-- Discussion containing changed information from previous version are highlighted. --
419
FXUS64 KHUN 201123
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
623 AM CDT Thu Jun 20 2024

...New AVIATION...

.NEAR TERM...
(Today)
Issued at 357 AM CDT Thu Jun 20 2024

An area of high altitude moisture and mostly cloudy skies that
have been over this region the past few days have faded, as drier
air works in aloft. Strong upper level ridging was in place over
the coastal Mid Atlantic with upper 590s decameter heights at
500mb. An easterly flow prevailed, rounding the SW periphery of
a surface high centered off of the East Coast. Quiet weather
continues over this region with area temperatures thus far cooling
into the upper 60s and lower 70s. Lows by daybreak Thursday should
cool into the upper 60s to around 70.

Drier conditions aloft should yield mostly sunny to partly cloudy
skies today. And with a strong summer sun (today also the first
day of summer that starts around 351 PM CDT), high temperatures
should respond appropriately, warming into the lower 90s. Heat
indexes should range in the mid/upper 90s. Daytime heating
produced cumulus are expected this afternoon thanks to the very
warm to hot surface conditions.

&&

.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 --
(12Z TAFS)
Issued at 623 AM CDT Thu Jun 20 2024

VFR conditions should continue into Fri, as strong upper level
high pressure controls the weather. A light easterly flow this
morning, should become ESE in the 5-10kt range later this morning
and in the afternoon. Light winds from the east are forecast
tonight.
-- End Changed Discussion --

&&

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

$$

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