518
FXUS64 KMRX 011026
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
626 AM EDT Tue Jul 1 2025

...New AVIATION...

.SHORT TERM...
(Today and tonight)
Issued at 1227 AM EDT Tue Jul 1 2025

Key Messages:

1. Showers and thunderstorms expected ahead of a cold front today.
Most areas should receive rain this evening with more widespread
coverage.

2. Heavy rain rates are expected which will result in isolated
flash flooding.

Discussion:

A shortwave trough will amplify the longwave pattern across the
Tennessee and Ohio Valleys. With height falls and an associated
surface front, more widespread convection is expected this
afternoon and evening. At this time, the most probable frontal
passage is around 21z to 03z which will be when the highest
chances of thunderstorms is expected area-wide. RAP forecast PW
values ahead of the front will be in the 2.0 to 2.2 inch range
across the area which will be favorable to heavy rain rates of 3
to 4 inches per hour. This can quickly lead to flash flooding
issues, especially for urban areas with large amounts of
impervious surfaces. There will be enough instability for some
stronger updrafts as MLCAPE approaches 2000 to 2500 J/Kg between
Knoxville and Chattanooga this afternoon. However, the RAP shows
forecast soundings remaining saturated with heights which will
limit thermodynamic damaging wind potential and increase tropical
rain rates. Because of this, the overall severe weather risk is
low, but some isolated gusty winds are possible with the strongest
storms.

Behind the front, drier air begins to arrive tonight into
Wednesday morning. With the front across our southern areas, some
overnight convection may continue to linger across far southeast
Tennessee and southwest North Carolina.

&&

.LONG TERM...
(Wednesday through Tuesday)
Issued at 1227 AM EDT Tue Jul 1 2025

Key Messages:

1. Low chances of thunderstorms Wednesday across far southeast
Tennessee and southwest North Carolina.

2. Dry weather through Independence Day and into the weekend.

3. Moisture begins to increase this weekend with a return of hot,
humid conditions and isolated thunderstorms, mainly across the
mountains. Heat index values will be in the 100-105F range this
weekend near Chattanooga.

Discussion:

The front will begin to become stationary to our south and may
result in some isolated to scattered convection in the vicinity of
our far southeastern counties of southeast Tennessee and southwest
North Carolina on Wednesday. However, most areas remain dry.

With subsidence and northwest flow aloft, Thursday and Friday are
forecast to remain dry with mostly clear and warm conditions. The
only impacts will be the heat beginning to return on Friday as
ridging begins to build in from the west. Those outdoors will need
to practice heat safety and remain hydrated on this hot, sunny
Independence Day.

This weekend, the ridge axis begins to shift over our region with
hot, humid conditions. Isolated convection will be possible across
the mountains and the highest peaks of the plateau, but most
areas remain dry. There`s considerable spread in potential weather
early next week with the potential for a shortwave across the
Great Lakes or a tropical low pressure system to our south. At
this time, there`s no likely impacts for our area. Overall,
precipitation chances will begin to increase as moisture begins to
increase across the region with isolated to scattered diurnal
convection each afternoon.

&&

.AVIATION...
(12Z TAFS)
Issued at 624 AM EDT Tue Jul 1 2025

VFR conditions prevail this morning with some brief MVFR at TRI
early. VCSH prevails this afternoon with highest probability for
TSRA at terminals between 22z and 03z this afternoon and evening.
Behind the thunderstorms and frontal boundary, winds begin to
shift to the W/NW with MVFR cigs expected at TYS and TRI through
12z Wednesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             88  70  90  68 /  70  40  10   0
Knoxville McGhee Tyson Airport, TN  88  70  88  67 /  80  60  10   0
Oak Ridge, TN                       86  69  88  66 /  80  50  10   0
Tri Cities Airport, TN              85  67  85  63 /  80  80  20   0

&&

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

$$

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