Srain Posted December 25, 2012 Share Posted December 25, 2012 For the cold sector: MESOSCALE DISCUSSION 2211 NWS STORM PREDICTION CENTER NORMAN OK 1211 PM CST TUE DEC 25 2012 AREAS AFFECTED...S-CNTRL/SERN/E-CNTRL OK...W-CNTRL/CNTRL/N-CNTRL AR CONCERNING...WINTER MIXED PRECIPITATION VALID 251811Z - 252315Z SUMMARY...MIXED PRECIPITATION WILL OCCUR FROM S-CNTRL OK EWD/ENEWD INTO CNTRL/N-CNTRL AR...WITH A PHASE CHANGE TO SNOW OCCURRING FROM W TO E THIS AFTERNOON INTO THE EVENING. DISCUSSION...RECENT WATER VAPOR IMAGERY DEPICTS A MID-LEVEL VORT MAX BECOMING INCREASINGLY SHEARED ACROSS N-CNTRL TX. THE LEADING WARM CONVEYOR BELT EXHIBITS A SHARP BACK EDGE INVOF THE SABINE RIVER AT THE INTERFACE OF AN IMPINGING DRY CONVEYOR BELT. STRONG WAA WITHIN THE WARM CONVEYOR BELT WILL CONTINUE TO YIELD AN INCREASE IN PRECIPITATION RATES DURING THE NEXT SEVERAL HOURS...WHILE PRECIPITATION IS MAINTAINED ON THE BACKSIDE OF A CORRESPONDING SFC CYCLONE AS WELL. ...THROUGH 21Z... ACROSS CNTRL AR...FORECAST SOUNDINGS DEPICT 4-6C TEMPERATURES WITHIN AN ELEVATED WARM LAYER BETWEEN 900 AND 850 MB...WITH THE LITTLE ROCK 12Z RAOB HAVING SAMPLED 6-7C TEMPERATURES IN THAT LAYER. MELTING PROCESSES/LATENT COOLING AND INCREASING FORCING FOR ASCENT HAVE LIKELY CONTRIBUTED TO SOME COOLING ALOFT...THOUGH THE WARM LAYER WILL LIKELY STILL BE SUFFICIENT FOR HYDROMETEOR MELTING. AND...WITH MANY SFC OBSERVATIONS INDICATING WET-BULB ZERO TEMPERATURES BELOW 0C...FREEZING RAIN WITH RATES OF 0.05-0.10 IN/HR MAY EVOLVE. FARTHER TO THE N/W ACROSS N-CNTRL AR INTO PARTS OF E-CNTRL OK...COOLER TEMPERATURE PROFILES ALOFT WILL SUPPORT ONLY PARTIAL MELTING OF HYDROMETEORS ATOP SUBFREEZING WET-BULB ZERO SFC TEMPERATURES...YIELDING SLEET/SNOW. SNOWFALL RATES OF 1-1.5 IN/HR MAY ENSUE WITHIN BANDS OF HEAVIER PRECIPITATION...OWING TO STRONG MESOSCALE ASCENT ACCOMPANYING FRONTOGENETIC CIRCULATIONS. ACROSS S-CNTRL/SERN OK...WARMER LOW-LEVEL PROFILES ARE INITIALLY SUPPORTING RAIN...THOUGH THE INTRUSION OF A DEEPER LAYER OF COLD AIR WILL SUPPORT A TRANSITION TO SLEET/SNOW FROM W TO E. SNOWFALL RATES OF 1-1.5 IN/HR WILL BE POSSIBLE...AS STRONG DCVA PRECEDING THE VORT MAX CROSSES THE AREA. ...AFTER 21Z... PRECIPITATION WILL PROGRESSIVELY TRANSITION TO SNOW FROM W TO E AS DEEPER COLD AIR ENTERS THE AREA...WHILE WRAPPING AROUND THE DEEP CYCLONE. SNOWFALL RATES OF 1-1.5 IN/HR WILL REMAIN POSSIBLE INTO THE EVENING...AS ASCENT IS MAINTAINED IN ASSOCIATION WITH CONFLUENT FLOW ON THE BACKSIDE OF THE CORRESPONDING 700-MB CYCLONE. ..COHEN.. 12/25/2012 ATTN...WFO...LZK...SHV...TSA...FWD...OUN... Link to comment Share on other sites More sharing options...
andyhb Posted December 25, 2012 Share Posted December 25, 2012 Edit: NAM disagrees and makes the line discrete later. http://raleighwx.ame...ctivity_SE.html There are also several pre-frontal confluence bands that the hi-res NAM ignites later. Link to comment Share on other sites More sharing options...
Superstorm93 Posted December 25, 2012 Share Posted December 25, 2012 Starting to cut ahead of the convection now. If this can become discrete, things could get very dangerous during the Christmas evening mass time. Link to comment Share on other sites More sharing options...
Buckeye05 Posted December 25, 2012 Share Posted December 25, 2012 Intense kink in the line near Temple, LA. Hint of discrete transitions starting? Link to comment Share on other sites More sharing options...
Superstorm93 Posted December 25, 2012 Share Posted December 25, 2012 Temple, LA Link to comment Share on other sites More sharing options...
tmagan Posted December 25, 2012 Share Posted December 25, 2012 18Z Slidell, LA sounding Link to comment Share on other sites More sharing options...
andyhb Posted December 25, 2012 Share Posted December 25, 2012 18Z Slidell, LA sounding Amazing sounding... Link to comment Share on other sites More sharing options...
OUGrad05 Posted December 25, 2012 Share Posted December 25, 2012 18Z Slidell, LA sounding oh wow... On a brief sidenote is anyone else having problems with gibson ridge stuff today? My warnings are not loading... Link to comment Share on other sites More sharing options...
Ellinwood Posted December 25, 2012 Share Posted December 25, 2012 oh wow... On a brief sidenote is anyone else having problems with gibson ridge stuff today? My warnings are not loading... In GR, go to View -> Warning Settings and replace the link with http://warnings.allisonhouse.com/ ...the CoD site hasn't been working today, but the Allison House one is fine. Link to comment Share on other sites More sharing options...
Superstorm93 Posted December 25, 2012 Share Posted December 25, 2012 oh wow... On a brief sidenote is anyone else having problems with gibson ridge stuff today? My warnings are not loading... Check to make sure your warning server is working properly. The program itself does not provide the server for the warnings. Link to comment Share on other sites More sharing options...
janetjanet998 Posted December 25, 2012 Share Posted December 25, 2012 1216 PM TORNADO BEAUMONT 30.09N 94.14W 12/25/2012 JEFFERSON TX EMERGENCY MNGR Link to comment Share on other sites More sharing options...
Ground Scouring Posted December 25, 2012 Share Posted December 25, 2012 DISCUSSION...LATE THIS MORNING...THERE HAS BEEN AN INCREASE IN CG LIGHTNING STRIKES ACROSS SE THROUGH EAST CENTRAL TX TO NWRN LA INVOF A SURFACE LOW NOW LOCATED IN FAR EAST CENTRAL TX /NEAR JASPER TX/. THIS LIGHTNING AND SIMILAR INCREASE IN REFLECTIVITIES EXTENDED SSWWD ALONG A DRY LINE/PACIFIC FRONT THROUGH SE TX/UPPER TX COAST /TO THE N-SW OF THE HOUSTON METRO AREA/. TSTMS /MAINLY ELEVATED/ ALSO EXTENDED NEWD OF THE SURFACE LOW INTO NWRN LA. THIS INCREASE IN TSTM DEVELOPMENT IS LIKELY INDICATIVE OF THE ARRIVAL OF STRONG FORCING FOR ASCENT WITHIN THE EXIT REGION OF A 90-100 KT MIDLEVEL JET ACCOMPANYING THE POWERFUL SRN PLAINS SHORTWAVE TROUGH. SUBSEQUENT AND EXPECTED STRENGTHENING OF A SSWLY LLJ WAS EVIDENT OVER SWRN-CENTRAL LA PER 17Z LCH WSR-88D VAD SHOWING 60 KT AT 1 KM AGL. THE STRONG VERTICALLY VEERING WINDS HAVE GREATLY ENHANCED THE EFFECTIVE SRH VALUES UP TO 400-600 M2/S2 TO SUPPORT AN INCREASED TORNADO THREAT...EXPECTED TO SPREAD EWD THIS AFTERNOON INTO THE SRN PART OF THE LOWER MS VALLEY...WITHIN THE WARM SECTOR. MEANWHILE...THE WARM FRONT HAS MOVED N OF WW 692...THOUGH THE WARM SECTOR ACROSS THIS WW HAS ONLY SLOWLY DESTABILIZED THUS FAR DUE TO THE MIXING RELATED DECREASE IN THE DEWPOINTS. 18Z SLIDELL SPECIAL SOUNDING INDICATED AN INVERSION LOCATED BETWEEN 700-800 MB AND THIS SHOULD CONTINUE TO INHIBIT DEEPER CU DEVELOPMENT UNTIL THE ARRIVAL OF GREATER ASCENT WITH THE EXIT REGION OF THE IMMEDIATELY UPSTREAM MIDLEVEL JET. SOME VEERING OF LOW LEVEL WINDS ACROSS SWRN LA SHOULD ADVECT RICHER MOISTURE INTO SERN LA/SRN MS SUPPORTING STRONGER DESTABILIZATION TO SUPPORT AN ENVIRONMENT FAVORABLE FOR SUSTAINED...DEEP UPDRAFTS. The bolded portions suggest a High Risk forthcoming. Given the 0-6-km bulk shear and the strong Td inversion in the 700-mb column, I think the QLCS will transition to more discrete supercells within the next few hours. Link to comment Share on other sites More sharing options...
andyhb Posted December 25, 2012 Share Posted December 25, 2012 Watch 695 is up, don't think it is PDS...unless that doesn't show until the full watch page is updated. Edit: Nevermind. Link to comment Share on other sites More sharing options...
OUGrad05 Posted December 25, 2012 Share Posted December 25, 2012 The bolded portions suggest a High Risk forthcoming. I agree, I think we could see a high risk at 2pm and It'll extend from about 75 miles west of NO back to the ENE and north to the Hattiesburg area then back to Natchez. Link to comment Share on other sites More sharing options...
Superstorm93 Posted December 25, 2012 Share Posted December 25, 2012 331WWUS20 KWNS 251857 SEL5 SPC WW 251857 ALZ000-LAZ000-MSZ000-CWZ000-260200- URGENT - IMMEDIATE BROADCAST REQUESTED TORNADO WATCH NUMBER 695 NWS STORM PREDICTION CENTER NORMAN OK 1255 PM CST TUE DEC 25 2012 THE NWS STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR PORTIONS OF SOUTHWESTERN AND WEST-CENTRAL ALABAMA EASTERN AND SOUTHEASTERN LOUISIANA CENTRAL AND SOUTHERN MISSISSIPPI COASTAL WATERS EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 1255 PM UNTIL 800 PM CST. ...THIS IS A PARTICULARLY DANGEROUS SITUATION... DESTRUCTIVE TORNADOES...LARGE HAIL TO 1.5 INCHES IN DIAMETER... THUNDERSTORM WIND GUSTS TO 75 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 125 STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES SOUTHWEST OF BOOTHVILLE LOUISIANA TO 40 MILES NORTHEAST OF JACKSON MISSISSIPPI. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5). REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. OTHER WATCH INFORMATION...THIS TORNADO WATCH REPLACES TORNADO WATCH NUMBER 692. WATCH NUMBER 692 WILL NOT BE IN EFFECT AFTER 1255 PM CST. CONTINUE...WW 693...WW 694... DISCUSSION...WARM SECTOR SPREADING INLAND ACROSS WW AREA WILL BECOME INCREASINGLY JUXTAPOSED WITH STRENGTHENING DEEP SHEAR AND ENLARGED LOW-LEVEL HODOGRAPHS. MCS MOVING EWD INTO THIS REGIME WILL ENCOUNTER MLCAPE 500-1500 J/KG...WITH EFFECTIVE SRH MAXIMIZED NEAR WARM FRONT AT 400-600 J/KG. ANY RELATIVELY SUSTAINED/DISCRETE SUPERCELLS WILL OFFER RISK OF LONG-TRACKED/DAMAGING TORNADOES. DAMAGING GUSTS AND OCNL TORNADOES ARE ALSO LIKELY FROM QLCS/LEW/BOW STRUCTURES. AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR 24040. Link to comment Share on other sites More sharing options...
Disc Posted December 25, 2012 Share Posted December 25, 2012 Watch 695 is up, don't think it is PDS...unless that doesn't show until the full watch page is updated. It's a PDS. 80/70 tor risk. Link to comment Share on other sites More sharing options...
OUGrad05 Posted December 25, 2012 Share Posted December 25, 2012 what software are you guys using? Link to comment Share on other sites More sharing options...
Superstorm93 Posted December 25, 2012 Share Posted December 25, 2012 Cells are begging to fire ahead of the main QLCS now. Have to see what these do over the next 1-3 hours. Link to comment Share on other sites More sharing options...
ILMRoss Posted December 25, 2012 Share Posted December 25, 2012 This is the first tornado outbreak I can remember in my young life that has happened so close to the winter solstice. Since the sun will be setting at around 5:30-6:00 around most of the south, doesn't this mean there is a much smaller window for these areas to be in the sunlight and destabilize, and thus a much smaller window for supercells to form? Or will warm air advection override the sun going down? Link to comment Share on other sites More sharing options...
Ground Scouring Posted December 25, 2012 Share Posted December 25, 2012 Cells are begging to fire ahead of the main QLCS now. Have to see what these do over the next 1-3 hours. I fully expect the developing cells alone a line from KHEZ to KLFT to become super-cellular and produce tornadoes within the next one and a half hour. Link to comment Share on other sites More sharing options...
audioguy3107 Posted December 25, 2012 Share Posted December 25, 2012 This is the first tornado outbreak I can remember in my young life that has happened so close to the winter solstice. Since the sun will be setting at around 5:30-6:00 around most of the south, doesn't this mean there is a much smaller window for these areas to be in the sunlight and destabilize, and thus a much smaller window for supercells to form? Or will warm air advection override the sun going down? Being late December, there isn't as much instability (especially further north) as there would be in April of course. Sunlight would keep things going maybe a little longer, but the extreme dynamics of this system is going to make up for the fact of shorter days. That being said, if we were in a situation in, say, May where the sun was out all day and temps warmed to the upper 70's to lower 80's, then we wouldn't even be discussing the amount of instability out there. Link to comment Share on other sites More sharing options...
Superstorm93 Posted December 25, 2012 Share Posted December 25, 2012 Wow... Hearing reports of major damage from Rapides, LA. At least 25-30 homes damaged with numerous injuries. Not sure if it's from TSTM Wind damage or a possible tornado. Link to comment Share on other sites More sharing options...
Srain Posted December 25, 2012 Share Posted December 25, 2012 In the cold sector, mixed precip has transitioned to snow in Ft Worth. Snow/rain mix reported in DT Dallas. Link to comment Share on other sites More sharing options...
SquatchinNY Posted December 25, 2012 Share Posted December 25, 2012 Radar Update for you all Link to comment Share on other sites More sharing options...
Ground Scouring Posted December 25, 2012 Share Posted December 25, 2012 SPC keeps MDT Risk at 20Z, but cuts it from KHEZ-KLFT eastward: DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0150 PM CST TUE DEC 25 2012 VALID 252000Z - 261200Z ...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF SRN/ERN LA...CENTRAL/SRN MS...ANS WEST CENTRAL/SWRN AL... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MS AND TN VALLEYS EWD INTO THE SERN STATES... ...A SEVERE WEATHER OUTBREAK CONTINUING ACROSS THE GULF COAST STATES... LITTLE CHANGES NEEDED TO THE PREVIOUS OUTLOOK...EXCEPT TO CLEAR WRN PART OF THE OUTLOOK AREA AS THE LINE OF SEVERE STORMS MOVES EWD ACROSS PARTS OF LA AND EXTREME SERN TX. SURFACE LOW CURRENTLY OVER WEST CENTRAL LA IS EXPECTED TO MOVE NEWD TOWARD THE TN VALLEY TONIGHT...AS A WARM FRONT ACROSS SRN PARTS OF MS AND AL LIFTS NWD. 19Z SURFACE MESOANALYSIS SHOWS LARGE PRESSURE FALLS CONCENTRATING JUST NORTH OF THE WARM FRONT FROM NERN LA INTO WEST CENTRAL MS/SERN AR...SUGGESTING THE LOW LEVEL JET MAY BE STRENGTHENING ALONG THE AXIS OF THE MS RIVER. THE AIR MASS SOUTH OF THE WARM FRONT IS CHARACTERIZED BY TEMPERATURES IN THE 70S AND DEW POINTS IN THE 60S...ALTHOUGH A SMALL DECREASE IN DEW POINT VALUES HAS BEEN NOTED OVER THE PAST FEW HOURS AS VERTICAL MIXING OCCURS. OBJECTIVE ANALYSES INDICATE SUFFICIENT INSTABILITY WITH MLCAPE AROUND 1000 J/KG TO SUPPORT SEVERE STORMS GIVEN STRONG DEEP LAYER SHEAR /EFFECTIVE SHEAR OF 50-60 KT/. LATEST RADAR REFLECTIVITY AND NLDN DATA INDICATE NEW CONVECTIVE STORMS DEVELOPING IN THE WARM SECTOR OVER SOUTH CENTRAL/SERN LA INTO SRN MS AHEAD OF THE FRONTAL QLCS. THE STRONG DEEP LAYER SHEAR WILL PROMOTE DEVELOPMENT OF SUPERCELL STRUCTURES...EMBEDDED WITHIN BOWS/LEWPS ALONG THE QLCS AND WITH DISCRETE CELLS AND CLUSTERS IN THE WARM SECTOR. DAMAGING WIND GUSTS AND TORNADOES WILL BE THE PRIMARY SEVERE THREATS...INCLUDING POTENTIAL FOR A FEW LONG-TRACK STRONG TORNADOES WITH ANY PERSISTENT SUPERCELL THAT DEVELOPS. 12Z MODEL CONSENSUS INCLUDING CONVECTION-ALLOWING MODEL SOLUTIONS SHOW A BOWING QLCS ACCELERATING EWD/ENEWD ACROSS THE LOWER MS VALLEY THIS AFTERNOON AND EVENING WITH THE SEVERE THREAT LIKELY CONTINUING DURING THE OVERNIGHT HOURS...REACHING AS FAR EAST AS GA AND POSSIBLY WRN SC BY THE END OF THE PERIOD. Link to comment Share on other sites More sharing options...
SmokeEater Posted December 25, 2012 Share Posted December 25, 2012 BULLETIN - EAS ACTIVATION REQUESTED TORNADO WARNING NATIONAL WEATHER SERVICE NEW ORLEANS LA 152 PM CST TUE DEC 25 2012 THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A * TORNADO WARNING FOR... WESTERN EAST FELICIANA PARISH IN SOUTHEAST LOUISIANA... THIS INCLUDES THE CITY OF JACKSON... NORTH CENTRAL POINTE COUPEE PARISH IN SOUTHEAST LOUISIANA... WEST FELICIANA PARISH IN SOUTHEAST LOUISIANA... THIS INCLUDES THE CITY OF ST. FRANCISVILLE... SOUTHERN WILKINSON COUNTY IN SOUTHERN MISSISSIPPI... * UNTIL 245 PM CST * AT 149 PM CST...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO NEAR BATCHELOR...OR 10 MILES NORTHEAST OF MELVILLE...MOVING EAST AT 45 MPH. * OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO WAKEFIELD...SPILLMAN...WOODVILLE AND NORWOOD Link to comment Share on other sites More sharing options...
Ground Scouring Posted December 25, 2012 Share Posted December 25, 2012 Cells are rapidly beginning to rotate in S/C MS with warnings cropping up--I think this is like 05/03/1999 in that the MDT Risk is underdone. TORNADO WARNING MSC037-085-252045- /O.NEW.KJAN.TO.W.0096.121225T1955Z-121225T2045Z/ BULLETIN - EAS ACTIVATION REQUESTED TORNADO WARNING NATIONAL WEATHER SERVICE JACKSON MS 155 PM CST TUE DEC 25 2012 THE NATIONAL WEATHER SERVICE IN JACKSON HAS ISSUED A * TORNADO WARNING FOR... LINCOLN COUNTY IN SOUTH CENTRAL MISSISSIPPI... THIS INCLUDES THE CITY OF BROOKHAVEN... EASTERN FRANKLIN COUNTY IN SOUTHWEST MISSISSIPPI... * UNTIL 245 PM CST * AT 155 PM CST...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 6 MILES SOUTH OF LITTLE SPRINGS MOVING NORTHEAST AT 50 MPH. * THE TORNADO WILL BE NEAR... LITTLE SPRINGS BY 200 PM CST... CENTER POINT AND MCCALL CREEK BY 205 PM CST... WEST LINCOLN AND BOGUE CHITTO BY 215 PM CST... VAUGHN...LOYD STAR AND ENTERPRISE BY 220 PM CST... BROOKHAVEN BY 225 PM CST... PRECAUTIONARY/PREPAREDNESS ACTIONS... A TORNADO WARNING MEANS THAT A TORNADO IS OCCURRING OR IMMINENT. YOU SHOULD ACTIVATE YOUR TORNADO ACTION PLAN AND TAKE PROTECTIVE ACTION NOW. A TORNADO WATCH REMAINS IN EFFECT UNTIL 800 PM CST TUESDAY EVENING FOR NORTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI. A SEVERE THUNDERSTORM WATCH ALSO REMAINS IN EFFECT UNTIL 400 PM CST TUESDAY AFTERNOON FOR SOUTHEAST ARKANSAS AND NORTHEAST LOUISIANA AND WEST CENTRAL MISSISSIPPI. Link to comment Share on other sites More sharing options...
SouthernNJ Posted December 25, 2012 Share Posted December 25, 2012 The storm west of McComb MS looks to have powerful potential. Link to comment Share on other sites More sharing options...
Superstorm93 Posted December 25, 2012 Share Posted December 25, 2012 In the cold sector, mixed precip has transitioned to snow in Ft Worth. Snow/rain mix reported in DT Dallas. Soon a full transition will be making it's way into Dallas. Link to comment Share on other sites More sharing options...
Superstorm93 Posted December 25, 2012 Share Posted December 25, 2012 Discrete cells are firing up and going tornadic. Hope everyone stays safe. Link to comment Share on other sites More sharing options...
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