andyhb Posted December 25, 2012 Share Posted December 25, 2012 Cantore is heading down to Hattiesburg, MS for tomorrow...that alone is a bad sign. Link to comment Share on other sites More sharing options...
ksstormhunter Posted December 25, 2012 Share Posted December 25, 2012 SmartCast Analysis for 25 Dec/01Z to 26 Dec 01Z ( Base on my model output only) http://smartwxmodel.net/update.htm First the winter side of the storm system: Currently Targeting the area of Tinker to McAlester this hour. My model showing the heaviest snow along this corridor. McAlester Region: Tracking the snow to begin around 18Z, with periods of heavy snow, with snowfall rates of 1.3” per hour. In addition, winds look to increase to around 30MPH along the same timeframe, so look for blowing snow. Right now looking at 8.5” of snow in this area. Tinker AFB/OKC Region: Showing a period of mixed precip from 06Z to 11Z, then changing to all snow by 12Z. Looking at visibilities down to less than ½ mile, and snowfall rates of up to 1.1” per hour possible. Right now looking max of 7.1” of snow accumulation in this area. In addition, looking at winds gusting to 35 to 40mph, which will create temporary blizzard conditions in this area. Vance AFB Region: Looking to be on the fringe of the snow, but still looking at 3.1” of snow possible. Snow will begin around 09Z, and will be heaviest from 16Z to 20Z. In addition, winds will be gusting up to 35MPH during this time, so look for reduce visibility and blowing snow. Damaging Wind Potential: Hobart, Lawton, Lubbock, Childress, and Clinton are all targeted for winds 45 to 50MPH winds during the next 24 hours. In addition, looking at snowfall from 1” to 3” possible. This will also cause tempo conditions of reduce vis and blowing snow. Severe Wx Potential: My model currently tracking the highest instability areas in the Lufkin to Lake Charles area. Looking at over 65% chance for tornadic events in this area. In addition, forecasted hail projected around 2.3” to 2.6” and convective winds of 55 to 60MPH Possible. In addition, heavy rainfall is possible in these areas with precip totals of 1.3 to 1.9” possible. Link to comment Share on other sites More sharing options...
Ed Lizard Posted December 25, 2012 Share Posted December 25, 2012 Cantore is heading down to Hattiesburg, MS for tomorrow...that alone is a bad sign. NAM SIM radar indicates storms reach them before 9 pm tomorrow night. Crazy sounding. Link to comment Share on other sites More sharing options...
andyhb Posted December 25, 2012 Share Posted December 25, 2012 NAM definitely trended south, some really impressive parameters across SE TX, S LA and MS. Includes areas like Houston, Lake Charles, Lafayette, NOLA, Baton Rouge, Hattiesburg... Link to comment Share on other sites More sharing options...
Disc Posted December 25, 2012 Share Posted December 25, 2012 Probability of the supercell composite exceeding 6, 21z Tuesday. This is continuing to increase as well.. Link to comment Share on other sites More sharing options...
andyhb Posted December 25, 2012 Share Posted December 25, 2012 Forecast soundings across the region that I outlined are nothing short of diabolical for this time of year. Link to comment Share on other sites More sharing options...
tornadotony Posted December 25, 2012 Share Posted December 25, 2012 Yeah, this run of the NAM is really bad news...I've got Christmas things tonight including Midnight Mass but I'll hopefully get around to detailing a little more. Link to comment Share on other sites More sharing options...
Disc Posted December 25, 2012 Share Posted December 25, 2012 Lake Charles, LA: (This one is nasty) Natchez, MS: Link to comment Share on other sites More sharing options...
andyhb Posted December 25, 2012 Share Posted December 25, 2012 Lake Charles, LA: (This one is nasty) Natchez, MS: For a lack of a better word...unreal. Link to comment Share on other sites More sharing options...
brettjrob Posted December 25, 2012 Share Posted December 25, 2012 Christ, those soundings. I'd shift the MDT south but certainly go 15 hatched for LA into S MS. Link to comment Share on other sites More sharing options...
L.B. LaForce Posted December 25, 2012 Share Posted December 25, 2012 Yeah, I ran a 3km WRF-ARW run with the 18Z NAM data, and it was just spittin out supercell after supercell, and max updraft helicities were pretty high as well. Definitely worst case scenario down there. Link to comment Share on other sites More sharing options...
Indystorm Posted December 25, 2012 Share Posted December 25, 2012 Yeah, this run of the NAM is really bad news...I've got Christmas things tonight including Midnight Mass but I'll hopefully get around to detailing a little more. Between evening services up here in Elkhart, Tony, but am shifting my attention from snow to the svr wx in Dixie for Christmas. Having just vacationed in NOLA and Natchez a month ago I am quite concerned. Link to comment Share on other sites More sharing options...
Disc Posted December 25, 2012 Share Posted December 25, 2012 I really hope people in those areas are paying attention and it concerns me more than usual because they won't be expecting this stuff during this time of the year. Many of the folks will be occupied with family and friends and may not get the message. Very scary soundings throughout the entire risk area. Link to comment Share on other sites More sharing options...
beneficii Posted December 25, 2012 Share Posted December 25, 2012 00z NAM is further southeast and gives Memphis another shot at snow Tuesday night into Wednesday. Link to comment Share on other sites More sharing options...
SmokeEater Posted December 25, 2012 Share Posted December 25, 2012 Can we split the 2 aspects of this storm, or no? Link to comment Share on other sites More sharing options...
WeatherQ Posted December 25, 2012 Share Posted December 25, 2012 Yeah, this run of the NAM is really bad news...I've got Christmas things tonight including Midnight Mass but I'll hopefully get around to detailing a little more. Tony, those hodographs, low level shear profiles and just the power of that system suggest A very ill-winded Christmas in the Deep South. Be careful. Merry Christmas. Link to comment Share on other sites More sharing options...
tornadotony Posted December 25, 2012 Share Posted December 25, 2012 Tony, those hodographs, low level shear profiles and just the power of that system suggest A very ill-winded Christmas in the Deep South. Be careful. Merry Christmas. I'm luckily in nrn IN with my family for Christmas, so I'll be okay, but thanks! Link to comment Share on other sites More sharing options...
Ground Scouring Posted December 25, 2012 Share Posted December 25, 2012 Lake Charles, LA: (This one is nasty) Natchez, MS: The projected 0-1-km SRH values coupled with the SR winds in the 900-850-mb column are near the parameters that would support violent tornadoes, especially given the 35-kt+ SR inflow over southern MS north almost to KGWO. The consistent trend toward a more rapid deepening of the surface low in SE TX, along with the minimum of junk convection (which I have mentioned before), on the NAM allows the warm front to progress to about KGWO by 21Z Tuesday, with Td's AOB 60°F just to the south--in the area with maximum mean 0-3-km SRH. This really widens the corridor for strong/violent tornadoes in a region boxed by KESF-KMSY in the south and KMLU-north of KMEI. At this point areas as far north as Delhi, LA, Pickens, MS, and Geiger, AL, are in play for strong tornadoes beginning tomorrow afternoon. 0-1-km helicity really maximizes near these northern cities, where all the factors mentioned--juicy Td's, retreating warm-frontal convergence, likely outflow boundaries, and insane potential for rotation along with moderately-sized hail and intense downbursts--really come together to favor a potential for a few violent tornadoes. I would also keep the MDT along a line extending to BMH due to very strong low-level shear and a temperature profile which favors possible, isolated strong tornadoes and large downbursts overnight Tuesday-Wednesday as the pre-frontal QLCS moves into S/C AL. Overall, I am getting very concerned that we will probably see at least one violent tornado with several long-lived supercells plus a high damaging-wind/moderate hail threat. At least insofar as the violent/long-track tornado probability is concerned, climatology for December probably should be thrown out a bit as the dynamics involved here suggest more of a January-type potential for violent tornadoes. Link to comment Share on other sites More sharing options...
Ground Scouring Posted December 25, 2012 Share Posted December 25, 2012 With off-the-charts SRH and incredible hodographs, the risk for embedded spinups in this area will still be noteworthy, but I'm skeptical of long-trackers along the I-20 corridor as things stand. The 12z WRF-NMM shows no discrete activity ahead of the line, FWIW. This is not directed against you specifically, but to others...the NAM reflectivity is not always an accurate predicator of mesoscale convective coverage due to issues with resolution. Its parameters are useful to determine overall convective modes, but the resolution does not always allow the model to accurately display what its parameters would define as the actual QPF / storm-modular output. Link to comment Share on other sites More sharing options...
Srain Posted December 25, 2012 Share Posted December 25, 2012 Can we split the 2 aspects of this storm, or no? Adam and I decided in the beginning to cover both aspects of this event. Since the societal impacts are for both winter and severe, we'll leave this thread as a general event thread on the Main Page for greater exposure to the community as a whole. We are in Storm Mode for that reason... Link to comment Share on other sites More sharing options...
brettjrob Posted December 25, 2012 Share Posted December 25, 2012 This is not directed against you specifically, but to others...the NAM reflectivity is not always an accurate predicator of mesoscale convective coverage due to issues with resolution. To clarify, I was referring to the 4km NMM, so resolution should not be an issue there (and it's decent at predicting mode). We'll see what 00z shows shortly. Link to comment Share on other sites More sharing options...
andyhb Posted December 25, 2012 Share Posted December 25, 2012 You can toss N FL into the mix for early Wednesday. Link to comment Share on other sites More sharing options...
Srain Posted December 25, 2012 Share Posted December 25, 2012 Interesting discussion from FWD this evening. One of the things I noticed this afternoon was the short wave was in fact a bit further S in New Mexico ~vs~ SE Colorado that the models had been suggesting. This could have rather significant implications in both the cold and warm sector and the severe threat expected. AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 912 PM CST MON DEC 24 2012 .UPDATE... WE HAVE ANALYZED THE 00Z UPPER AIR DATA AND HAVE WATCHED THE SURFACE OBS CLOSELY FOR SIGNS OF ANY DISCREPANCIES BETWEEN THEM AND THE MODEL DATA. THE BIG THING THAT STANDS OUT ARE THAT THE SURFACE LOW IN NORTHEAST NEW MEXICO AT 6PM WAS ABOUT 80 MILES FARTHER SOUTH THAN ALL OF THE MODELS HAD FORECAST 24 HOURS AGO. WHEN DEALING WITH A SWINGING/DIGGING UPPER LEVEL SYSTEM...THE SURFACE PRESSURE PATTERN AND PRESSURE TENDENCIES OFFER ENORMOUS CLUES ON THE FUTURE TRACK OF A POTENTIAL VORTICITY ANOMALY BEFORE IT CLOSES OFF TO BECOME A FULL FLEDGED UPPER LOW. THE 3PM AND 6PM SURFACE ANALYSIS SHOWED A LARGE REGION OF PRESSURE FALLS ACROSS NEW MEXICO AND WEST TEXAS IN ADVANCE OF THE SYSTEM. GIVEN THE ORIENTATION OF THE PRESSURE FALLS AND LOCATION OF THE SURFACE LOW...IT CAN BE DETERMINED WITHOUT EVEN LOOKING AT A FORECAST MODEL THAT THE UPPER LOW HAS NOT FINISHED DIGGING SOUTH. THE BIG QUESTION IS HOW FAR SOUTH WILL THE UPPER LOW MAKE IT BEFORE IT BEGINS TO SWING BACK TO THE NORTHEAST. AT THIS HOUR PRESSURE FALLS CONTINUE IN THE REGION FROM LUBBOCK TO MIDLAND...WITH ANOTHER PRESSURE FALL AREA DEVELOPING IN SOUTHEAST TEXAS. EXTRAPOLATING SUGGESTS THE UPPER LOW WILL TRACK JUST SOUTH OF LUBBOCK BY SUNRISE AND TO NEAR WACO BY SUNSET. AS THE LOW APPROACHES WACO...A WARM FRONT WILL BE ORGANIZING OUT OF THE WEAK STATIONARY FRONT CURRENTLY ANALYZED FROM SAN ANTONIO TO HOUSTON. BAROCLINIC QG THEORY SUGGESTS THAT ONCE LOW LEVEL WARM ADVECTION BEGINS IN EARNEST ACROSS SOUTHEAST TEXAS BY MORNING...IT WILL INDUCE HEIGHT RISES TO THE SOUTHEAST OF OUR UPPER LOW WHICH WILL CAUSE THE LOW TO CLOSE OFF AND FINISH DIGGING SOUTH...AND START ITS GRADUAL TURN TO THE NORTHEAST. TOMORROW EVENING I WOULD EXPECT THE LOW TO TRACK FROM NEAR WACO TO NEAR SHREVEPORT. IN SUMMARY THE USUAL MEDIUM RANGE MODELS APPEAR TO BE A LITTLE TOO FAR NORTH WITH THE TRACK OF THE UPPER LOW. OUR EXPECTATIONS FOR THE TRACK OF THE LOW ALIGN WELL WITH THE RAP FORECAST WHICH IS TO THE SOUTH OF ALL OTHER MODELS...SO WE WILL USE THE RAP HEAVILY. OUR FORECAST HAS BEEN ON THE SOUTHERLY SIDE AND SNOWIER SIDE OF THE MODEL GUIDANCE. SO ALTHOUGH WE ARE SEEING AN EVEN MORE SOUTHERLY TRACK COME TO FRUITION...THIS DOES NOT NECESSARILY MEAN THE FORECAST SNOW AMOUNTS NEED TO BE AMENDED MUCH. THIS IS IN PART DUE TO THE DIFFICULTY IN GETTING THE COLDER/SUBFREEZING AIR FARTHER SOUTH BEFORE THE PRECIPITATION ENDS. THE EXCEPTION IS THE NORTHWEST ZONES WHERE THE MORE SOUTHERLY TRACK SUGGESTS MORE PRECIP WILL FALL IN SUBFREEZING AIR. DUE TO THE TERRAIN EFFECTS HERE...COLD AIR HAS AN EASY TIME GETTING INTO OUR NORTHWEST ZONES WHEN WE HAVE A NORTH/NORTHEAST SURFACE WIND. HAVE EXPANDED THE SNOW ADVISORY TO INCLUDE YOUNG/JACK/WISE COUNTIES...AND HAVE INCREASED SNOW TOTALS TO THE 2-4 INCH RANGE FROM BOWIE TO SHERMAN. THE NORTHEAST ZONES LIKELY WONT SWITCH TO SNOW UNTIL LATE AFTERNOON...AS COLD AIR WILL HAVE TROUBLE MOVING IN AT THE SURFACE DUE TO THE LEE SHADOW WARMING EFFECT OF THE OZARK PLATEAU. MOST OF THE SNOW THAT OCCURS THERE WILL BE AFTER 6 PM AND WILL BE HIGHLY DEPENDENT ON WHETHER MESOSCALE BANDING CAN SET UP IN THE WAKE OF THE UPPER LOW. THE NEW NAM HAS FINALLY FORECAST SOME SIGNIFICANT BANDING TO OCCUR...THUS WILL LEAVE THE ADVISORY ALONE IN THIS AREA...BUT CONFIDENCE IS A LITTLE LOWER IN THE NORTHEAST ZONES FOR 2+ INCHES OF SNOW. FARTHER TO THE SOUTH OF THE ADVISORY...FOR THE I-20 CORRIDOR AND INCLUDING THE METROPLEX...THERE IS NOW HIGH CONFIDENCE THAT SNOW WILL OCCUR. HOWEVER ALL INDICATIONS ARE THAT IT WILL STILL BE A BRIEF 1-3 HOUR EVENT WITH NOT ENOUGH TIME TO GET ACCUMULATIONS OVER AN INCH. IT MUST BE STRESSED THAT WITH TEMPERATURES FALLING INTO THE 20S BY SUNSET...ANY APPRECIABLE MOISTURE REMAINING ON BRIDGES...OVERPASSES AND EVEN SURFACE STREETS WILL LIKELY RE- FREEZE INTO BLACK ICE. ALTHOUGH WE ARE USING 1+ INCH AS CRITERIA FOR THE COUNTIES IN THE WINTER WEATHER ADVISORY AREA...WE MAY EXPAND THE ADVISORY SOUTH INTO THE METROPLEX OVERNIGHT DUE SOLELY TO TRAVEL IMPACTS. FINALLY CONCERNING THE SEVERE WEATHER THREAT. WITH A MORE SOUTHERLY TRACK OF THE UPPER LOW...THIS MEANS THERE IS LESS OF A CHANCE OF THE WARM FRONT MAKING IT INTO THE SOUTHEAST CWA TONIGHT AS IT WILL LIKELY STAY SOUTHEAST OF THE AREA. ELEVATED THUNDERSTORMS ARE STILL EXPECTED TO RAPIDLY INCREASE IN COVERAGE AFTER 3 AM...WITH ELEVATED INSTABILITY HIGH ENOUGH FOR A FEW SEVERE HAIL STORMS SOUTH OF I-20. HAVE TONED DOWN THE DAMAGING WIND AND TORNADO THREAT FROM OUR PRODUCTS...BUT WE WILL CONTINUE TO ADVERTISE HAIL STORMS POSSIBLE LATE TONIGHT AND EARLY TOMORROW MORNING. Link to comment Share on other sites More sharing options...
andyhb Posted December 25, 2012 Share Posted December 25, 2012 This may be one of the most frightening high-res model frames I have ever seen from the 4km NAM... Link to comment Share on other sites More sharing options...
Thundersnow12 Posted December 25, 2012 Share Posted December 25, 2012 This may be one of the most frightening high-res model frames I have ever seen from the 4km NAM... was just about to post this, pretty crazy to see this. Link to comment Share on other sites More sharing options...
brettjrob Posted December 25, 2012 Share Posted December 25, 2012 This may be one of the most frightening high-res model frames I have ever seen from the 4km NAM... The 00z 4km NMM is a lot more impressive than the 12z, too: http://www.emc.ncep....yle/spcprod/00/ Link to comment Share on other sites More sharing options...
andyhb Posted December 25, 2012 Share Posted December 25, 2012 The 00z 4km NMM is a lot more impressive than the 12z, too: http://www.emc.ncep....yle/spcprod/00/ I see multiple lines of supercells on that thing... Link to comment Share on other sites More sharing options...
Ground Scouring Posted December 25, 2012 Share Posted December 25, 2012 The strength of the dry punch between 00-06Z Wednesday on the 00Z NAM is just incredible...indicating the intensity of the mid-level system. This allows the QLCS to remain mostly or entirely discrete supercells from extreme E LA / SW MS all the way to GA. In particular, it shows three rounds of tornado-producing supercells: a first round of storms starting 12Z Tuesday with elevated storms becoming surface-based in E/C LA; a second, prolonged (meaning nocturnal) outbreak beginning at 21Z Tuesday in S/C MS; and a third, afternoon event at 21Z Wednesday in C AL extending into W GA. The orientation of the surface-700-mb bulk shear relative to the front, in particular, really helps to maintain discrete supercells for a long period of time. This almost reminds me of 04/27/2011, as frightening as it may be to invoke. http://www.emc.ncep....yle/spcprod/00/ Given the trends, I am starting to think that a Day-1 High Risk for overall TOR and Severe Wind probabilities may be in order. Link to comment Share on other sites More sharing options...
jrips27 Posted December 25, 2012 Share Posted December 25, 2012 Yeah that's scary. Looks like the storms are becoming more linear in nature as they approach the Atlanta area, no? I'm not letting my guard down at all though! Edit: Well the post above me disagrees with my assessment haha Link to comment Share on other sites More sharing options...
Srain Posted December 25, 2012 Share Posted December 25, 2012 Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.