795
FXUS64 KMRX 271749
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
149 PM EDT THU AUG 27 2026
..NEW DISCUSSION, AVIATION
KEY MESSAGES
UPDATED AT 142 PM EDT THU AUG 27 2026
- SCATTERED STORMS EXPECTED THIS AFTERNOON AND EVENING, WITH THE
POSSIBILITY OF A SEVERE STORM OR TWO. ISOLATED TO SCATTERED
STORMS EXPECTED ON FRIDAY TOO, WITH LESS COVERAGE OVERALL AND
LITTLE TO NO THREAT OF SEVERE STORMS.
- MOST LOCATIONS WILL BE DRY FOR THE WEEKEND WITH RETURN OF HOT
AND HUMID CONDITIONS EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 142 PM EDT THU AUG 27 2026
SYNOPTIC SCALE TROUGHING FROM THE HUDSON BAY AREA SOUTHWARD THROUGH
THE EASTERN CONUS, ALONG WITH UPPER RIDGING FROM THE FOUR CORNERS
REGION THROUGH THE NORTHERN ROCKIES, WILL CONTINUE THROUGH FRIDAY. A
PATTERN CHANGE TO A WARMER AND DRIER REGIME BEGINS OVER THE WEEKEND,
BUT BEFORE THAT HAPPENS WE'LL HAVE SOME SCATTERED STORMS TO DEAL
WITH THIS AFTERNOON. MORE ON THAT BELOW. BY SATURDAY MORNING THE
UPPER TROUGH BEGINS TO PULL AWAY TO THE NORTHEAST AND THE WESTERN
RIDGE STARTS ITS EASTWARD TREK TOWARDS THE SOUTHERN APPALACHIAN
REGION. THE RIDGE SHOULD BE CENTERED OVER TENNESSEE BY MONDAY
AFTERNOON, WHERE IT WILL REMAIN THROUGH THE END OF THE PERIOD, AND
LEAD TO INCREASINGLY WARM CONDITIONS ACROSS THE NWS MORRISTOWN
FORECAST AREA.
GOING INTO A BIT MORE DETAIL, THIS AFTERNOON WE STILL HAVE CYCLONIC
FLOW ALOFT, WITH A SHORTWAVE SLATED TO MOVE THROUGH THIS AFTERNOON
AND INTO THE EVENING HOURS. THIS WILL PUSH A WEAK FRONT OUR
DIRECTION, WHICH, WHEN COUPLED WITH SLIGHT HEIGHT FALLS ALOFT AND
SUFFICIENT MOISTURE AND INSTABILITY IN PLACE, SHOULD LEAD TO THE
DEVELOPMENT OF SCATTERED THUNDERSTORMS LATER TODAY. EXPECT
INITIATION OVER THE APPALACHIANS AND THE HIGHER TERRAIN OF THE
PLATEAU AREAS, BUT CONVECTION WILL EVENTUALLY SPREAD INTO THE VALLEY
AS TIME PROGRESSES, ESPECIALLY LATER ON AS THE FRONT DRAWS NEAR AND
FORCES THINGS EASTWARD. THE SPC DAY 1 CONVECTIVE OUTLOOK HAS BEEN
ADJUSTED TODAY TO EXPAND THE MARGINAL RISK AREA SOUTHWARD TO
ENCOMPASS MUCH OF OUR CWA. THIS SEEMS REASONABLE TO ME. THE NORMALLY
BULLISH NAM (WITH REGARD TO MOISTURE AND INSTABILITY) IS ACTUALLY
HANDLING CURRENT SURFACE CONDITIONS WELL I THINK, AND IT SHOWS
MLCAPE VALUES RANGING FROM NEAR 2,000 J/KG IN THE SOUTH TO AROUND
3,000 J/KG IN THE CENTRAL AND NORTHERN VALLEY LATE THIS AFTERNOON
AND EARLY EVENING, WITH OVER 7 C/KM LAPSE RATES ALOFT AS WELL. DCAPE
VALUES ARE IN THE 1,000 - 1,200 J/KG RANGE. IN THIS ENVIRONMENT, I
WOULDN'T BE SURPRISED TO SEE SOME STRONG TO SEVERE STORMS CAPABLE OF
SOME +60 MPH WINDS DEVELOP. COVERAGE WILL BE THE LIMITING FACTOR IN
OUR SEVERE CHANCES. NO GUIDANCE SOURCE IS OVERLY ENTHUSIASTIC WITH
REGARDS TO STORM COVERAGE THIS AFTERNOON, SO THE THREAT OF SEVERE
STORMS SHOULD BE ISOLATED IN NATURE. FOR FRIDAY, EXPECT LESS
AFTERNOON SHOWER AND THUNDERSTORM COVERAGE THAN TODAY. INSTABILITY
WILL ALSO BE LESS, SO THE THREAT OF ANY STRONG TO SEVERE STORMS SEEM
VERY LOW.
LOOKING AHEAD TO NEXT WEEK, THE UPPER RIDGE CENTERED OVER MIDDLE AND
EAST TENNESSEE WILL MEAN DRY CONDITIONS AND A NOTABLE WARMING TREND.
IT DOESN'T APPEAR THAT WE WILL APPROACH ANY RECORD HIGHS, BUT IT
WILL BE WARM, AND HEAT INDEX VALUES COULD CLIMB TO AROUND OR EVEN
SLIGHTLY OVER 100 DEGREES AT TIMES. FOR THOSE WHO CARE ABOUT SUCH
THINGS, AUGUST 24TH WAS THE DAY THAT AVERAGE HIGHS START THEIR
DECLINE FOR THE YEAR, AND OCTOBER 9TH IS THE LAST DAY WHERE RECORD
HIGHS IN KNOXVILLE REACH THE 90 DEGREE MARK. DON'T LOSE HOPE, FALL
IS ON THE WAY. I MEAN, FOR THOSE WHO CARE ABOUT SUCH THINGS.
AVIATION
(18Z TAFS)
ISSUED AT 142 PM EDT THU AUG 27 2026
SCATTERED SHRA/TSRA ARE EXPECTED THIS AFTERNOON AND EVENING
ACROSS THE TN VALLEY, BUT CONFIDENCE IN WHETHER THEY AFFECT ANY
TERMINALS IS NOT HIGH ENOUGH TO GO BEYOND A PROB30 GROUP. DEVELOPMENT
WILL BE DRIVEN LARGELY BY TERRAIN AND/OR OUTFLOW BOUNDARY
INTERACTIONS. THAT SAID, WOULD EXPECT THAT KTYS AND KTRI WILL HAVE
THE BEST CHANCES RELATIVELY SPEAKING. CONVECTION SHOULD DIE DOWN
BY 02-03Z OR SO, WITH DRY CONDITIONS OVERNIGHT. GUIDANCE IS FAIRLY
INSISTENT ON FOG DEVELOPMENT IN THE TN VALLEY TONIGHT. INTRODUCED
SOME 5SM AT KTRI, BUT I DIDN'T HAVE CONFIDENCE TO GO WITH LOWER
VSBY JUST YET, NOR TO INCLUDE IT ELSEWHERE.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 70 92 69 93 / 30 20 10 10
KNOXVILLE MCGHEE TYSON AIRPORT, TN 69 89 67 91 / 50 20 10 10
OAK RIDGE, TN 68 88 67 90 / 40 30 10 0
TRI CITIES AIRPORT, TN 65 86 64 87 / 30 20 10 10
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
DISCUSSION...CD
AVIATION...CD
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