390
FXUS64 KMRX 261141 AAA
AFDMRX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MORRISTOWN TN
741 AM EDT MON MAY 26 2025
..NEW AVIATION
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 320 AM EDT MON MAY 26 2025
KEY MESSAGES:
1. SCATTERED SHOWERS CONTINUE IN THE CENTRAL VALLEY THROUGH
SHORTLY AFTER DAYBREAK. BUT DECENT UNCERTAINTY ABOUT RAIN CHANCES
FROM THERE THROUGH THE LATE AFTERNOON/EARLY EVENING HOURS.
2. A SHORTWAVE MOVES THROUGH WESTERN/MIDDLE TN INTO KENTUCKY THIS
AFTERNOON THROUGH TONIGHT, BRINGING CHANCES FOR FAIRLY WIDESPREAD
RAINFALL THIS EVENING AND OVERNIGHT.
DISCUSSION:
ISENTROPIC ANALYSIS SHOWS SOME WEAK ASCENT IN THE LOW LEVELS
CONTINUING ACROSS EAST TN, WHICH IS BORN OUT IN RADAR TRENDS
SHOWING SCATTERED ONGOING ACROSS THE FORECAST AREA, ESPECIALLY
ACROSS THE CENTRAL TN VALLEY WHERE MODELS SAY THE LIFT IS
MAXIMIZED. BELIEVE THAT SHOWERS WILL MOSTLY BE ON A DOWNWARD
TREND AFTER DAYBREAK AS LOW LEVEL ASCENT BEGINS TO WEAKEN AND H5
START TO RISE IN RESPONSE TO AN ARKANSAS SHORTWAVE EJECTING
EASTWARD ACROSS TN AND KY TODAY. THAT SAID, CONFIDENCE IN RAIN
CHANCES THROUGH THE DAY IS LOW TO BE HONEST. THERE ARE MIXED
REVIEWS IN GUIDANCE, WITH SOME SHOWING A DISTINCT LULL IN PRECIP
CHANCES THROUGH THE DAY AND OTHERS SHOWING SCATTERED SHOWERS
PERSISTING. THE ARKANSAS SHORTWAVE SHOULD INDUCE CYCLOGENESIS
OVER WESTERN/MIDDLE TN TODAY WHICH WILL PULL THAT STATIONARY FRONT
NORTHWARD TOWARDS OUR FORECAST AREA BY LATE THIS AFTERNOON AND
EVENING. THAT SHOULD PROVE TO BE A STRONG IMPETUS FOR ADDITIONAL
CONVECTION LATE THIS AFTERNOON AND EVENING, BUT CONFIDENCE IN WHAT
HAPPENS BETWEEN DAYBREAK AND THE FRONT LIFTING NORTHWARD IS LOW.
I THINK THE LULL LIKELY WINDS UP BEING CORRECT AS FORECAST
SOUNDINGS SHOW A STABLE AIR MASS DUE TO RISING UPPER HEIGHTS AND
US BEING WELL NORTH OF THE STATIONARY FRONT. BUT THERE'S ALSO SOME
CONTINUED WEAK LOW LEVEL ASCENT ALL DAY AS WELL, SO I CAN'T RULE
OUT AT LEAST SOME SPORADIC SHOWERS THROUGH THE DAY LIKE SOME CAM
GUIDANCE SHOWS.
BY LATE TONIGHT, THE ARKANSAS SHORTWAVE WILL HAVE LIFTED NORTHEAST
THROUGH EASTERN KENTUCKY, LEAVING SOUTHWESTERLY FLOW ALOFT JUST TO
OUR WEST, AND A WARM FRONT SITUATED FROM THE PLATEAU AREAS
SOUTHWARD TOWARDS THE ATLANTA METRO IN A PSEUDO CAD SETUP. MORE
ROBUST CONVECTION WILL HAVE CLOSELY FOLLOWED THE SHORTWAVE TRACK,
BUT ADDITIONAL WEAK IMPULSES IN THE SOUTHWEST FLOW ALOFT WILL
LEAD TO CONVECTION AFFECTING THE CWA BETWEEN LATE THIS EVENING
THROUGH THE END OF THE SHORT TERM PERIOD. I DON'T THINK SEVERE
CHANCES ARE MUCH TO WRITE HOME ABOUT AS INSTABILITY AND SHEAR WILL
BE MEAGER AT BEST.
LONG TERM
(TUESDAY THROUGH SUNDAY)
ISSUED AT 320 AM EDT MON MAY 26 2025
KEY MESSAGES:
1. RAIN WILL BE LIFTING NORTH TUESDAY MORNING WITH POTENTIALLY SOME
DRIZZLE LINGERING BEHIND. SCATTERED SHOWERS AND THUNDERSTORMS LATER
IN THE AFTERNOON LINGERING INTO THE EVENING, ESPECIALLY ALONG THE
MAJOR TERRAIN.
2. UNSETTLED PATTERN THROUGH THE REMAINDER OF THE WEEK, WITH
PERIODIC CHANCES FOR SHOWERS OR A THUNDERSTORM.
3. MILD TEMPERATURES TO PERSIST THROUGH THE WEEK AND INTO THE
WEEKEND.
DISCUSSION:
NBM IS LIKELY TOO AGGRESSIVE WITH POPS ON TUESDAY - THOUGH I'M NOT
ENTIRELY CONFIDENT ON HOW THE DAY EVOLVES. MUCH OF THE CAMS AND THE
GLOBAL MODELS DEPICT MORNING RAIN SHOWERS LIFTING OUT OF THE AREA,
POTENTIALLY WITH SOME LINGERING LOW CLOUDS AND DRIZZLE LEFT BEHIND.
THAT SEEMS TO BE HIGH CONFIDENCE. HOW MUCH AIRMASS RECOVERY HAPPENS
AFTERWARDS WILL DETERMINE THE DEGREE TO WHICH THUNDERSTORMS CAN FORM
IN THE AFTERNOON, AND THAT SEEMS TO BE A MAJOR OPEN QUESTION AT THIS
POINT. SHOULD THE ATMOSPHERE BE ABLE TO BUILD INSTABILITY THROUGH
CLEARING SKIES, THEN A MORE ROBUST DEVELOPMENT OF STORMS WILL BE
MORE LIKELY WITH HEAVIER RAINFALL. EC-AIFS SEEMS TO BE SUPPORTIVE OF
THUNDERSTORM POTENTIAL, WITH A BROAD BRUSH OF HEAVIER QPF LATE
TUESDAY.
SIMILAR QUESTIONS IN PLAY FOR WEDNESDAY REGARDING ANY MORNING
SHOWERS VERSUS THE ATMOSPHERE'S ABILITY TO RECOVER. THOUGH IF I TAKE
THE COARSER GFS AND EURO AT FACE VALUE, WEDNESDAY AFTERNOON MAY BE
DRIER THAN CURRENTLY DEPICTED, WITH MORE ISOLATED CHANCES. UNSETTLED
WEATHER SEEMS TO BE THE MODE THIS WEEK THOUGH, WITH PERIODIC CHANCES
FOR RAIN, AND MAYBE A FEW THUNDERSTORMS OWING TO THE ACTIVE BUT
RELATIVELY WEAK AND SOMEWHAT STAGNANT UPPER PATTERN. THURSDAY HAS
LOWER POPS BUT ANY STORM ABLE TO FIRE IN THE AFTERNOON WILL HAVE A
MOIST ATMOSPHERE TO WORK WITH, AND COULD PRODUCE EFFICIENT RAINFALL
AS DEPICTED BY THE GFS'S TALL AND SKINNY CAPE PROFILES & 90TH
PERCENTILE PWATS. BY FRIDAY A COLD FRONT SHOULD BE ON APPROACH,
THOUGH THE GFS IS UNCHARACTERISTICALLY THE SLOW ONE WITH FROPA, SO
SOME TIMING QUESTIONS TO RESOLVE. AS OF NOW FRIDAY LOOKS TO BE THE
MILD DAY OF A MILD WEEK, BEFORE WE RETURN A TAD WARMER OVER THE
WEEKEND.
ONE STATISTICAL THING OF INTEREST IS CHATTANOOGA ONLY NEEDS 1.5
INCHES OF RAINFALL NOW TO BREAK THE MAY MONTHLY RECORD, SOMETHING TO
KEEP IN MIND AS THIS SOGGY MONTH FOR THE CENTRAL AND SOUTHERN
VALLEYS CONTINUES.
AVIATION
(12Z TAFS)
ISSUED AT 726 AM EDT MON MAY 26 2025
MODEL SOUNDINGS AND OBSERVATIONS SHOW THE LOWEST 2500 FT OR SO OF
THE ATMOSPHERE ARE PRETTY SATURATED. AS SUCH, THINK WE'LL BE
DEALING WITH MVFR, OR LOWER, FLIGHT CATEGORIES AT ALL SITES FOR
MUCH OF THE PERIOD. ALSO THINK THERE WILL BE AREAS OF LIGHT SHRA
OR EVEN RADZ MUCH OF THE DAY AS WELL. GUIDANCE SUGGESTS IT WILL BE
MOSTLY FOCUSED UP TOWARDS KTRI. OTHERWISE, ANOTHER ROUND OF
CONVECTION WILL MOVE IN FROM THE SOUTHWEST LATE TONIGHT. NOT
SUPREMELY CONFIDENT IN HOW SOLID A LINE OF SHRA/TSRA THIS WILL BE
SO ONLY WENT WITH A PROB30. TIMING WISE SEEMS CONSISTENT ACROSS
MULTIPLE GUIDANCE SOURCES, WITH THE CONSENSUS BEING IT MOVES
THROUGH BETWEEN ROUGHLY 05Z AND 10Z.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 78 63 75 64 / 60 70 90 80
KNOXVILLE MCGHEE TYSON AIRPORT, TN 73 62 76 63 / 40 70 90 80
OAK RIDGE, TN 73 61 73 63 / 30 70 90 80
TRI CITIES AIRPORT, TN 68 57 69 58 / 50 30 90 80
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
SHORT TERM...CD
LONG TERM....WELLINGTON
AVIATION...CD
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