316
FXUS64 KMRX 191805 AAC
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
205 PM EDT Fri Jul 19 2024

...New AVIATION...

.UPDATE...
Issued at 1021 AM EDT Fri Jul 19 2024

Regional radar mosaic imagery shows an area of showers moving
northeast through the northern parts of Alabama and into portions
of middle Tennessee. This is associated with a weak disturbance
ejecting from Louisiana last night. CAM guidance is handling the
areal extent of these returns ok, but they`re too slow/too far
south with them. Additionally, current placement and expected path
suggests we`re too low with PoPs outside of the mountains for
today. As such, have sped up the rain chances through this
afternoon and evening and increased the PoPs in the western half
of our CWA through the plateau areas. Not expecting a deluge, nor
wall to wall coverage of convection today, but there is enough
support to expect at least scattered convection across the entire
CWA by late this afternoon.

Otherwise, no significant changes made to the going forecast.
Forecast highs, dewpoints, etc, all seem to be in good shape at
the moment.

&&

.SHORT TERM...
(Today and tonight)
Issued at 224 AM EDT Fri Jul 19 2024

Key Messages:

1. Showers and thunderstorms are likely in the mountains and SW NC
this afternoon, with isolated to scattered coverage elsewhere.

Discussion:

A front has pushed south and east of the area, located across
northern AL, northern GA, and western NC. Today, a shortwave
trough will move across the MS Valley, which will induce the front
to push back to the north. Convective activity associated with
this front will affect our mountains and SW NC this afternoon,
with a gradual northward spread through the late afternoon and
evening. Slow storm motion and deep moisture may present some
localized flooding issues, mainly in SW NC and the mountains where
storms will be most numerous. With the trough remaining to our
west and the front nearby, low to slight chance PoPs will continue
overnight. CLoud cover today in the moist air mass will limit
temperatures to the lower to mid 80s in most spots.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 224 AM EDT Fri Jul 19 2024

Key Messages:

1. An unsettled weather pattern continues through the long term with
daily chances for showers and thunderstorms.

2. Slightly below normal temperatures expected through the extended
forecast.

Discussion:

In the upper levels by Saturday morning, ridging lies across the
western states and a deep upper low lies over southeast Canada with
a trough over the upper Mississippi Valley, Great Lakes, Ohio Valley
and extending into the Tennessee Valley. To the southeast upper
level ridging will be off the southeast coast. This pattern will be
around for the weekend with the troughing in the east becoming more
pronounced as ridging strengthens off the southeast coast.

The front that moved through Thursday is forecast to move back north
Saturday with increasing moisture and a chance for showers and
thunderstorms. Southerly to southwesterly flow around the southeast
coast surface high pressure combined with some daytime heating and
weak impulses moving through the upper trough will help to initiate
widespread showers and thunderstorms during the afternoon and early
evenings. Significant rainfall amounts will be possible especially
in the eastern mountains Sunday. For the period Monday through
Thursday a new frontal boundary will be to the northwest of the
forecast area and this should help to enhance moisture and lift with
a south to southwest low level flow continuing. After Sunday more
significant rainfall is possible Wednesday and Thursday. Rainfall
amounts forecast for the 5 day period Saturday through Thursday
range from 1.5 to 3.0 inches across much of the area. The higher
east Tennessee mountains and southwest North Carolina could get 2.5
to 4.5 inches. As stated in the earlier discussion this might be a
drought busting pattern. Cloud cover will also be extensive and with
high rain chances highs will be lower this period, mostly lower to
mid 80s lower elevations and 70s higher elevations which is around 5
degrees below normal for late July.

&&

.AVIATION...
(18Z TAFS)
Issued at 154 PM EDT Fri Jul 19 2024

Main concern for the 18z TAF period is chances for SHRA/TSRA.
Think KCHA and KTYS have the highest likelihood, so will carry
TEMPO groups there. Unsure whether northward moving wave of
convection will affect KTRI, so will stick with VCSH there.
Another round of convection is expected before daybreak tomorrow,
but uncertainty in coverage and timing precludes going with
anything more than a PROB30 group for now. Fog does not seem like
an issue tonight but MVFR CIGS could develop after 08z.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             85  69  86  71 /  70  50  70  60
Knoxville McGhee Tyson Airport, TN  86  69  85  70 /  40  40  70  60
Oak Ridge, TN                       87  68  84  69 /  30  40  70  50
Tri Cities Airport, TN              86  67  81  66 /  30  50  80  40

&&

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

$$

SHORT TERM...CD
LONG TERM....TD
AVIATION...CD