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646
FXUS64 KMRX 281326
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
926 AM EDT Fri Jun 28 2024

...New UPDATE...

.UPDATE...
-- Changed Discussion --
Issued at 923 AM EDT Fri Jun 28 2024

The ongoing forecast package is in good shape. Still looking for
the highest chances of showers and storms across the higher
terrain along the Appalachians. Isolated storms possible farther
west into the Valley and Plateau measurable rain chances very low.
The daytime temperatures will be hot (and well above normal)
warming into the 90s for most locations.
-- End Changed Discussion --

&&

.SHORT TERM...
(Today and tonight)
Issued at 315 AM EDT Fri Jun 28 2024

Key Messages:

1. Some mainly isolated showers and thunderstorms around especially
this afternoon.

2. Above normal temperatures.

Discussion:

Some very weak short wave energy moving across the area early this
morning may support a few showers mainly south early this morning,
but heights will be rising today as upper ridging builds. With
heating today we will see additional convection develop with the
best coverage expected to be over the eastern mountain terrain. Will
carry chance PoPs in the eastern mountain zones and slight chance
for isolated showers/storms elsewhere today.  Convective energy
looks modest and shear will be weak, so the threat of strong/severe
storms is very low. Some weak convection may linger into tonight
over the eastern mountains but most areas should be dry overnight.

Temperatures will be above normal for the period. Highs today will
generally be in the lower 90s across valley locations.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 315 AM EDT Fri Jun 28 2024

Key Messages:

1. Scattered showers and thunderstorms through the weekend with a
diurnal increase in coverage. Isolated high rainfall totals possible.

2. Drier next week with ridge building across the region. Signals
for hot weather returning.

Discussion:

A strong shortwave trough will shove the upper ridge that`s been
pestering us to the south over the weekend. Accompanying the trough
is a rather decent front that won`t bring its lovely temperatures
this far south but it will help force showers and thunderstorms.
High resolution guidance looks very hit and miss on Saturday, with
more popcorn convection yielding standard thunderstorm fare in the
form of wet downdrafts. PW values look to pool in the valley ahead
of the front on both Saturday and Sunday, approaching 2.1 inches or
greater. This is pretty moist, and is significant especially on
Sunday when it becomes combined with ensemble probability of 1000
CAPE around 80%. This would be supportive of efficient rain rates
from thunderstorms. Despite the USDA Drought Monitor adding in an
abnormally dry indicator for much of the area, efficient heavy
rainfall can still yield localized issues, especially in urban
areas. Knoxville in particular has been the wet spot this month,
with near average rainfall.

Frontal passage Sunday night into Monday will bring a return to a
drier atmosphere. Monday serves as a transition day, with the dry
post frontal airmass still yielding a summer day, but with low
relative humidities likely stifling any chance for a shower. After
that the upper level ridge that`s been haunting us builds back in,
returning us to our above normal temperatures through the midweek.
By late week, southerly flow returns moisture to our area, and with
the moisture comes the diurnal thunderstorm chances once again.

&&

.AVIATION...
(12Z TAFS)
Issued at 506 AM EDT Fri Jun 28 2024

Will see scattered to sometimes broken clouds around for much of
the period, but any cigs will generally be at VFR levels. The best
chance for MVFR cigs looks to be at CHA early this morning, and
will include a tempo group there for a few hours to include this
possibility. There will be some isolated convection around mainly
during the day, but the probability looks too low to include at
the terminals for now.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             93  75  92  76 /  20  20  50  30
Knoxville McGhee Tyson Airport, TN  92  73  92  75 /  20  10  50  50
Oak Ridge, TN                       92  73  91  74 /  20  10  50  50
Tri Cities Airport, TN              90  70  91  72 /  20  10  60  50

&&

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

$$

SHORT TERM...
AVIATION...