Area Forecast Discussion Issued by NWS Knoxville/Tri Cities, TN
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000
FXUS64 KMRX 291127 AAA
AFDMRX
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
727 AM EDT Fri Mar 29 2024
...New AVIATION...
.SHORT TERM...
(Today and tonight)
Issued at 321 AM EDT Fri Mar 29 2024
Key Messages:
1. Low afternoon humidity coupled with breezy conditions again
today. Mainly in the north though.
Discussion:
About the only forecast concern we have going in the short term
will be another of low afternoon humidity values that will
coincide with some gusty winds. This will be mainly in the
northern third or so of the forecast area.
An upper trough will continue to pull away to the east today, with
surface high pressure building in behind it. While overall
moisture levels will be on the increase, as evident in an upward
trend in forecast PWAT values across the CWA today, the low levels
will still be quite dry. Forecast soundings show PWATs still below
1" over the northern parts of the forecast area this afternoon
especially. Expect to see resulting afternoon RH values drop into
the 25-30 percent range for a majority of the forecast area.
In addition to the dry air, the upper ridge will be positioned to
our west today, leaving us beneath WNW upper level and H85 flow
through the day. While the H85 winds will be decreasing as the
stronger flow pulls away to the east, we will likely still keep
+20kt of H85 winds for much of the area north of the I-40 corridor
today. Coupled with mixing heights extending up to around 8,000
ft, this should promote gusts over 20 mph for that same region.
I wouldn`t be surprised if areas near/north of the VA and TN line
saw some gusts over 30 mph before early afternoon as forecast H85
winds will likely still be in the 30-40kt range during that time
and mixing may very well be deep enough to tap into some of that
by that time. Will likely go with a fire danger statement to
highlight the fire weather concerns with today`s dry and breezy
conditions.
Otherwise, not much going on in the short term as we`ll be dry and
mostly clear.
&&
.LONG TERM...
(Saturday through Thursday)
Issued at 321 AM EDT Fri Mar 29 2024
Key Messages:
1. Much warmer this weekend. Chances of rain mainly across southwest
Virginia Saturday and Sunday.
2. An upper level system will bring unsettled weather and warmer
temperatures for next week, especially thunderstorm potential on
Tuesday.
3. Cooler temperatures behind a cold front Wednesday and Thursday of
next week. Higher elevation rain/snow mix possible.
Discussion:
We start the forecast period with quasizonal flow aloft and a weak
frontal system to the north, that will bring increased chances for
showers for southwest Virginia and possibly just across the border
into Tennessee over the weekend. Otherwise, Easter weekend expected
to be a warm one with temperatures 10+ degrees above normal for the
end of March. Expect highs approaching 80 across the middle and
southern valley Sunday afternoon.
High pressure positioned over the SE paired with southwesterly
return flow, will allow temperatures to remain warm into the first
part of next week, as well as increase the humidity. Dew points will
be nearing 60 degrees Monday and Tuesday.
The system to watch will be beginning on Tuesday, as a cold front is
forecast to cross the area, sending much cooler temperatures in its
wake Wednesday and the rest of the period. A low will develop near
the lee of the Rockies early in the week, before deepening and
moving towards the eastern Great Lakes. Models show this system
deepening further after the front passes our area. This will be one
to monitor as it is subject to change and the SPC yesterday morning
highlighted a part of our forecast area under a 15% chance of severe
weather on Day 6 Tuesday (now considered Day 5). Timing of the
frontal passage will affect just how much severe weather our area
could potentially see.
Following the frontal passage late Tuesday into Wednesday, winds
will shift to the northwest sending a much cooler airmass into the
area. NW flow induced showers may linger into Thursday. There is a
possibility of mixed precip across higher terrain once cold air
settles in. Coldest morning will be Thursday, which could pose a
frost and freeze threat. We end the forecast period with surface
high pressure and ridging aloft moving in from the west, thus dry
weather and rebounding temperatures.
&&
.AVIATION...
-- Changed Discussion --
(12Z TAFS)
Issued at 718 AM EDT Fri Mar 29 2024
Only aviation concern for the 12z TAF package remains the gusty
winds at KTRI today. Expect those to begin around 15z as we see a
fairly quick rise in the mixed layer this morning. Initial gusts
should be in the 18-20kt range, with peak values in the low to mid
20kt range by this afternoon. Elsewhere, believe that winds will
remain below 10kt, with KCHA being light and variable through the
period. Only clouds around will be some increasing cirrus late in
the period.-- End Changed Discussion --
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 71 49 76 53 / 0 0 0 0
Knoxville McGhee Tyson Airport, TN 68 47 74 55 / 0 0 0 10
Oak Ridge, TN 70 45 76 53 / 0 0 0 10
Tri Cities Airport, TN 65 42 71 52 / 0 0 0 20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...Frost Advisory until 9 AM EDT this morning for Cherokee-Clay.
TN...Frost Advisory until 9 AM EDT /8 AM CDT/ this morning for
Anderson-Bledsoe-Bradley-Campbell-Claiborne-East Polk-
Grainger-Hamblen-Hancock-Hawkins-Jefferson-Knox-Loudon-
McMinn-Meigs-Morgan-North Sevier-Northwest Blount-Northwest
Carter-Northwest Cocke-Northwest Greene-Northwest Monroe-
Rhea-Roane-Scott TN-Sullivan-Union-Washington TN-West Polk.
VA...Frost Advisory until 9 AM EDT this morning for Lee-Scott VA-
Washington VA.
&&
$$
SHORT TERM...CD
LONG TERM....KS
AVIATION...CD