Huntsville, Alabama 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

215
FXUS64 KHUN 201600
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1100 AM CDT Sun Jul 20 2025

...New NEAR TERM, SHORT TERM, CLIMATE...

.NEAR TERM...
(Rest of Today and Tonight)
Issued at 1059 AM CDT Sun Jul 20 2025

Another sweltering July day is in store with dew points starting
out the morning in the upper 70s. Some diurnal mixing will drop
these into the mid 70s, but portions of the TN Valley may briefly
touch heat index values of 105 or greater. Not enough confidence
nor duration for an advisory, but certainly something to be
mindful of today.

As of 10 AM, we are just starting to reach today`s convective
temperatures in the mid 80s. Fields of cumulus are bubbling up
with a few convergence axes becoming prominent. One extends
through southern middle TN and the other over portions of Colbert
and Lawrence counties. PWATs from 12z soundings at OHX and BMX
were over 2" with nearly moist adiabatic profiles throughout.
Coupled with max temps this afternoon reaching the low to mid 90s,
today is another high CAPE day with scattered convective
development expected. Primary concern will be efficient rainfall
rates leading to localized flooding, especially in central Jackson
County where Scottsboro received near 3" of rainfall yesterday.
Secondary concern, as is typical with summertime, is a downburst
threat with hydrometeor loading assisting strengthening downdrafts
today. Wind gusts near 40-50 mph are on the table, but with so
much recent rainfall, as last night`s AFD mentioned, even sub-
severe winds can topple trees.

Diurnal convective development should wane around sunset. With
surface high pressure maintaining its grip over the area, overnight
winds should weaken enough to allow for patchy fog in areas that
received rainfall, particularly near sheltered valleys. Otherwise,
high dew points will allow for little overnight relief from the
heat with low temperatures only reaching 73-75 F.

&&

.SHORT TERM...
(Monday through Tuesday)
Issued at 1059 AM CDT Sun Jul 20 2025

Monday will be the first day of a multi-day heat wave this week. A
Heat Advisory has been issued for counties along I-65 and
westward, as well as our southern middle TN counties. Heat index
values will peak between 105 and 107 with HeatRisk criteria
reaching level 3 out of 4 for a majority of the counties,
indicating dangerous conditions for prolonged outdoor exposure for
the general population.

In addition to the heat, a low-end risk for severe weather exists
as the surface high pressure and ridging aloft shifts westward.
This will shift the subsident stagnant airmass westward (as
evidenced by the heat advisory extent) and bring in weak northerly
winds briefly, although they will bring no respite from the heat.
On the right side of the ridge axis, this also opens northeast AL
more up for upstream convection moving into the area. High heat,
high moisture, and more surface convergence from the northerly
winds moving in will result in a threat for strong to severe
storms, so the area highlighted by SPCs marginal risk aligns well
with our assessments. Additionally, weak corfidi upshear vectors
will allow for backbuilding of the slow-moving storms. Motion
largely driven by cold pool propagation, indicated by the corfidi
downshear vector, indicates storms moving to the southeast at
10-15 kts. All this to say, there will be high rain rates coupled
with slow, persistent storm development, so in addition to the
downburst threat from severe storms, there may be brief but
impactful flooding.

The heat wave continues into the remainder of the week with the
highest max temperatures expected on Tuesday, peaking at 95-96F.
Widespread heat index values will peak between 105 and 110 for
north central and northwest AL, and southern middle TN. Expect
another heat advisory, at least, for the same areas on Tuesday.
Diurnal convection bubbling in the afternoon and evening will be
the only relief as a brief outflow boundary may be a semi-
refreshing breeze before sweltering heat resumes.

&&

.LONG TERM...
(Wednesday through Saturday)
Issued at 956 PM CDT Sat Jul 19 2025

In the extended portion of the forecast period, global models
suggest that an easterly wave will undercut a strong mid-level high
(initially centered across the Lower OH Valley). As the wave
progresses westward across the Gulf from Wednesday-Saturday, it will
effectively create a break in the subtropical ridge extending from
the central Gulf Coast northward into the central Appalachians/OH
Valley by the end of the period. In the low-levels, our region will
remain in a light-moderate SE flow regime between a high to our east
and a weak area of surface low pressure that will evolve within the
base of the easterly wave and retrograde westward across the northern
Gulf (perhaps in close proximity to the coastline).

Prior to the development of the weakness in the mid-level
subtropical ridge, coverage of showers/thunderstorms from the late
morning-early evening hours will be quite limited on
Wednesday/Thursday and perhaps into Friday as well, with the greater
spatial concentration of convection expected to occur within a plume
of deeper tropical moisture to our southeast. However, by Saturday,
the axis of deeper moisture will likely have spread northwestward
into our region, promoting an increase in shower/thunderstorm
activity (especially for the southeastern half of the CWFA).

Regarding temperatures and heat index values, it appears as if
Wednesday will mark the last day of overlap between afternoon temps
in the l-m 90s and dewpoints in the l-m 70s, as drier low-level air
will be advected into the region from the northeast (lowering heat
risk on Thursday/Friday in spite of highs remaining in the l-m 90s).
Beyond Friday, boundary layer dewpoints will begin to increase once
again, but with an increasing coverage of showers/storms expected as
well, the risk from excessive heat is more uncertain heading into
next weekend.

&&

.AVIATION...
(12Z TAFS)
Issued at 541 AM CDT Sun Jul 20 2025

VFR conditions will be the prevailing flight category through the
TAF period. There is a low chance of isolated storms this
afternoon. Due to low confidence, thunder was excluded from the
TAFS. That being said, should an isolated storm move directly over
the terminals, ceilings and visibilities may be briefly lowered.
Future TAF issuances will address this if confidence increases in
this possibility.

&&

.CLIMATE...
Issued at 1059 AM CDT Sun Jul 20 2025

Moderate Risk for Much Above Normal Temperatures:

The Climate Prediction Center has included all of north Alabama and
southern middle Tennessee in a Moderate Risk for Much Above Normal
Temperatures for July 26th through August 1st. Temperatures reaching
or exceeding the mid to upper 90s with heat indices between 100-105
degrees F are possible during this period.

More information on the CPC U.S. Hazards Outlook can be found at:
https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory from 11 AM to 8 PM CDT Monday for ALZ001>007-016.

TN...Heat Advisory from 11 AM to 8 PM CDT Monday for TNZ076-096-097.

&&

$$

NEAR TERM...30
SHORT TERM....30
LONG TERM....70
AVIATION...RAD