Srain Posted January 9, 2012 Share Posted January 9, 2012 MESOSCALE DISCUSSION 0009 NWS STORM PREDICTION CENTER NORMAN OK 0651 AM CST MON JAN 09 2012 AREAS AFFECTED...PORTIONS W TX. CONCERNING...HEAVY SNOW VALID 091251Z - 091745Z RAIN-SNOW TRANSITION HAS BEGUN OVER LOWER PECOS REGION GENERALLY FROM INK-FST. PRIND RATES WILL INCREASE TO 1-2 INCHES/HOUR IN INCREASINGLY WELL-ORGANIZED PRECIP BAND INITIALLY EXTENDING FROM WRN PECOS COUNTY NWD OVER WINKLER COUNTY. EMBEDDED TSTMS WILL OFFER LOCALIZED/BRIEF RATES ABOVE 2 INCHES/HOUR. SNOW AREA SHOULD PIVOT CYCLONICALLY IN KEEPING WITH EWD SHIFT OF MID-UPPER LOW...WHILE EXPANDING IN COVERAGE BENEATH ELEVATED MOIST CONVEYOR. THIS WILL OCCUR AS STRONGEST DEEP-LAYER ASCENT WITHIN OPTIMAL DENDRITIC-GROWTH LAYER MOVES ACROSS REGION. EXPECT INCREASE IN SNOW RATES OVER MAF AREA AND NWD/NEWD TOWARD PORTIONS GARZA/LYNN/TERRY COUNTIES...WHILE HEAVY SNOW AREA SNOW EXPANDS/SHIFTS EWD ACROSS PORTIONS PECOS/CROCKETT/REAGAN/ GLASSCOCK/HOWARD COUNTIES THROUGH 16Z. SFC TEMPS WILL CONTINUE TO DECREASE THROUGH MID-LOW 30S F FROM W-E...FROM COMBINATION OF BOUNDARY-LAYER CAA...WEAK WET-BULB COOLING...AND COLUMNAR DYNAMIC COOLING. MEANWHILE RELATIVE WARM LAYER BETWEEN 700-800 MB WILL CONTINUE TO COOL...WHILE RH INCREASES WITHIN DENDRITIC GROWTH COLUMN AS WELL. THESE PROCESSES WILL FOSTER RAIN-SNOW CHANGEOVER IN ERN PARTS OF DISCUSSION AREA...AND MAINTAIN SNOW AS DOMINANT WINTER-PRECIP PHASE. OBSERVED 12Z MAF SOUNDING AND MODIFIED RUC FCST SOUNDINGS INDICATE THIS TREND...AS WELL AS SUFFICIENTLY STEEP MIDLEVEL LAPSE RATES TO SUPPORT MUCAPE 100-300 J/KG ROOTED NEAR 700 MB AND EXTENDING INTO ICING LAYERS SUITABLE FOR LTG GENERATION. THEREFORE OCNL THUNDERSNOW IS EXPECTED OVER MORE OF AREA...WITH LTG ALREADY DETECTED BETWEEN MAF-FST. ..EDWARDS.. 01/09/2012 ATTN...WFO...SJT...LUB...MAF... Link to comment Share on other sites More sharing options...
Ed Lizard Posted January 9, 2012 Share Posted January 9, 2012 Midland AFD had a chance locally at 12Z following GFS, 15Z following NAM, and they changed between 9Z and 10Z, so MAF on track to have near record breaking snow. Real time hotlink Link to comment Share on other sites More sharing options...
Srain Posted January 9, 2012 Author Share Posted January 9, 2012 We've already had nearly 4 inches of rain is some areas in SE TX. Training/rotating storms with several TOR Warnings already and some damage reports out of the Bryan/College Station area... MESOSCALE DISCUSSION 0008 NWS STORM PREDICTION CENTER NORMAN OK 0559 AM CST MON JAN 09 2012 AREAS AFFECTED...PORTIONS S-CENTRAL TX...MIDDLE-UPPER TX COASTAL PLAIN...SWRN LA. CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 091159Z - 091430Z CONVECTIVE REGIME DISCUSSED IN EARLIER MESOSCALE DISCUSSION 7 IS UNDERGOING EWD AND COASTWARD SHIFTS IN GEOGRAPHY AND AMIDST GEN INCREASE IN TSTM COVERAGE...HOWEVER OVERALL SVR THREAT APPEARS TOO MRGL/ISOLATED FOR WW ATTM. STILL...THREAT FOR A TORNADO AND/OR ISOLATED DAMAGING GUST IS NONZERO...AND EXPECTED TO CONTINUE THROUGH REMAINDER EARLY-MID MORNING WITH SLOW SHIFT EWD OVER AREA. FURTHERMORE...MID-UPPER LEVEL CYCLONE OVER NRN CHIHUAHUA APPEARS TO HAVE BEGUN ITS EWD TURN AS PROGGED. AS RELATED FIELDS OF MID-LEVEL DESTABILIZATION SHIFT EWD...LAPSE RATES AWAY FROM ANTECEDENT TSTMS SHOULD INCREASE THROUGH REMAINDER MORNING...FROM W-E...WHILE FAVORABLE DEEP-LAYER SHEAR IS MAINTAINED. AS SUCH...HAIL WILL BECOME MORE PROBABLE ON EITHER SIDE OF SFC FRONT...SIZES BEING PRIMARILY SUBSEVERE TO ISOLATED MRGL-SVR BASED ON SOUNDING ANALOGS AND OUTPUT FROM 2-D HAIL MODEL. 1130Z SFC MESOANALYSIS SHOWED QUASISTATIONARY FRONTAL ZONE FROM CENTRAL/NRN LA SWWD THROUGH INFLECTION POINT OVER HOUSTON/WALKER COUNTIES TX...CORRESPONDING CLOSELY TO MESOCYCLONE OF POTENTIALLY SVR TSTM THERE. FRONT EFFECTIVELY HAS BEEN SHUNTED SOUTHWARD BY CUMULATIVE OUTFLOW FARTHER SW...PRODUCED BY INCREASINGLY DENSE BAND OF TSTMS...AND WAS EVIDENT ACROSS PORTIONS GRIMES/COLORADO/KARNES COUNTIES. FRONT THEN ARCHED THROUGH WAVE LOW THAT HAS MOVED ENEWD FROM MEX...TO NEAR COT. EXPECT MOST OF FRONT TO SHIFT SEWD THROUGH REMAINDER MORNING TOWARD COAST...AIDED ON MESOBETA SCALE BY TSTM OUTFLOW. THIS WILL SHRINK THAT PORTION OF WARM SECTOR CONTAINING EFFECTIVELY SFC-BASED PARCELS...WITH MLCAPE RANGING FROM AROUND 250 J/KG OVER SWRN LA TO AROUND 1000 J/KG ALONG MIDDLE TX COAST. PROFILER/VWP DATA INDICATE EFFECTIVE SHEAR AND SRH EACH HAVE DECREASED SOMEWHAT SINCE 07Z IN RESPONSE TO SOME WEAKENING/VEERING OF LOW-LEVEL FLOW...BUT STILL REMAIN FAVORABLE FOR OCNL SUPERCELL ORGANIZATION. STRONGEST LOW-LEVEL MESOCYCLONES AND POTENTIAL FOR A TORNADO SHOULD BE INVOF FRONT. WITH WEAK CINH...EXPECT OVERALL INCREASE IN TSTM COVERAGE TO CONTINUE. WITH TIME...THIS WILL FURTHER COMPLICATE CONVECTIVE MODES...WITH CLUSTERED AND QUASI-LINEAR STRUCTURES BECOMING MORE PREVALENT. ..EDWARDS.. 01/09/2012 ATTN...WFO...LCH...SHV...HGX...CRP...EWX... Link to comment Share on other sites More sharing options...
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