-- Discussion containing changed information from previous version are highlighted. --
102
FXUS64 KHUN 201717
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1217 PM CDT Thu Jun 20 2024

...New AVIATION...

.NEAR TERM...
(Rest of Today)
Issued at 1010AM CDT Thu Jun 20 2024

An upper-level ridge axis is oriented SW-NE across western MS.
This, along with an upper-level low near the Yucatan Peninsula are
helping to bring NE flow in the upper-levels. Some convergence is
evident at 250 mb, which should translate to subsidence across the
TN Valley today. As a result, surface high pressure remains firmly
in control. Highs are forecast to reach the upper 80s in the
higher elevations to the low 90s across the rest of the local area.
Mostly clear conditions are expected throughout the day today
with little to no rain chances. There is some model disagreement
with dewpoints from 18z through 00z, but most are trending with
slightly lower than previous runs, in the upper 50s to the mid 60s
by the afternoon.

&&

.SHORT TERM...
(Tonight through Saturday night)
Issued at 357 AM CDT Thu Jun 20 2024

Seasonably mild conditions are forecast tonight, with lows in the
upper 60s and lower 70s. The above noted upper ridge by then
should be weakening somewhat, but moving to the SW and across the
Tennessee Valley Friday into early Saturday. High temperatures
should warm into the low/mid 90s on Fri, and mid/upper 90s Sat.
Apparent temperatures on Fri should rise into the mid 90s to 101,
and mid 90s to 103 Sat. Dry weather should continue as we close
out the week.

&&

.LONG TERM...
(Sunday through Wednesday)
Issued at 357 AM CDT Thu Jun 20 2024

Latest extended range models indicate that a strong subtropical
ridge in the mid/upper-levels will be centered across AZ/NM at the
beginning of the forecast period. Although a gradual increase in
NW flow aloft is anticipated across the TN Valley through Sunday
night (as a northern stream trough riding along the edge of the
ridge dives southeastward across the Great Lakes), highs will
manage to reach the m-u 90s for most valley locations on Sunday,
with corresponding heat indices in the 98-102F range. It is
becoming increasingly apparent that diurnal shower and
thunderstorm activity on Sunday afternoon will be confined to an
axis of greater low-level moisture and instability positioned to
our S/E but we have retained a very low POP in our southeastern
zones during the afternoon hours.

Overall probabilities for showers and thunderstorms may increase
across our region during the early morning hours on Monday as a weak
surface cold front (related to the northern stream trough) spreads
southeastward from the OH Valley. We have indicated a low (15-20%)
POP on Monday morning to account for this, and increased these values
during the afternoon, which is when the frontal wind shift should
cross the local area. However, with precipitation coverage still
expected to be rather sparse, highs will reach the m-u 90s once
again, with a slight increase in dewpoints providing max apparent
temps in the 100-105F range. Any lingering convection will dissipate
south of the TN River Monday evening as the front advances further
southward.

During the period from Tuesday-Wednesday, guidance suggests that the
frontal boundary will begin to lift northeastward in response to
another northern stream trough and related surface low moving
eastward across Ontario/Quebec. The introduction of light SW
flow/richer low-level moisture, coupled with less influence from the
subtropical ridge aloft, should allow for a greater coverage of
afternoon/evening showers and storms both days, along with slightly
cooler afternoon high temperatures.

&&

.AVIATION...
-- Changed Discussion --
(18Z TAFS)
Issued at 1218 PM CDT Thu Jun 20 2024

VFR conditions are expected at KHSV and KMSL through the TAF
period. Winds though Thursday should be from the east-southeast at
around 5 to 10 mph. Overnight, winds become light and variable at
both sites.
-- End Changed Discussion --

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.
&&

$$

NEAR TERM...Serre
SHORT TERM....RSB
LONG TERM....70
AVIATION...Serre