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

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000 FXUS64 KMRX 040852 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 352 AM EST THU FEB 4 2016 .SHORT TERM...
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(TODAY AND TONIGHT)...HIGH PRESSURE WAS BUILDING ACROSS THE FORECAST AREA THIS MORNING IN THE WAKE OF A STRONG COLD FRONT THAT PASSED THROUGH EARLIER WEDNESDAY AFTERNOON AND EVENING. UPPER FLOW FROM THE NORTHWEST WAS BRINGING IN SOME LOW CLOUDS FROM SOUTHEAST KY INTO THE CUMBERLAND PLATEAU WHILE LOW CLOUDS WERE FORMING OVER PARTS OF THE CENTRAL VALLEY AND OTHER CLOUDS LINGERED ACROSS SOUTHWEST VIRGINIA. TEMPERATURES WERE IN THE LOWER TO MID 30S PLATEAU AND UPPER 30S TO MID 40S ELSEWHERE WITH VARYING AMOUNTS OF CLOUD COVER. MOISTURE AT 850 MB AND LOWER WILL KEEP SOME LOW CLOUD COVER ACROSS THE NORTHERN AND CENTRAL AREAS TODAY WITH SKIES EXPECTED TO BE MOSTLY CLOUDY. FARTHER SOUTH LOW LEVEL MOISTURE WILL BE A LITTLE SHALLOWER SO EXPECT CLEARING SKIES TO BEGIN SOONER. HIGHS TODAY MUCH COOLER THAN WEDNESDAY AND CLOSER TO AVERAGE FOR THIS TIME OF YEAR...MOSTLY MID 40S TO NEAR 50. AS UPPER TROUGH TO THE WEST MOVES THROUGH TONIGHT A WEAK SHORT WAVE MAY PRODUCE SOME CLOUDS IN THE NORTHEAST AS IT INTERACTS WITH SURFACE LOW MOVING UP THE FRONT THROUGH THE CAROLINAS. HOWEVER NO PRECIPITATION SHOULD FALL. TEMPERATURES WILL BE MOSTLY MID TO UPPER 20S UNDER CLEARING SKIES TONIGHT. ACROSS THE NORTHEAST SKIES WILL KEEP MORE CLOUDS BUT SHOULD BECOME CLEAR BY MORNING. .LONG TERM...(FRIDAY THROUGH WEDNESDAY)... THE WEEKEND WILL FEATURE DRY CONDITIONS WITH TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL. ON FRIDAY...SURFACE HIGH PRESSURE WILL BE LOCATED TO THE WEST WITH A SURFACE LOW MOVING NORTHWARD ALONG THE EAST COAST. RIDGING ALOFT IN THE WAKE OF THE SYSTEM WILL KEEP SKIES SUNNY THROUGHOUT THE DAY. HOWEVER...COLD AIR ADVECTION BEHIND THE EXITING SYSTEM WILL KEEP TEMPERATURES IN THE MID 30S TO UPPER 40S DESPITE THE AMPLE SUPPLY OF SUNSHINE. SURFACE HIGH PRESSURE WILL MOVE OVERHEAD FRIDAY NIGHT INTO SATURDAY MORNING WITH IDEAL RADIATIONAL COOLING CONDITIONS SETTING UP WITH LIGHT WINDS AND CLEAR SKIES. EXPECT OVERNIGHT LOWS WILL DROP INTO THE 20S AREAWIDE. LATE SATURDAY INTO SUNDAY...A HIGHLY AMPLIFIED TROUGH WILL DIVE ACROSS THE SOUTHEAST. HOWEVER...MOISTURE VALUES REMAIN LOW WITH PW VALUES ONLY IN THE 0.2-0.3 INCH RANGE. THEREFORE...NOT EXPECTING MUCH OF ANYTHING WITH THIS SYSTEM OTHER THAN A SLIGHT INCREASE IN CLOUD COVER LATE SATURDAY NIGHT INTO SUNDAY MORNING. THIS SYSTEM WILL LEAD TO CYCLOGENESIS ALONG THE CAROLINA COAST SUNDAY MORNING BUT MODELS INDICATE THAT THE PRECIP. WITH THIS SYSTEM WILL REMAIN WELL OFF TO THE EAST. THE MAIN STORY IN THE EXTENDED WILL BE THE WINTRY WEATHER AND ARCTIC AIR THAT WILL MOVE INTO THE AREA EARLY NEXT WEEK. MODELS HAVE BEEN HOLDING CONSISTENT WITH AN EXTREMELY COLD AIR MASS MOVING INTO THE AREA NEXT WEEK. LATE SUNDAY INTO EARLY MONDAY AN UPPER LEVEL TROUGH WILL DIVE OUT OF THE NORTHERN PLAINS INTO THE TENNESSEE VALLEY WITH IT BRINING IN THE FULL BRUNT OF THE ARCTIC AIR MASS. THE LATEST 00Z SUITE OF MODELS HAVE TRENDED A BIT QUICKER WITH THE ONSET OF PRECIPITATION. THE LATEST MODELS INDICATE THAT PRECIP. WILL BEGIN BETWEEN MIDNIGHT AND 6AM ON MONDAY MORNING. IF THIS WERE THE CASE...EXPECT TEMPERATURES WOULD COOL ACROSS THE REGION THROUGHOUT THE DAY MONDAY WITH MOSTLY SNOW ACROSS THE AREA. THE LATEST 00Z GFS MODEL SOUNDINGS INDICATE THAT THE FREEZING LEVEL IS NO MORE THAN 1 KFT AGL ACROSS THE VALLEY WITH TEMPERATURES QUICKLY COOLING ALOFT ON MONDAY. THE LAPSE RATES WITH THE SYSTEM CONTINUE TO BE IMPRESSIVE AND EXPECT ALL SNOW WITH SURFACE TEMPERATURES OF 36-38 DEGREES BASED ON THESE LAPSE RATES. THE UPPER TROUGH CONTINUES TO AMPLIFY ACROSS THE EASTERN CONUS AS THE LOW BECOMES CLOSED OFF. SEVERAL SHORTWAVE TROUGHS WILL CONTINUE TO ROTATE THROUGH THE MAIN SYSTEM WITH SNOW SHOWERS CONTINUING TUESDAY AND INTO WEDNESDAY. REGARDLESS OF THE AMOUNT OF SNOW...TEMPERATURES WILL BE MUCH COLDER THAN AVERAGE WITH HIGHS BELOW FREEZING AND LOWS IN THE TEENS WEDNESDAY AND THURSDAY MORNINGS. IN FACT...SOME LOCATIONS MAY NOT GO ABOVE FREEZING BETWEEN MONDAY AND THURSDAY AFTERNOONS. MODELS CONTINUE TO HOLD TRUE TO THIS SOLUTION WITH ARCTIC AIR AND WIDESPREAD SNOW SHOWERS MOVING INTO THE AREA EARLY NEXT WEEK. MONDAY LOOKS TO FEATURE THE HIGHEST POPS BUT FOR THOSE LOCATIONS NORTH OF I-40 AND IN THE FAVORED UPSLOPE REGIONS...LIGHT SNOW COULD LINGER AS LATE AS WEDNESDAY NIGHT. FOR NOW EXPECT A 2-4 INCH SNOW ACROSS THE AREA WOULD BE REASONABLE WITH THE LOWEST AMOUNTS ACROSS THE SOUTHERN VALLEY AND HIGHER AMOUNTS NORTH OF I-40 AND IN THE FAVORED UPSLOPE REGIONS. WILL CONTINUE TO HIGHLIGHT THE MENTION OF SNOWFALL IN THE HWO BUT PLEASE CONTINUE TO CHECK BACK WITH SEVERAL MORE MODEL RUNS TO COME BETWEEN NOW AND MONDAY.
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&& .PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN 49 28 49 28 / 0 0 0 0 KNOXVILLE MCGHEE TYSON AIRPORT, TN 47 25 45 28 / 10 0 0 0 OAK RIDGE, TN 47 26 46 28 / 0 0 0 0 TRI CITIES AIRPORT, TN 46 24 42 24 / 10 10 0 0
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ TD/MA

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