461
FXUS64 KHUN 072342
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
642 PM CDT Sat Jun 7 2025

...New AVIATION...

.NEAR TERM...
(Tonight)
Issued at 304 PM CDT Sat Jun 7 2025

General thinking for this afternoon through the overnight period
has not changed significantly. We are in active warning operations
for a squall line moving across the area with segments gusting to
70+ mph and numerous trees down across the CWA. Segments of this
morning`s near term AFD are included below with minor revisions to
align with the latest observations and guidance.

Previous Discussion:

A split MCS is currently crossing the I-65 corridor and bringing
bowing segments with gusts near 70 mph downing trees and
powerlines. The strongest portions are moving through southern
middle Tennessee and then south of the TN river. Gusty winds
continue to be our primary concern and large hail will be a
secondary concern.

Now for the bigger question: tornado threats. Looking at radar
VWPs for both GWX and HTX, the easterly motion of the MCS places
almost entirely crosswise vorticity in the critical low levels of
the atmosphere for the storm to ingest. However, should the storm
start pushing to the southeast more, then a tornado threat would
develop as low-level wind orientation relative to storm inflow
would be more favorable for rotation. The northern edge of any
bowing segments would be the area of concern for tornadic
development, primarily along a moisture gradient close to the
state line between AL and TN.

Not to be outdone, corfidi upshear vectors are near 250 degrees at
15 kts. This raises alarm bells in my head for a flash flooding
threat. Especially for the southern portion of the line that is
more oriented west to east, redevelopment on the west-southwest
would create training cells and result in a higher flash flood
threat. Even for more north-south oriented line segments, this
rain will be brief yet intense. PWATs exceeding 2 inches are
nearly the sounding daily max, according to SPC`s sounding
climatology for BMX. This will also enhance the likelihood of
precipitation loading contributing to stronger downburst potential
today, enhancing my concern for damaging winds with the line.
Indeed, the leading edge of reflectivity for the line is
increasing its reflectivity gradient.

Attention then turns to any residual outflow boundaries from this
MCS and the threat for additional development this evening.
Whatever your wishcast scenario, there is a 12Z CAM run that will
support it. Whether it is no storms at all or a giant MCS also
tracking through the area, everything is on the table. What we do
know is that the main window for concern will be 8 PM to at least
3 AM. Shear will be more favorable, as will low level helicity, so
a higher tornado threat exists overnight, in addition to wind and
hail. Should convection continue for the entire overnight period
(highest confidence south of the TN river), then flash flooding
appears more of a certainty. HREF LPMM indicates localized
bullseyes of rainfall totals reaching 3-4 inches. Otherwise, look
for widespread 1-1.5 inches of rain.

&&

.SHORT TERM...
(Sunday through Tuesday)
Issued at 304 PM CDT Sat Jun 7 2025

Split flow aloft becomes more uniform and zonal on Sunday as a
surface low tracks across the Midwest and drags a cold front
through the TN Valley. A few lingering storms overnight have a low
chance of forming, but once the cold front sweeps through in late
morning, weak cold air advection will move into the area. Surface
high pressure will scour out most cloud cover by Sunday evening
after high temperatures reach the low to mid 80s.

Longwave troughing is then established over the eastern CONUS on
Monday. An occluded low over the Great Lakes will have an
attendant weak cold front push through the TN Valley Monday into
Monday evening. Surface based instability increases Monday to near
2500 J/kg with minimal CIN. Convective temperatures in the low 80s
would have storm clusters beginning around noon. Working in our
favor is the displaced shear, that shouldn`t move in until late
Monday night into early Tuesday. Therefore, the severe risk on
Monday should be primarily confined to damaging wind gusts and
hail. Low-level hodographs show uniform weak flow, providing very
little confidence in a tornado threat. Most activity should wane
with loss of diurnal heating in the evening hours. Surface high
pressure moves in on Tuesday and although a lingering rain chance
is still present primarily south of the TN river, Tuesday should
shape up to be a typical June day with highs in the mid 80s and
mostly clear skies.

&&

.LONG TERM...
(Tuesday night through Friday)
Issued at 355 AM CDT Sat Jun 7 2025

Rain chances will remain low and confined mainly to areas south
of the TN River during the mid-week period as a stalled sfc
boundary sits near or south of the Birmingham area. Temperatures
will also be on the lower side Tuesday and Wednesday with highs in
the low to mid 80s and lows near the mid 60s. Upper ridging will
move in toward the late week period and will result in both rising
temperatures and thunderstorm chances as we head toward the
weekend. As of now, no severe thunderstorms are expected as
synoptic forcing remains week, but diurnal heating alone may
provide enough instability to result in a strong storm or two each
afternoon. Stay tuned for updates as we head closer to next week.

&&

.AVIATION...
(00Z TAFS)
Issued at 640 PM CDT Sat Jun 7 2025

Main question for this TAF period involves the development and
potential impacts for TSRA/SHRA at TAF sites, especially beginning
after ~0400Z. Currently, a boundary stretching W-E across central
portions of AR and extending in NW Miss is seeing recent TSRA/SHRA
development per satellite/radar data. What is not certain is the
eastward extent and timing of any resulting activity into the KMSL
and KHSV TAF sites. The TAF forecast utilized VCTS/VCSH to
indicate this uncertainty generally during the ~0400 to 0900
period. Latest hi-res guidance suite indicates a variety of
solutions as expected, some of which suggest impacts of TSRA/SHRA
at TAF sites, and potential reductions to cigs/vis which could
warrant AMDs before the next TAF issuance.


&&

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

$$

NEAR TERM...30
SHORT TERM....30
LONG TERM....JMS
AVIATION...KDW