513
FXUS64 KMRX 200748
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
348 AM EDT THU MAR 20 2025
..NEW SHORT TERM, LONG TERM
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 336 AM EDT THU MAR 20 2025
KEY MESSAGES:
1. LIGHT RAIN MOVES ACROSS THE AREA THIS MORNING, WITH LINGERING
LIGHT RAIN/DRIZZLE AND COOLER TEMPERATURES THIS AFTERNOON.
2. RAIN WILL TRANSITION TO SNOW SHOWERS FOR THE EAST TENNESSEE
MOUNTAINS AND HIGHER ELEVATIONS OF SOUTHWEST VIRGINIA LATE THIS
AFTERNOON INTO THURSDAY NIGHT. LIGHT ACCUMULATIONS ARE EXPECTED.
SEE WINTER WEATHER ADVISORY OR SPECIAL WEATHER STATEMENT FOR
ADDITIONAL DETAILS.
DISCUSSION:
A DECAYING LINE OF SHOWERS IS CURRENTLY PROGRESSING FROM THE
CUMBERLAND PLATEAU INTO THE EAST TENNESSEE VALLEY AHEAD OF AN
EASTWARD PROPAGATING COLD FRONT. LATEST SPC MESOANALYSIS AND
SOUNDINGS FROM HI-RESOLUTION GUIDANCE SUGGEST MUCAPE IS LESS THAN
100 J/KG, IF NOT ZERO, WITH NO SURFACE BASED INSTABILITY. AS A
RESULT, THERE IS A VERY LOW CHANCE OF A RUMBLE OF THUNDER OR TWO AS
THIS ACTIVITY TRACKS EASTWARD INTO THE MORNING HOURS AND WORDING HAS
BEEN REMOVED FROM THE FORECAST. ANY MODERATE INTENSITY RAINFALL
COULD LEAD TO SOME GUSTS OF 20-30MPH WITH A STRONG H85 JET NEAR
50KTS ALOFT. THIS LOW-LEVEL JET WILL CONTINUE TO PRODUCE STRONG
GUSTY WINDS IN THE MOUNTAINS AND ADJACENT FOOTHILLS OVER THE NEXT
FEW HOURS. NO CHANGE TO THE REMAINING WIND ADVISORY PRODUCTS ARE
NEEDED.
FLOW WILL GRADUALLY VEER NORTHWESTERLY BEHIND THE COLD FRONT INTO
THE AFTERNOON HOURS. WRAP AROUND MOISTURE WILL LINGER LIGHT
RAIN/DRIZZLE FOR MUCH OF THE CUMBERLAND PLATEAU AND CENTRAL VALLEYS
NORTHWARD. DEPTH OF SATURATION WILL BE LIMITED TO AROUND NO GREATER
THAN 800MB WHICH GENERALLY RANGES FROM -10 TO -12 DEGREES CELSIUS.
AS THE H85 NWLY JET AMPLIFIES TO NEAR 35KTS LATE THIS AFTERNOON AND
INTO THE OVERNIGHT, OROGRAPHIC LIFT WILL PROMOTE A TRANSITION TO
SNOW SHOWERS IN FAVORED NWFS LOCATIONS. CURRENT FORECAST IS FOR 1-3
INCHES 2.5KFT AND HIGHER, WITH ISOLATED HIGHER TOTALS POSSIBLE
ACROSS 5KFT AND ABOVE. TEMPERATURES WILL TREND MUCH COOLER DO TO
THE STRONG CAA, AND WE HAVE LIKELY ALREADY SEEN OUR HIGH
TEMPERATURES AROUND OR SHORTLY AFTER MIDNIGHT THIS MORNING.
WIDESPREAD TEMPERATURES AT OR A FEW DEGREES BELOW FREEZING ARE
EXPECTED TONIGHT.
LONG TERM
(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 336 AM EDT THU MAR 20 2025
1. DRY AND MILDER CONDITIONS ARE EXPECTED FRIDAY AND SATURDAY.
2. A SYSTEM WILL BRING CHANCES FOR WIDESPREAD SHOWERS AND EVEN SOME
THUNDERSTORMS SUNDAY EVENING THROUGH MONDAY MORNING. STRONGER AND
MORE ORGANIZED STORMS CURRENTLY LOOK TO STAY TO OUR WEST.
3. DRIER AND COOLER CONDITIONS ARRIVE BY TUESDAY WITH ANOTHER WEAK
SYSTEM BRINGING A RETURN OF RAIN CHANCES BY WEDNESDAY.
FRIDAY THROUGH SUNDAY
AT THE START OF THE PERIOD, THE RECENT SYSTEM THAT IS AFFECTING THE
AREA WILL BE WELL OFF TO THE EAST WITH UPPER-LEVEL RIDGING BUILDING
IN. SURFACE HIGH PRESSURE WILL ALSO BE EXPANDING INTO THE AREA FROM
THE GULF. ALL OF THE MOISTURE ASSOCIATED WITH THIS SYSTEM WILL HAVE
PULLED OUT OF THE AREA WITH SUBSIDENCE AND HEIGHT RISES SUPPORTING
WARMER AND DRIER CONDITIONS. LOW RHS CAN BE EXPECTED AGAIN ON
FRIDAY, LIKELY DROPPING BELOW 30 PERCENT. HOWEVER, LOW-LEVEL WINDS
AND THE MSLP GRADIENT SUGGEST FAIRLY LIGHT WINDS OVERALL. FRIDAY
NIGHT INTO SATURDAY, ANOTHER SHORTWAVE WILL PROGRESS WELL TO OUR
NORTH WITH LIMITED MOISTURE KEEPING THE AREA DRY. INCREASED CLOUD
COVER MAY LIMIT THE DROP IN RHS, BUT WINDS WILL LIKELY BE STRONGER
WITH 850MB FLOW OVER 20 KTS AND A TIGHTER MSLP GRADIENT.
SATURDAY NIGHT INTO SUNDAY, ANOTHER SYSTEM WILL DEVELOP ACROSS THE
NORTHERN PLAINS AND PROGRESS EASTWARD. SOME RAIN CHANCES START TO
ARRIVE IN WESTERN AREAS ON SUNDAY, BUT THE MAIN TREND DURING THE DAY
WILL BE BROAD SOUTHERLY FLOW AND FURTHER WARMING.
SUNDAY NIGHT THROUGH WEDNESDAY
SUNDAY NIGHT INTO MONDAY MORNING, THIS SYSTEM IS EXPECTED TO
PROGRESS INTO THE UPPER GREAT LAKES REGION WITH A NEAR 995MB LOW
PRESSURE CENTER. THIS TIMEFRAME WILL ALSO BE WHEN WIDESPREAD RAIN IS
EXPECTED AHEAD OF ITS ASSOCIATED FRONT. BASED ON THE LATEST MODEL
GUIDANCE, A LINE OF SHOWERS AND STORMS IS LIKELY TO BE ONGOING TO
OUR WEST AND ARRIVING IN OUR AREA OVERNIGHT. SOME ELEVATED
INSTABILITY IS INDICATED IN WESTERN PORTIONS OF THE AREA WITH
MINIMAL INSTABILITY IN THE LOWER-LEVELS. THIS TIMEFRAME WILL BE
WORTH WATCHING, BUT THE BETTER CHANCES FOR ANY ORGANIZED CONVECTION
STILL LOOK TO BE WELL WEST OF THE AREA. BEHIND THIS SYSTEM, DEEP
UPPER TROUGHING AND CAA WILL BRING TEMPERATURES BACK BELOW NORMAL.
HIGH PRESSURE WILL LIKELY KEEP THE REGION DRY BY TUESDAY. SOME
MODELS INDICATE ANOTHER WEEK SYSTEM MID-WEEK THAT WILL BRING SOME
ADDITIONAL RAIN CHANCES, MAYBE EVEN MIXED PRECIPITATION IN THE
MOUNTAINS.
AVIATION
(06Z TAFS)
ISSUED AT 142 AM EDT THU MAR 20 2025
A WEAKENING LINE OF SHOWERS HAS MOVED ONTO THE CUMBERLAND PLATEAU
AND WILL GRADUALLY TRANSITION EASTWARD OVERNIGHT. INCREASING LOW-
LEVEL CLOUDS WITH A LOW CHANCE OF MVFR CIGS ARE EXPECTED WITH THIS
ACTIVITY. BASED OFF UPSTREAM OBSERVATIONS HAVE CURRENTLY OPTED TO
NOT INCLUDE MVFR MENTION AT THIS TIME. WRAP AROUND MOISTURE WILL
REINFORCE LOW-LEVEL CLOUDS THURSDAY AFTERNOON WITH LIGHT
PRECIPITATION POSSIBLE AT TYS/TRI IN THE AFTERNOON AND EVENING
HOURS. AGAIN, SOME PERIODS OF MVFR CIGS ARE POSSIBLE AT THESE TWO
SITES AND HAS BEEN INCLUDED WITHIN PROB30S. WINDS WILL REMAIN
BREEZY FROM THE SOUTHWEST OVERNIGHT BUT GRADUALLY VEER WESTERLY
INTO MID-DAY, CONTINUING TO VEER TO THE NORTHWEST BY THE EVENING.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 51 33 62 40 / 20 0 0 0
KNOXVILLE MCGHEE TYSON AIRPORT, TN 53 30 58 40 / 30 10 0 0
OAK RIDGE, TN 51 29 57 38 / 30 10 0 0
TRI CITIES AIRPORT, TN 55 28 54 36 / 50 50 0 0
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...WIND ADVISORY UNTIL 8 AM EDT THIS MORNING FOR BLOUNT SMOKY
MOUNTAINS-COCKE SMOKY MOUNTAINS-EAST POLK-JOHNSON-SEVIER
SMOKY MOUNTAINS-SOUTHEAST CARTER-SOUTHEAST GREENE-SOUTHEAST
MONROE-UNICOI.
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 4 AM EDT
FRIDAY FOR BLOUNT SMOKY MOUNTAINS-COCKE SMOKY MOUNTAINS-
SEVIER SMOKY MOUNTAINS.
VA...NONE.
SHORT TERM...KRS
LONG TERM....BW
AVIATION...KRS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page