Damaging Wind in Alabama, July 24, 2022

Area Forecast Discussion
National Weather Service Huntsville AL
259 PM CDT Sun Jul 24 2022

...New NEAR TERM, SHORT TERM, LONG TERM...

.NEAR TERM...
(Remainder of today and tonight)
Issued at 259 PM CDT Sun Jul 24 2022

Overall, forecast reasoning from the morning update remains
valid, with no significant changes made to the grids for the rest
of the afternoon. However, we did increase POPs a bit based on
current radar data, as the coverage of showers and thunderstorms
appears as if it will be a bit greater than previously
anticipated. Regardless, storm threats remain identical to those
mentioned earlier this morning. In locations that do not
experience a cooling shower or storm (or convective outflow),
conditions will be uncomfortably hot/humid as temps in the l-m 90s
and dewpoints in the lower 70s will yield heat indices in the
100-105 degree range.

Overnight, models suggest that the center of a strong subtropical
high to our west will slowly migrate eastward, becoming centered
across eastern OK/western AR by 12Z. With the eastward-extending
ridge axis expected to remain firmly planted across the TN Valley,
afternoon convection should dissipate by around 3Z. As skies
partially clear and temperatures fall into the l-m 70s during the
early morning hours, a combination of mist/haze/fog will likely
develop, especially in locations that receive measurable
rainfall.

&&

.SHORT TERM...
(Monday through Tuesday night)
Issued at 259 PM CDT Sun Jul 24 2022

Present indications are that the mid-level high discussed above
will become centered across southeastern AR/northwestern MS on
Monday and Monday night, before shifting directly across the TN
Valley on Tuesday/Tuesday night. Based on this, we expect the
southern extent of the stronger mid-latitude westerlies to remain
between 35-40 N latitude, with little to no synoptic scale forcing
for ascent aloft across the local area during this period. That
said, a scattered to perhaps numerous coverage of showers and
thunderstorms is expected both days, as weak but persistent low-
level moisture advection will contribute to a gradual increase in
PWAT values to around or slightly above 2 inches by Monday
night/Tuesday morning.

At this point, we have indicated the highest POPs on Monday, as
there are still some indications in both the global models and
higher-resolution CAMs that an outflow boundary may drop south-
southeastward into the region from more extensive frontal
convection predicted to impact the OH Valley region. This activity
could potentially begin as early as the mid/late morning hours
tomorrow (which may have an impact on the high temperature
forecast) and will likely last a bit longer into the evening hours
compared to the last couple of days. A similar setup could evolve
across the region on Tuesday, with the greatest spatial coverage
of showers and storms expected to be across the eastern half of
the CWFA both days. With shear predicted to remain very weak, we
expect storms to be unorganized and slow-moving but capable of
producing very heavy rainfall that may result in localized flash
flooding. That said, MLCAPE will increase into the 2000-2500 J/kg
range as boundary layer dewpoints creep up, and this along with
steep low-level lapse rates will support brief strong wind gusts
of 40-50 MPH with some cells. Based on the anticipated coverage of
showers and storms, we have lowered highs a bit into the u80s-
l90s both Monday/Tuesday, with lows expected to remain in the l-m
70s.

&&

.LONG TERM...
(Wednesday through Sunday)
Issued at 259 PM CDT Sun Jul 24 2022

It appears as if the subtropical ridge in place across the TN
Valley will begin to gradually weaken on Wednesday, as an easterly
wave retrograding across the northeastern Gulf coast during the
short term period should create a weakness in the height field
aloft across much of the southern CONUS. However, a more
significant pattern change will begin to unfold toward the latter
half of the work week, as a northern stream trough digging
southeastward across southern Ontario on Wednesday/Wednesday night
will begin to amplify as it tracks eastward through the Great
Lakes and into western Quebec Thursday/Thursday night. The
southern edge of stronger mid-latitude westerly flow will shift
southward into the TN Valley as this occurs, resulting in an
increasingly favorable environment for convection. At this point,
it seems reasonable to believe that several clusters of showers
and thunderstorms will develop in the warm/moist airmass to the
south of a cold front that should advance as far south as the
Ozarks/Lower OH Valley region Friday morning before stalling. This
activity will spread generally eastward across the TN Valley,
warranting an extended period of fairly high POPs (both during the
day and at night) from Friday-Saturday night. There are some
indications that the subtropical ridge may begin to build across
the region late in the extended period, with a gradual reduction
in precipitation coverage noted on Sunday. Due to the anticipated
coverage of clouds and convection, highs will fall into the m-u
80s by Friday/Saturday/Sunday, with lows in the u60s-l70s.

&&

.AVIATION...
(18Z TAFS)
Issued at 1203 PM CDT Sun Jul 24 2022

Local doppler radar data indicates the progressive development of
scattered SHRA invof the HSV/MSL terminals late this morning,
with this trend expected to persist throughout the aftn. Due to
the greater coverage of this activity today compared to yesterday,
we have included TEMPO groups for brief MVFR vsby reductions from
18-22Z, with VCTS/CB extended through 25/00Z. Outside of impacts
from convection, we anticipate prevailing VFR conditions, although
with subsiding winds and partial clearing during the late
evening/early morning hours, development of patchy BR/FG will be
possible btwn 6-13Z. A greater coverage of SHRA/TSRA is expected
tomorrow, which could potentially begin as early as 12-14Z if an
outflow boundary drops southward into the region overnight.
However, due to uncertainty in this scenario, we will not include
any precip in the latter hours of the TAF at this point.

&&

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

&&

NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...70/DD
AVIATION...70/DD

Hazardous Weather Outlook...UPDATED
National Weather Service Huntsville AL
310 PM CDT Sun Jul 24 2022

ALZ001>010-016-TNZ076-096-097-251130-
Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan-
Marshall-Jackson-DeKalb-Cullman-Moore-Lincoln-Franklin TN-
310 PM CDT Sun Jul 24 2022

This Hazardous Weather Outlook is for north central Alabama,
northeast Alabama, northwest Alabama and southern middle Tennessee.

.DAY ONE...Remainder of today and tonight.

Scattered thunderstorms will impact portions of the Tennessee Valley
this afternoon, before dissipating shortly after sunset. The
strongest storms will be capable of producing brief wind gusts of
40-50 MPH, frequent lightning and locally heavy rainfall. In areas
that do not experience a cooling shower or storm, heat index readings
will remain in the 100-105 degree range.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Scattered to numerous afternoon and evening thunderstorms are
expected across the outlook area each day from Monday through
Thursday. The coverage of thunderstorms is expected to increase both
during the day and at night on Friday and Saturday, as a weak cold
front will approach the region from the northwest during this period.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

70/DD