MRX Discussion

by **weatherbob** 2015-02-14, 3:50 pm

Check out the MRX discussion below

Code:: .SHORT TERM...(TONIGHT AND SUNDAY)...ARCTIC FRONT WILL BE MOVING QUICKLY THROUGH THE AREA LATE THIS AFTERNOON/EARLY EVENING...WITH A SURGE OF BITTER COLD AIR BEHIND IT. SIGNIFICANT CONVECTIVE ENERGY IN THE LOW LEVELS LATE THIS AFTERNOON/EARLY EVENING...WITH SOME SQUALL LIKE SNOW SHOWERS POSSIBLE WITH STRONG GUSTY WINDS AND VERY LOW VIS MAINLY NORTH. THIS ENHANCED ACTIVITY SHOULD BE BRIEF...BUT SOME SNOW SHOWERS/FLURRIES WILL LINGER INTO TONIGHT. LIGHT SNOW ACCUMULATIONS CAN BE EXPECTED ACROSS PORTIONS OF THE MOUNTAINS AND SW VA...ESPECIALLY HIGHER ELEVATIONS...AND WILL KEEP WINTER WEATHER ADVISORY IN EFFECT TO ADDRESS THIS. IN ADDITION...WINDS WILL CONTINUE TO BE STRONG AND GUSTY INTO TONIGHT...ESPECIALLY IN THE HIGHER ELEVATIONS OF EAST TN MOUNTAINS AND PORTIONS OF SW VA. WILL KEEP WIND ADVISORY AS IS. THE WINDS AND COLD TEMPERATURES WILL LEAD TO BITTER COLD WIND CHILL VALUES...ESPECIALLY HIGHER ELEVATIONS. WILL KEEP WIND CHILL ADVISORIES AND WIND CHILL WARNINGS AS THEY ARE FOR NOW. SUNDAY WILL BE DRY AND COLD AHEAD OF THE NEXT SYSTEM. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)... ...SIGNIFICANT WINTER STORM POSSIBLE FOR THE TENNESSEE VALLEY AND SOUTHERN APPALACHIAN REGION LATE SUNDAY NIGHT THROUGH MONDAY NIGHT... CONFIDENCE IS INCREASING THAT A SIGNIFICANT WINTER STORM WITH WIDESPREAD HEAVY SNOWFALL WILL IMPACT THE REGION EARLY THIS UPCOMING WEEK. THE COMBINATION OF COLD...SUBFREEZING AIR AT THE SURFACE COMBINED WITH POTENTIALLY SOME GOOD MOISTURE AND LIFT FROM A 700 MB JET WILL HELP TO GENERATE WIDESPREAD AND POTENTIALLY LOCALLY HEAVY PRECIPITATION. ALL MODELS SOLUTIONS...WITH SOME MINOR TIMING DIFFERENCES SHOW THIS SITUATION...THE NAM BEING SLIGHTLY DRIER ON THE INITIAL ROUND OF QPF MONDAY. HOWEVER...THE GFS ENSEMBLES IN PARTICULAR HAVE COME MUCH MORE IN LINE WITH THE ECMWF AND CANADIAN SOLUTIONS OF SHOWING SNOW /WITH SOME FAIRLY HIGH QPF AMOUNTS/ MOVING INTO THE REGION FROM WEST TO EAST EARLY MONDAY MORNING...AND OVERSPREADING THE FORECAST AREA THROUGHOUT THE DAY. THIS SNOWFALL WILL INCREASE IN INTENSITY AS IT OVERSPREADS THE REGION...WITH MODELS SHOWING THE CENTRAL AND SOUTHERN VALLEYS AND SOUTHERN PLATEAU RECEIVING SLIGHTLY HIGHER AMOUNTS...ALONG WITH THE EAST TENNESSEE AND NORTH CAROLINA MOUNTAINS. STILL...WIDESPREAD MEANINGFUL SNOWFALL ACCUMULATIONS ARE EXPECTED EVERYWHERE...WITH 3 TO 6 INCHES /WITH LOCALLY HIGHER AMOUNTS/ THROUGHOUT THE VALLEY...AND 6-10 INCHES /WITH LOCALLY HIGHER AMOUNTS IN THE MOUNTAINS/. GIVEN THE COLD...SUBFREEZING AIR THAT WILL HAVE BEEN IN PLACE FOR 24-36 HOURS...ANY SNOW THAT FALLS WILL QUICKLY ACCUMULATE. THE COLD AIR IN PLACE ALOFT WILL RESULT IN A DRIER SNOW...WITH RATIOS OF 13:1 OR 14:1 BEING COMMON. THIS FACTOR COULD LEAD TO EVEN HIGHER AMOUNTS IN LOCALIZED AREAS WHERE MESOSCALE BANDING SETS UP. SNOW WILL BEGIN TO TAPER OFF DURING THE EVENING...BUT LOCATIONS ACROSS FAR SOUTHEAST TENNESSEE AND SOUTHWEST NORTH CAROLINA COULD SEE AN EXTENDED PERIOD OF SNOW INTO THE EVENING AND NIGHT...BEFORE THINGS TAPER OFF. WITH THE COLD TEMPERATURES IN PLACE...ANY SNOW THAT FALLS COULD LINGER ON THE GROUND FOR SEVERAL DAYS....RESULTING IN HUGE SOCIETAL IMPACT POTENTIALLY. GIVEN THE INCREASED CONFIDENCE AND ALL OF THIS...HAVE ISSUED A WINTER STORM WATCH FOR THE ENTIRE FORECAST AREA FROM 06Z MONDAY THRU 12Z TUESDAY. THEREAFTER...THE FORECAST BECOMES A BIT MORE COMPLICATED. AS MENTIONED THE GFS...CANADIAN AND ECMWF SOLUTIONS FAVOR A SOMEWHAT DRIER AND COOLER PERIOD ON TUESDAY. THE 12Z NAM ON THE OTHER HAND WANTS TO ADVECT WARMER AIR ALOFT AND A LOT MORE MOISTURE INTO THE REGION ON TUESDAY...GIVING ANOTHER ROUND OF ACCUMULATING SNOWFALL AND SOME SLEET/ICE TO THE SOUTHERN VALLEY. GIVEN THAT THE NAM IS THE OUTLIER...HAVE MAINTAINED AN ALL SNOW FORECAST FOR MOST OF TUESDAY FOR NOW...BUT WILL CONTINUE TO MONITOR. OVERALL...THINK THAT ACCUMULATIONS WILL FAVOR THE MOUNTAINS AND DEFINITELY BE MUCH LIGHTER THAN MONDAY. BUT SOME LOCATIONS COULD PICK UP AN ADDITIONAL INCH OR SO IF MOISTURE/PRECIPITATION TRENDS FURTHER WEST. MODELS SHOW A STRONG COOL DOWN FOR THE MIDDLE OF THE WEEK AS THINGS CLEAR OFF BY WEDNESDAY INTO WEDNESDAY NIGHT. LOWS BY THURSDAY MORNING WILL LIKELY BE IN THE LOWER SINGLE DIGITS...WITH SOME AREAS POTENTIALLY DROPPING BELOW ZERO...A RARITY FOR OUR VALLEY LOCATIONS! THIS WILL ONLY HELP TO REINFORCE ANY SNOWPACK IN PLACE...AND KEEP UNTREATED ROADS SLICK AND ICY. ANOTHER STORM SYSTEM IS POSSIBLE LATE NEXT WEEK...BUT FOR NOW...HAVE FOCUSED MOST OF THE DETAIL IN THE NEXT 4 TO 5 DAYS.