-- Discussion containing changed information from previous version are highlighted. --
829
FXUS64 KMRX 201747
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
147 PM EDT Thu Jun 20 2024

...New AVIATION...

.UPDATE...
Issued at 1100 AM EDT Thu Jun 20 2024

A mostly sunny morning across the forecast area today with
temperatures warming up to the upper 70s to lower 80s at late
morning. Dew points are still running in the lower to mid 60s.
Current forecast looks good with warmer temperatures today as
clouds from the tropical system have moved away. Upper ridge is
holding strong over the mid Atlantic and Ohio Valley. Winds should
be light with only scattered clouds. Heat index values should only
reach into the lower to mid 90s, just above actual highs. No zone
forecast update needed.

&&

.SHORT TERM...
(Today and tonight)
Issued at 258 AM EDT Thu Jun 20 2024

Key Messages:

1. Patchy fog early this morning mainly near area waterways.

2. Hot and dry conditions continue with strong ridging in place.

Discussion:

Early this morning, patchy fog has developed mainly near area
waterways. Fog will dissipate soon after sunrise.

Also, thicker ci/cs over far southwest Virginia, northeast
Tennessee, and southwest North Carolina will move out this
morning. Overall, mostly clear sky but do expect scattered cloud
cover development over the orographic areas this afternoon.

NAFES anomalies continues to depict a strong upper ridge across
the mid-Atlantic states into the Tennessee valley and Appalachians.
Dry airmass with model soundings depicting PWs in the bottom
quartile with a subsidence inversion around the 700mb layer.

Surface ridging into the southern Appalachians with weak pressure
gradients will produce light winds.

For tonight, dry airmass remains with mostly clear sky.

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 258 AM EDT Thu Jun 20 2024

Key Messages:

1. Above average temperatures continue with strong ridging in place.

2. Diurnal convection probabilities increasing Sunday into early
next week.

Discussion:

Anomalously strong ridging continues across the Eastern CONUS Friday
through the weekend with 500mb heights of 594 to 596 dam across the
Tennessee and Ohio Valleys. NAEFS anomalies show this near the max
of climatology. The 850mb ridge also remains across the Ohio Valley
with weak easterly flow resulting in subsidence and limited moisture
transport across the region on Friday and Saturday. This will keep
LFC heights higher with limited probabilities for diurnal convection
on Friday and Saturday.

The upper ridge retrogrades and flattens across the Ohio Valley on
Sunday as a shortwave trough and associated surface frontal features
moves eastward across the Great Lakes and Ohio Valley. The 850mb
ridge shifts east with southerly flow resulting in increasing
moisture beginning Sunday. This increased moisture and lower upper
heights will increase instability with higher probabilities for
diurnal convection into early next week. While timing of
thunderstorms outside of diurnal convective trends is still
uncertain, northwesterly upper level flow and the general synoptic
pattern will bear watching with potential MCS/MCV thunderstorm
complexes riding the periphery of the ridge.

&&

.AVIATION...
-- Changed Discussion --
(18Z TAFS)
Issued at 140 PM EDT Thu Jun 20 2024

Upper and surface ridging persists across east Tennessee
producing VFR conditions at all TAF sites through early tonight.
Some MVFR fog is expected to form near TRI for a few hours Friday
morning so included a 3 hour group at 5SM from 09-12Z Friday.
Surface ridge along with a weak pressure gradient will keep winds
light.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             93  72  95  73 /   0   0   0   0
Knoxville McGhee Tyson Airport, TN  91  70  93  72 /   0   0  10   0
Oak Ridge, TN                       91  70  93  72 /   0   0  10   0
Tri Cities Airport, TN              90  64  92  68 /   0   0  10   0

&&

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

$$

SHORT TERM...TD
LONG TERM....JB
AVIATION...TD