545
FXUS64 KMRX 182005
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
305 PM EST WED DEC 18 2024
..NEW SHORT TERM, LONG TERM
SHORT TERM
(THIS EVENING THROUGH THURSDAY)
ISSUED AT 241 PM EST WED DEC 18 2024
KEY MESSAGES:
1. THUNDERSTORMS WILL CONTINUE TO WIND DOWN THIS EVENING WITH
TIME, TURNING INTO SHOWERS. TRENDING DRIER AFTER SUNSET INTO
TONIGHT.
2. COLD FRONT PASSAGE TONIGHT WILL SEND DRIER AIR AND COOLER
TEMPERATURES FOR THURSDAY. SUNSHINE WILL RETURN AS WELL.
DISCUSSION:
LEFT OVER THUNDERSTORMS FROM THE INITIAL LINE ARE ABOUT AT OUR
EASTERN CWA BORDER AT THIS TIME. SPS OR LESS LEVEL WITH ISOLATED
LIGHTNING. THINGS WILL CONTINUE TO TREND DOWNWARD AS FAR AS ANY
SORT OF WIND THREAT OR THUNDERSTORM POTENTIAL. MOST OF THE SHOWERS
OUT THERE DON'T HAVE ANY THUNDER WITH THEM. PEAK GUSTS ONLY
RECORDED IN THE LOW TO MID 30'S MPH, ESPECIALLY AT CHA, TYS, AND
SOUTHWEST VA. LOOKING AT HISTORICAL RAINFALL REPORTED SINCE THIS
MORNING, THE HEAVIEST OF THE RAINFALL FELL WEST OF THE PLATEAU
MAKING IT SEEM LIKE THE PLATEAU RUNG OUT MOST OF THE MOISTURE. AS
MUCH AS OVER A HALF INCH MAXES WITH TODAY'S EVENT CURRENTLY, BUT
OF COURSE THAT MIGHT NOT CAPTURE THE HEAVIEST SHOWER/STORM OVER AN
AREA WITHOUT REPORTING EQUIPMENT.
ANY THREAT FOR THUNDERSTORMS AND GUSTY WINDS WILL SOON END AND
TURN MORE SHOWERY BEHIND THE SQUALL LINE THAT MOVED THROUGH
EARLIER THIS AFTERNOON. RAINFALL EXPECTED TO END WEST TO EAST.
TOWARDS 00Z AND AFTER, CHANCES FOR PRECIPITATION DROP OFF WITH THE
GREATEST CHANCES LINGERING OVER THE MOUNTAINS. PATCHY FOG MAY BE
POSSIBLE TONIGHT FOR ANYWHERE THAT MAY CLEAR OUT BEFORE SUNRISE.
DRY AIR AND THUS COOLER TEMPERATURES, WILL FOLLOW THE DECREASING
PRECIPITATION CHANCES TONIGHT AND INTO TOMORROW. 50S DEW POINTS
TODAY WILL DROP TO THE 30S AND 40S FOR THURSDAY. LOW TEMPERATURES
MAY RANGE IN THE 30S. WITH HIGH PRESSURE SHIFTING EAST FROM
CENTRAL CANADA, CLOUDS WILL DISSIPATE INTO THURSDAY, PROVIDING DRY
WEATHER AND HIGHS RANGING IN THE 40S TO 50S AFTER HIGHS THIS
AFTERNOON NEARING 70 DEGREES.
LONG TERM
(THURSDAY NIGHT THROUGH NEXT WEDNESDAY)
ISSUED AT 241 PM EST WED DEC 18 2024
KEY MESSAGES:
1. TURNING COLDER FOR THURSDAY THROUGH THE WEEKEND.
2. SCATTERED RAIN AND SNOW EXPECTED FRIDAY AFTERNOON AND NIGHT.
ACCUMULATING SNOWFALL EXPECTED IN THE MOUNTAINS WITH 1 TO 3 INCHES
ABOVE 2500 FEET.
3. DRY SUNDAY THROUGH TUESDAY, WITH A GRADUAL WARMING TREND FOR
MONDAY AND TUESDAY.
4. MILD CONDITIONS AND RAIN CHANCES ARRIVE BY CHRISTMAS.
DISCUSSION:
A QUICK MOVING SHORTWAVE TROUGH AND CLIPPER LOW PRESSURE SYSTEM WILL
DIVE SOUTHEAST ACROSS THE OHIO VALLEY AND CENTRAL APPALACHIANS ON
FRIDAY WITH NORTHWEST FLOW BEHIND THE FRONT. THIS WILL PRODUCE
OROGRAPHIC LIFT AND CONTINUED PRECIPITATION ACROSS THE HIGHER
ELEVATIONS OF OUR FORECAST AREA FRIDAY AFTERNOON THROUGH SATURDAY
MORNING. ACCUMULATING SNOW IS EXPECTED ACROSS THE MOUNTAINS WITH A
MIX OF RAIN AND SNOW ACROSS LOWER TERRAIN WITH NO IMPACTS FOR VALLEY
LOCATIONS. OVERALL, 1 TO 3 INCHES OF SNOW WILL BE POSSIBLE ACROSS
THE HIGHER ELEVATIONS OF THE MOUNTAINS WITH LOCALLY HIGHER AMOUNTS.
IF THIS FORECAST TREND CONTINUES, A WINTER WEATHER ADVISORY WILL
LIKELY BE NEEDED IN SUBSEQUENT FORECAST UPDATES.
FLURRIES TAPER OFF ON SATURDAY WITH CLEARING SKY CONDITIONS. AS
RIDGING BUILDS IN, UPPER-LEVEL HEIGHTS RISE TO ABOVE NORMAL LEVELS
EARLY NEXT WEEK WITH GRADUAL WARMING CONDITIONS. DRY WEATHER
CONTINUES THROUGH EARLY NEXT WEEK.
SOUTHERLY FLOW AND INCREASING MOISTURE AHEAD OF A LOW PRESSURE
SYSTEM TO OUR WEST WILL RESULT IN GRADUALLY INCREASING RAIN CHANCES
BY THE MIDDLE OF NEXT WEEK. AT THIS TIME, PROBABILITIES ARE
INCREASING FOR CLOUDY, AND POTENTIALLY WET, CONDITIONS ON CHRISTMAS.
AVIATION
(18Z TAFS)
ISSUED AT 1244 PM EST WED DEC 18 2024
DENSE FG AND LOW CIG STUCK AROUND TRI FOR MUCH LONGER THAN
THOUGHT. THEY HAVE RECENTLY SCATTERED OUT, BUT MAY BE IMPACTED
SOON ONCE THE SQUALL LINE COMES THROUGH. THE LINE IS SEEMINGLY
BOWING OUT AND APPEARS WILL REACH TYS MUCH FASTER THAN WHEN THIS
TAF PACKAGE WAS MADE. PRECIPITATION IS ABOUT THE SAME DISTANCE
AWAY AT CHA AT TRI. CAN EXPECT GUSTS IN THE 20-30KT RANGE,
LIGHTNING, MOD TO HEAVY RAIN AT TIMES, AND LOWERING CIG. BEYOND
00-03Z, PRECIPITATION IS EXPECTED TO BE MOVED OUT FROM THE
TERMINALS AND WINDS WILL THEN TURN MORE NORTHERLY AFTER THE COLD
FRONTAL PASSAGE. MVFR CIG MAY STICK AROUND THROUGH THE NIGHT WITH
POSSIBLE VSBY RESTRICTIONS. TOMORROW EXPECTED TO EVENTUALLY
IMPROVE TO VFR.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 39 54 35 50 / 40 0 0 0
KNOXVILLE MCGHEE TYSON AIRPORT, TN 39 50 35 47 / 60 0 0 20
OAK RIDGE, TN 37 50 33 46 / 40 0 0 20
TRI CITIES AIRPORT, TN 37 48 35 44 / 70 0 10 50
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
SHORT TERM...KS
LONG TERM....JB
AVIATION...KS
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