Area Forecast Discussion Issued by NWS Knoxville/Tri Cities, TN
000
FXUS64 KMRX 130256 AAB
AFDMRX
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
1056 PM EDT Fri Apr 12 2024
...New UPDATE...
.UPDATE...
Issued at 1047 PM EDT Fri Apr 12 2024
Mainly updated trends in precip chances for the overnight hours
for the late evening update. Still have several showers to the
northeast of the Morristown area this hour. Between the steep
lapse rates aloft and what meager instability there is, these
showers continue to produce some stray lightning strikes and
plenty of small hail. Expect these to be east of the area in the
next few hours, with dry conditions expected thereafter across the
CWA. No changes to forecast lows for the time being. Winds look to
remain elevated overnight, so forecast values in the 40s seem
reasonable. That said, there will almost certainly be some places
where the winds die off and in those cases, lows in the 30s would
be possible. Hard to say exactly where that would be, hence no
effort to make substantive changes to the lows...but some of the
higher resolution guidance does show pockets of upper 30s here and
there and that seems very plausible.
&&
.SHORT TERM...
(This evening through Saturday)
Issued at 320 PM EDT Fri Apr 12 2024
Key Messages:
1. Numerous showers and a few thunderstorms this afternoon and
early evening with small hail to about 0.50 inch already reported.
Strong winds this afternoon with gusts up to 35 mph most
locations and above 40 mph higher elevations.
2. Tonight clearing skies with winds only slowly diminishing.
3. Sunny and much warmer Saturday with still breezy west winds.
Discussion:
Deep trough lies over the Eastern U.S. this afternoon. A shortwave
is moving through the region now, bringing mostly cloudy to cloudy
skies for all but the extreme south. Some thunderstorms have
brought small hail across the northern half of east Tennessee and
southwest Virginia. Gusty west to northwest winds up to 35 to 40
mph have been recorded area wide. Temperatures have been in the
mid 60s at Chattanooga but mostly 50s elsewhere and in some places
with the showers 40s and also higher elevations. Dew points are in
the 30s to the lower 40s. The strong winds should decrease after
00Z tonight in the valley but should stay elevated most of the
night in the mountains where the pressure gradient stays tighter.
As the moisture moves out and upper trough shifts east tonight
expect clearing from southwest to northeast. High pressure will
build in from the southwest overnight and Saturday. Lows tonight
quite cool and in the 40s by morning. Saturday with high pressure
still building in it will still be breezy with wind gusts as high
as 40 mph in the northeast in the morning and with much lower
relative humidities around 30 percent. Highs will be in the 60s to
lower 70s.
&&
.LONG TERM...
(Saturday night through next Friday)
Issued at 320 PM EDT Fri Apr 12 2024
Key Messages:
1. Warming trend begins over the weekend, and warm weather continues
next week.
2. Generally dry conditions expected for the first half of next
week, with rain chances increasing mid to late next week.
Discussion:
At the start of this period, a large high pressure are will be
centered near the Gulf Coast region, with a ridge axis extending
northward to the Great Lakes. This ridge will shift east through
Sunday, resulting in a SW flow pattern that will bring warm
temperatures to the TN Valley region. On Sunday night, models
indicate that a shortwave trough will cross the area, while a
surface cold front will be moving SE across KY. Moisture will be
limited but a few showers may be possible Sunday night and Monday in
northern sections closer to the front, so some slight chance PoPs
will be mentioned in SW VA/NE TN. The front will stall to our north
and begin a northward retreat on Monday night as low pressure
develops over the Plains.
A more unsettled pattern unfolds through the middle and end of next
week. A closed low tracks from the central Plains to the Great
Lakes, with its trailing cold front bringing a chance of showers and
thunderstorms to our area on Wednesday. Instability looks limited
due to weak amplification of the midlevel trough, and good dynamic
forcing passes us to the north. The severe potential appears low,
but we could get some breezy SW gradient winds up the Valley on
Wednesday, with showers that produce locally higher gusts.
A better chance of showers and storms arrives on Thursday night and
Friday as another closed low drops from the northern Plains to the
Great Lakes/OH Valley. This system appears to have been northward
moisture flux from the Gulf and a more sharply amplified trough and
jet streak over the OH Valley, and a strong push of cold air behind
the cold front. Still a long way out but this may be a system to
watch over the next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 741 PM EDT Fri Apr 12 2024
Observations up stream support keeping some MVFR CIGS at KTRI for
a few hours, otherwise VFR conditions are expected at all
terminals through the period. This leaves winds as the main
forecast concern over the next 24 hours. Given the fluctuation in
winds at KTRI the last few hours, believe that all sites should
lose gusts during the overnight hours. Gusts return between
14z-16z tomorrow morning however.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 65 46 75 52 / 0 0 0 0
Knoxville McGhee Tyson Airport, TN 59 44 69 51 / 50 10 0 0
Oak Ridge, TN 60 45 71 49 / 50 0 0 0
Tri Cities Airport, TN 55 42 65 44 / 90 60 0 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...CD
LONG TERM....DGS
AVIATION...CD