Jim Martin Posted January 18, 2017 Share Posted January 18, 2017 Looking as if some severe weather mischief is a possibility for this weekend across the Southeast. From the National Weather Service Area Forecast Discussion from Birmingham... Threat 2 over the weekend still has some disagreement between the models this time out, but certainly has the potential for some significant impacts. The GFS has better continuity than the ECMWF this run, as the ECMWF has trended back toward solutions a few days ago. The GFS is picking up on several impulses riding through the flow and the potential of severe storms Saturday, Saturday night, and Sunday. The ECMWF is a bit more limited to Saturday night and Sunday. The flow suggest that there will be additional impulses and am leaning toward the GFS here. Additionally, the GFS parameters are better for a longer period. ECMWF would suggest a better risk south. Therefore, we will keep the severe threat going for the entire area both Saturday and Sunday and not focus specifically on these parameters. The synoptic pattern is favorable and the mesoscale will have impacts. Analogues have indications that the pattern is very conducive to severe storms. Stay tuned. Link to comment Share on other sites More sharing options...
audioguy3107 Posted January 18, 2017 Share Posted January 18, 2017 I've been paying attention to this setup the last day or two.....FFC and BHM is really highlighting the chances for a potential severe weather outbreak over Alabama and Georgia, especially on Sunday afternoon. The GFS has CAPE in the 1000 - 2200 range nosing into western Georgia with surface temps in the low 70's and no CAD to protect us this time which is a rarity in the heart of winter. LI as high as -5 over parts of the area. If some of the models are correct in showing dryer air punching in from the west giving us clearing on Sat/Sun., this has potential we haven't seen in quite awhile. - Buck Link to comment Share on other sites More sharing options...
monsoonman1 Posted January 18, 2017 Share Posted January 18, 2017 Potential is certainly there for a significant event, but there are some caveats. Models have been inconsistent with the timing of the 500mb trough, with 12z GFS notably faster than earlier runs (though this could easily change in future runs). Overall low-level wind profiles are also a question mark. With that said, whenever you get a decent EML and good moisture in January, it's definitely something to watch. Link to comment Share on other sites More sharing options...
Jim Martin Posted January 19, 2017 Author Share Posted January 19, 2017 Here is the 18z NAM Sounding for Fayette County, Alabama Saturday Night. Link to comment Share on other sites More sharing options...
MattPetrulli Posted January 19, 2017 Share Posted January 19, 2017 Kinda funny when there is more discussion of this severe weather event here than the SE thread, and this isn't even the main threat area. Nonetheless, Still could be one of the more significant events in the past few years. Link to comment Share on other sites More sharing options...
Jon Posted January 19, 2017 Share Posted January 19, 2017 8 hours ago, MattPetrulli said: Kinda funny when there is more discussion of this severe weather event here than the SE thread, and this isn't even the main threat area. Nonetheless, Still could be one of the more significant events in the past few years. Large majority of the posters in the SE forum are a little North and East of the threatened area with this storm. Not many Alabama posters, and not many who live along the gulf coast. Im concerned for Florida, the CIPs analogs exceeding 1 tor report is at 57% of Top 15 analogs, centered just west of orlando Sun night. Link to comment Share on other sites More sharing options...
Solak Posted January 19, 2017 Share Posted January 19, 2017 There should be a date attached to the thread title. "This weekend" is kind of ambiguous. From RAH: A few strong storms remain possible from mid afternoon Sun through Sun evening, with a 70-90 kt mid level jet streak accompanying the powerful upper divergence and steep 700-500 mb lapse rates, topping 7.5 C/km according to the GFS. Timing will be crucial, as the ECMWF is up to 12 hrs faster than the GFS with the arrival of the mid level low. CIPS analog guidance at this range hints at a greater threat for FL, historically speaking, but GFS forecast soundings for central NC showing lengthy wavy hodographs and moderate instability support at least a modest risk of severe storms in our area, including a tornado risk along and north of the occluding frontal system. Link to comment Share on other sites More sharing options...
downeastnc Posted January 19, 2017 Share Posted January 19, 2017 1 hour ago, Jon said: Large majority of the posters in the SE forum are a little North and East of the threatened area with this storm. Not many Alabama posters, and not many who live along the gulf coast. Im concerned for Florida, the CIPs analogs exceeding 1 tor report is at 57% of Top 15 analogs, centered just west of orlando Sun night. Yeah Dixie Alley usually post in the central forum during big severe weather days....you don't see a lot of folks talking about severe in the SE forum until it gets FL/GA/SC/NC....where most of us are. Still I am much more a severe weather guy, snowstorms tracking is slow and frustrating, so I will be in whichever forum the thread sets up in on Sat and Sunday... Florida has a bloody history of winter tornado events....Feb seems to be the worst month for it in Florida, the threat here in the Carolinas is still a pretty big question mark, it doesn't take much to mitigate the threat up this way, that said when they do work out they can be pretty rough. Jan 2011 had a couple of nasty tornados out in western NC etc.... Link to comment Share on other sites More sharing options...
monsoonman1 Posted January 19, 2017 Share Posted January 19, 2017 Already seeing Tornado Warnings with TDSs in Mississippi. Starting off early. Link to comment Share on other sites More sharing options...
janetjanet998 Posted January 19, 2017 Share Posted January 19, 2017 confirmed tornado this morning in MS look like a multi day event with the main bang saturday night into sunday here is the current day 2 and day 3 outlooks outlook WER MISSISSIPPI VALLEY FRIDAY NIGHT/SATURDAY MORNING GENERAL SCENARIO REMAINS CONSISTENT WITH PREVIOUS DAY 3 OUTLOOK, WITH A SERIES OF LEAD SHORTWAVE TROUGHS EJECTING FROM THE CENTRAL/SOUTHERN PLAINS TO THE MISSISSIPPI VALLEY, DOWNSTREAM FROM A STRONG MID-UPPER JET CORE FROM NEAR THE CA COAST TO NORTHERN MEXICO. OF GREATEST INTEREST IS A SUBTLE SPEED MAX THAT IS EXPECTED TO EJECT NORTHEASTWARD FROM NORTHEAST MEXICO AND SOUTH TX TO THE LOWER MS VALLEY FRIDAY NIGHT. LOW-LEVEL MASS RESPONSE TO THIS MIDLEVEL WAVE WILL FOSTER STRENGTHENING LOW-LEVEL WARM/MOIST ADVECTION AND LOW-LEVEL SHEAR FRIDAY NIGHT ACROSS THE NORTH-CENTRAL GULF COAST. SEVERAL CLUSTERS OF THUNDERSTORMS WILL LIKELY FORM WITHIN THIS REGIME AND SPREAD NORTHEASTWARD INTO AL THROUGH SATURDAY MORNING. BOUNDARY-LAYER DEWPOINTS OF 65-70 F ARE ALREADY PRESENT ACROSS THE GULF COAST, AND SHOULD REMAIN THERE THROUGH THE END OF THIS FORECAST PERIOD. STRENGTHENING VERTICAL SHEAR WITH THE APPROACH OF THE MID-UPPER SPEED MAX, AS WELL AS STEEPENING MIDLEVEL LAPSE RATES FROM AY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0211 AM CST THU JAN 19 2017 VALID 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM LOUISIANA AND MISSISSIPPI EASTWARD TO GEORGIA... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE SLIGHT RISK AREA... ..SUMMARY A FEW EPISODES OF SEVERE STORMS WILL BE POSSIBLE FROM SATURDAY MORNING THROUGH SUNDAY MORNING ACROSS A BROAD AREA OF THE LOWER MISSISSIPPI VALLEY AND THE SOUTHEAST STATES. ..LOWER MISSISSIPPI VALLEY TO THE NORTHEAST GULF COAST A STRONG MID-UPPER TROUGH, NOW SOUTH OF THE ALEUTIANS, WILL REACH THE CA COAST AND NORTHWEST MEXICO BY DAY 2 (FRIDAY), AND CONTINUE EASTWARD ACROSS THE SOUTHERN PLAINS TO THE LOWER MS VALLEY BY SATURDAY NIGHT/SUNDAY MORNING (END OF DAY 3). THERE ARE SOME DISAGREEMENTS AMONG THE OPERATIONAL MODELS, WITH THE NAM APPEARING TO REFLECT SOME CONVECTIVE FEEDBACK AND EASTWARD DEVELOPMENT OF THE SYNOPTIC CYCLONE TOO FAST COMPARED TO THE GFS/ECMWF. WITHOUT THE FEEDBACK, LOW-LEVEL MASS RESPONSE/FLOW SHOULD REMAIN RELATIVELY WEAK DURING THE DAY SATURDAY ACROSS LA/MS IN THE MAIN PART OF THE WARM SECTOR. THE PRIMARY SYNOPTIC CYCLONE AND ASSOCIATED LARGE-SCALE FORCING FOR ASCENT WILL APPROACH THE MS RIVER BY THE END OF THE PERIOD. COMPLICATING FACTORS THIS PERIOD WILL BE ANY LINGERING INFLUENCE OF ONGOING CONVECTION SATURDAY MORNING FROM MS INTO AL, AND A SOMEWHAT NEBULOUS FOCUS FOR ADDITIONAL STORMS DURING THE AFTERNOON ACROSS LA/MS (WELL AHEAD OF THE SYNOPTIC WAVE/COLD FRONT). ANY STORMS THAT FORM HERE WILL DO SO IN AN ENVIRONMENT WITH STEEP MIDLEVEL LAPSE RATES, MODERATE BUOYANCY, AND SUFFICIENT DEEP-LAYER SHEAR FOR SUPERCELLS CAPABLE OF PRODUCING LARGE HAIL (POTENTIALLY SOME VERY LARGE) AND DAMAGING WINDS. THE STRONGER LOW-LEVEL WIND PROFILES ARE EXPECTED FARTHER EAST AND OVERNIGHT IN ASSOCIATION WITH A LEAD SPEED MAX PROGRESSING INLAND FROM THE GULF. ENHANCEMENT TO LOW-LEVEL SHEAR/SRH FROM SOUTH/SOUTHEAST AL INTO THE FL PANHANDLE AND SOUTHWEST GA WILL FAVOR SUPERCELLS WITH DAMAGING WINDS AND POTENTIALLY SOME TORNADO RISK, DEPENDING ON THE DETAILS ON THE LOW-LEVEL SHEAR AND NEAR-GROUND LAPSE RATES INLAND. WILL OPT TO MAINTAIN A RATHER BROAD 15%/SLIGHT RISK AREA IN THIS UPDATE, THOUGH PORTIONS OF THE OUTLOOK AREA MAY NEED TO BE CONSIDERED FOR HIGHER COVERAGE/INTENSITY PROBABILITIES ONCE UNCERTAINTIES ARE REDUCED. THE WEST-SOUTHWEST, WILL CONTRIBUTE TO AN INCREASINGLY FAVORABLE ENVIRONMENT FOR SEVERE STORMS FRIDAY NIGHT INTO SATURDAY MORNING. SUPERCELLS WILL BE POSSIBLE WITHIN THE CONVECTIVE CLUSTERS, WITH A COUPLE OF TORNADOES POSSIBLE GIVEN BUOYANCY ROOTED AT THE SURFACE AND EFFECTIVE SRH INCREASING TO 200-300 M2/S2. THE STEEPENING LAPSE RATES AND RELATIVELY COOL UPSTREAM MIDLEVEL TEMPERATURES WILL SUPPORT A RISK OF LARGE HAIL, ESPECIALLY WITH ANY EMBEDDED SUPERCELLS, AS WELL AS DAMAGING WINDS. -------------------------- Link to comment Share on other sites More sharing options...
janetjanet998 Posted January 19, 2017 Share Posted January 19, 2017 If the 12z NAM is correct this is going to be a very long thread including all the way north into VA sunday the thing that makes this stands out is the very cold temps aloft (-20C sometimes at 500mb) over the warm sector also looks like several fast moving impulses in the longwave Link to comment Share on other sites More sharing options...
monsoonman1 Posted January 19, 2017 Share Posted January 19, 2017 Looks like today has been upgraded to Slight risk along immediate coastal areas from SE Louisiana to FL panhandle, with 5% tornado probabilities. Link to comment Share on other sites More sharing options...
monsoonman1 Posted January 19, 2017 Share Posted January 19, 2017 From new Day 2 outlook for primarily Friday night: By late Friday night, forcing for ascent may become strong enough, southward along the 850 mb jet axis toward southeast Louisiana/Mississippi/Alabama coastal areas, to overcome inhibition and support increasing convective development. In the presence of increasingly boundary layer based instability, the risk for supercells with potential for tornadoes, in addition to large hail and damaging winds, may increase by or shortly after 12Z Saturday. Link to comment Share on other sites More sharing options...
mackerel_sky Posted January 19, 2017 Share Posted January 19, 2017 TORCON OF 3 for Sunday in the Carolinas!! Very impressive in any month, especially January! Link to comment Share on other sites More sharing options...
monsoonman1 Posted January 20, 2017 Share Posted January 20, 2017 SPC outlook excerpts Day 1: The more pronounced mass response to the midlevel trough will occur tonight across the lower MS Valley, where strengthening low-level flow/warm advection will contribute to multiple thunderstorm clusters near and after midnight. Boundary layer dewpoints in the mid-upper 60s will maintain surface-based buoyancy through the overnight hours, while the increasing low-level shear will favor supercells and some risk for tornadoes. Day 2: In addition, a few tornadoes also appear likely, though stronger low-level shear will be maximized along the northward-lifting warm front, and much farther east beneath the LLJ. Day 3: Current thinking is a squall line should migrate across the Gulf states, eventually progressing across the FL peninsula as flow strengthens from the west. Damaging winds and perhaps some hail and possibly a few tornadoes can be expected with this activity. Link to comment Share on other sites More sharing options...
monsoonman1 Posted January 20, 2017 Share Posted January 20, 2017 Tonight has been upgraded to Enhanced risk for Central MS, with 30% damaging wind probabilities. Link to comment Share on other sites More sharing options...
monsoonman1 Posted January 20, 2017 Share Posted January 20, 2017 And new Day 2 outlook: One or two strong tornadoes are possible, particularly across parts of the western Florida Panhandle into southeastern Alabama and southwestern Georgia. Link to comment Share on other sites More sharing options...
janetjanet998 Posted January 20, 2017 Share Posted January 20, 2017 the lack of activity in this thread is strange enhanced risk 3 outlooks in a row if the atmosphere can recover after the first wave tomorrow, Saturday night into Sunday could be really nasty new day 1 ..NORTHWESTERN GULF COAST AND LOWER MISSISSIPPI VALLEY CONVECTIVE DEVELOPMENT, ASSOCIATED WITH LOW/MID-LEVEL WARM ADVECTION ON THE LEADING EDGE OF A DEVELOPING SOUTHERLY RETURN FLOW, NOW APPEARS UNDERWAY NEAR LOWER TO MIDDLE TEXAS COASTAL AREAS. THIS STILL APPEARS LIKELY TO GRADUALLY INCREASE IN COVERAGE LATE THIS AFTERNOON THROUGH TONIGHT, WHILE DEVELOPING NORTHEASTWARD THROUGH THE LOWER MISSISSIPPI VALLEY BY 12Z SATURDAY. THE RISK FOR SEVERE HAIL MAY BE THE PRIMARY THREAT WITH INITIAL DEVELOPMENT ACROSS PARTS OF UPPER TEXAS COASTAL AREAS INTO LOUISIANA AND MISSISSIPPI. HOWEVER, THE RISK FOR POTENTIALLY DAMAGING WIND GUSTS, AND TORNADOES, PROBABLY WILL INCREASE AS ACTIVITY GROWS UPSCALE LATER TONIGHT, AS THIS INCREASINGLY COINCIDES WITH INLAND BOUNDARY LAYER MOISTENING AND DESTABILIZATION, ACROSS PARTS OF SOUTHEASTERN LOUISIANA INTO SOUTHERN MISSISSIPPI. LATEST MODEL OUTPUT SEEMS TO SUGGEST A GREATER LIKELIHOOD THAT COULD OCCUR CLOSER TO LOUISIANA/MISSISSIPPI COASTAL AREAS THAN PREVIOUSLY INDICATED. Link to comment Share on other sites More sharing options...
mackerel_sky Posted January 20, 2017 Share Posted January 20, 2017 2 minutes ago, janetjanet998 said: the lack of activity in this thread is strange enhanced risk 3 outlooks in a row if the atmosphere can recover after the first wave tomorrow, Saturday night into Sunday could be really nasty new day 1 ..NORTHWESTERN GULF COAST AND LOWER MISSISSIPPI VALLEY CONVECTIVE DEVELOPMENT, ASSOCIATED WITH LOW/MID-LEVEL WARM ADVECTION ON THE LEADING EDGE OF A DEVELOPING SOUTHERLY RETURN FLOW, NOW APPEARS UNDERWAY NEAR LOWER TO MIDDLE TEXAS COASTAL AREAS. THIS STILL APPEARS LIKELY TO GRADUALLY INCREASE IN COVERAGE LATE THIS AFTERNOON THROUGH TONIGHT, WHILE DEVELOPING NORTHEASTWARD THROUGH THE LOWER MISSISSIPPI VALLEY BY 12Z SATURDAY. THE RISK FOR SEVERE HAIL MAY BE THE PRIMARY THREAT WITH INITIAL DEVELOPMENT ACROSS PARTS OF UPPER TEXAS COASTAL AREAS INTO LOUISIANA AND MISSISSIPPI. HOWEVER, THE RISK FOR POTENTIALLY DAMAGING WIND GUSTS, AND TORNADOES, PROBABLY WILL INCREASE AS ACTIVITY GROWS UPSCALE LATER TONIGHT, AS THIS INCREASINGLY COINCIDES WITH INLAND BOUNDARY LAYER MOISTENING AND DESTABILIZATION, ACROSS PARTS OF SOUTHEASTERN LOUISIANA INTO SOUTHERN MISSISSIPPI. LATEST MODEL OUTPUT SEEMS TO SUGGEST A GREATER LIKELIHOOD THAT COULD OCCUR CLOSER TO LOUISIANA/MISSISSIPPI COASTAL AREAS THAN PREVIOUSLY INDICATED. We are just looking for snow! We score severe thunderstorms and severe , like Buffalo does Lake effect! just saw TWC has a TORCON of 5 for most of SC and S Ga for Sunday Link to comment Share on other sites More sharing options...
Jon Posted January 20, 2017 Share Posted January 20, 2017 Looks like a long-track or two isn't out of the question based on the latest 4km NAM Link to comment Share on other sites More sharing options...
mackerel_sky Posted January 20, 2017 Share Posted January 20, 2017 Local weatherperson said" a few rumbles of thunder Sunday " lol ! No need for concern, move along Link to comment Share on other sites More sharing options...
SmokeEater Posted January 20, 2017 Share Posted January 20, 2017 18 minutes ago, Jon said: Looks like a long-track or two isn't out of the question based on the latest 4km NAM Big track right through Jackson, possibly Tuscaloosa and Birmingham too. Link to comment Share on other sites More sharing options...
kayman Posted January 20, 2017 Share Posted January 20, 2017 5 minutes ago, SmokeEater said: Big track right through Jackson, possibly Tuscaloosa and Birmingham too. That track is southeast of Jackson, but definitely lining up with Tuscaloosa and the Birmingham area. Link to comment Share on other sites More sharing options...
Solak Posted January 20, 2017 Share Posted January 20, 2017 RAH: Friday 1/20... Severe threat: Forcing for ascent will not be lacking on Sunday given lead disturbances aloft and the eventual 100+ meter height falls late Sunday Deep layer shear is plenty strong in excess of 50kt, and low-level hodographs are long and increasingly cyclonically curved owing to a 40-50kt LLJ and the isallobaric response to the deepening surface low. The CAD airmass that developed this morning may still be around in the western Piedmont, and thus the early morning convection is more likely to be elevated than later in the day when backed low level flow has a better chance to advection the warm sector inland. The late day convection should evolve into a squall line as the forcing becomes more linear. Highs in the mid 60s northwest to mid 70s southeast, along with dewpoints potentially in the low/mid 60s, below mid-level lapse rates of 6.5-7C/km could definitely support CAPE values of near 1000 J/KG. Destablization is always a tough thing for models to handle in the pattern, and they typically over mix the eastern edges of the CAD airmass and overestimate SBCAPE. There is always the potential for convection along the Gulf Coast to alter the downstream mass fields and disrupt moisture transport. However, the strengthen of the surface low does warrant some concern for damaging winds and a few tornadoes inland to maybe the US-1 corridor later Sunday? QPF and Flooding: Total QPF is between 2-3 inches through the weekend, which may not be a significant flooding threat when spread out over a couple of days. However, PW around 1.25" and a cutoff low to our SW are favorable for at least some minor flooding. Link to comment Share on other sites More sharing options...
pcbjr Posted January 21, 2017 Share Posted January 21, 2017 And for your southern most neighbor: http://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf Link to comment Share on other sites More sharing options...
monsoonman1 Posted January 21, 2017 Share Posted January 21, 2017 New Day 1 outlook for tonight has a 10% hatched area of tornado probabilities for S Louisiana, S Mississippi and far S Alabama (including NOLA and Mobile, AL). In addition, a 10% tornado probability area has been included for parts of southern LA/MS and far southwest AL, including the Mobile metro area. There will be a greater potential for discrete supercell development with southward extent ahead of the previously mentioned line of thunderstorms. Forecast soundings across this region suggest that any tornadoes that do form in this environment could be strong with southwesterly winds around 850 mb strengthening to around 50 kt overnight, and corresponding effective SRH in excess of 300 m2/s2. Link to comment Share on other sites More sharing options...
MattPetrulli Posted January 21, 2017 Share Posted January 21, 2017 Interestingly strong wording on this evening's day 1 outlook. Another thing to note is that they put; Reminder: This Day 1 Convective Outlook will be valid THROUGH 12Z Saturday (7 AM EST/6 AM CST). An upcoming Day 1 Convective Outlook will be issued around 06Z (1 AM EST/Midnight CST), which will be valid BEGINNING at 12Z Saturday, and continuing through 12Z Sunday. One thing to point out; Forecast soundings across this region suggest that any tornadoes that do form in this environment could be strong Strong wording with that. Link to comment Share on other sites More sharing options...
monsoonman1 Posted January 21, 2017 Share Posted January 21, 2017 Tornado watch out for far SE TX and parts of South and west Louisiana. 50/20 probabilities. The tornado threat, while marginal at first, will increase with time and with eastward extent across the watch area tonight, into southern Louisiana, as shear and instability increase. Link to comment Share on other sites More sharing options...
andyhb Posted January 21, 2017 Share Posted January 21, 2017 The kinematics on Sunday over FL and GA (perhaps into the Carolinas too) look pretty ridiculous. Euro has an appreciable plume of instability into the area as well. Going to come down to the amount of convection between now and then and also the mode, but I could certainly see a widespread damaging wind event or significant tornadoes if the intensity of the low level jet being shown by the Euro/NAM verifies. Tomorrow is more clouded given the high res almost uniformly indicating a lot of contamination from MCS activity, but if anything resembling a healthy warm sector ends up being in place, effective shear is certainly high enough for a pretty broad swath of severe reports. Link to comment Share on other sites More sharing options...
MattPetrulli Posted January 21, 2017 Share Posted January 21, 2017 The National Weather Service in Lake Charles has issued a * Tornado Warning for... Northwestern Jefferson County in southeastern Texas... * Until 815 PM CST * At 748 PM CST, a severe thunderstorm capable of producing a tornado was located near China, or near Nome, moving northeast at 35 mph. HAZARD...Tornado and quarter size hail. SOURCE...Radar indicated rotation. IMPACT...Flying debris will be dangerous to those caught without shelter. Mobile homes will be damaged or destroyed. Damage to roofs, windows, and vehicles will occur. Tree damage is likely. Link to comment Share on other sites More sharing options...
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