Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN

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536 FXUS64 KMRX 091959 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 259 PM EST TUE FEB 9 2016 .SHORT TERM (TONIGHT THROUGH WEDNESDAY NIGHT)...
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EVENT IS ROLLING ALONG WITH PERSISTENT LIGHT SNOW AND SNOW SHOWERS OVER THE AREA. SHORT RANGE MODELS ENSEMBLES HAVE BEEN HAVING A DIFFICULT TIME WITH THE LIGHT PRECIP...AND SEEM TO BE RUSHING WITH IMPROVING CONDITIONS TOO FAST. HAVE GONE WITH SLOWER CLEARING OF POPS AND SKY COVER THROUGH THIS PERIOD. STEADY UPSLOPE FLOW INTO THE MOUNTAINS SHOULD CONTINUE THERE AS WELL...ACCUMULATIONS IN THE MOUNTAINS SHOULD KEEP STACKING UP INTO WEDNESDAY EVENING. STILL LOOKING LIKE BRISK WINDS WILL KEEP WIND CHILL VALUES VERY COLD DURING THIS PERIOD...AND HAVE WIND CHILL ADVISORY STARTING AT 6PM THIS EVENING FOR THE E TN MOUNTAINS...RUNNING UNTIL NOON ON THURSDAY. WIND WILL VALUES WILL BE IN THE -5 TO -15 RANGE FOR MUCH OF THIS TIME IN THE MOUNTAINS. .LONG-TERM (THURSDAY THROUGH TUESDAY)... THE WEATHER WILL BEGIN TO TAKE ON A MORE TRANQUIL PATTERN AT THE BEGINNING OF THE EXTENDED PERIOD AS NORTHWEST FLOW SNOW SHOWERS BEGIN TO DECREASE ACROSS THE HIGH TERRAIN. A FRONTAL BOUNDARY WILL CONTINUE TO PUSH TO THE SOUTH THROUGH THE GULF STATES AS PERSISTENT SHORTWAVE TROUGHS ROTATE THROUGH THE CLOSED LOW ACROSS THE NORTHEASTERN U.S. EARLIER...MODELS WERE SHOWING SOME LIGHT PRECIP. MOVE DOWN WITH THIS TROUGH ON THURSDAY BUT HAVE BACKED OF OVER THE LAST COUPLE OF RUNS...THEREFORE...CONTINUED WITH A DRY FORECAST ON THURSDAY. COLD AIR ADVECTION WILL BE IN FULL FORCE ACROSS THE AREA WITH HIGHS REMAINING BELOW FREEZING EVERYWHERE OUTSIDE OF THE VALLEY WHERE HIGHS WILL BE IN THE MID 30S TO LOW 40S. ANOTHER SHOT OF ARCTIC AIR WILL MOVE INTO THE AREA FRIDAY INTO SATURDAY AS A TROUGH DIVES SOUTHEAST OUT OF THE NORTHERN PLAINS. MODELS HAVE ALSO BACKED OFF ON THE PRECIP. WITH THIS SYSTEM. EXPECT THE NORTHWEST FLOW FAVORED AREAS WILL SEE SOME LIGHT SNOW AS THE ARCTIC AIR RETURNS. KEPT POPS IN THOSE FAVORED NORTHWEST FLOW AREAS BUT BACKED OFF ELSEWHERE. SATURDAY WILL BE ON OF THE COLDEST DAYS OF THE EXTENDED FORECAST WITH 850 MB TEMPERATURES IN THE -20 TO -10 DEGREE CELSIUS RANGE. HIGHS WILL REMAIN BELOW FREEZING ACROSS MOST OF THE AREA. OVERALL...THE COLD WILL BE THE STORY FOR THE REMAINDER OF THE WEEK WITH THE SYSTEM BREWING EARLY NEXT WEEK BEING THE MAIN HEADLINE IN THE EXTENDED FORECAST. MODELS CONTINUE TO TO DIFFER WITH THE SYSTEM EARLY NEXT WEEK BUT ARE BEGINNING TO COME CLOSER TO A CONSENSUS. ARCTIC AR WILL BE IN PLACE THIS WEEKEND AS MENTIONED EARLIER. ANOTHER 500 MB TROUGH WILL DIVE SOUTHEAST OUT OF THE NORTHERN PLAINS WITH A WEAKER SYSTEM MOVING ACROSS THE DESERT SOUTHWEST. MODELS INDICATE THAT THE TROUGHS WILL PARTIALLY PHASE TO THE WEST OF THE AREA WITH PRECIP SPREADING NORTHEASTWARD. THE GFS IS NOT SHOWING MUCH IN THE WAY OF CYCLOGENESIS WITH THE SYSTEM. WARM AIR ADVECTION IN THE LOW LEVELS WILL DEVELOP PRECIP. AHEAD OF THE TROUGH. A STRONG WEDGE IS IN PLACE TO THE SOUTHEAST OF THE MOUNTAINS WITH TEMPERATURES REMAINING NEAR FREEZING ACROSS THE AREA. THEREFORE...EXPECT THIS SOLUTION WOULD SUPPORT MOSTLY SNOW BUT QPF AMOUNTS ARE LIGHT COMPARED TO THE OTHER RAW MODEL GUIDANCE. ON THE OTHER HAND...THE ECMWF...GEM AND SOME OF THE GFS ENSEMBLE MEMBERS INDICATE CYCLOGENESIS NEAR THE GULF COAST WITH A LOW TRACKING ALONG THE NORTHERN GULF. IF THIS WERE THE CASE...THERE WOULD BE MUCH MORE MOISTURE ADVECTING INTO THE SYSTEM. THESE MODELS INDICATE SIGNIFICANTLY HIGHER QPF ACROSS THE AREA. THERE ARE STILL SEVERAL DETAILS TO WORK OUT BEFORE EARLY NEXT WEEK. ONE OF THE MANY DETAILS IS THAT WITH THE WARM AIR ADVECTION...SOME OF THE MODELS HAVE 850 MB TEMPERATURES IN THE 1-3 DEGREE CELSIUS RANGE. THIS COULD BE ENOUGH TO CAUSE COMPLICATIONS WITH PRECIP TYPE. WITH THE SYSTEM STILL 6 DAYS OUT...WILL KEEP THINGS SIMPLE WITH JUST RAIN/SNOW IN THE GRIDS. ALSO...KEPT HIGHS ON MONDAY MUCH LOWER THAN GUIDANCE WITH EVERY MODEL RUN INDICATING HIGHS IN THE LOW TO MID 30S. AGAIN...THERE ARE STILL SEVERAL MORE MODEL RUNS BETWEEN NOW AND MONDAY BUT THINGS HAVE TRENDED MORE TOWARDS A SIGNIFICANT SNOW ACROSS THE AREA WITH HIGHEST AMOUNTS NORTH OF I-40 DUE TO THE POTENTIAL PRECIP TYPE ISSUES FURTHER SOUTH. FOR NOW...WILL ADD THE MENTION OF SNOW INTO THE HWO AND CONTINUE TO MONITOR MODEL TRENDS OVER THE NEXT SEVERAL DAYS.
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&& .PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN 21 33 25 43 / 30 10 0 10 KNOXVILLE MCGHEE TYSON AIRPORT, TN 20 28 21 39 / 30 10 10 10 OAK RIDGE, TN 21 29 20 38 / 40 10 10 10 TRI CITIES AIRPORT, TN 17 25 14 31 / 50 40 10 10
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...WINTER WEATHER ADVISORY UNTIL 7 PM EST WEDNESDAY FOR CHEROKEE- CLAY. TN...WINTER STORM WARNING UNTIL 7 PM EST WEDNESDAY FOR BLOUNT SMOKY MOUNTAINS-COCKE SMOKY MOUNTAINS-JOHNSON-SEVIER SMOKY MOUNTAINS-SOUTHEAST CARTER-SOUTHEAST GREENE-SOUTHEAST MONROE-UNICOI. WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO NOON EST THURSDAY FOR BLOUNT SMOKY MOUNTAINS-COCKE SMOKY MOUNTAINS-JOHNSON- SEVIER SMOKY MOUNTAINS-SOUTHEAST CARTER-SOUTHEAST GREENE- SOUTHEAST MONROE-UNICOI. WINTER WEATHER ADVISORY UNTIL 7 AM EST /6 AM CST/ WEDNESDAY FOR ANDERSON-BLEDSOE-BRADLEY-GRAINGER-HAMBLEN-HAMILTON- JEFFERSON-KNOX-LOUDON-MARION-MCMINN-MEIGS-NW BLOUNT-NORTH SEVIER-NORTHWEST COCKE-NORTHWEST MONROE-RHEA-ROANE- SEQUATCHIE-UNION-WEST POLK. WINTER WEATHER ADVISORY UNTIL 7 PM EST WEDNESDAY FOR CAMPBELL- CLAIBORNE-EAST POLK-HANCOCK-HAWKINS-MORGAN-NORTHWEST CARTER- NORTHWEST GREENE-SCOTT TN-SULLIVAN-WASHINGTON TN. VA...WINTER WEATHER ADVISORY UNTIL 7 PM EST WEDNESDAY FOR LEE-RUSSELL- SCOTT-WASHINGTON-WISE. && $$ GM/MA

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