394
FXUS64 KMRX 151720
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
1220 PM EST SUN DEC 15 2024
..NEW AVIATION
UPDATE
ISSUED AT 1007 AM EST SUN DEC 15 2024
SLIGHT UPDATE TO THE FORECAST THIS MORNING. BASED ON LATEST OBS,
DECIDED TO EXTEND THE WIND ADVISORY UNTIL 18Z. CAMP CREEK IS STILL
GUSTING IN THE MID 50S AS OF 10 AM. WINDS SHOULD BEGIN TO TAPER
OFF LATER THIS AFTERNOON. OTHERWISE FORECAST ON TRACK AND NO
CHANGES.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 306 AM EST SUN DEC 15 2024
KEY MESSAGES:
1. WIND ADVISORY CONTINUES INTO THE MORNING HOURS FOR THE EAST TN
MOUNTAINS AND FOOTHILLS.
2. RAIN TODAY WILL DIMINISH BY TONIGHT, BUT STILL EXPECT SOME LIGHT
RAIN/DRIZZLE AROUND DURING THE OVERNIGHT HOURS.
DISCUSSION:
WE START THE PERIOD WITH AN UPPER LOW TO OUR NORTHWEST OVER WESTERN
ILLINOIS AND STRONG SURFACE HIGH PRESSURE TO OUR NORTHEAST. THE LOW
WILL TRACK NORTHEAST AND WEAKEN DURING THE PERIOD, WITH LOW
AMPLITUDE SHORT WAVE RIDGING BUILDING OVER OUR AREA TONIGHT IN ITS
WAKE. A 40+KT 850 MB JET FROM THE SOUTH AND SOUTHEAST OUT AHEAD OF
THE LOW PRESSURE SYSTEM IS BRINGING INCREASED MOISTURE AND WE ARE
SEEING SOME MAINLY LIGHT RAIN ACROSS THE AREA. THE LOW LEVEL JET IS
ALSO IS PRODUCING SOME GUSTY WINDS AIDED BY MOUNTAIN WAVE
ENHANCEMENT TO THE NORMAL HIGHER ELEVATIONS AND FOOTHILLS OF THE E
TN MOUNTAINS. WE HAVE BEEN SEEING SOME GUSTS TO NEAR 50 MPH IN
LOCATIONS LIKE COVE MTN AND CAMP CREEK, AND THE GUSTY WINDS WILL
CONTINUE INTO THE MORNING HOURS BEFORE SUBSIDING. WILL ALLOW THE
WIND ADVISORY TO CONTINUE AS IS FOR NOW. IN ADDITION TO THE RAIN, A
FEW SPOTS OVER THE HIGHEST ELEVATIONS OF THE MOUNTAINS NEAR THE
TN/NC BORDER IN CARTER AND JOHNSON COUNTIES MAY SEE SOME LIGHT
FREEZING RAIN LATE TONIGHT INTO THE MORNING. HOWEVER, IF IT DOES
OCCUR THE COVERAGE AREA SHOULD BE VERY SMALL AND MAINLY CONFINED TO
THE HIGHEST PEAKS.
THE LIGHT RAIN WILL DIMINISH BY TONIGHT AS THE DEEPER MOISTURE
EXITS, BUT LOW LEVEL MOISTURE WILL LINGER AND SOME PATCHES OF VERY
LIGHT RAIN AND/OR DRIZZLE WILL CONTINUE TO BE POSSIBLE OVERNIGHT.
LONG TERM
(MONDAY THROUGH SATURDAY)
ISSUED AT 306 AM EST SUN DEC 15 2024
KEY MESSAGES:
1. ACTIVE WEATHER PATTERN CONTINUES WITH MULTIPLE CHANCES OF
BENEFICIAL RAIN SHOWERS THROUGH MIDWEEK.
2. MILD TEMPERATURES THROUGH THE FIRST HALF OF THE WEEK, WITH A
TRANSITION TO COLDER WEATHER LATE NEXT WEEK.
DISCUSSION:
SOGGY AND MILD START TO THE WORK WEEK, WITH THE NORTHERN JET STREAM
REMAINING ACTIVE AS A COUPLE OF SHORTWAVE TROUGHS MOVE QUICKLY
THROUGH THE EASTERN US. FIRST ONE PASSES WELL TO OUR NORTH, AND THE
COLD FRONT THAT IT BRINGS WITH IT DECOMPOSES AS IT REACHES EAST TN.
WITH THE BETTER UPPER DYNAMICS TOO FAR AWAY TO SUPPORT THE SYSTEM,
RAIN AMOUNTS WILL BE FAIRLY LOW WITH THIS SYSTEM, PROBABILITIES OF
EVEN A QUARTER OF AN INCH ARE ONLY NEAR 50% ALONG THE KENTUCKY
BORDER AND ON THE PLATEAU. FLOW ALOFT QUICKLY RETURNS TO A
SOUTHWESTERLY DIRECTION AND BRINGS THE MILDER AIRMASS BACK TO THE
NORTH REALLY IN TIME FOR WEDNESDAY, BUT WITH NO STING BEHIND THE
FRONT, TUESDAY WILL REMAIN STEADY.
SECOND SHORTWAVE WILL DIG DEEPER INTO THE HEART OF THE COUNTRY ON
APPROACH LATE WEDNESDAY. OUT AHEAD OF IT A MORE SUBSTANTIAL COLD
FRONT WILL HELP DELIVER THE ACCOMPANYING COLDER AIRMASS INTO THE
TENNESSEE VALLEY. TIMING FOR THE SYSTEM ON WEDNESDAY IS STARTING TO
COME INTO FOCUS ON THE DAYTIME HOURS, WHERE A FEW HUNDRED JOULES OF
SURFACE BASED CAPE MIGHT BE AVAILABLE TO BE TAKEN ADVANTAGE OF.
ANYTHING MORE THAN THAT IS UNLIKELY, WITH ENSEMBLE PROBABILITIES OF
500J NEAR 0. A MOIST ATMOSPHERIC PROFILE PLUS THE ACCOMPANYING KICK
OF THE FRONT SHOULD ALLOW FOR A MORE BOUNTIFUL, BUT STILL MEASURED,
RAIN EVENT.
THEN THE COOLER AIR ARRIVES. I DON'T EXPECT RIGHT NOW ANY
ACCUMULATING SNOW ON THE BACKSIDE OF THE WEDNESDAY FRONT, THERE'S A
SHALLOW MOIST AIRMASS LEFT BEHIND IN THE VALLEY, BUT NORTHWEST FLOW
TO BRING IT INTO THE MOUNTAINS DOESN'T APPEAR STRONG. AS WE ROLL
INTO THE WEEKEND, A MAJOR LONGWAVE TROUGH IS APPARENT ON BOTH GFS
AND EURO, WITH A SIGNIFICANT SHOT OF COLD AIR IN TOW. EVEN AT THIS
RANGE THE NBM PROBABILITIES FOR LOW TEMPERATURES BELOW 20F ARE 40 TO
70% FOR SUNDAY MORNING NEXT WEEKEND.
AVIATION
(18Z TAFS)
ISSUED AT 1217 PM EST SUN DEC 15 2024
POOR FLIGHT CONDITIONS ACROSS THE REGION THROUGH THE PERIOD. CHA
AND TYS WILL LIKELY BE IFR THROUGH MOST OF THE PERIOD. HOWEVER,
PERIODS OF MVFR AND LIFR MAY ALSO OCCUR. TRI SHOULD STAY VFR
UNTIL THIS EVENING, THEN DROP TO MVFR OVERNIGHT. HOWEVER, IT'S
POSSIBLE TRI REMAINS JUST ABOVE MVFR CONDITIONS AT AROUND 3500
FEET. LLWS REMAINS IN PLACE AT TRI THROUGH THE REST OF THE
AFTERNOON.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 46 62 54 65 / 30 10 80 30
KNOXVILLE MCGHEE TYSON AIRPORT, TN 46 64 54 63 / 40 20 80 20
OAK RIDGE, TN 46 61 52 61 / 40 30 90 20
TRI CITIES AIRPORT, TN 43 61 51 59 / 50 20 80 20
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...WIND ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR BLOUNT SMOKY
MOUNTAINS-COCKE SMOKY MOUNTAINS-JOHNSON-SEVIER SMOKY
MOUNTAINS-SOUTHEAST CARTER-SOUTHEAST GREENE-SOUTHEAST
MONROE-UNICOI.
VA...NONE.
SHORT TERM...
LONG TERM....WELLINGTON
AVIATION...
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