817
FXUS64 KMRX 170523 AAC
AFDMRX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MORRISTOWN TN
123 AM EDT THU APR 17 2025
..NEW AVIATION
UPDATE
ISSUED AT 1013 PM EDT WED APR 16 2025
FORECAST REMAINS IN GOOD SHAPE THIS EVENING WITH JUST SOME MINOR
TOUCH UPS TO THE HOURLY T/TD TRENDS BASED ON LATEST SURFACE
OBSERVATIONS. A QUIET BUT COOL OVERNIGHT IS EXPECTED.
SHORT TERM
(THIS EVENING THROUGH THURSDAY)
ISSUED AT 300 PM EDT WED APR 16 2025
HIGH PRESSURE NOW LIES OVER THE FORECAST AREA. A WEAK SURFACE
TROUGH WAS JUST ACROSS THE APPALACHIANS IN NC. THE PRESSURE
GRADIENT WAS RELAXING BUT WITH THE TROUGH TO THE EAST THERE WAS
STILL SOME GUSTY WINDS OVER SOUTHWEST VIRGINIA AND NORTHEAST
TENNESSEE. GOOD MIXING HAS ALLOWED DEW POINTS TO DROP INTO THE
UPPER 20S TO AROUND 32. RELATIVE HUMIDITY VALUES ARE IN THE 20S
TODAY SOMEWHAT HIGHER THAN ON TUESDAY BUT STILL LOW. KEPT DEW
POINTS LOW THROUGH ABOUT 7PM WITH RH VALUES 20 TO 25 PERCENT OVER
MUCH OF THE AREA. THEN RISE SLOWLY TONIGHT AS TEMPERATURES DROP
QUICKLY AND WINDS DECOUPLE.
TEMPERATURES THIS AFTERNOON ARE IN THE 60S WHICH IS A FEW DEGREES
WARMER IN MOST PLACES THAN TUESDAY. FOR TONIGHT AND THURSDAY
WINDS DECREASE AS HIGH PRESSURE SHIFTS EAST AND WILL BE OVER THE
SOUTHERN APPALCHIANS LATE TONIGHT AND THURSDAY MORNING. SOME FROST
WILL FORM ACROSS MAINLY SOUTHWEST VIRGINIA AND NORTHEAST
TENNESSEE WITH LOWS IN THE MID TO UPPER 30S. ALSO SOUTHWEST NORTH
CAROLINA WILL DROP INTO THE UPPER 30S WITH PATCHY FROST THERE. A
WEAK WARM FRONT WILL MOVE NORTHWARD LATER THURSDAY MORNING THROUGH
THE AFTERNOON FROM SOUTHWEST TO NORTHEAST AND PRODUCE SOME
SPRINKLES AND POSSIBLE LIGHT SHOWERS. DO NOT EXPECT ANY
SIGNIFICANT RAINFALL. TEMPERATURES MAY BE HELD DOWN SLIGHTLY IN
THE NORTHEAST. OTHERWISE HIGH TEMPERATURES CLOSER TO THE AVERAGE
OF UPPER 60S TO NEAR 70 NORTHEAST TO LOWER TO MID 70S CENTRAL AND
SOUTHWEST. FOR FIRE WEATHER THURSDAY EXPECT RH VALUES AS LOW AS 25
PERCENT IN SPOTS BUT MOSTLY AROUND 30 PERCENT, COULD BE HIGHER
WITH MORE CLOUDS NORTH.
LONG TERM
(THURSDAY NIGHT THROUGH NEXT WEDNESDAY)
ISSUED AT 300 PM EDT WED APR 16 2025
KEY MESSAGES:
1. WARMING TREND FRIDAY.
2. POTENTIAL FOR WEAK SYSTEM LATE SUNDAY INTO MONDAY, TIMING
UNCERTAIN ALONG WITH EXACT IMPACTS, BUT NEXT GOOD CHANCE FOR AT
LEAST SCATTERED SHOWERS AND THUNDERSTORMS.
DISCUSSION:
INCREASED CLOUDINESS NEAR ENHANCED VORTICITY ON THURSDAY WILL
ATTEMPT TO SPARK SOME HIGH BASED SHOWERS. LOOKS UNLIKELY THAT ANY OF
IT REACHES THE GROUND BETWEEN THE COMBINATION OF BRIEF COVERAGE,
WEAK FORCING, AND LOW LEVEL DRY AIR TURNING ANYTHING THAT FALLS INTO
LIKELY VIRGA, BUT CANNOT COMPLETELY RULE OUT SOME DRIVERS HAVING TO
TURN ON THEIR WIPERS ONCE OR TWICE.
RIDGE OF HIGH PRESSURE ANCHORS ITSELF OFF THE SOUTHEASTERN COAST BY
SATURDAY AND PLAYS A SIGNIFICANT ROLE IN MAINTAINING A PLEASANTLY
WARM REGIONAL ATMOSPHERE OVER OUR AREA FROM THE WEEKEND ONWARDS INTO
NEXT WEEK. NBM KEEPS SLIGHT CHANCE POPS IN ON A SW TO NE TANGENT
ALONG THE WESTERN AND NORTHERN EDGES OF TENNESSEE AND VIRGINIA OVER
THE WEEKEND. IF THE DETERMINISTIC GUIDANCE IS ANY CLUE, WE MIGHT BE
DRIER THAN THAT AREA WIDE, KEEPING RAIN CHANCES OFF FURTHER WEST, AT
LEAST UNTIL SOMETIME LATER ON SUNDAY.
A WEAK UPPER SHORTWAVE WILL THEN ATTEMPT TO BRING A COLD FRONT INTO
THE AREA LATE SUNDAY INTO MONDAY TIMEFRAME, THIS SHOULD HELP SPARK
SHOWERS AND STORMS AHEAD OF THE FRONT. NOT CERTAIN THIS FRONT WILL
BE ABLE TO PUSH THROUGH OR JUST WASH OUT ENTIRELY LEAVING A WARMER
PATTERN IN PLACE. BEYOND MONDAY, THE UPPER RIDGE OFFSHORE IS LIKELY
TO FLATTEN OUT, AS DEPICTED BY BOTH ENSEMBLE MEANS.
AVIATION
(06Z TAFS)
ISSUED AT 1234 AM EDT THU APR 17 2025
VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. HIGH CLOUDS WILL
GRADUALLY LOWER TO AROUND SCT-BKN100 FOR AREAS NORTH OF KTYS
AFTER 18Z AS A WARM FRONT LIFTS MIDDLE TN INTO EASTERN KY.
WOULDN'T BE SURPRISED TO SOME LIGHT RAIN IN NORTHEAST TN THIS
AFTERNOON AND EVENING AS A RESULT, GENERALLY NEAR KTRI. BUT ODDS
ARE LOW ENOUGH TO PRECLUDE MENTIONING IN THE TAF FOR NOW. WINDS
WILL BE LIGHT THROUGH THE PERIOD AS WELL.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 75 53 83 60 / 0 0 0 0
KNOXVILLE MCGHEE TYSON AIRPORT, TN 72 51 83 62 / 0 0 0 0
OAK RIDGE, TN 72 50 81 61 / 10 0 0 0
TRI CITIES AIRPORT, TN 69 48 81 55 / 20 10 0 0
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
SHORT TERM...TD
AVIATION...CD
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