105
FXUS64 KMRX 200532
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
132 AM EDT Fri Sep 20 2024

...New AVIATION...

.UPDATE...
Issued at 838 PM EDT Thu Sep 19 2024

An update will be issued to extend the chance of showers in NE TN.
HRRR shows these showers persisting until around 02Z. Will have
slight chance PoPs going a little past that time, until around
midnight, as models have been underdone with convection today. Fog
is a good bet later tonight, mainly in northern sections and near
rivers and lakes, and may be dense in some areas. We will see how
this evolves before issuing any products.

&&

.SHORT TERM...
(This evening through Friday)
Issued at 314 PM EDT Thu Sep 19 2024

Key Messages:

1. A few isolated to scattered showers, and possibly a storm,
through early evening.

2. Patchy to areas of fog overnight.

3.  Dry and warmer tomorrow, with temperatures around 5 to 8 degrees
above normal.

Short term models did a poor job earlier today with the current
showers across the area. Models kept precip east of I-75 and mainly
across our higher terrain areas. Based on latest radar trends and
CU field, went ahead and put in a 15 (Slight Chance) POP for most
areas through early evening. Most locations will remain dry, but
some may cash in on a quick downpour.

Tonight, dry with patchy to areas of fog developing after midnight.
This will be especially true for any areas that receive a shower
this afternoon and evening.

Tomorrow, expect a dry day with warmer temperatures as the ridge
further builds across the area. Temperatures will be around 5 to 8
degrees above normal. Went a little lower with dewpoints tomorrow
based on today`s trends. Went with NBM10. Based on the higher temps,
we can expect min RH values down in the mid to upper 30s for some
areas. Winds remain light though which will help to alleviate most
fire weather concerns.

&&

.LONG TERM...
(Friday night through next Thursday)
Issued at 314 PM EDT Thu Sep 19 2024

Key Messages:

1. Continued well above normal temperatures (5 to 10F) through the
middle of next week.

2. Higher uncertainty for next week, but expect moderating
temperatures with gradual increase in rain chances.

Discussion:

Upper-level 500mb 590-591 dam ridge across the Southern Plains and
Lower Mississippi Valley will result in dry and warm weather into
the Tennessee Valley through the weekend. Northwest flow aloft and
subsidence will bring clear sky conditions and plenty of sunshine.

A stronger shortwave will approach the Ohio Valley by the middle of
next week with an associated surface low and cold front approaching
the Tennessee Valley on Tuesday or Wednesday. Current PoPs are
limited to 30 to 40 percent, and a look at the ensembles histogram
shows that most of these members are placing around 0.25 inch or
less across the region. Only about 15 percent of members have more
than one inch of QPF, and with the westerly zonal flow ahead of the
front, a drier solution appears more probable. If the cold front can
make it through the area, some cooler, near normal, air would be
likely late next week.

&&

.AVIATION...
(06Z TAFS)
Issued at 104 AM EDT Fri Sep 20 2024

Fog development tonight is the main concern, and while the details
are uncertain there is a very high probability of significant fog
development at TRI in the next few hours. Will continue to
include dense fog there with 1/4SM vsby toward sunrise.
Confidence lower at TYS, but will continue to include MVFR vsby in
fog there. Other than the late night/early morning fog at TRI and
TYS, will have a VFR forecast for the period all sites.



&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             92  65  94  68 /   0   0   0   0
Knoxville McGhee Tyson Airport, TN  89  63  91  65 /  10   0   0   0
Oak Ridge, TN                       89  63  90  64 /  10   0   0   0
Tri Cities Airport, TN              84  60  85  60 /  10  10  10  10

&&

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

$$

SHORT TERM...DGS
LONG TERM....JB
AVIATION...