- through Day 6/Tuesday Dec. 13. Days 7-8, differences in evolution of the large upper cyclone over the central U.S. lead to differences in timing of surface frontal advance/evolution across the Southeast, with uncertainty thus precluding assessment severe risk beyond Day 6. During the first half of the period, when models are in remarkable agreement, severe risk is expected to gradually increase, from negligible at best (Day 4/Sunday), to increasing over the Oklahoma vicinity Day 5/Monday, and through what is expected to be substantial potential Day 6 from eastern portions of the southern Plains to the Lower Mississippi Valley. The event should begin overnight Monday and into early Tuesday, focused on the Oklahoma vicinity, as a deep upper low crosses the Rockies through the day, and then the central/southern High Plains overnight. This upper low progression will be accompanied by a mature surface low that should shift out of the central High Plains, while a trailing cold front crosses Texas/Oklahoma overnight. Strong southerly winds ahead of the front will result in an increase in low-level moisture -- and thus modest destabilization. Despite the unfavorable time of day, very strong/favorable flow aloft accompanying this system suggests an increase in all-hazards severe weather through the latter stages of the period. Later on into the day on Tuesday (Day 6), continued eastward advance of the deep upper cyclone, and an occluding surface low over the Nebraska vicinity, is expected. As the cold front continues eastward across the southern Plains and into the Ozarks/Arklatex, high theta-e low-level air and modest heating should yield ample CAPE -- particularly across Louisiana and into Arkansas during the afternoon. With a very strong/veering flow field with height that should prove quite supportive of severe/supercell storms, risk for tornadoes is apparent, along with damaging winds and hail. This risk will shift gradually eastward in tandem with frontal advance, likely crossing into the Mississippi and western Tennessee vicinity into the overnight hours. While convection, and some severe potential, should continue spreading eastward/southeastward, increasing uncertainty precludes delineation of a Day 7 area at this time. ..Goss.. 12/08/2022 1 Link to comment Share on other sites More sharing options...
cheese007 Posted December 9, 2022 Share Posted December 9, 2022 Monday contour dropped entirely citing elevated nature of storms 1 Link to comment Share on other sites More sharing options...
Ed, snow and hurricane fan Posted December 10, 2022 Share Posted December 10, 2022 I-20 and I-30 corridors of Louisiana and SW Arkansas in 30% risk area. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted December 11, 2022 Share Posted December 11, 2022 Some of the forecast hodographs/SRH values being spit out by the NAM over portions of LA/MS for Tuesday evening are pretty scary in the presence of any instability at all and dewpoints in the mid-upper 60s. Link to comment Share on other sites More sharing options...
Quincy Posted December 11, 2022 Share Posted December 11, 2022 Forecasts show a robust trough sweeping across the Plains on Tuesday. More potent than the broader trough that accompanied the 11/29 moderate risk event in the same general area. Wind fields look impressive. The GFS is rather aggressive with moisture return and instability surging northward into Arkansas. Most other guidance, including high resolution models and the ECMWF show a more confined area of favorable instability across east Texas into Louisiana. It’s the cool season and with such wind fields, you don’t need much instability for trouble. Definitely a high shear/low CAPE setup. The main question to me is, are isolated storms able to form ahead of the expected QLCS? Lapse rates are not nearly as impressive as 11/29, so this looks like mainly a wind and tornado threat. Less capping, but a potentially narrower warm sector, especially if high resolution guidance is correct. Some key details need to be ironed out, but Tuesday definitely bears watching. Not sold on Tuesday AM pre-dawn severe, due to a stable near-surface layer, but who knows. (North Texas/southern Oklahoma) I’m also mildly intrigued by a *possible* cold core setup over Kansas. Maybe it’s too late in the season, but steep lapse rates and strong wind fields suggest a non-zero severe risk could evolve closer to the surface low in Kansas. In December, we chase? 3 Link to comment Share on other sites More sharing options...
Chinook Posted December 11, 2022 Share Posted December 11, 2022 Interesting to see the CIPS analogs from 2-3 days out. 1 Link to comment Share on other sites More sharing options...
Chinook Posted December 12, 2022 Share Posted December 12, 2022 The 00z convection allowing models seem to have a generic look for severe weather in Louisiana and maybe Arkansas at 48 hours. (day-3) Link to comment Share on other sites More sharing options...
CryHavoc Posted December 12, 2022 Author Share Posted December 12, 2022 Interesting that the entire enhanced region is also 10% hatched for tornadoes. Not sure how common that is for "just" enhanced on a day 2, but I wouldn't rule out a late d2 MDT or early day 1 mdt with some strong wording being issued on this. Agree with you Quincy, it'll be interesting to see if storms have enough to fire out ahead of the frontal boundary. Seems like a situation where either they won't and we'll have a pretty marginal threat for embedded TORs, or they will and we could see a really rough day of activity. Given the projected hodos I think any cell that really starts building strength and breaks the cap is going to be pretty concerning. 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted December 13, 2022 Share Posted December 13, 2022 Smallish supercells ongoing in the Oklahoma panhandle/extreme SW KS, multiple tornado warnings on them. 2.5" hail reported in Beaver County, OK. Nocturnal destabilization is being driven by strong cooling aloft despite modest moisture. CAPE is meager but concentrated in the low levels which is ripe for development. Link to comment Share on other sites More sharing options...
Sydney Claridge Posted December 13, 2022 Share Posted December 13, 2022 Decent circulations on tornado-warned storms near Bray, OK, Coleman, TX, and Cross Plains, TX at this early hour. If the storm around Cross Plains holds together it could become a problem for DFW a few hours from now; I’m also keeping an eye on a (non-warned) storm just north of Eastland, TX. Link to comment Share on other sites More sharing options...
cheese007 Posted December 13, 2022 Share Posted December 13, 2022 D2/Wednesday upgraded to ENH with SigTor potential. Also that line heading into dfw in the next few hours is still looking pretty discrete, has a couple tor warnings on it 1 Link to comment Share on other sites More sharing options...
Sydney Claridge Posted December 13, 2022 Share Posted December 13, 2022 Confirmed tag on tornado warning near Wayne, OK. Correlation coefficient seems to show a possible debris signature. I’m a little surprised to see this given the marginal surface conditions (temperatures around 60) in this area. Link to comment Share on other sites More sharing options...
Sydney Claridge Posted December 13, 2022 Share Posted December 13, 2022 Also there’s three tornado warnings west of DFW now. I’m in central Fort Worth and I’m starting to wonder about that southernmost cell possibly becoming a problem at my location later this morning; I’m expecting the Palo Pinto (central) cell to pass to my north. EDIT: that rotational signature north of Gorman, on the southernmost cell, is looking quite concerning. EDIT 2: might this be a debris signature on the correlation coefficient? I can’t tell completely, but it wouldn’t surprise me either. Link to comment Share on other sites More sharing options...
cheese007 Posted December 13, 2022 Share Posted December 13, 2022 Confirmed tor with debris sig on the tor out near Carbon, also that storm heading into Mineral Wells looking nasty based on the cc on TX storm chasers live stream Link to comment Share on other sites More sharing options...
cheese007 Posted December 13, 2022 Share Posted December 13, 2022 Tor warning with debris sig including city of Weatherford, could very much be a problem for DFW metro within the next hour or so Link to comment Share on other sites More sharing options...
Sydney Claridge Posted December 13, 2022 Share Posted December 13, 2022 Oh boy… that’s a concerning looking rotation signature (and possible debris signature?) near the I-20/US-281 interchange. EDIT: Confirmed/observed tornado. Hopefully no one is trying to travel on I-20 in SE Palo Pinto and western Parker counties right now. Link to comment Share on other sites More sharing options...
cheese007 Posted December 13, 2022 Share Posted December 13, 2022 TDS in Wise county Link to comment Share on other sites More sharing options...
Sydney Claridge Posted December 13, 2022 Share Posted December 13, 2022 1 minute ago, cheese007 said: TDS in Wise county This is a concerning situation for areas in southern Decatur and south of Decatur. Link to comment Share on other sites More sharing options...
cheese007 Posted December 13, 2022 Share Posted December 13, 2022 PDS warning for the Wise county storm Severe Weather Statement National Weather Service Fort Worth TX 720 AM CST Tue Dec 13 2022 TXC121-497-131345- /O.CON.KFWD.TO.W.0074.000000T0000Z-221213T1345Z/ Wise TX-Denton TX- 720 AM CST Tue Dec 13 2022 ...A TORNADO WARNING REMAINS IN EFFECT UNTIL 745 AM CST FOR EAST CENTRAL WISE AND NORTHWESTERN DENTON COUNTIES... At 719 AM CST, a confirmed large and extremely dangerous tornado was located near Decatur, moving northeast at 30 mph. This is a PARTICULARLY DANGEROUS SITUATION. TAKE COVER NOW! HAZARD...Damaging tornado. SOURCE...Weather spotters confirmed tornado. IMPACT...You are in a life-threatening situation. Flying debris may be deadly to those caught without shelter. Mobile homes will be destroyed. Considerable damage to homes, businesses, and vehicles is likely and complete destruction is possible. This tornadic thunderstorm will remain over mainly rural areas of east central Wise and northwestern Denton Counties, including the following locations... Bolivar and Slidell. PRECAUTIONARY/PREPAREDNESS ACTIONS... To repeat, a large, extremely dangerous and potentially deadly tornado is on the ground. To protect your life, TAKE COVER NOW! If you are outdoors, in a mobile home, or in a vehicle, move to the closest substantial shelter now! Get to an interior room on the lowest floor of a sturdy building and avoid windows. && LAT...LON 3343 9723 3329 9722 3319 9752 3326 9755 3343 9738 TIME...MOT...LOC 1319Z 236DEG 28KT 3325 9749 TORNADO...OBSERVED TORNADO DAMAGE THREAT...CONSIDERABLE MAX HAIL SIZE...<.75 IN $$ Stalley Link to comment Share on other sites More sharing options...
mob1 Posted December 13, 2022 Share Posted December 13, 2022 Looks to have weakened or occluded on the last scan. Looked really nasty before that. Link to comment Share on other sites More sharing options...
cheese007 Posted December 13, 2022 Share Posted December 13, 2022 Tor warning for northern Tarrant county, severe tstorm for the southern portion Link to comment Share on other sites More sharing options...
cheese007 Posted December 13, 2022 Share Posted December 13, 2022 Tor warning for downtown Fort Worth, TDS near River Oaks per TX Storm Chasers livestream Link to comment Share on other sites More sharing options...
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