384
FXUS64 KHUN 031718
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1218 PM CDT Wed Jul 3 2024

...New AVIATION...

.NEAR TERM...
(Rest of Today)
Issued at 820 AM CDT Wed Jul 3 2024

The 12Z surface map shows a ridge of high pressure from the mid
Atlantic into the southeast U.S. Dew points were in the upper 50s
to lower 60s just to our east in north GA into the Carolinas. Some
of this airmass will mix and lower dew points a few degrees today
in eastern AL. Fairly widespread low clouds have overspread north
AL and southern middle TN. These will delay heating a bit this
morning, but should tend to scatter out by midday into early
afternoon. Have adjusted the forecast to account for sky trends,
and to lower dew points a couple of degrees per latest guidance,
especially in our eastern counties.

&&

.SHORT TERM...
(Tonight through Friday Night)
Issued at 251 AM CDT Wed Jul 3 2024

We`ll get almost no relief from the heat overnight, with
temperatures only dropping into the 75-80 degree range. The ridge
begins to flatten, but remain centered across the Deep South on
Thursday (4th of July). This weakness in the ridge and the deep
Gulf moisture in place will allow for a better potential for
afternoon showers/storms (30-50%). Most locations will remain dry,
however, even with these pulse storms briefly developing during
the afternoon/early evening window. The main story for the 4th of
July will be the heat, with mid/upper 90s highs and mid/upper 70s
dewpoints creating heat index values between 105-110 degrees over
much of the area. Heat index values over 110 are possible across
portions of northern Alabama, especially the HSV/DCU/MSL metros.
It`s possible an Excessive Heat Warning may be needed on Thursday
if these higher heat indices are realized. The Heat Advisory
continues tonight and will last through Thursday/Thursday night
and the day on Friday.

The center of the high pressure ridge that will bring us the
dangerous heat over the next 2-3 days will become squeezed to the
SE of the area over the GA/SC/NC coast. Meanwhile, a fairly
robust mid/upper trough will swing from the northern Plains into
the Great Lakes, with its associated cold front pushing from the
mid- Mississippi and lower Ohio Valleys into the Tennessee Valley
and Deep South region on Friday. Ahead of the front, appreciable
destabilization of the boundary layer will take place as
temperatures again warm into the mid 90s (with heat index values
between 105-109 again). This instability combined with the forcing
from the cold front will create an environment favorable for
showers and thunderstorms (70-90%), including a few strong storms.
Gusty winds and heavy downpours will be the main threats with the
strongest activity.

&&

.LONG TERM...
(Saturday through Tuesday)
Issued at 251 AM CDT Wed Jul 3 2024

Upper level high pressure will persist over the northern Gulf coast
through much of the long term period. Meanwhile, an upper trough over
the central CONUS will very slowly begin to shift to the east and
northeast over the Midwest, Ohio Valley, and Great Lakes regions
early next week. This pattern leaves the Tennessee Valley in a sort
of weakness into early next week, with southwesterly flow aloft. At
the surface, a cold front looks to enter the Tennessee Valley
Saturday morning and meander over the region through early next week.
High pressure looks to build in to the north, with high pressure
over the northeastern Gulf of Mexico. With these upper level and
surface patterns, expect daily chances of showers/storms from
Saturday through Tuesday, especially during the peak heating hours of
the afternoon. Generally, chances are low to medium (20-50%) each
day with the exception of Sunday where chances are low (15-30%).

We`ll be keeping an eye on trends for Monday and Tuesday because
model guidance suggests that shear will increase to between 20-30
knots. While model instability values are under 1000 J/kg at this
point, it`s sufficient for the development of thunderstorms. Overall,
what this means is that there is potential for a few stronger storms
Monday and Tuesday. Confidence in anything severe is low, but heavy
downpours, lightning, and gusty winds are all possible.

As for temperatures, the daily chances of showers and storms may
quell the heat a bit this weekend through early next week. Highs on
Saturday are forecast to only reach the upper 80s to around 90
degrees, whereas Sunday and Monday it`ll be a bit warmer (low 90s).
Then, on Tuesday, highs looks to be similar to Saturday. This will
result in heat indices generally in the 90s this coming weekend, then
mid 90s to around 101-102 degrees in spots Monday and Tuesday. While
these values as a whole are a fair bit below Heat Advisory criteria
(105-109 degree heat indices), please remember heat safety if you
have outdoor plans. Take breaks in the shade and drink plenty of
water!

&&

.AVIATION...
(18Z TAFS)
Issued at 1218 PM CDT Wed Jul 3 2024

Mainly VFR conditions are expected at both KHSV and KMSL through
the TAF period. Scattered to broken clouds are expected through
about about 22z. Winds this afternoon are generally from the SSE
at around 6 kts, with gusts up to 12 kts. By 14z, winds should
turn to the SSW at around 5 kts.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory until 7 PM CDT Friday for ALZ001>010-016.

TN...Heat Advisory until 7 PM CDT Friday for TNZ076-096-097.

&&

$$

NEAR TERM...17
SHORT TERM....AMP
LONG TERM....26
AVIATION...Serre