Cheeznado Posted December 19, 2013 Share Posted December 19, 2013 Spans a couple of regions so posted here. This is beginning to look like we may have another chance at a few strong tornadoes in the Mid-South/lower MS Valley Saturday as the old CA upper low ejects with a negative tilt which will bring some very strong low- mid-level wind fields into the area which should have more than enough moisture. I expect a MOD risk day with at least several tornadoes perhaps with individual supercells and/or imbedded line segments. Link to comment Share on other sites More sharing options...
tmagan Posted December 19, 2013 Share Posted December 19, 2013 I was waiting for someone to mention the possibility of strong tornadoes, my question would be the degree of surface instability given the SST's in the NW Gulf of Mexico. Link to comment Share on other sites More sharing options...
WeatherDA Posted December 19, 2013 Share Posted December 19, 2013 I know this possibility would come up given the dynamics that were coming together. I also seen that maybe the main mode of severe weather would be a squall line with isolated embedded tornadoes. They did not rule out the possibility of maybe a few discrete supercells however. Link to comment Share on other sites More sharing options...
andyhb Posted December 19, 2013 Share Posted December 19, 2013 I was waiting for someone to mention the possibility of strong tornadoes, my question would be the degree of surface instability given the SST's in the NW Gulf of Mexico. There are 65-70˚+ dewpoints projected across a large portion of the south ahead of this system, with low level flow not just from the Gulf, but deep in the Caribbean as well. This event does have significant potential, with a pre-frontal trough being shown by many models. This may initiate discrete convection well in advance of the cold front across the Arklamiss and perhaps moving into AL with time. Link to comment Share on other sites More sharing options...
Ed Lizard Posted December 19, 2013 Share Posted December 19, 2013 Just looking at some GFS soundings locally (SETX) around 18Z Saturday, about action time locally per GFS, besides a warm nose around 700 mb that has to be overcome, the best speed and directional shear are surface to 850 mb, where the poorest lapse rates are. So I'm thinking at least in SETX that would tend to limit the tornado threat. One thing in favor of tornadoes, LCLs will be below 900 mb. OTOH, NETX, around GGG, the cap looks much more breakable, and the lapse rates near surface are't as poor as SETX, At least per 18Z NAM. 18Z GFS forecast sounding, not as impressive, at least partly because winds already shifting from SSE to SW. I assume NAM will trend towards somewhat quicker Euro/GFS guidance as we get closer, but there are still differences. Still using GFS at this point, and if the cap can break, while I have concerns about low level lapse rates, 850 mb winds 40-50 knots and strong bulk shear 0-6 km, we could have quite a show locally. 18Z GFS has some decent LI for December. Link to comment Share on other sites More sharing options...
Hoosier Posted December 20, 2013 Share Posted December 20, 2013 850 mb winds look hellacious...60-70 kts down south and around 90 kts in the Ohio Valley Saturday night/Sunday morning though that is north of where the main threat is. Link to comment Share on other sites More sharing options...
1900hurricane Posted December 20, 2013 Share Posted December 20, 2013 So much potential with this one, but things just might not hook up right in SETX. With a faster surface low, there's not going to be much time to break the cap prior to fropa Saturday around midday or so, and by then, veer-backing will probably be prevalent. Still looks like things could get interesting around here, but it looks like a lot will end up being left on the table with potential to be so much more... Link to comment Share on other sites More sharing options...
Cheeznado Posted December 20, 2013 Author Share Posted December 20, 2013 SRH values are off the charts on the 00Z NAM with values in SE AR 0-1KM AOA 500 m2/s2. If at least 1000 J of CAPE can be realized.....watch out. Link to comment Share on other sites More sharing options...
WeatherDA Posted December 20, 2013 Share Posted December 20, 2013 SPC just issued a moderate risk for severe weather for Saturday. http://www.spc.noaa.gov/products/outlook/day2otlk.html Link to comment Share on other sites More sharing options...
Srain Posted December 20, 2013 Share Posted December 20, 2013 Link to comment Share on other sites More sharing options...
1900hurricane Posted December 20, 2013 Share Posted December 20, 2013 So it looks like I have the choice to chase in either darkness or in trees. Even before taking storm mode into consideration, I think I might pass on this one. And I had so much hope for this one too... LATER TNGT AND...ESPECIALLY...EARLY SAT...APPRECIABLE /ON THE ORDEROF 60 M/ HEIGHT FALLS WILL BEGIN TO OVER SPREAD S CNTRL TX AS THEBAJA SYSTEM APPROACHES THE REGION. COUPLED WITH AN ASSOCIATEDSTRENGTHENING OF SSWLY 850 MB FLOW /SPEEDS INCREASING TO AOA 65 KTS/AND PERSISTENT MOISTENING...SETUP SHOULD SUPPORT A FAIRLY WIDESPREADBLOSSOMING OF SHOWERS AND TSTMS ALONG AND N OF THE FRONT FROM WRNAND S CNTRL TX NEWD THROUGH THE ARKLATEX INTO SE MO/SRN IL.MOST OF THE ELEVATED ACTIVITY SHOULD REMAIN NON-SVR...ALTHOUGHSUFFICIENT ELEVATED BUOYANCY MAY ARISE FOR MARGINALLY SVR HAIL IN SCNTRL TX. OF GREATER SVR CONCERN...HOWEVER...WILL BE THE CONDITIONALRISK FOR SFC OR NEAR SFC-BASED STORMS ALONG THE IMMEDIATE FRONT...ORPERHAPS JUST AHEAD OF IT...LATER TNGT AND EARLY SAT FROM S CNTRL TXNE TO THE ARKLATEX.GIVEN THE STRENGTH OF THE LLJ...700 MB FLOW INCREASING TO AOA 60KTS...LIKELY PROGRESSION OF UPR TROUGH...AND SFC DEWPOINTSAPPROACHING 70F OVER WRN PARTS OF THE TX CSTL PLN...SETUP MAY YIELDA CONDITIONAL RISK FOR SUPERCELL/LEWP CIRCULATIONS CAPABLE OF DMGGWIND AND/OR TORNADOES. THIS THREAT WOULD BE GREATEST AFTER 09Z...ANDLIKELY WILL PERSIST/SPREAD FARTHER E/NE BEYOND 12Z SAT. Link to comment Share on other sites More sharing options...
Srain Posted December 20, 2013 Share Posted December 20, 2013 Link to comment Share on other sites More sharing options...
wxmeddler Posted December 20, 2013 Share Posted December 20, 2013 So it looks like I have the choice to chase in either darkness or in trees. Even before taking storm mode into consideration, I think I might pass on this one. And I had so much hope for this one too... Even if I was in the region, storm motion alone would of cancled my chase for this one. Perhaps doable if your a local and you know your favorite spots and watch it go by. Link to comment Share on other sites More sharing options...
Cheeznado Posted December 20, 2013 Author Share Posted December 20, 2013 18Z NAM still has some off-the-scale 0-1KM SRH values of 5-600 in SE AR to NE LA. Link to comment Share on other sites More sharing options...
wxtrackercody Posted December 20, 2013 Share Posted December 20, 2013 Still have subtle veer-back profiles in the soundings across the MDT risk area as forecast by the GFS and NAM. Something to watch out for tomorrow. Link to comment Share on other sites More sharing options...
andyhb Posted December 20, 2013 Share Posted December 20, 2013 Still have subtle veer-back profiles in the soundings across the MDT risk area as forecast by the GFS and NAM. Something to watch out for tomorrow. There's actually a lot less of it with the NAM than there was in previous runs over the main threat area, owing to a stronger SSW-NNE component of the 700 mb jet streak. Also, these storms are going to be racing with the H7 jet streak at 60-80 kts. Link to comment Share on other sites More sharing options...
Thrasher Fan Posted December 20, 2013 Share Posted December 20, 2013 Getting things started a day early. TOR on the ground per trained spotters. TORNADO WARNINGMSC049-210015-/O.NEW.KJAN.TO.W.0073.131220T2324Z-131221T0015Z/BULLETIN - EAS ACTIVATION REQUESTEDTORNADO WARNINGNATIONAL WEATHER SERVICE JACKSON MS524 PM CST FRI DEC 20 2013THE NATIONAL WEATHER SERVICE IN JACKSON HAS ISSUED A* TORNADO WARNING FOR... NORTHERN HINDS COUNTY IN CENTRAL MISSISSIPPI...* UNTIL 615 PM CST* AT 522 PM CST...A TORNADO WAS INDICATED NEAR EDWARDS...AND MOVING NORTHEAST AT 25 MPH. HAZARD...TORNADO.* THIS DANGEROUS STORM WILL BE NEAR... BOLTON AROUND 540 PM CST. BROWNSVILLE AROUND 555 PM CST. POCAHONTAS AROUND 615 PM CST. Link to comment Share on other sites More sharing options...
SouthernNJ Posted December 21, 2013 Share Posted December 21, 2013 Couple of spinners in AR. One near the town of Redfield which may have damaging winds. Link to comment Share on other sites More sharing options...
SouthernNJ Posted December 21, 2013 Share Posted December 21, 2013 Follow-up from Redfield: 0033 Redfield Jefferson County AT LEAST FOUR HOMES SUFFERED ROOF DAMAGE ... WITH TREES AND POWER LINES DOWNED. NO INJURIES WERE REPORTED. A BRIEF TORNADO MAY HAVE BEEN RESPONSIBLE FOR THE DAMAGE. No warning was issued for the storm, an SPS appeared at 0036. From what I viewed seeing it live, a Microburst-type velocity signature appeared at 0018, and a potentially tornadic scan at 0036. Link to comment Share on other sites More sharing options...
WeatherFanMatt Posted December 21, 2013 Share Posted December 21, 2013 Nevermind, just checked the convectives. Link to comment Share on other sites More sharing options...
tornadotony Posted December 21, 2013 Share Posted December 21, 2013 I'm thinking that mdt risk might need to be expanded quite a bit to the N and E. It appears increasingly likely that widespread wind damage and both mesovortex and embedded supercell tornadoes are likely at least from the OH River (maybe all the way to I-70) all the way to darn near the Gulf Coast. And if we do get embedded supercells or some supercells ahead of the main line, there's going to be a very high threat of significant tornadoes with the enormous low-level hodos and instability in place with any of those features. Hell, some of the QLCS tornadoes are probably going to be EF2 or even EF3 with this kind of shear. And I'd expect that threat to exist at a pretty high level well through the night and well east of the current mdt risk, likely across much of AL, middle TN, central KY, and even SW OH. Link to comment Share on other sites More sharing options...
Hoosier Posted December 21, 2013 Share Posted December 21, 2013 Link to comment Share on other sites More sharing options...
Srain Posted December 21, 2013 Share Posted December 21, 2013 MESOSCALE DISCUSSION 2096 NWS STORM PREDICTION CENTER NORMAN OK 0757 AM CST SAT DEC 21 2013 AREAS AFFECTED...PARTS OF E TX...WRN/NRN LA...AND SRN AR CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 211357Z - 211500Z PROBABILITY OF WATCH ISSUANCE...60 PERCENT SUMMARY...TORNADO WATCH ISSUANCE MAY BE REQUIRED BY 15-17Z FOR PARTS OF EAST TX INTO WRN/NRN LA AND SRN AR. DISCUSSION...LIGHTNING TRENDS THROUGH 1330Z SHOWED TSTMS CONTINUING TO DEVELOP FROM NERN TX /NEAR THE COLD FRONT/ AND SSWWD ALONG A PRE-FRONTAL CONFLUENCE ZONE TO 45 NNE KVCT. THIS CONVECTIVE EVOLUTION IS LIKELY OCCURRING AS STRONGER HEIGHT FALLS/DEEP LAYER ASCENT IS BEGINNING TO SPREAD NEWD FROM CENTRAL TX. ENVIRONMENT ALONG AND E OF THE FRONT/PRE-FRONTAL CONFLUENCE ZONE IS SUFFICIENTLY SHEARED TO RESULT IN ORGANIZED STORMS...GIVEN 50-60 KT SLY LLJ. HOWEVER...THE STRONGER ASCENT TO SUPPORT STORMS BECOMING ROOTED IN THE BOUNDARY LAYER REMAINS WEST OF THE SURFACE FRONT. AS THIS ASCENT MAKES NEWD ADVANCEMENT...SUSTENANCE OF UPDRAFTS IS EXPECTED TO BECOME GREATER ESPECIALLY BETWEEN 15-17Z. ..PETERS/CORFIDI.. 12/21/2013 ATTN...WFO...JAN...LZK...LCH...SHV...HGX... Link to comment Share on other sites More sharing options...
Srain Posted December 21, 2013 Share Posted December 21, 2013 LCH will be conducting a special 1Z sounding. Link to comment Share on other sites More sharing options...
1900hurricane Posted December 21, 2013 Share Posted December 21, 2013 Sneaky (two miles from me)... Don't think there was anything there, but that was a quick little mesocyclone spin within that line. Next frame had it over the radar site, so I can't tell exactly how transient it was, but I'm guessing pretty. KHGX radar hardly showed anything at the same time. Link to comment Share on other sites More sharing options...
wxmeddler Posted December 21, 2013 Share Posted December 21, 2013 Add a little surface heating and cooling midlevels and Link to comment Share on other sites More sharing options...
Indystorm Posted December 21, 2013 Share Posted December 21, 2013 SPC did move that moderate risk northward and eastward in their 1630 outlook just as tornadotony anticipated. Probably gonna be an active day that might well overshadow the winter aspect of this storm. Slight risk now extends all the way to Indianapolis and Cleveland. Link to comment Share on other sites More sharing options...
Indystorm Posted December 21, 2013 Share Posted December 21, 2013 And so we begin. Not going to be able to chase these storms with speeds like this today. BULLETIN - EAS ACTIVATION REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE MEMPHIS TN 1132 AM CST SAT DEC 21 2013 THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... NORTHEASTERN MISSISSIPPI COUNTY IN EASTERN ARKANSAS... WEST CENTRAL DYER COUNTY IN NORTHWEST TENNESSEE... SOUTHERN PEMISCOT COUNTY IN SOUTHEAST MISSOURI... WEST CENTRAL LAUDERDALE COUNTY IN SOUTHWEST TENNESSEE... * UNTIL NOON CST * AT 1132 AM CST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR KEISER...AND MOVING NORTHEAST AT 80 MPH. * LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO BLYTHEVILLE...GOSNELL...KEISER...LUXORA...OSCEOLA... CARUTHERSVILLE...DENTON...STEELE...TEMPLES CORNER...BRAGGADOCIO... SHADE...STUBTOWN...CANADY AND NEW SURVEY. THIS WARNING ALSO INCLUDES AREAS NEAR BIG LAKE. Link to comment Share on other sites More sharing options...
wxtrackercody Posted December 21, 2013 Share Posted December 21, 2013 Surface-based CAPE seems to be lagging quite a bit compared to what the forecast was. The 500j/kg remains all the way down in central Louisiana and Mississippi. We'll have to wait and see how quickly it advances northward. Link to comment Share on other sites More sharing options...
1900hurricane Posted December 21, 2013 Share Posted December 21, 2013 CAPE should increase as soon as the mid level energy begins to kick east, but will it happen fast enough? With PVA so far west still, not so sure. Link to comment Share on other sites More sharing options...
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