Area Forecast Discussion Issued by NWS Knoxville/Tri Cities, TN
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000
FXUS64 KMRX 141807
AFDMRX
Area Forecast Discussion
National Weather Service Morristown TN
207 PM EDT Thu Mar 14 2024
...New SHORT TERM, LONG TERM...
.SHORT TERM...
-- Changed Discussion --
(This evening through Friday)
Issued at 204 PM EDT Thu Mar 14 2024
Key Messages:
1. Very warm temperatures the rest of this afternoon.
2. A line of showers and thunderstorms will move across the area
tomorrow morning. Bringing strong gusty winds and locally heavy
rainfall as the primary hazards.
Discussion:
Currently mostly clear skies today along with very warm temperatures
as lower dew points, high pressure, and lots of sun combine to drive
up temperatures today. Most locations have crossed above the 70
degree mark today, but still look like they`ll remain several
degrees below the record highs for today.
The weather pattern will change dramatically overnight and into
tomorrow as a strong jet moves through the Ohio Valley,
strengthening low level convergence... This jet will be accompanied
by an incoming frontal boundary to help focus shower and
thunderstorm activity overnight into Friday morning. High
resolution models are still in good agreement on the location of the
strongest storms, but still some timing differences on when the main
line will move into the eastern Tennessee Valley. As of now still
expect the strongest storms to move through the eastern Tennessee
Valley between 6am and noon EDT, with a few lingering storms
possible along the mountains after that. Forecast soundings and CAMs
are still showing a few hundred J/Kg of CAPE with the incoming
storms, but with the current timing, most of the instability is
elevated, hopefully limiting the tornadic threat. With the very warm
atmosphere precipitable water values continue to remain very high,
nearing 1.5 inches, which is well above the 90th percentile for this
time of year.
So the primary threats with the incoming storms on Friday will be
damaging straight line winds and locally heavy downpours leading to
isolated flooding... With areas along the Cumberland Plateau,
southeast TN, and southwest NC being at the highest risk.
The biggest change has been to exit the precipitation a bit faster
than previously forecasted as most guidance is showing a quicker
exit of the system. Temperatures will be cooler, but still warmer
than normal tomorrow behind the departing storms as cloudy weather
lingers the rest of the day.-- End Changed Discussion --
&&
.LONG TERM...
-- Changed Discussion --
(Friday night through next Thursday)
Issued at 204 PM EDT Thu Mar 14 2024
Key Messages:
1. Showers/storms quickly diminish Friday night, with mostly dry
conditions expected the remainder of the extended forecast period.
2. Hard Freeze growing increasingly likely for much of the area
Tuesday morning. This would be accompanied by wind chills in the the
teens for portions of SW Virginia, the Cumberland Plateau, NE
Tennessee Valley, and the E TN mountains.
Discussion:
A cold front will be moving through the forecast area by the start
of the long term period, with showers quickly coming to an end
Friday night. Upper flow will be largely westerly over Kentucky and
Tennessee on Saturday and Sunday, with another weak front moving
through early Sunday. This front looks to be moisture-starved, so
will continue to advertise dry conditions both days. That said, some
models do show some scattered showers south of I-40 on Sunday
afternoon. This seems to be the outlier though. Temps will cool
down, especially Sunday behind the next front, but they`ll continue
to run several degrees above normal.
On Monday, a sharp upper trough swings through the Ohio valley and
southern Appalachians. Could see some light precip in the far
northeast but expect most places to remain dry. The more important
aspect of this will be the cold air moving in behind the trough for
Monday night. Temperatures Monday night likely drop into the 20s
area wide. Additionally, light northwesterly winds will result in
windchill values in the teens for portions of NE TN, SW VA, and the
Cumberland Plateau. Wind chills in higher elevations of the East
Tennessee mountains may fall into the single digits. The cold blast
will be short-lived however. Height rises will lead to a gradual
warming trend through the remainder of the work week.
Could see rain chances return by the Thu/Fri timeframe next week as
a southern stream trough moves through the central Gulf states. NBM
PoPs come back up to the 20-30 percent range by Thu night, which
seems reasonable for now.-- End Changed Discussion --
&&
.AVIATION...
(18Z TAFS)
Issued at 1259 PM EDT Thu Mar 14 2024
Mostly clear skies with occasional wind gusts expected the rest
of the daytime hours today. Late tonight and into tomorrow morning
a line of showers and thunderstorms will quickly blast through
the region. Have put in PROB30 during the most likely time period
of heaviest showers/storms, but will hold off on the details until
later TAF issuances. Expect lower ceilings to remain in place
tomorrow after the initial round of storms.
&&
.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Chattanooga Airport, TN 60 71 55 71 / 50 80 60 0
Knoxville McGhee Tyson Airport, TN 59 69 51 67 / 50 70 30 0
Oak Ridge, TN 59 68 50 69 / 60 70 30 0
Tri Cities Airport, TN 53 67 47 64 / 40 80 50 10-- End Changed Discussion --
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...
LONG TERM....CD
AVIATION...