538
FXUS64 KMRX 141552
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
1152 AM EDT Sun Jul 14 2024

...New UPDATE...

.UPDATE...
Issued at 1150 AM EDT Sun Jul 14 2024

Forecast is very similar to yesterday with a persistence pattern
across the region. Temperatures are heating up very quickly with
max temperatures in the mid to upper 90s expected with some
locations near Chattanooga making it to 100F. Cu development is
occurring across the higher elevations, and slight risk PoPs exist
for these higher elevation areas. However, with high LFC heights
and minimal instability due to the dry boundary layer airmass,
the risk of widespread or especially intense convection is
unlikely.

JB

&&

.SHORT TERM...
(Today and tonight)
Issued at 204 AM EDT Sun Jul 14 2024

Key Messages:

1. Another hot day, with temps in the mid to upper 90s for most
locations.

2. A few isolated showers and storms expected this afternoon, most
locations dry though.

Discussion.

Overall, another hot and mostly dry day. High temps will be similar
to yesterday, with most areas in the mid to upper 90s. The southern
TN Valley is likely to hit 100 again. A few isolated showers and
storms are expected this afternoon. This is due to weak upper
divergence in place across our area from the 300mb jet. As well as a
weak mid level shortwave rotating across northern AL/MS. The most
favored locations for precip will be the southern Cumberland Plateau
and the east TN mountains. A few isolated showers and storms will be
possible across valley locations as well. Again though, most areas
will remain dry. Lastly, undercutting NBM dewpoints again today and
using NBM10. This means another afternoon with RH values in the
upper 20s to mid 30s, so although hot not very muggy.

&&

.LONG TERM...
(Monday through Saturday)
Issued at 204 AM EDT Sun Jul 14 2024

Key Messages:

1. Dangerous, near record heat is expected Monday and Tuesday with
temperatures near 100 degrees. Heat index values will generally
range from upper 90s to near 105 Monday through Wednesday. Make sure
to practice heat safety.

2. Daily chances of isolated to weakly scattered precipitation
cannot be ruled out Monday and Tuesday, with more widespread chances
returning Wednesday and into the second half of the week.

3. Welcomed relief from the heat expected by Thursday into the
weekend.

Discussion:

Upper level ridging will be present across the western CONUS and
atop the mid-Atlantic to begin the long term period. Troughing
digging into central Canada will lead to quasi-zonal flow locally.
H85 temperatures near 22-24 degrees celsius will translate to
potentially record breaking daily high temperatures at the surface
Monday afternoon, with heat indices in the low 100s across the
southern and central valley. Northern valley locations into
southwest Virgina could see heat indices into the upper 90s to near
100. The surface high pressure controlling weather over the southern
States is also expected to weaken roughly 2-4mb from the weekend,
resulting in additional chances of some diurnally driven showers or
perhaps a few storms.

A closed upper level low develops over eastern Texas Tuesday. A
subtle decrease in H85 temps will also lead to surface MaxTs falling
a few degrees relative to Monday. However, increasing moisture will
promote similar heat indices and it will be important to continue
practicing heat safety. Weak shortwave aloft and associated vort
lobe suggest potential for slightly increased coverage of afternoon
activity comparative to previous days.

A pattern change will begin to take place Wednesday as upper level
height falls occur among an upper trough digging into the Midwest. A
surface boundary sagging into the Ohio valley and towards the TN/KY
state line will promote widespread chances for showers and
thunderstorms that are expected to continue into at least Thursday.
Precipitation chances may linger late week into the weekend as the
surface boundary slows and stalls out but uncertainty remains to
where exactly this axis of forcing will stall out. While muggy
conditions remain possible on Wednesday, more persistent clouds and
expected rainfall will finally lead to relief from the heat by the
latter half of the week.

Daily Record High Maximum Temperatures

Date    Chattanooga    Knoxville      Tri-Cities     Oak Ridge
07-15   103(1977)      98(1995)       96(1995)       100(1980)
07-16   105(1980)      100(1980)      100(1988)      103(1980)
07-17   103(1980)      101(1980)      94(1980)       103(1980)

&&

.AVIATION...
(12Z TAFS)
Issued at 710 AM EDT Sun Jul 14 2024

VFR conditions through the period. Light winds generally out of
the west at all sites this afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN            100  74  99  75 /  20  10  30  10
Knoxville McGhee Tyson Airport, TN  98  71  98  75 /  10  10  20  10
Oak Ridge, TN                       98  70  98  73 /  10  10  20  10
Tri Cities Airport, TN              96  66  94  70 /  10  10  20  10

&&

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

$$

SHORT TERM...
LONG TERM....KRS
AVIATION...