Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN

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000
FXUS64 KMRX 291925
AFDMRX

AREA FORECAST DISCUSSION
National Weather Service Morristown TN
325 PM EDT Sun Mar 29 2020

.SHORT TERM (Tonight and Monday)...

A broad mid/upper trough pattern will continue across the eastern
Conus through tonight and shift slightly east on Monday. Behind an
exiting cold front, high pressure over the Ark/LA/Tex region will
build over the TN Valley tonight, relaxing the pressure gradient
that has brought gusty winds today. We will have some scattered high
clouds tonight but temperatures should drop quickly after sunset in
this dry air mass, with lows in the 40s to lower 50s. While highs
tomorrow should be cooler due to the NW flow aloft and some high
cloud cover, highs are expected to remain above normal, in the
mid/upper 60s to lower 70s.

DGS

.LONG TERM (Monday night through Sunday)...

The extended begins with troughing and unsettled weather across the
Tennessee Valley and Southern Appalachians.

Models are in good agreement through midweek. An upper trough will
be located across the Mid-Mississippi Valley on Monday night with an
associated surface low across Mississippi. This low will track
eastward during the day on Tuesday across Alabama and Georgia. The
track of the surface low has shifted significantly south over the
past two days, and that has reduced forecast rainfall amounts for
our area. Any kind of instability near the surface low and warm
sector is forecast to remain far to our south, so do not have
thunder included for Tuesday. As the upper low tracks across the
region on Tuesday afternoon and night, dynamic cooling will lower
the freezing level to around 6000 ft MSL by Tuesday evening and to
3500 ft MSL by Wednesday morning. On April 1, and no this is not an
April fool`s joke, we currently expect to see some light snow in the
mountains, generally at or above 5000 ft MSL elevation.
Accumulations appear very light, generally about a half-inch or
less. Surface Canadian high pressure builds in on Wednesday with
decreasing clouds and drier weather. Temperatures are forecast to be
below normal on Tuesday and Wednesday.

Ridging builds back in on Thursday and Friday with warmer
temperatures. There are still significant model differences on
Friday through the weekend, so have slight chance PoPs for Friday
afternoon and Saturday. The GFS is much quicker than the ECMWF and
Canadian to break down the ridge and bring precipitation back into
the area late Friday through Saturday. The ECMWF maintains the ridge
through Sunday with a weak front bringing a chance of precip. The
Canadian holds onto the ridge through the remainder of the extended
with dry weather. Regardless, do not expect very high PoPs based on
any of these outcomes, and precip totals would likely be light.

JB

&&

.AVIATION...
18Z TAF DISCUSSION.

The main aviation impact through the rest of today will be gusty
winds, which will be primarily from the W-SW at 20-25 kts. The
gusty winds should subside by around 00Z, with sustained winds
overnight in the 5-10 kt range. VFR conditions will continue
through the forecast period.

DGS


&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             52  72  50  55  43 /   0   0  60 100  30
Knoxville McGhee Tyson Airport, TN  50  69  50  53  42 /   0   0  40 100  60
Oak Ridge, TN                       50  69  49  53  42 /   0   0  40 100  50
Tri Cities Airport, TN              45  67  44  52  41 /   0   0  10  90  80

&&

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

$$



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