Corryton, Tennessee Weather Forecast Discussion

519
FXUS64 KMRX 261126
AFDMRX
Area Forecast Discussion
National Weather Service Morristown TN
726 AM EDT Fri Sep 26 2025
...New AVIATION...
.KEY MESSAGES...
Updated at 708 AM EDT Fri Sep 26 2025
- Continued showery and unsettled weather through Saturday, and
perhaps even Sunday in the north, due to proximity of upper low.
- Yes, some guidance does show rain from a tropical system affecting
the region during the first half of next week. However, the forecast
is highly uncertain at this time.
&&
.DISCUSSION...
Issued at 133 AM EDT Fri Sep 26 2025
Discussion
A portion of an approaching upper trough from the northwest will
transition to a closed low over northern Mississippi/Alabama
tomorrow afternoon then meander into the southern Appalachian region
through the weekend. Expect to see plenty of showers across the
forecast area tomorrow and Saturday as a result, with lessening rain
chances Sunday as the upper low shifts a bit to our northeast.
Severe chances are essentially negligible both days, but downdraft
CAPE is forecast to be in excess of 500 J/kg so some of the stronger
showers could produce some gusty winds. Outside of some sort of
training convection, flooding threat looks to be low as well.
For next week, with the anniversary of Helene at hand, and the
tropics waking up, you`re undoubtedly beginning to hear about what
may happen with Humberto and the current disturbance in the
Caribbean that is being monitored for development. There`s support
for the Caribbean disturbance to develop into a tropical system in
the coming days. And some...not all, not even a consensus...but some
guidance brings that system into the Carolina coast and westward to
the Appalachians from there. However I want to address this head on
by saying a couple of things. First...we`re still many days out and
the uncertainty level regarding this system is still quite high.
While some ensemble members do bring it inland towards the
Appalachians, plenty others keep it at sea and even have it
interacting with Humberto which remains well off the coast. And
second...of the guidance that does bring it inland, the forecast
rainfall amounts are not even remotely close to what we saw with
Helene. It is completely understandable the attention that is being
paid to the tropics right now and the concerns that some may have.
But, at least for the time being, there`s too much uncertainty to be
overly concerned.
&&
.AVIATION...
(12Z TAFS)
Issued at 726 AM EDT Fri Sep 26 2025
This morning, fog only materialized at TRI with CHA seeing brief
periods due to rain and TYS seeing FEW just above the surface. TRI
is expected to improve to IFR or MVFR by 13Z or so but will likely
not reach VFR until the early afternoon. Additional showers and
storms are expected this afternoon with the latest data suggesting
the best coverage around CHA and TRI. Temporary reductions to MVFR
can be expected. Activity may linger later in the evening at TRI,
but otherwise the area should stay mostly dry overnight. Fog will
be possible again.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             82  64  81  63 /  40  10  20   0
Knoxville McGhee Tyson Airport, TN  80  64  79  63 /  40  30  50  10
Oak Ridge, TN                       79  63  79  60 /  40  20  40  10
Tri Cities Airport, TN              78  63  76  61 /  50  40  80  20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
DISCUSSION...CD
AVIATION...BW

NWS MRX Office Area Forecast Discussion