am19psu Posted December 22, 2012 Share Posted December 22, 2012 A major winter storm is taking shape from Texas on Christmas to New England by Friday (potentially). Use this thread to discuss severe weather in the South and winter weather across the Midwest and Northeast. Link to comment Share on other sites More sharing options...
Srain Posted December 22, 2012 Share Posted December 22, 2012 While we are still a couple of days out and there remains some uncertainty in the eventual track of the Storm system, there are strong indications that both winter weather as well as a severe potential may well unfold across portions of E Texas extending E into the Deep South S of the I-20 Corridor. Further N into Eastern Oklahoma/Arkansas and on ENE in Mid West/Tennessee Valley within the cold sector, a variety of winter weather including snow and ice and very gusty winds and blowing snow creating the potential for a high impact event affecting travel as well as societal impacts during the busy Holiday period. The storm system is currently nearing the California Coast and should be onshore and in the RAOB network tomorrow. One concern we are following closely in the South is the Severe aspect of this dynamic Winter Storm. The SPC has outlined a Day 4 threat for severe storms in their Outlook. At this time the main threat appears to be damaging winds with a linear line of rapidly moving storms, but the tornado potential cannot be dismissed during the late Christmas Day time frame beginning in SE Texas and extending overnight into Southern Louisiana/Mississippi and Alabama on the 26th.The severe potential may extend further E into GA/FL and SC on the 27th. Link to comment Share on other sites More sharing options...
am19psu Posted December 22, 2012 Author Share Posted December 22, 2012 Should he noted that the low track above is for the pre-Christmas wave, not the main event that begins in Texas on Christmas Link to comment Share on other sites More sharing options...
Srain Posted December 22, 2012 Share Posted December 22, 2012 Should he noted that the low track above is for the pre-Christmas wave, not the main event that begins in Texas on Christmas Excellent point Adam and the lead wave will play a pivotal role as to how things evolve for the Christmas Storm. A warm front will move N from the Western Gulf across Central/SE Texas into Louisiana during the day Christmas Eve setting the stage for the Severe potential outlined above. There are strong suggestions a Coastal Low/wave will develop along the Middle/Upper Texas Coast setting the stage for all the potential events that will follow. This appears to be a very dynamic storm complex with many implications for a large part of the Eastern half of the CONUS. SHORT RANGE FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD 239 AM EST SAT DEC 22 2012 VALID 12Z SAT DEC 22 2012 - 12Z MON DEC 24 2012 ***STRONG LOW PRESSURE SYSTEM DEPARTING THE NORTHEAST U.S.*** ***MORE BAD WEATHER FOR THE WEST COAST STATES*** ***VERY COLD FOR THE NORTHERN PLAINS AND UPPER MIDWEST*** THE STRONG AREA OF LOW PRESSURE THAT AFFECTED MUCH OF THE CENTRAL AND EASTERN U.S. OVER THE PAST COUPLE OF DAYS IS FORECAST TO MOVE INTO EASTERN CANADA DURING THE DAY ON SATURDAY. SOME LINGERING LIGHT SNOW SHOWERS ARE STILL POSSIBLE NEAR THE GREAT LAKES AND INTO NORTHERN NEW ENGLAND THROUGH EARLY SUNDAY. THE HIGHER ELEVATIONS OF THE CENTRAL APPALACHIANS WILL ALSO RECEIVE SOME ADDITIONAL SNOWFALL. IN ADDITION, STRONG AND GUSTY WINDS ARE LIKELY THROUGH SATURDAY WITH GUSTS UP TO 50 MPH POSSIBLE. OVER THE WEST COAST STATES, STEADY RAIN AND HIGHER ELEVATION SNOW IS EXPECTED TO CONTINUE AS ONSHORE FLOW CONTINUES UNABATED AHEAD OF A FRONTAL TROUGH. THE HEAVIEST PRECIPITATION IS LIKELY FOR CENTRAL AND NORTHERN CALIFORNIA, WITH A COUPLE INCHES OF RAIN FOR COASTAL AREAS AND AT LEAST TWO FEET OF SNOW IN THE HIGHER MOUNTAINS OF THE SIERRA NEVADA RANGE. ELSEWHERE, BITTERLY COLD AIR WILL CONTINUE FOR THE NORTHERN PLAINS AND UPPER MIDWEST THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK. OVER THE DEEP SOUTH AND INTO TEXAS, MUCH COOLER AND CONSIDERABLY DRIER WEATHER HAS ARRIVED BEHIND THE COLD FRONT AND IT WILL FEEL MORE LIKE DECEMBER. Link to comment Share on other sites More sharing options...
OUGrad05 Posted December 22, 2012 Share Posted December 22, 2012 Ok folks forgive me, I'm pretty good at severe weather forecasting and prediction but I absolutely suck at reading models and interpretation for winter weather. Anyone have specifics on how this will impact the Tulsa metro area and the timing of the various impacts? The models don't seem to have a good grasp on this system yet, which isn't surprising since it won't really be over the data network for another 12 to 18 hours. Link to comment Share on other sites More sharing options...
Srain Posted December 22, 2012 Share Posted December 22, 2012 HPC Model Diagnostic Discussion for the 12Z suite of guidance: ...SFC LOW IMPACTING THE WEST COAST ON SUN... PREFERENCE: 12Z NAM / 12Z ECMWF CONFIDENCE: AVERAGE REGARDING THE SFC LOW REACHING THE WEST COAST ON SUN...THE GFS LOOKS FAST...AND THE 12Z ECMWF HAS SPED UP CLOSER TO THE CONSENSUS BUT THE 12Z NAM AND 00Z EC MEAN ARE STILL A BIT BACK TOWARD THE ENSEMBLE CONSENSUS...SLIGHTLY BEHIND THE 12Z ECMWF. GIVEN DOWNSTREAM PREFERENCES...A 12Z NAM/ECMWF BLEND IS LIKELY BEST WITH THE SFC LOW COMING INTO THE WEST COAST ON SUN GIVEN PLACEMENT IN THE MIDDLE OF THE SPREAD...WITH CONSIDERATION OF SOME OF THE FASTER GUIDANCE. ...SHRTWV ENERGY AMPLIFYING THROUGH THE INTERMOUNTAIN WEST ON MON AND REACHING THE CNTRL/SRN PLAINS TUE... PREFERENCE: 12Z ECMWF / 12Z UKMET CONFIDENCE: BELOW AVERAGE THE NAM IS ON THE WEAKER AND NRN SIDE OF THE MODEL SPREAD WITH BOTH THE SHORTWAVE AND SFC LOW BY THE TIME THE SYSTEM REACHES THE PLAINS. THE GFS HAS TRENDED QUICKER WITH THE SHORTWAVE EJECTING OUT INTO THE PLAINS ON TUE AND IS ON THE FASTER SIDE OF THE SPREAD. GIVEN THE 12Z CMC IS A BIT OUTSIDE OF THE CONSENSUS...BLENDING THE 12Z ECMWF AND 12Z UKMET APPEAR THE BEST WAY TO GO AND FALL RIGHT IN THE MIDDLE OF THE CONVERGING ENSEMBLE SPAGHETTI LOW PLOTS...LOOKING OVER THE PAST 5 RUNS. THE 12Z ECMWF LOOKS MOSTLY UNCHANGED FROM ITS 00Z RUN WITH THIS SYSTEM. Link to comment Share on other sites More sharing options...
Srain Posted December 22, 2012 Share Posted December 22, 2012 SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE NORMAN OK 340 PM CST SAT DEC 22 2012 OKZ004>048-050>052-TXZ083>090-231200- HARPER-WOODS-ALFALFA-GRANT-KAY-ELLIS-WOODWARD-MAJOR-GARFIELD- NOBLE-ROGER MILLS-DEWEY-CUSTER-BLAINE-KINGFISHER-LOGAN-PAYNE- BECKHAM-WA****A-CADDO-CANADIAN-OKLAHOMA-LINCOLN-GRADY-MCCLAIN- CLEVELAND-POTTAWATOMIE-SEMINOLE-HUGHES-HARMON-GREER-KIOWA-JACKSON- TILLMAN-COMANCHE-STEPHENS-GARVIN-MURRAY-PONTOTOC-COAL-COTTON- JEFFERSON-CARTER-JOHNSTON-ATOKA-LOVE-MARSHALL-BRYAN-HARDEMAN- FOARD-WILBARGER-WICHITA-KNOX-BAYLOR-ARCHER-CLAY- INCLUDING THE CITIES OF...BUFFALO...ALVA...CHEROKEE...MEDFORD... PONCA CITY...ARNETT...WOODWARD...FAIRVIEW...ENID...PERRY... CHEYENNE...TALOGA...WEATHERFORD...CLINTON...WATONGA... KINGFISHER...GUTHRIE...STILLWATER...ELK CITY...SAYRE...CORDELL... ANADARKO...YUKON...EL RENO...MUSTANG...OKLAHOMA CITY...CHANDLER... CHICKASHA...PURCELL...NORMAN...MOORE...SHAWNEE...SEMINOLE... HOLDENVILLE...HOLLIS...MANGUM...HOBART...ALTUS...FREDERICK... LAWTON...DUNCAN...PAULS VALLEY...SULPHUR...ADA...COALGATE... WALTERS...WAURIKA...ARDMORE...TISHOMINGO...ATOKA...MARIETTA... MADILL...DURANT...QUANAH...CHILLICOTHE...CROWELL...VERNON... WICHITA FALLS...MUNDAY...KNOX CITY...SEYMOUR...ARCHER CITY... HOLLIDAY...LAKESIDE CITY...HENRIETTA 340 PM CST SAT DEC 22 2012 ...WINTER PRECIPITATION REMAINS POSSIBLE CHRISTMAS DAY... WEATHER FORECAST MODELS CONTINUE TO DEPICT THE POTENTIAL FOR A WINTER STORM TO AFFECT OKLAHOMA AND NORTHERN TEXAS CHRISTMAS EVE NIGHT THROUGH CHRISTMAS NIGHT...WITH THE BEST CHANCES FOR PRECIPITATION ON CHRISTMAS DAY. A BRIEF PERIOD OF A VERY LIGHT WINTRY MIX WILL BE POSSIBLE CHRISTMAS EVE NIGHT ACROSS WESTERN OKLAHOMA...WITH LIGHT RAIN POSSIBLE ACROSS SOUTHERN OKLAHOMA AND WESTERN NORTH TEXAS. THE PRECIPITATION WILL THEN CHANGE OVER TO SNOW ON CHRISTMAS. MODERATE TO STRONG WINDS COULD ALSO LEAD TO SOME BLOWING AND DRIFTING OF THE SNOW IN SOME AREAS BUT BLIZZARD CONDITIONS APPEAR UNLIKELY. THE SNOW IS EXPECTED TO END FROM WEST TO EAST CHRISTMAS NIGHT. THE AMOUNT OF SNOW AND WHERE THE HEAVIEST SNOWFALL WILL OCCUR REMAINS UNCERTAIN...AS DIFFERENCES REMAIN BETWEEN THE SOLUTIONS FROM THE COMPUTER MODELS. SOME MODELS CONTINUE THE TRACK OF HEAVIEST SNOW ACROSS NORTHERN PORTIONS OF OKLAHOMA...WHILE OTHERS TAKE IT ACROSS SOUTHERN OKLAHOMA INTO NORTHERN TEXAS. CONTINUING WITH A CONSENSUS APPROACH...THE HIGHEST SNOW TOTALS ARE EXPECTED FROM WEST CENTRAL OKLAHOMA INTO CENTRAL AND SOUTHEAST OKLAHOMA WHERE AMOUNTS COULD AVERAGE THREE TO SIX INCHES. WITH THE VARIATION IN FORECAST TRACKS AND SNOW AMOUNTS...EVERYONE ACROSS THE STATE OF OKLAHOMA AND THOSE ACROSS NORTHERN TEXAS SHOULD PAY CLOSE ATTENTION TO REFINED FORECASTS OVER THE WEEKEND. IF YOU ARE PLANNING TO TRAVEL ACROSS THE SOUTHERN PLAINS FOR THE UPCOMING HOLIDAY WEEK...HAVE A CONTINGENCY PLAN IN PLACE AND PREPARE FOR WEATHER-RELATED DELAYS AND CANCELLATIONS. SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE TULSA OK 339 PM CST SAT DEC 22 2012 ARZ001-002-010-011-019-020-029-OKZ049-053>076-230945- BENTON-CARROLL-WASHINGTON AR-MADISON-CRAWFORD-FRANKLIN-SEBASTIAN- PUSHMATAHA-CHOCTAW-OSAGE-WASHINGTON OK-NOWATA-CRAIG-OTTAWA-PAWNEE- TULSA-ROGERS-MAYES-DELAWARE-CREEK-OKFUSKEE-OKMULGEE-WAGONER- CHEROKEE-ADAIR-MUSKOGEE-MCINTOSH-SEQUOYAH-PITTSBURG-HASKELL- LATIMER-LE FLORE- INCLUDING THE CITIES OF...ROGERS...BENTONVILLE...BERRYVILLE... EUREKA SPRINGS...FAYETTEVILLE...SPRINGDALE...HUNTSVILLE... VAN BUREN...OZARK...CHARLESTON...FORT SMITH...ANTLERS...CLAYTON... HUGO...PAWHUSKA...BARTLESVILLE...NOWATA...VINITA...MIAMI... PAWNEE...TULSA...CLAREMORE...PRYOR...JAY...BRISTOW...OKEMAH... OKMULGEE...WAGONER...TAHLEQUAH...STILWELL...MUSKOGEE...EUFAULA... SALLISAW...MCALESTER...STIGLER...WILBURTON...POTEAU 339 PM CST SAT DEC 22 2012 ...CHRISTMAS DAY/NIGHT WINTER WEATHER POTENTIAL ACROSS EASTERN OKLAHOMA AND NORTHWEST ARKANSAS... A WINTER STORM WILL DEVELOP OVER THE SOUTHERN PLAINS CHRISTMAS DAY WITH THE POTENTIAL FOR ACCUMULATING SNOW ACROSS MUCH OF EASTERN OKLAHOMA AND NORTHWESTERN ARKANSAS. ALTHOUGH THE EXACT TRACK REMAINS SOMEWHAT UNCERTAIN...MOST OF THE REGION WILL LIKELY RECEIVE AT LEAST AN INCH OR TWO FROM THIS SYSTEM. THE STORM WILL LIKELY LAY DOWN A HEAVIER BAND OF SNOW ACROSS A PORTION OF THE REGION. LATEST DATA SUGGEST THE GREATEST SNOW POTENTIAL WILL OCCUR ALONG AND SOUTH OF A EUFAULA TO EUREKA SPRINGS LINE. PEOPLE TRAVELING ACROSS THE REGION CHRISTMAS DAY SHOULD CONTINUE TO MONITOR THE LATEST FORECAST. WE ARE CURRENTLY POSTING PRELIMINARY SNOW AMOUNT INFORMATION TO OUR DECISION SUPPORT PAGE AT WWW.WEATHER.GOV/TULSA/DSP/DSP.PHP. THE LOCATION AND MAGNITUDE OF ANY WINTER WEATHER IMPACTS WILL CONTINUE TO BE REFINED AS THIS SYSTEM APPROACHES. GIVEN THE SYSTEM IS STILL OFF THE NORTHWEST PACIFIC COAST...ANY SMALL DEVIATION IN THE STORM TRACK COULD RESULT IN SIGNIFICANT FORECAST CHANGES EARLY NEXT WEEK. THEREFORE...SNOW AMOUNTS WILL CONTINUE TO BE ADJUSTED AND THE LOCATION OF THE HEAVIEST SNOW SWATH COULD SHIFT SEVERAL COUNTIES IN ANY DIRECTION. PERSONS ACROSS SOUTHEAST OKLAHOMA AND NORTHWEST ARKANSAS SHOULD BE PREPARED FOR ACCUMULATING SNOW CHRISTMAS DAY INTO CHRISTMAS NIGHT. ROADS MAY BECOME SLICK AND HAZARDOUS CAUSING TRAVEL DELAYS. SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE FORT WORTH TX 205 PM CST SAT DEC 22 2012 TXZ091>095-100>107-116>123-231200- MONTAGUE-COOKE-GRAYSON-FANNIN-LAMAR-YOUNG-JACK-WISE-DENTON-COLLIN- HUNT-DELTA-HOPKINS-PALO PINTO-PARKER-TARRANT-DALLAS-ROCKWALL- KAUFMAN-VAN ZANDT-RAINS- 205 PM CST SAT DEC 22 2012 ...WINTER WEATHER OUTLOOK FOR DECEMBER 25TH... A STRONG STORM SYSTEM IS EXPECTED TO MOVE ACROSS THE REGION ON CHRISTMAS DAY. BASED ON THE LATEST FORECAST DATA...THERE WILL BE A GOOD CHANCE OF A COLD RAIN ON CHRISTMAS DAY ACROSS NORTH AND CENTRAL TEXAS. ALONG AND TO THE NORTH OF I-20...ATMOSPHERIC PROFILES WILL BECOME COLD ENOUGH FOR THE RAIN TO MIX WITH OR CHANGE OVER TO SNOW DURING THE AFTERNOON AND EVENING HOURS. THE LATEST MODEL GUIDANCE SUGGESTS SNOWFALL ACCUMULATIONS UP TO 2 INCHES ARE POSSIBLE CHRISTMAS AFTERNOON AND EVENING ALONG AND NORTH OF A BOWIE TO EMORY LINE. SOUTH OF THIS LINE...LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE. AS THE CHANGE OVER TO SNOW OCCURS...NORTHWEST WINDS ARE EXPECTED TO INCREASE IN SPEED TO 20 TO 30 MPH. ANY SNOW ACCUMULATIONS WILL BLOW AROUND IN THESE WINDS...WHICH MAY REDUCE VISIBILITY IF TRAVELING AFTER SUNSET ON CHRISTMAS DAY. AS OF THIS AFTERNOON...THE UPPER LEVEL STORM SYSTEM WAS ENTERING THE PACIFIC NORTHWEST. AT THIS TIME...THERE STILL REMAINS A GREAT DEAL OF UNCERTAINTY REGARDING THE EXACT TRACK AND ANY ASSOCIATED WINTRY PRECIPITATION FALLING OVER NORTH TEXAS ON CHRISTMAS DAY. IF THE TRACK OF THE SYSTEM WERE TO SHIFT FARTHER SOUTH...THE POTENTIAL FOR HIGHER SNOWFALL ACCUMULATIONS ACROSS THE REGION WOULD INCREASE AND THE RAIN/SNOW LINE WOULD SHIFT FARTHER TO THE SOUTH. IN ADDITION TO THE WINTER PRECIPITATION POTENTIAL...THERE IS ALSO A THREAT FOR SOME SEVERE STORMS EARLY CHRISTMAS MORNING AND POSSIBLY INTO THE DAY ON THE 25TH. THE THREAT FOR SEVERE WEATHER AT THIS TIME IS MAINLY SOUTH OF I-20 AND EAST OF I-35. THE DETAILS OF THE SEVERE WEATHER POTENTIAL ARE JUST NOW COMING TO FRUITION AND WILL ALSO BE REFINED OVER THE NEXT FEW DAYS. BOTTOM LINE...WINTRY PRECIPITATION IS POSSIBLE MAINLY ALONG AND NORTH OF THE I-20 CORRIDOR FOR THE AFTERNOON AND EVENING HOURS OF CHRISTMAS DAY. SOME SNOW ACCUMULATIONS UP TO 2 INCHES ARE POSSIBLE ALONG AND NORTH OF A BOWIE TO EMORY LINE. CHECK BACK FOR THE LATEST FORECAST UPDATES IN THE COMING DAYS AS THESE DETAILS ARE VERY LIKELY TO CHANGE WITH FUTURE FORECASTS. SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE SHREVEPORT LA 156 PM CST SAT DEC 22 2012 ARZ050-051-059>061-070>073-LAZ001>006-OKZ077-TXZ096-097-108>112- 124>126-136>138-231200- BOSSIER-BOWIE-CADDO-CAMP-CASS-CLAIBORNE-COLUMBIA-FRANKLIN-GREGG- HARRISON-HEMPSTEAD-HOWARD-LAFAYETTE-LINCOLN-LITTLE RIVER-MARION- MCCURTAIN-MILLER-MORRIS-NEVADA-RED RIVER TX-SEVIER-SMITH-TITUS- UNION AR-UNION LA-UPSHUR-WEBSTER-WOOD- 156 PM CST SAT DEC 22 2012 ...WINTER WEATHER WILL BE POSSIBLE CHRISTMAS AFTERNOON AND NIGHT MAINLY NORTH OF THE INTERSTATE 20 CORRIDOR... A STRONG UPPER LEVEL STORM SYSTEM IS EXPECTED TO DEVELOP CHRISTMAS DAY OVER OKLAHOMA...AS VERY COLD AIR DEEPENS AND BEGINS TO PUSH SOUTHEAST BEHIND A COLD FRONT INTO SOUTHEAST OKLAHOMA AND SOUTHWEST ARKANSAS CHRISTMAS AFTERNOON AND EVENING. SCATTERED TO NUMEROUS SHOWERS AND A FEW THUNDERSTORMS WILL QUICKLY DEVELOP EARLY CHRISTMAS MORNING ACROSS THE REGION AHEAD OF THE FRONT...AND PERSIST THROUGH AT LEAST MIDDAY AS AN UPPER LEVEL DISTURBANCE LIFTS NORTHEAST THROUGH THE AREA. TO THE NORTH OF THE AREA OVER CENTRAL AND EASTERN OKLAHOMA WHERE THE SUBFREEZING TEMPERATURES ARE EXPECTED...AREAS OF SNOW WILL DEVELOP AND GRADUALLY SPREAD EAST NEAR THE COLD CORE CENTER OF THIS STORM SYSTEM. THE RAIN IS EXPECTED TO CHANGE OVER TO A RAIN SNOW MIX BEFORE TRANSITIONING OVER TO ALL SNOW CHRISTMAS AFTERNOON AND EVENING OVER PORTIONS OF EXTREME NORTHEAST TEXAS...SOUTHEAST OKLAHOMA...AND SOUTHWEST ARKANSAS...MAINLY NORTH OF THE INTERSTATE 30 CORRIDOR AS THE COLDER AIR DEEPENS OVER THESE AREAS. SOME SNOW ACCUMULATIONS WILL BE POSSIBLE CHRISTMAS AFTERNOON AND EVENING MAINLY NORTH OF A MOUNT VERNON AND NEW BOSTON TEXAS...TO HOPE ARKANSAS LINE. THESE POTENTIAL ACCUMULATIONS WILL BE DEPENDENT ON THE TRACK OF THIS STORM SYSTEM...AND HOW QUICKLY THE COLDER SUBFREEZING AIR IS ABLE TO PENETRATE SOUTHEAST INTO THE AREA. A MORE SOUTHWARD STORM TRACK WOULD RESULT IN A POTENTIAL INCREASE IN SNOW ACCUMULATIONS FARTHER SOUTH ACROSS THE AREA CHRISTMAS AFTERNOON AND NIGHT. AT THIS TIME...AREAS ALONG THE INTERSTATE 20 CORRIDOR OF NORTHEAST TEXAS AND NORTH LOUISIANA MAY SEE A LIGHT RAIN SNOW MIX CHRISTMAS NIGHT AS THIS STORM SYSTEM BEGINS TO PULL AWAY FROM THE AREA. NO SNOW OR ICE ACCUMULATIONS ARE EXPECTED...AS SURFACE TEMPERATURES SHOULD REMAIN ABOVE FREEZING. UNCERTAINTIES STILL REMAIN AS TO THE TRACK...TIMING...AND DEPTH OF THE COLDER SUBFREEZING AIR OF THIS STORM SYSTEM. RESIDENTS ACROSS THESE AREAS SHOULD STAY TUNED TO THE LATEST STATEMENTS AND FORECASTS IN THE FEW DAYS FROM THE NATIONAL WEATHER SERVICE IN SHREVEPORT CONCERNING THIS POTENTIAL WINTER STORM. SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LITTLE ROCK AR 243 PM CST SAT DEC 22 2012 ARZ003>007-012>016-021>025-030>034-037>047-052>057-062>069-231200- ARKANSAS-BAXTER-BOONE-BRADLEY-CALHOUN-CLARK-CLEBURNE-CLEVELAND- CONWAY-DALLAS-DESHA-DREW-FAULKNER-FULTON-GARLAND-GRANT-HOT SPRING- INDEPENDENCE-IZARD-JACKSON-JEFFERSON-JOHNSON-LINCOLN-LOGAN-LONOKE- MARION-MONROE-MONTGOMERY-NEWTON-OUACHITA-PERRY-PIKE-POLK-POPE- PRAIRIE-PULASKI-SALINE-SCOTT-SEARCY-SHARP-STONE-VAN BUREN-WHITE- WOODRUFF-YELL- 243 PM CST SAT DEC 22 2012 ...WINTER WEATHER POTENTIAL ACROSS MUCH OF ARKANSAS CHRISTMAS DAY AND CHRISTMAS NIGHT... AN UPPER LEVEL STORM SYSTEM IS FORECAST TO TRACK INTO THE SOUTHERN PLAINS STATES CHRISTMAS DAY. PRECIPITATION WILL BEGIN TO OVERSPREAD THE STATE FROM THE SOUTH STARTING LATER MONDAY NIGHT AND CONTINUING CHRISTMAS DAY. AT THIS TIME...THE POTENTIAL FOR WINTER WEATHER EXISTS FOR MUCH OF ARKANSAS. THE PRECIPITATION WILL START OFF MAINLY AS RAIN ACROSS SOUTHERN AND CENTRAL PARTS OF THE STATE CHRISTMAS MORNING. WITH COLDER AIR IN PLACE AT THE SURFACE...SOME SLEET OR SNOW COULD MIX WITH THE RAIN AT THE ONSET AS IT ADVANCES NORTHWARD. OVER NORTHERN ARKANSAS...IT APPEARS THAT MAINLY SNOW OR A PERIOD OF RAIN AND SNOW WILL OCCUR TUESDAY. AS THE STORM SYSTEM BEGINS TO MOVE EAST OF THE AREA CHRISTMAS NIGHT...THE PRECIPITATION WILL TRANSITION TO ALL SNOW AS COLDER AIR MOVES BACK INTO THE AREA. SIGNIFICANT ACCUMULATIONS OF SNOWFALL WILL BE POSSIBLE ACROSS PARTS OF ARKANSAS. HOWEVER...WITH THE UNCERTAINTY OF THE TRACK...THE LOCATIONS THAT WILL SEE THE MOST SIGNIFICANT ACCUMULATIONS ARE UNKNOWN AT THIS TIME. PLEASE CONTINUE TO MONITOR THE LATEST FORECAST AND STATEMENTS FROM YOUR NATIONAL WEATHER SERVICE. Link to comment Share on other sites More sharing options...
Srain Posted December 22, 2012 Share Posted December 22, 2012 DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0205 AM CST SAT DEC 22 2012 VALID 241200Z - 251200Z ...NO SVR TSTM AREAS FORECAST... ...TX COASTAL PLAINS/LOWER MS VALLEY... A PROGRESSIVE UPPER-LEVEL TROUGH IS FORECAST TO MOVE EWD ACROSS THE INTERMOUNTAIN WEST ON MONDAY AND INTO THE ROCKIES. AHEAD OF THE SYSTEM...MOISTURE WILL RETURN ACROSS THE TX COASTAL PLAINS AND LOWER MS VALLEY. AS THE UPPER-LEVEL TROUGH MOVES INTO THE SRN PLAINS MONDAY NIGHT AND LARGE-SCALE ASCENT INCREASES IN THE SRN PLAINS...THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE ACROSS THE SERN THIRD OF TX EXTENDING EWD ACROSS SRN LA. AT THIS POINT...MODEL FORECASTS SHOW SFC DEWPOINTS IN SE TX IN THE LOWER TO MID 60S F WITH ABOUT 50 KT OF DEEP LAYER SHEAR. THIS ENVIRONMENT SHOULD SUPPORT A SEVERE THREAT LATE MONDAY NIGHT AND ROTATING STORMS WILL BE POSSIBLE ACROSS THE TX COASTAL PLAINS AFTER MIDNIGHT. IF THE UPPER-LEVEL TROUGH IS A BIT SLOWER THAN FORECAST...THE BRUNT OF THE THUNDERSTORM DEVELOPMENT COULD BE DELAYED UNTIL TUESDAY AFTER DAYBREAK. FOR THIS REASON...WILL GO WITH A SEE TEXT FOR MONDAY NIGHT WITH THE POTENTIAL TO UPGRADE TO SLIGHT RISK IN LATER OUTLOOKS. ..BROYLES.. 12/22/2012 Link to comment Share on other sites More sharing options...
Ed Lizard Posted December 22, 2012 Share Posted December 22, 2012 If we get enough hail in Houston (glass quarter full optimistic) to turn the ground white, I will claim this as a White Christmas. Not a true snow miracle, ala 2004, but more like a team that is +5 winning outright. Link to comment Share on other sites More sharing options...
Ellinwood Posted December 23, 2012 Share Posted December 23, 2012 Some potential for tornadic activity along the Gulf Coast on Christmas... hodos are looking very nice, but the instability will be limited mostly to the southern Southeast. Doesn't look like the main threat will make it north of Birmingham. The low-level lapse rates are impressive on the forecast soundings. A wind and maybe tornado threat could/should extend into the eastern Carolinas on the 26th. 55 kt. jet at 925 mb could make for a windy afternoon. Both threats have been fairly consistent on the models. Link to comment Share on other sites More sharing options...
Srain Posted December 23, 2012 Share Posted December 23, 2012 Neutral trending to negative troughs/upper air disturbances (short wave) along with a potent upper jet raise an eyebrow for the severe potential in the warm sector. Link to comment Share on other sites More sharing options...
wxsmwhrms Posted December 23, 2012 Share Posted December 23, 2012 What makes me particularly nervous about the severe potential with this setup is that the lead wave moving through Monday will pull up quite a bit of moisture which will just be left behind as that wave moves off and everything waits for the big system Tuesday/Tuesday night. This will result in an unusually moist and unstable airmass (especially for late December) for an extremely potent weather system to work with. Link to comment Share on other sites More sharing options...
Srain Posted December 23, 2012 Share Posted December 23, 2012 Heh... AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 958 PM CST SAT DEC 22 2012 .UPDATE... EVENING SURFACE OBSERVATIONS AND FORT WORTH SOUNDING INDICATE A STEADY MOISTENING OF THE LOWER PARTS OF THE ATMOSPHERE OVER THE LAST 24 HOURS. THIS IS IN RESPONSE TO INCREASING SOUTHERLY FLOW AHEAD OF A WEAK DISTURBANCE WHICH WILL MOVE THROUGH THE PLAINS LATE TOMORROW. A WEAK SURFACE LOW CURRENTLY OVER THE TX PANHANDLE WILL MOVE EAST WITH THIS DISTURBANCE ON SUNDAY ALLOWING A COLD FRONT FRONT TO APPROACH THE AREA. LATEST HIGH RESOLUTION GUIDANCE INDICATES THAT THE FRONT WILL ACTUALLY ENTER OUR NORTHWEST COUNTIES BY MIDDAY SUNDAY...SO HAVE LOWERED HIGH TEMPERATURES BY SEVERAL DEGREES ACROSS THOSE AREAS. THIS COLD FRONT WILL CONTINUE SOUTH SUNDAY EVENING WITH LOWS IN THE UPPER 20S AND LOWER 30S ACROSS THE NORTHERN HALF OF THE AREA SUNDAY NIGHT. THIS COLD AIR WILL NOT BE VERY DEEP ON MONDAY AND IS LIKELY TO BE MIXED OUT TO SOME DEGREE IN RESPONSE TO INCREASING SOUTHERLY WINDS AHEAD OF OUR NEXT SYSTEM OF INTEREST...WHICH WILL BE THE CHRISTMAS DAY STORM. THERE IS SIGNIFICANT INTEREST IN THIS SYSTEM FOR ITS POTENTIAL TO PRODUCE SOME HEAVY WINTRY PRECIP TOTALS ACROSS PARTS OF THE SOUTHERN PLAINS AND MID SOUTH. AS IS OFTEN THE CASE IN NORTH TEXAS HOWEVER...THE EXACT TRACK HAS MAJOR IMPACTS TO PRECIPITATION TYPE ACROSS OUR AREA. A LOOK AT SEVERAL ANALOGS TO THE CONSENSUS FORECAST FOR EARLY TUESDAY MORNING YIELDED A HANDFUL OF EVENTS WITH SIMILAR SYNOPTIC SETUPS. ONE EVENT IN PARTICULAR STANDS OUT FOR ITS STRIKING SIMILARITIES TO THE CURRENT FORECAST PATTERN. IN EARLY DECEMBER 1989 A STRONG DISTURBANCE ENTERED THE PACIFIC NORTHWEST MOVED SOUTHEAST ACROSS THE GREAT BASIN BEFORE DIGGING ACROSS WEST TEXAS AND EVENTUALLY MOVING OVER NORTH TEXAS. THIS SYSTEM DUG SLIGHTLY FARTHER SOUTH THAN THE CURRENT SYSTEM IS FORECAST...HOWEVER SIMILAR SURFACE FEATURES DEVELOPED ACROSS SOUTHEAST TEXAS BEFORE QUICKLY MOVING TO THE NORTHEAST. THE BULK OF THE PRECIPITATION WAS LOCATED ACROSS EAST TEXAS AND LOUISIANA WITH WRAP AROUND WINTRY PRECIP PRIMARILY ACROSS OKLAHOMA. THE ONE DIFFERENCE WITH THIS SYSTEM...WAS SURFACE TEMPERATURES WERE SEVERAL DEGREES WARMER THAN CURRENTLY FORECAST. SEVERAL OF THE OTHER ANALOGS WITH SLIGHT DIFFERENCES IN TRACKS OF THE MAIN UPPER TROUGHS YIELDED SIMILAR RESULTS. THIS INCREASES CONFIDENCE IN THE CURRENT FORECAST OF PRIMARILY RAIN DEVELOPING INITIALLY AND MOVING NORTHEAST WITH THE MAIN SURFACE LOW...AND A CHANGEOVER TO SOME SNOW ON THE BACK SIDE OF THE SYSTEM. THE CURRENT FORECAST HANDLES THIS WELL...AND FORECAST SOUNDINGS STILL SUPPORT A CHANGEOVER TO SNOW ON CHRISTMAS AFTERNOON/EVENING AS THE COLDER AIR FILTERS IN. WITH SUCH A FAST MOVING SYSTEM...AND STRONG WESTERLY WINDS ALOFT... A SIGNIFICANT DRY SLOT WILL ADVANCE EASTWARD ON CHRISTMAS DAY AS THE SYSTEM DEEPENS. THIS SHOULD ALLOW FOR A SHARP PRECIPITATION GRADIENT ON THE BACK SIDE OF THE LOW AND FROM NORTH TO SOUTH WHERE ANY WINTRY PRECIPITATION SHOULD OCCUR. THE CURRENT MENTION OF NORTH OF THE I-20 CORRIDOR LOOKS GOOD FOR ANY POSSIBLE SNOW DURING THE DAY ON TUESDAY. Link to comment Share on other sites More sharing options...
Ed Lizard Posted December 23, 2012 Share Posted December 23, 2012 GFS would be elevated in the HOU area, NAM has HOU near Southern end of rain, but suggestive of surface based storms. And, of course, everyone wonders who gets tagged hardest Christmas day in the interior Southern Plains and Mid-South. Link to comment Share on other sites More sharing options...
andyhb Posted December 23, 2012 Share Posted December 23, 2012 What makes me particularly nervous about the severe potential with this setup is that the lead wave moving through Monday will pull up quite a bit of moisture which will just be left behind as that wave moves off and everything waits for the big system Tuesday/Tuesday night. This will result in an unusually moist and unstable airmass (especially for late December) for an extremely potent weather system to work with. Strongly agreed with this, that thing acts like a nearly ideal moisture pump, not too strong as to drop a cold FROPA into the Gulf, but not too weak as to have little/no influence on moisture trajectories. Link to comment Share on other sites More sharing options...
thewxmann Posted December 23, 2012 Share Posted December 23, 2012 Could someone add the severe threat into the thread title? Thank you! Link to comment Share on other sites More sharing options...
CUmet Posted December 23, 2012 Share Posted December 23, 2012 The darkness coupled with the fast 40-50 kt storm motions make for a potentially dangerous nocturnal tornado outbreak. The mid-level temps are quite cold, especially being so close to the Gulf Coast, and it's these cool mid-level events that tend to be particularly productive in the cool season. The shear vectors being oriented normal to the cold front are highly suggestive of cellular convective mode. The mid-level dry intrusion into the warm sector, particularly shown on the NAM and ECMWF, is quite impressive and may help in keeping the convection more discrete as well. Finally, in contrast to most southern tornado outbreak events, the threat in this case truly does extend all the way to the Gulf Coast, with the threat coming from supercells that initiate offshore as well. Link to comment Share on other sites More sharing options...
tornadotony Posted December 23, 2012 Share Posted December 23, 2012 What makes me particularly nervous about the severe potential with this setup is that the lead wave moving through Monday will pull up quite a bit of moisture which will just be left behind as that wave moves off and everything waits for the big system Tuesday/Tuesday night. This will result in an unusually moist and unstable airmass (especially for late December) for an extremely potent weather system to work with. All the big systems seem to evolve like this. I'm about ready to sound the full alarm on this one. It's going to have better lapse rates in the warm sector, a MUCH WIDER unstable warm sector than the last system, plenty of moisture, and plenty of forcing for ascent over a broad area of the warm sector. The warm sector forecast soundings show hodographs bigger than William Howard Taft, with 50-60kt right off the deck at 850 hPa. Also of note, there's been a subtle but noticeable NW trend in the sfc low track, which easily places BHM and TCL in play and even starts to get HSV and even the Shoals into the discussion. I don't want to quite go full tilt into this, but the pieces certainly seem to be trying to line up for a nasty Christmas in Dixie. Link to comment Share on other sites More sharing options...
CUmet Posted December 23, 2012 Share Posted December 23, 2012 All the big systems seem to evolve like this. I'm about ready to sound the full alarm on this one. It's going to have better lapse rates in the warm sector, a MUCH WIDER unstable warm sector than the last system, plenty of moisture, and plenty of forcing for ascent over a broad area of the warm sector. The warm sector forecast soundings show hodographs bigger than William Howard Taft, with 50-60kt right off the deck at 850 hPa. Also of note, there's been a subtle but noticeable NW trend in the sfc low track, which easily places BHM and TCL in play and even starts to get HSV and even the Shoals into the discussion. I don't want to quite go full tilt into this, but the pieces certainly seem to be trying to line up for a nasty Christmas in Dixie. It seems that over the past several runs of the GFS/ECMWF, the cyclogenesis starts a bit earlier and ends up being a bit stronger, which ends up pulling the warm front further north. I always get a bit hestitant about that around the Gulf Coast, because there have been a lot of times in the past where the precip along and north of the warm front tends to make the retreat of the warm front slower than what was progged. What makes this case different though is the strong cyclogenesis. Link to comment Share on other sites More sharing options...
andyhb Posted December 23, 2012 Share Posted December 23, 2012 It has that WSW/SW kick at H5 that seems to be characteristic of dynamic neutral-trending negatively tilted troughs...and yeah as Tony mentioned, the lift would be impressive in that case. The upper level setup (H3 to H2) looks favorable as well, with some areas being in that left front of the incoming/right rear of the departing setup, especially on the GFS/Euro. Also, good to see CUmet back. Link to comment Share on other sites More sharing options...
andyhb Posted December 23, 2012 Share Posted December 23, 2012 D2 already has some stronger wording for Christmas Eve. DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1256 AM CST SUN DEC 23 2012 VALID 241200Z - 251200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS CNTRL AND EAST TX... ...SRN PLAINS AND LOWER MS VALLEY... AN UPPER-LEVEL TROUGH IS FORECAST TO AMPLIFY AND MOVE QUICKLY ESEWD ACROSS THE ROCKIES ON MONDAY AND INTO THE SRN PLAINS MONDAY NIGHT. AHEAD OF THE SYSTEM...MOISTURE WILL RETURN NWD ONTO THE TX COASTAL PLAINS WHERE SFC DEWPOINTS SHOULD BE IN THE LOWER TO MID 60S F. THIS SHOULD ALLOW FOR MODERATE DESTABILIZATION MONDAY EVENING FROM SCNTRL TX EWD TO THE HOUSTON AREA. THE MOIST AND UNSTABLE AIRMASS COMBINED WITH RAPIDLY STRENGTHENING DEEP LAYER SHEAR UPON THE APPROACH OF THE EXIT REGION OF A POWERFUL MID-LEVEL JET...WILL RESULT IN THE POSSIBILITY OF A SEVERE THREAT BETWEEN 06Z AND 12Z. FORECAST SOUNDINGS IN THE HOUSTON AREA AT 09Z TO 12Z TUESDAY MORNING SHOW MLCAPE AROUND 1500 J/KG WITH 0-6 KM SHEAR NEAR 60 KT. THIS ENVIRONMENT COULD BE FAVORABLE FOR SUPERCELLS IF CELLS CAN REMAIN DISCRETE AFTER INITIATION. IN ADDITION...SUBSTANTIAL LOW-LEVEL SHEAR WITH 0-3 KM STORM RELATIVE HELICITIES OF AROUND 400 M2/S2 SHOULD BE FAVORABLE FOR A TORNADO THREAT. IF A SQUALL-LINE QUICKLY ORGANIZES ACROSS THE TX HILL COUNTRY AND MOVES QUICKLY EWD ACROSS EAST TX...THEN THE WIND DAMAGE THREAT COULD BE THE GREATER THREAT LATE MONDAY NIGHT. UNCERTAINTY STILL EXISTS CONCERNING THE TIMING OF THE UPPER-LEVEL SYSTEM. IN SPITE OF THIS...AN UPGRADE TO SLIGHT RISK APPEARS WARRANTED DUE TO THE POTENT SHEAR ENVIRONMENT WHICH IS FORECAST TO COINCIDE WITH CONVECTIVE DEVELOPMENT AND AN UNSTABLE AIRMASS. FURTHER TO THE EAST...DESTABILIZATION IS FORECAST TO OCCUR ACROSS LA AND CNTRL MS LATE MONDAY NIGHT AS MOISTURE RETURNS NWD. FORECAST SOUNDINGS AT 09Z/TUE IN LA AND CNTRL MS GENERALLY SHOW WEAK INSTABILITY BUT HAVE STRONG DEEP LAYER SHEAR PROFILES IN PLACE. IF CELLS CAN INITIATE ALONG THE INSTABILITY AXIS...THEN THE ENVIRONMENT COULD SUPPORT A MARGINAL SEVERE THREAT LATE MONDAY NIGHT. ..BROYLES.. 12/23/2012 Link to comment Share on other sites More sharing options...
thewxmann Posted December 23, 2012 Share Posted December 23, 2012 It has that WSW/SW kick at H5 that seems to be characteristic of dynamic neutral-trending negatively tilted troughs...and yeah as Tony mentioned, the lift would be impressive in that case. The upper level setup (H3 to H2) looks favorable as well, with some areas being in that left front of the incoming/right rear of the departing setup, especially on the GFS/Euro. Also, good to see CUmet back. Agreed on all accounts, especially the third line. And yes -- there's tons of lift. The GFS adds fuel to the fire with dual jets aloft. I'm a little concerned that there will be too much convection, which may block moisture transport northward (or equivalently, might prevent the WF from reaching as far north as progged). I know CUmet mentioned strong surface cyclogenesis overcoming this, but it's still on the back of my mind. That said, the strong windfields, broad-based trough, quality moisture trajectories, and cold mid-level temps of -15C are strong signals for what looks like the best significant tornado potential since Spring. Link to comment Share on other sites More sharing options...
andyhb Posted December 23, 2012 Share Posted December 23, 2012 D3: DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0229 AM CST SUN DEC 23 2012 VALID 251200Z - 261200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN PLAINS...LOWER MS VALLEY AND CNTRL GULF COAST STATES... ...GULF COAST STATES... AN IMPRESSIVE UPPER-LEVEL SYSTEM IS FORECAST TO MOVE EWD INTO THE SRN PLAINS EARLY TUESDAY MORNING AS THE EXIT REGION OF A POWERFUL MID-LEVEL JET MOVES INTO THE GULF COAST STATES. AHEAD OF THE SYSTEM...MOISTURE IS FORECAST TO RETURN NWD INTO THE LOWER MS VALLEY AND CNTRL GULF COAST STATES WITH MODERATE INSTABILITY DEVELOPING ACROSS THE SRN AND WRN PART OF THE SLIGHT RISK AREA EARLY IN THE DAY ON TUESDAY. A CLUSTER OF THUNDERSTORMS OR SQUALL-LINE MAY BE ALREADY DEVELOPED BY DAYBREAK ON TUESDAY ACROSS EAST TX WITH ADDITIONAL STORMS POSSIBLY ONGOING ACROSS THE LOWER MS VALLEY. MODEL FORECASTS INCREASE CONVECTIVE COVERAGE ACROSS THE LOWER MS VALLEY AND APPEAR TO MOVE A WELL-DEVELOPED MCS EWD ACROSS THE REGION DURING THE DAY. FORECAST SOUNDINGS AT MIDDAY TUESDAY IN THE LOWER MS VALLEY DEVELOP AN IMPRESSIVE SHEAR ENVIRONMENT AS THE MID-LEVEL JET APPROACHES THE REGION FROM THE WEST. NAM FORECAST SOUNDINGS VALID TUESDAY AT 21Z JUST SOUTHWEST OF JACKSON MS SHOW MLCAPE VALUES AROUND 1500 J/KG WITH ABOUT 60 KT OF DEEP LAYER SHEAR. THIS COMBINED WITH 0-3 KM STORM RELATIVE HELICITIES AROUND 400 M2/S2 COULD BE FAVORABLE FOR SUPERCELLS AND TORNADOES. IF MANY CELLS CAN REMAIN DISCRETE...THEN CONDITIONS COULD ALSO BE FAVORABLE FOR STRONG TORNADOES AS THE LOW-LEVEL JET MOVES EWD ACROSS THE CNTRL GULF COAST STATES FROM TUESDAY MORNING INTO THE AFTERNOON. AT THIS POINT...THE POTENTIAL FOR WIDESPREAD WIND DAMAGE APPEARS JUST AS VIABLE. THE MAGNITUDE OF THESE THREATS MAY DEPEND UPON THE DOMINANT STORM MODE. IF THE FAVORED MODE ENDS UP BEING LINEAR...THEN WIND DAMAGE COULD BE THE GREATER THREAT. FORECAST SOUNDINGS ACROSS THE LOWER MS VALLEY AND CNTRL GULF COAST STATES TUESDAY INTO TUESDAY NIGHT SHOW POTENTIAL FOR A SUBSTANTIAL SEVERE WEATHER EVENT. THE COMBINATION OF SHEAR AND INSTABILITY COMBINED WITH A POTENT WEATHER SYSTEM SUGGESTS A 30 PERCENT PROBABILITY AND SIGNIFICANT SEVERE HATCHED AREA ARE WARRANTED. THE SEVERE THREAT SHOULD CONTINUE INTO TUESDAY EVENING AND POSSIBLY INTO THE OVERNIGHT PERIOD AS THE UPPER-LEVEL TROUGH MOVES QUICKLY EWD ACROSS THE GULF COAST STATES. ..BROYLES.. 12/23/2012 Link to comment Share on other sites More sharing options...
Stebo Posted December 23, 2012 Share Posted December 23, 2012 I have been personally following this side of things along with the snow side of things, and I completely agree with what Tony and CUmet are saying. The key trend through out the day has been for this system to eject out a bit more NW. This would allow for a larger warm sector and more locations to be in play. The one main key with respect to this event is the strong low level shear and the flow straight out of the gulf, there will be instability in place with dew points potentially greater than 65 degrees. With the magnitude of the wind field over top this warm sector and the strength of lift associated with this system, it has a decently high ceiling. Link to comment Share on other sites More sharing options...
andyhb Posted December 23, 2012 Share Posted December 23, 2012 I also gotta point out, based on latest progs, this might not be done by the end of the 25th...when I look at the shear/instability combo into the Carolinas by Wednesday afternoon (as Ellinwood posted earlier). Link to comment Share on other sites More sharing options...
thewxmann Posted December 23, 2012 Share Posted December 23, 2012 Near Houston on the morning of Christmas Link to comment Share on other sites More sharing options...
andyhb Posted December 23, 2012 Share Posted December 23, 2012 Yeah, that too actually, especially looking at the thermodynamic profile with that sounding and also just the raw CAPE maps on twisterdata. That wind vector in the mid/upper levels also favors right-moving cells as well potentially. Link to comment Share on other sites More sharing options...
Srain Posted December 23, 2012 Share Posted December 23, 2012 Could someone add the severe threat into the thread title? Thank you! We are covering ALL aspects of this Winter Storm. That was the sole purpose of creating a Main Page thread to cover all the societal impacts of this dynamic Winter Storm. Link to comment Share on other sites More sharing options...
NavarreDon Posted December 23, 2012 Share Posted December 23, 2012 Great write up this am on the severe potential from MOB. I hope this really gets out to the "non-weather" public or a lot of people are going to get caught off guard. [CHRISTMAS DAY]... ...SIGNIFICANT INCREASE IN SEVERE WEATHER WILL OCCUR FROM EARLY CHRISTMAS MORNING THROUGH THE EVENING HOURS... AN EXTREMELY POWERFUL UPPER LEVEL SHORTWAVE OVER NORTH TEXAS IN THE MORNING WILL MOVE VERY QUICKLY TOWARD EAST THEN NORTHEAST...REACHING WESTERN TENNESSEE BY MIDNIGHT. AN 80 TO 100 KNOT JET STREAK AT 500 MB WILL ACCOMPANY THIS SYSTEM...BUT MORE IMPRESSIVELY IS THE 50 TO 55 KNOT JET MAX AT 850 MB THAT WILL EXTEND FROM NEW ORLEANS TO BIRMINGHAM BY LATE IN THE AFTERNOON. AT THE SURFACE...A VERY STRONG SURFACE LOW CENTERED ACROSS TEXAS WILL MOVE QUICKLY EAST-NORTHEAST OVER NORTHERN MISSISSIPPI BY LATE AFTERNOON AND DEEPEN TO 998 MB...PLACING THE ENTIRE FORECAST AREA WELL WITHIN THE WARM SECTOR. PLENTY OF MOISTURE WILL BE AVAILABLE TO FEED INTO THE SYSTEM WITH 850 MB DEWPOINTS RANGING FROM 8C TO 11C AND SURFACE DEWPOINTS IN THE LOWER 60S F ACROSS THE FORECAST AREA. ATTENDANT STRONG COLD FRONT APPROACHING FROM THE WEST WILL REACH THE MISSISSIPPI RIVER BY LATE AFTERNOON AND THEN QUICKLY SWEEP THROUGH THE FORECAST AREA FROM MID EVENING THROUGH JUST AFTER MIDNIGHT. CHRISTMAS DAY LOOKS TO HAVE ALL THE INDICATIONS OF A CLASSIC SEVERE WEATHER EVENT SETTING UP. UNLIKE THE LAST EVENT WHICH EXHIBITED LOW TOPPED / LOW LIGHTNING CONVECTION...THIS EVENT IS MORE CONDUCIVE TO DEEP CONVECTION AS 500-300 MB LAPSE RATES WILL BE NEAR 8 C/KM AND MUCAPES APPROACH 1600 J/KG. WE ARE EXPECTING A DUAL THREAT WITH SUPERCELLS IMPACTING THE AREA DURING THE DAY AHEAD OF AN AREA OF LOW PRESSURE AND COLD FRONT...AND THEN WITH BOWING RADAR STRUCTURES/LINE ECHO WAVE PATTERNS IMPACTING THE AREA DURING THE EVENING ALONG AND AHEAD OF THE COLD FRONT. BRN INDICES GREATER THAN 10 AND SFC-3 KM STORM RELATIVE HELICITY BETWEEN 300 AND 400 M^2/S^2 SUGGEST THAT SUPERCELLS ARE FAVORABLE. IN ADDITION...MOST OF THIS HELICITY RESIDES IN THE SFC-1 KM LAYER AND EHI VALUES ACROSS THE FORECAST WILL BE BETWEEN 1 (ONE) AND 3 (THREE)...SUGGESTING THE FORMATION OF STRONG CONVECTIVE SUPERCELLS WITH EF-2 AND EF-3 TORNADOES POSSIBLE. WITH THE DECREASED STABILITY...CLOUD TOPS ARE NOW PROJECTED TO BE NEAR 50000 FEET AND MAXIMUM VERTICAL VELOCITIES NEAR 50 M/S. WITH THIS...AND THE FACT THAT THE MODELS ARE NOW BRINGING A LAYER OF DRY AIR INTO THE MID LEVELS...INDICATE THAT LARGE HAIL THROUGHOUT THE DAY IS POSSIBLE WITH THE STRONGEST OF STORMS. DUE TO EXTREMELY STRONG DEEP LAYER WINDS RESULTING IN STORMS MOVING TOWARD THE NORTHEAST AT 50 TO 60 MPH...ANY STORMS DEVELOPING IN THIS ENVIRONMENT HAVE A FAVORABLE CHANCE OF DAMAGING WINDS. ANY SEVERE WEATHER THREATS WILL LIKELY HAPPEN VERY QUICKLY IF A WARNING IS ISSUED UPSTREAM FROM YOU. DO NOT VENTURE OUTSIDE OR WAIT FOR A THREAT TO APPEAR IMMINENT BEFORE TAKING ACTION. STAY TUNED TO FURTHER DEVELOPMENTS AND INFORMATION AS THEY BECOME AVAILABLE. HIGH TEMPERATURES MONDAY AND TUESDAY WILL RANGE FROM 68 TO 73 DEGREES. LOW TEMPERATURES MONDAY NIGHT WILL ONLY FALL INTO THE UPPER 50S NORTH TO MID 60S ALONG THE COAST. COOLER OVERNIGHT LOWS BEHIND THE FRONT ARE EXPECTED TUESDAY NIGHT...FALLING INTO THE UPPER 30S TO LOWER 40S NORTHWEST OF I-65...WITH MID 40 TO LOWER 50S TO THE SOUTHEAST. /22 Link to comment Share on other sites More sharing options...
Srain Posted December 23, 2012 Share Posted December 23, 2012 I also want to comment on the winter aspect of this storm in the cold sector. Depending on the eventual track, a trowal may develop dropping impressive snow totals for Arkansas/Southern Missouri/NW Tennessee/Western Kentucky. Should the trough deepen more than progged a track a bit further S, snow chances could increase across Northern Louisiana and NW Mississippi. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.