andyhb Posted January 1, 2017 Share Posted January 1, 2017 A strong shortwave impulse looks to emerge over the south central portion of the country over the next 24 hours that will spur on a potentially significant severe threat across mainly the Gulf Coast states. SPC has a slight with a 5% tor for most of south-central/southeast Texas for New Years Day and then a large D2 enhanced for LA/MS/AL on Monday. Certainly looks like there will be plentiful instability with mid-upper 60s dewpoints and rather steep mid level lapse rates approaching or exceeding 7 C/km (barring deleterious morning convection) and ample shear (although perhaps not quite as strong as you'd expect for a cold season event). With that said, the factor of junk convection itself is very vague right now with almost every model having a different idea of how it is going to play out. The Euro and GFS suggest an area of enhanced NVA and dry air aloft will overspread the warm sector early on Monday that may prevent a lot of early convection, whilst the NAM wants to plow an MCS across the Gulf Coast and effectively wipeout a lot of the potential threat. I get the feeling like it may be somewhere in between. Link to comment Share on other sites More sharing options...
monsoonman1 Posted January 1, 2017 Share Posted January 1, 2017 Instability is pretty impressive for January, so the setup has that going for it. Junkvection is the biggest question mark, but even with a big MCS, there would probably be QLCS tornadoes and activity with discrete cells ahead of the line in the warm sector. Curious to see if the NAM is right with that thinking; if there isn't a big MCS, this could be a pretty big deal. Link to comment Share on other sites More sharing options...
janetjanet998 Posted January 1, 2017 Share Posted January 1, 2017 thread going here in the TN valley forum....this outbreak may cover small parts of 3 sub forums.....there is also a small thread in the SE forum...we need to pick a main thread for the overall system..one of the downfalls of smaller sub forums Link to comment Share on other sites More sharing options...
monsoonman1 Posted January 2, 2017 Share Posted January 2, 2017 Line of storms is already producing some damaging winds in East NM and west TX. Going to be a long night for much of TX. Link to comment Share on other sites More sharing options...
Jim Martin Posted January 2, 2017 Share Posted January 2, 2017 This line of severe thunderstorms now responsible for 69 MPH wind at Hobbs, New Mexico a short time ago. Link to comment Share on other sites More sharing options...
Jim Martin Posted January 2, 2017 Share Posted January 2, 2017 From the National Weather Service in Jackson, Mississippi Area Forecast Discussion this evening... Monday morning waa will increase over our CWA ahead of the approaching shortwave and associated surface low. This low pressure system will track across the ArkLaTex region and to the Tennessee Valley by Monday evening. All modes of severe weather will be possible over our CWA starting Monday morning in our northwest and ending over our southeast early Monday evening. The main threat will be damaging wind gusts but tornadoes, hail, and heavy rainfall will also be possible. An Elevated Threat for our whole CWA has been mentioned in our HWO. A couple of inches of rain across our southeast in a short period of time may result in flash flooding where a limited threat has been included again in our HWO. /22/ Link to comment Share on other sites More sharing options...
MattPetrulli Posted January 2, 2017 Share Posted January 2, 2017 SPC going with a large 5% risk for tor. NWS Storm Prediction Center Norman OK 1204 AM CST Mon Jan 02 2017 Valid 021200Z - 031200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF LOUISIANA...MISSISSIPPI...SOUTHERN ALABAMA AND THE WESTERN FLORIDA PANHANDLE... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM EAST TEXAS TO WESTERN GEORGIA AND THE EASTERN FLORIDA PANHANDLE... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE SLIGHT RISK FROM EAST TEXAS TO THE TENNESSEE VALLEY AND GEORGIA... ...SUMMARY... Severe thunderstorms are expected today into this evening across much of the western through central Gulf states and into portions of the Mid South. All severe hazards will be possible including a few tornadoes, with damaging wind gusts being the greatest threat from Louisiana through much of Mississippi into southern Alabama and the western Florida Panhandle. ...Synopsis... Models remain consistent with the track and timing of the compact and progressive shortwave trough, now emerging into west Texas per water vapor imagery, as this system moves east into the lower Mississippi Valley by 00Z and should reach Georgia and eastern Tennessee by 12Z Tuesday. Fast zonal mid-upper level flow is expected to develop across the Great Basin and southwest states into the central and southern Plains to lower Mississippi Valley this forecast period which will aid in a more eastward track of the compact Texas shortwave trough. A synoptic surface low attendant to this progressive trough is expected to track from east/northeast Texas into the ArkLaMiss region by early this evening and reach middle Tennessee by late in the forecast period. A warm front extending east from the surface low should make greater northward progress from central into northern Mississippi than locations farther east, as stronger surface pressure falls are forecast from northern Mississippi into the Tennessee Valley. Meanwhile, a cold front trailing south from the low will advance through the lower Mississippi Valley into the Gulf Coast states. ...East TX to the central/northeast Gulf coast states and TN Valley... Low-level moistening is already underway with middle 60s surface dew points expected across much of Louisiana and the southern halves of Mississippi, Alabama, and Georgia by early afternoon. This combined with pockets of surface heating and a plume of steep midlevel lapse rates (at least 7 c/km in the 500-700 mb layer) spreading across the lower Mississippi Valley to western Alabama will boost instability to moderate values (1000-1500 j/kg) across the Enhanced risk area. Ongoing showers and thunderstorms across the western Florida Panhandle through southern Alabama to central Georgia appear to be attendant to a midlevel impulse currently tracking across this region. This impulse should reach central Georgia by 12Z today, with the potential for some breaks in the cloudiness across the warm sector of southern Alabama and the Florida Panhandle to southeast Mississippi and southeast Louisiana through the morning to early afternoon. An ongoing band of strong to severe storms is expected across parts of East Texas at 12Z today with this band advancing east into a destabilizing warm sector across the lower Mississippi Valley through this morning and afternoon, while deep-layer wind fields strengthen and spread east with the trough. Deep-layer shear will be sufficient for an organized severe storm threat as activity spreads east and northeast, with all severe hazards possible. Given a 50 kt southwesterly 700-mb jet spreading across southern Louisiana to southern Alabama this afternoon and evening, this region may have the greatest coverage of severe storms with damaging winds being the primary threat. A separate area of strong to severe storms should develop across the central Gulf coast across southeast Louisiana into southwest Alabama attendant to a separate midlevel impulse, currently moving across Deep South Texas. Vertically veering and strengthening winds will favor all severe hazards with this activity as it spreads into the western Florida Panhandle, southern and perhaps central Alabama to parts of western Georgia. Farther north into Tennessee and southwest Kentucky, instability should be elevated with isolated hail being the primary threat with storms across these areas. Link to comment Share on other sites More sharing options...
Sydney Claridge Posted January 2, 2017 Share Posted January 2, 2017 http://www.spc.noaa.gov/products/watch/ww0001.html The first severe thunderstorm watch of the year is now in effect for central and east Texas, including D/FW, Waco, and Austin. Link to comment Share on other sites More sharing options...
andyhb Posted January 2, 2017 Author Share Posted January 2, 2017 82 mph gust reported in Hamilton, TX. Link to comment Share on other sites More sharing options...
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