Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 272112
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
312 PM CST Mon Feb 27 2017

.NEAR TERM...(Tonight)
Issued at 312 PM CST Mon Feb 27 2017

After the initial rainfall this morning, most of the rest of the day
has been dry for the Huntsville CWFA. While short-range model
guidance has suggested a dry period until late evening, radar is
picking up on additional showers over north-central MS perhaps
associated with another weak shortwave (as suggested by water vapor
imagery). Meanwhile, persistent cloud cover has made it tough to warm
up much from early lows in the upper 40s, but most of the area has
made it to at least the mid 50s.

Tonight`s forecast was going to be mostly dry through 06Z or so,
before transitioning to a wetter pattern as the next weak mid-level
shortwave trough and warm front move into the mid-Mississippi
valley. There is greater confidence in clouds lowering and thickening
more as isentropic lift strengthens. Either way, the temperature is
not going to fall that much tonight in general, but the low will
occur early in the night with temperatures rising towards daybreak.

.SHORT TERM...(Tuesday through Wednesday)
Issued at 312 PM CST Mon Feb 27 2017

Scattered showers and thunderstorms will continue into tomorrow; the
question is whether any of these storms can become severe. The low-
level and deep-layer wind shear are both strong. Instability is there
too; the question in our mind is whether the low-to-mid level
capping develops as hinted by the operational models. Elevated storms
capable of producing large hail look more likely, but it will take
more effort to produce any surface-based storms (though it is not out
of the question). PoPs for Tuesday will stay in the 50-60% range
given the relatively weak forcing. High temperatures in the warm
sector will easily be 10-15 degrees warmer than today and could
potentially flirt with records for the date.

Wednesday continues to be the main focus, as the parent long wave
troughs phase over the Plains and drive a strong cold front eastward,
likely creating a squall line/QLCS. There is no doubt that the
forcing Wednesday is much better and instability more pronounced.
However, the most unstable lapse rates (late in the day) and
strongest shear (earlier in the day) are displaced from one another.
A few tornadoes are possible, particularly if there are line breaks,
or if storms develop earlier when they can take advantage of more
favorable shear. However, wind damage looks like the more significant
threat with the expected timing (late morning thru afternoon).

.LONG TERM...(Wednesday night through Sunday)
Issued at 312 PM CST Mon Feb 27 2017

As the surface front continues southeastward into the Florida
panhandle Wednesday night, a decent pressure gradient will still be
in place, as cold air advection continues behind the front. This
will keep northwest winds between 10 and 15 mph with higher gusts to
between 20 and 25 mph above 1000 feet. These winds will slowly
diminish to between 5 and 10 mph with some higher gusts above 1000
feet after midnight. Since this air mass is Pacific in origin, very
cold air will not be advected in despite the strong northwesterly
winds. Also, mixing will likely help to temper low temperatures as
well, low temperatures will still drop into the upper 30s to around
40 degrees. It will be cooler on Thursday, as highs in the mid to
upper 50s are expected despite abundant sunshine. Higher elevations
above 1000 feet will be even cooler with highs only topping out in
the lower 50s.

Another weak and dry front is forecast by models to push southeast
through northern Alabama Thursday evening. There should be very
little cloud cover associated with this front. Behind the front on
Friday, even colder air into the Tennessee Valley. Lows in the lower
to mid 30s look reasonable. As colder air moves into the region,
highs on Friday will likely be cooler than guidance. Forecasted
highs in the lower 40s in Southern Middle Tennessee to the lower 50s
south of the Tennessee River. This may be generous given 925
temperatures. However, enough uncertainty exists with these
temperatures to not go much lower than stated temperatures.

A warmup looks to be in store for the weekend, as southerly to
southwesterly low level flow develops as the surface high pushes off
the Georgia coast. Highs should climb into the lower to mid 60s
again by Sunday. Models hint at weak forcing and maybe deep enough
moisture for showers to developing by Sunday night. Included isolated
to scattered showers during that period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1154 AM CST Mon Feb 27 2017

VFR ceilings should remain in place for KHSV and KMSL through at
least the early afternoon hours. There is high confidence in
worsening conditions during the late afternoon-evening hours, but
pinpointing exactly how rapidly ceilings fall is difficult (ceilings
could quickly fall to IFR before 00Z, but confidence is too low to
include in the TAFs at this time). The IFR ceilings (and restricted
visibility) should be in place by 02Z at KMSL, 05Z at KHSV, and
remain there for much of the night. Improvement to low-end MVFR is
expected around daybreak. SE winds at 8-12 kt will persist.

&&

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

$$

NEAR TERM...BCC
SHORT TERM...BCC
LONG TERM...KTW
AVIATION...BCC

For more information please visit our website
at weather.gov/huntsville.



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