Clevelnd, Tennessee Weather Forecast Discussion

653
FXUS64 KMRX 271753
AFDMRX
Area Forecast Discussion
National Weather Service Morristown TN
153 PM EDT Sat Sep 27 2025
...New DISCUSSION, AVIATION...
.KEY MESSAGES...
Updated at 149 PM EDT Sat Sep 27 2025
- Storms with gusty winds, small hail, and flooding are possible
  through the rest of the afternoon.
- Dense fog expected in many areas tonight, mainly where rain falls
this afternoon.
- Uncertainty remains high for next week regarding any kind of
impacts from a tropical system approaching the SC coast next week.
Trends do seem to be moving in a direction that would favor less
impacts locally, but uncertainty is still high.
&&
.DISCUSSION...
Issued at 149 PM EDT Sat Sep 27 2025
Convection today has been much more numerous and intense than
expected. The upper trough has likely provided fairly steep midlevel
lapse rates and a low WBZ height that has allowed for small hail to
form in some of the stronger storms. A S-N jet streak over the
Appalachians has likely enhanced mesoscale forcing as well. Through
the afternoon and evening, these storms will continue to be
monitored for hail and gusty winds. The slow movement of cells could
lead to isolated flooding and ponding on roads.
Conditions appear favorable for fog development tonight, with clouds
expected to clear out as the upper trough shifts east of the
mountains. Surface winds should be calm as a high pressure ridge
extends from the lower OH Valley across KY. Low level moisture from
today`s storms will be present as well, so dense fog is possible
everywhere, with the greatest risk area being the northern and
central TN Valley and SW VA where showers today have been most
numerous.
With the focus on the ongoing activity and overnight fog, no changes
have been made to the NBM in the forecast from Sunday onward. Below
is the previous discussion, as not much has changed.
Sunday onward the forecast becomes highly uncertain as the pattern
gets very complicated. A Mississippi valley ridge builds northeast
into the Ohio valley Sunday into Monday, which results in a sort of
rex block pattern by Monday as a tropical system, currently being
monitored in the Caribbean, approaches the SC coastline. Some
lingering energy from the departing southern Appalachian upper low
also gets pulled westward into the mix as well. All of that to say
that the forecast remains highly uncertain beyond Sunday as models
continue to show a decent spread of solutions with the upper pattern
and that approaching tropical system. As such, I mostly let the
forecast follow the NBM guidance for next week. It is worth noting
that there has been a significant shift in the guidance today in
favoring keeping this system along the coastline or even shifting it
east away from the coast instead of bringing it inland like they
were yesterday. Time will tell, but the trends seem to be moving in
the right direction.
&&
.AVIATION...
(18Z TAFS)
Issued at 149 PM EDT Sat Sep 27 2025
Fog appears likely tonight at TYS and TRI where rain this
afternoon has cooled the boundary layer and raised low level
moisture. With clear and calm conditions, visibilities are
expected to drop to at least LIFR overnight at both sites. With
the lowering sun angle, the fog may persist for a few hours after
sunrise tomorrow. Confidence in fog at CHA is lower as showers
have not occurred there yet, but that could still happen. Later
TAF issuances may need to add fog if a shower does occur there.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             63  85  64  85 /  20   0   0  10
Knoxville McGhee Tyson Airport, TN  63  83  62  83 /  20   0   0  10
Oak Ridge, TN                       61  82  62  83 /  20   0   0  10
Tri Cities Airport, TN              60  81  58  79 /  30  10  10  20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
DISCUSSION...DGS
AVIATION...DGS

NWS MRX Office Area Forecast Discussion