914
FXUS64 KMRX 161434
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
1034 AM EDT Thu May 16 2024

...New UPDATE...

.UPDATE...
Issued at 1027 AM EDT Thu May 16 2024

No forecast updates this morning other than to tweak hourly temps
based off latest obs. Morning clouds continue to slowly clear
with mostly sunny skies by this afternoon. Still looks like a few
isolated to scattered showers, possibly a thunderstorm, will
develop this afternoon across northeast TN and southwest VA but
most locations should be dry. Will send new zones to get rid of
morning fog wording.

&&

.SHORT TERM...
(Today and tonight)
Issued at 300 AM EDT Thu May 16 2024

Key Messages:

1. Warming trend today with mostly dry conditions across the
forecast area, save some isolated showers in our Virginia counties
and the Tri Cities area of Tennessee.

2. Dry overnight, but showers will be quickly approaching the
southern areas towards the end of the period.

Discussion:

The gist of the short term...An upper trough/low will continue to
pull away to the northeast today, moving off the mid-Atlantic and
New England coast by shortly after daybreak. Upper ridging will
build in across the region today in the wake of this feature,
leading to mostly dry conditions across the CWA along with warming
temperatures. The only caveat would be the potential for a handful
of showers over the far northeast parts of the CWA this afternoon.
Otherwise, dry conditions last late into the night before rain
chances increase as we head into the long term period with the next
system approaching.

Going into a bit more detail...Satellite imagery shows plenty of low
clouds across the CWA, especially in the northern parts covering VA
and far northeast TN. As mentioned above, I expect mostly dry
conditions across most all of the forecast area today. However,
model soundings do show some weak instability below 700 mb today. If
warming is as forecast, then LFC and LCL heights will be equal and
there`s enough low level moisture and surface-based instability
to support some shallow showers and perhaps even a rumble of
thunder in the northeast. Model guidance supports this thinking.
Did limit PoPs to slight chance values however, and went with a
blend to get the areal coverage where I wanted it, which was
basically along/east of a line from Wise to Unicoi counties. The
cloud layer in place seems to be somewhat thin vertically, and
there are plenty of breaks per satellite imagery early this
morning, so it seems reasonable to expect the mixing/warming
forecast by guidance and subsequent shower possibilities.

Otherwise, upper heights build in by mid to late afternoon and shut
off whatever shower activity there is rather quickly late this
afternoon. Tonight could see some dense fog potential depending on
how quickly high clouds increase ahead of the system moving in
tomorrow. Have some patchy fog in the forecast, but if the high
clouds remain thin enough, light winds and a moisture rich surface
layer will promote fairly widespread fog development. Time will tell
in that regard. Kept the forecast dry overnight, but showers will be
quickly approaching by daybreak or shortly thereafter into the long
term period.

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 300 AM EDT Thu May 16 2024

.LONG TERM...
(Friday through Wednesday)

 Key Messages:

1. Wet pattern setting up for Friday through Saturday.

2. Drier and warmer Monday and Tuesday.

3. Cold front and storms move into the area around next Wednesday.

A disorganized but wet pattern will be setting up for Friday and
Saturday.  On Friday an upper level low pressure center will be
located to our west in the Southern Plains.  It looks like a weak
upper shortwave, connected to this low, will move through the area
from southwest to northeast spreading rains into the area.  There
may be a lull behind this shortwave in the southern parts of the
area Friday for at least part of the afternoon.  Then in the late
afternoon, but especially in the evening a 50 knot low level jet is
expected to surge into the area bringing elevated instability into
the area overnight. As the overall pattern shifts east, this jet
will slide east of the area, probably before Noon on Saturday.  So
it looks like the best chances for stronger storms will be Friday
night. The SPC Marginal Risk fits this pretty well, with low-end
severe wind and hail threats.  It looks like the heaviest rain rates
will likely be during the Friday night early Saturday morning
timeframe as well.

For Saturday, the main axis of deep moisture moves into the area
from the west, but instability and especially shear look very
unimpressive.  So for Saturday, there may be widespread rains, but
the rain rates will not be as intense as Friday night`s.

For Saturday night through Sunday, we will be slowly getting rid of
the upper low and associated spokes of lift that are swirling around
it.  Left some thunder in for Saturday evening, then just rain
showers afterwards.  Western and southern parts of the forecast area
will be farther away from all this disturbed weather on Sunday and
may start the more favorable trend that the whole forecast area will
see by Monday.

Monday and Tuesday look dry as an upper ridge builds into the area.
Afternoon Max Temperatures should warm up as well.  By Tuesday night
and certainly by Wednesday the next weather system will be
approaching from the west.  This system looks a lot more organized,
with a stronger cold front moving into the area around Wednesday.

&&

.AVIATION...
(12Z TAFS)
Issued at 725 AM EDT Thu May 16 2024

Gradual improvement to VFR levels is expected at all terminals by
mid to late morning, persisting through late tonight at all sites
except KTRI. Expect another round of fog and low clouds to
redevelop at KTRI after midnight tonight. Elsewhere, increasing
high and mid clouds should keep the fog and low clouds at bay. Did
not include any SHRA in the 12z TAF package, but SHRA and possibly
some TSRA will be knocking on the doorstep of KCHA around or
shortly after 12z.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             85  64  75  66 /   0  10  80  80
Knoxville McGhee Tyson Airport, TN  80  61  75  64 /   0  10  80  90
Oak Ridge, TN                       81  61  75  63 /   0  10  80  90
Tri Cities Airport, TN              76  56  77  61 /  20  10  70  80

&&

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

$$

SHORT TERM...CD
LONG TERM....GM
AVIATION...CD