Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 301936

Area Forecast Discussion
National Weather Service Huntsville AL
236 PM CDT Mon Mar 30 2020

.NEAR TERM...(Tonight)
Issued at 236 PM CDT Mon Mar 30 2020

Mild/dry weather will come to an end this evening as an approaching
low pressure system looks to bring widespread precipitation to the
region tonight. Current radar shows some light rain trying to move
in from Mississippi, but with 20+ degree dewpoint depressions and
ceilings around 9-10 kft, expect most of this will be virga -- with
only a sprinkle or two possible. For this evening, mid/high clouds
will continue to overspread the area, though a few breaks will allow
temperatures to drop back off into the 50s after sunset. A fast-
moving upper-trough will track across the Southern Plains into the
Mid South region overnight, while a surface low tracks into the
Lower Mississippi Valley. As winds veer back to a more southerly
direction, Gulf moisture will begin to creep back into the area,
especially late tonight as the surface low approaches West Central
Alabama. The result will be a gradual uptick in rain showers
overnight, with this activity becoming widespread late tonight into
early Tuesday morning. It may take the atmosphere a bit of time to
moisten given some of drier air still present at the surface.
However, would expect between 1/4 to 1/2 inch of accumulation by
early Monday morning as this system moves into Alabama. With clouds
and rain moving in, expect temperatures to hold steady in the 50s for
the remainder of the night.

.SHORT TERM...(Tuesday through Wednesday)
Issued at 236 PM CDT Mon Mar 30 2020

A surface low will continue to shift across Central Alabama on
Tuesday, bringing widespread rain showers across the Tennessee
Valley, especially from the morning into the early afternoon. Model
data hints at PWATs increasing to near 1.5", creating an environment
favorable for efficient rain-producing showers, especially during
the 12-18z window. With the warm front (and any appreciable
instability remaining south of the I-20 corridor), the latest model
guidance keeps most of the thunder chances just out of the area.
However, a sliver of elevated instability from parcels lifted along
the 850-700mb warm front may be enough to generate a couple of
elevated storms in the far southern portions of the area. This
activity will begin to taper off Tuesday afternoon as a dry slot
works its way into North Alabama. Expect rain to completely end by
late Tuesday evening as a much cooler and drier post frontal air mass
settles into the region. In fact, if cloud cover breaks up a little
faster than expected, it`s possible radiational cooling and some CAA
could drop lows into the upper 30s to lower 40s Tuesday nigh. This
will also set the stage for a slightly cooler than normal start to
the month of April on Wednesday as temperatures will struggle to
reach the 60 degree mark despite the abundant afternoon sunshine. In
fact, northerly winds will make it feel rather brisk and in the 50s
for most of the day.

.LONG TERM...(Wednesday night through Sunday)
Issued at 236 PM CDT Mon Mar 30 2020

The axis of an upper level ridge will continue to move eastward on
Thursday and become anchored over the TN Valley. Meanwhile, at the
surface, light southerly flow will take hold and keep above normal
temperatures across the region through the weekend. A strong upper
low will dig into the Northern Rockies and Northern Plains on Friday
and then pivot to the northeast. This low will allow the ridge to
weaken a bit and send several shortwaves through the southeast.
Meanwhile, a cold front will trail from the associated surface low,
essentially stalling to our west as the upper low weakens and races
to the northeast. Given the moisture return over the TN Valley, along
with the weak shortwaves providing some forcing over the area,
expected rain chances to increase late Friday night and continue
through Sunday. Model discrepancies remain high regarding the
evolution of the extended pattern, so will cap rain chances below
50%. Isolated thunderstorms are possible Saturday afternoon, as
daytime heating provides some instability.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1159 AM CDT Mon Mar 30 2020

VFR conditions will prevail for the remainder of the afternoon and
evening as high clouds begin to increase ahead of a developing low
pressure system to the southwest. Ceilings will lower to MVFR levels
around midnight as -RA begins to expand across the region. Ceilings
will lower to LIFR levels late tonight into the day on Tuesday as the
surface low approaches Central Alabama, RA becomes more widespread,
and ceilings lower to less than 1 kft through the remainder of the





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