Decatur, Alabama 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

960
FXUS64 KHUN 071740
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1240 PM CDT Sat Jun 7 2025

...New AVIATION...

.NEAR TERM...
(Rest of Today and Tonight)
Issued at 1056 AM CDT Sat Jun 7 2025

A split MCS is currently crossing the Mississippi River and moving
eastward at 30-40 mph. Briefly going through the environment, we
are seeing a theta e (moisture) gradient set up across the
northern two tiers of counties in Alabama and that may present a
feature for line intensification as we head throughout the
afternoon. Instability will be much stronger south of that
demarcation but still sufficient to the north for severe weather.
Primary concerns will be damaging wind gusts with mid level lapse
rates 7-7.5 C/km and approaching 7 C/km from 0-3 km. MLCAPE will
be over 2000 J/kg south of the river yet still exceed 1000 J/kg to
the north. 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. We should enter watch
coordination with SPC closer to noon. Earlier, I would have leaned
toward tornado watch but if areas of rotation are not seen as it
crosses MS and western TN, then I would anticipate a severe watch
for the TN Valley this afternoon.

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.

Timing currently has this line entering NW AL closer to 1 PM,
crossing I-65 at 2:30 PM, and exiting NE AL around 5 PM. Attention
then turns to any residual outflow boundaries from this MCS and
the low end 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. 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...
(Saturday night through Monday)
Issued at 1004 PM CDT Fri Jun 6 2025

Showers and thunderstorms will likely be ending from NW-to-SE
after sunrise Sunday morning, as the cold front slips
southeastward and veers low-level flow to WNW. Although this may
allow a slightly drier airmass to advect into portions of the
region north of the TN River, and additional shower or storm may
occur across our southeastern zones through Sunday afternoon if
the front moves slower than indicated. Dry conditions are
anticipated Sunday night as high pressure will build into the
region from the north, with lows falling back into the l-m 60s.

&&

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

The upper ridge axis will begin to shift off to the northeast on
Tuesday and the Tennessee Valley will become more under the influence
of high pressure. 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...
(18Z TAFS)
Issued at 1239 PM CDT Sat Jun 7 2025

Main impact in the near term will be a squall line approaching
from the west with a history of 40-50 kt gusts at least. Isolated
thunderstorms ahead of it will impact both terminals. Gave timing
a best guess, but expect amendments and several AWWs this
afternoon and evening. Lower confidence overnight in additional
storm development timing and location, but TAF represents most
likely thinking. Tomorrow should be a mostly dry day after the
morning with gusty winds from the west.

&&

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

$$

NEAR TERM...30
SHORT TERM....12
LONG TERM....JMS
AVIATION...30