871
FXUS64 KMRX 160549 AAC
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
149 AM EDT Mon Sep 16 2024

...New AVIATION...

.UPDATE...
Issued at 1025 PM EDT Sun Sep 15 2024

No significant changes to the forecast. A pretty quiet evening is
expected under mostly clear skies, though enhanced moisture on the
northwest side of potential tropical cyclone 8 will lead to clouds
along the northeastern Tennessee mountains. Light winds will help
to inhibit impactful fog development once again.

&&

.SHORT TERM...
(This evening through Monday)
Issued at 229 PM EDT Sun Sep 15 2024

Key Message:

Warm and dry outside of a stray shower near the southern TN border.

Discussion:

Currently temperatures have climbed into the 80`s across much of the
eastern Tennessee Valley as we sit under a strong ridge aloft and
generally easterly flow near the surface. A few stray showers have
developed in this flow, but with how dry it is near the surface most
of it will fall as virga or drizzle. The downsloping effect has
helped drive temperatures 5+ degrees above seasonal normals, a trend
which should continue into tomorrow. Winds are breezy in some
locations with the more southeast oriented winds, gusting up above
20 miles per hour... Expect these breezy conditions to diminish once
the sun sets leading to another fairly warm overnight with
temperatures staying in the 60`s or upper 50`s for most locations.

&&

.LONG TERM...
(Monday night through next Sunday)
Issued at 229 PM EDT Sun Sep 15 2024

Key Messages:

1. Uncertainty remains on how much rain falls as coastal low
pressure system spins slowly across Eastern US this week. Best
chances for rain are in northeastern Tennessee into southwestern
Virginia.

2. Warm temperatures likely to continue through the period.

Discussion:

The biggest thing to watch in the extended is the evolution and
track of the Carolinas offshore low that the National Hurricane
Center has a 50% chance of development for. One thing that does
stand out, at least today, is the GFS is once again a speed outlier.
The model brings the low pressure system to East TN notably faster
than pretty much every other piece of computer guidance, bringing it
to northeast TN and southwest VA by Monday afternoon. So for now,
will opt to discard that solution.

In any case, the upper level pattern is not suitable for forward
motion of the offshore disturbance, with a significant trough out
west forcing higher heights over the Eastern US. The result is our
coastal low is liable to be stuck over the upper Ohio River valley
for the entire week, before finally sliding eastward as a weak upper
trough. Despite this, ensembles are not too excited about our
rainfall prospects this week, with the Euro Ensembles in particular
showing not much hope of decent rainfall over an inch. GEFS is more
favorable for the mountains, but overall QPF will likely be limited
in both amounts and areal extent of the rain. Guidance does not have
any significant other hazards, with winds likely to remain fairly
light through the period and no severe weather expected.

&&

.AVIATION...
(06Z TAFS)
Issued at 140 AM EDT Mon Sep 16 2024

Generally speaking, expect VFR categories to prevail through the
period at most sites. The caveat may be KTRI. Low pressure moving
inland (northwest) from the South Carolina coast will spread
SHRA across the Appalachians and into the northern TN valley this
evening. Guidance is mixed as to whether VSBY or CIGS will drop in
response to these showers encroaching on KTRI late in the period.
Tend to think it would be mainly VSBY reduction given the dry air
in place ahead of it. However, given the uncertainty, decided to
just go with a VCSH and show CIGS lowering into the lower VFR
ranges after 21z.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             86  63  87  61 /  10  10  10  10
Knoxville McGhee Tyson Airport, TN  84  60  81  60 /   0  20  20  10
Oak Ridge, TN                       84  60  81  59 /   0  20  20  10
Tri Cities Airport, TN              79  59  76  60 /  20  50  40  30

&&

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

$$

SHORT TERM...
LONG TERM....Wellington
AVIATION...CD