443
FXUS64 KMRX 181841
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
241 PM EDT Fri Apr 18 2025

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(This evening through Saturday)
Issued at 240 PM EDT Fri Apr 18 2025

Key Message:

1. Unseasonably warm temperatures are expected with breezy
southwesterly winds during the day.

This Evening/Tonight

Currently this afternoon, a broad ridge is centered across the
eastern U.S. with troughing and the upper jet well to our northwest.
At the surface, a weak low is moving into the Great Lakes region
with Bermuda High Pressure in the Atlantic. This pattern has
resulted in continued warming and broad southwesterly winds.
Efficient mixing will continue elevated fire weather concerns into
the early evening before sunset. Otherwise, warm and dry conditions
will continue overnight with breezy winds remaining over the higher
elevations.

Saturday

On Saturday, troughing to the northwest will slowly advance
eastward. Locally, the 500mb ridge will increase to an impressive
5,920m with heights over our area reaching to 5,880m. These values
are typical in June or July, which underscores the extent of heating
expected. This will also be combined with continued southwesterly
flow and Bermuda High Pressure to our east. The day will be breezy
but likely not as dry as today. Record high temperatures for the day
are 90 or higher, and we may not reach quite that high.

&&

.LONG TERM...
(Saturday night through next Friday)
Issued at 240 PM EDT Fri Apr 18 2025

Key Messages:

1. Dry and very warm this weekend. Near record high temperatures.

2. Weakening front brings showers/storms Monday into Monday night.
Overall severe risk is low because of limited instability.

3. It will remain warm for the remainder of the period, with a
shower or storm possible at times as the stationary front remains
near the area and lifts back north.


Discussion:

An anomalously strong 500mb ridge with 591-593 dam heights will
result in warm conditions across the Southeast CONUS this weekend
with temperatures 10 to 15 degrees above normal across our forecast
area. Afternoon highs will be near records, especially on Sunday.

Daily Record High Maximum Temperatures

Date    Chattanooga    Knoxville      Tri-Cities     Oak Ridge
04-19   91(2002)       90(1941)       90(1941)       90(2002)
04-20   89(2002)       87(2002)       85(2023)       88(2002)


A strong upper-level shortwave will flatten the upper-level ridge
across the region and bring a cold front west to east across the
Tennessee Valley and Southern Appalachians on Monday. With limited
height falls, mid-level lapse rates are weak resulting in limited
instability. This will mitigate much of a severe weather risk;
however, any thunderstorms that do occur may produce gusty winds
with gradient winds around 5k ft AGL of around 40 kt.

This front will struggle to clear the area Monday night and Tuesday,
and will likely stall near the southern parts of the forecast area.
This should result in drier conditions on Tuesday across most of the
area, especially northern counties near Kentucky and into Virginia.
By Tuesday night, this front will start to drift back north as a
warm front and southwesterly flow begins to increase once again
ahead of a shortwave across the Southern Plains.

We will become warm sectored once again by late next week. With less
influence from ridging expected across the area, instability appears
to be more favorable for diurnal convective development, especially
across the higher elevations each afternoon or any subtle
MCV/shortwave features that may locally enhance convective coverage.

&&

.AVIATION...
(18Z TAFS)
Issued at 109 PM EDT Fri Apr 18 2025

Breezy winds and limited high clouds will continue for the rest of
the day. Gusts to near 30 kts are possible, especially at TYS.
Tonight, winds at the surface will decrease with LLWS developing
at CHA and TYS. Currently, the LLWS looks stronger at TYS so was
increased to 40 kts. Otherwise, mostly clear conditions
southwesterly winds will return again into tomorrow.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             60  88  63  86 /   0   0   0   0
Knoxville McGhee Tyson Airport, TN  62  86  62  86 /   0   0   0  10
Oak Ridge, TN                       60  85  61  86 /   0   0   0  10
Tri Cities Airport, TN              55  83  58  84 /   0   0   0  10

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&

$$

SHORT TERM...BW
LONG TERM....JB
AVIATION...BW