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Area Forecast Discussion (AFD)

Issued by Huntsville, AL (HUN)

                            
000
FXUS64 KHUN 200126
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
726 PM CST Sat Jan 19 2019

.NEAR TERM...(Tonight)
Issued at 725 PM CST Sat Jan 19 2019

The cold front is now completely east of the area but winds behind
the front have ramped up quickly. RAP analysis shows the pressure
gradient across the area tightened quickly and resulted in wind gusts
of 35mph to 37mph. These stronger gusts should continue through the
rest of the overnight period and we will continue the Wind Advisory.
Temperatures are falling a bit quicker than the previous forecast and
most model guidance had advertised and have made adjustments to
reflect these cooler temps. With continued cloud cover overnight and
based on temperatures to our north think that our forecast for lows
in the upper 20s is reasonable. May end up having to nudge values
down a degree or so but we are on track. The combination of these low
temps and the breezy conditions will send Wind Chill values into the
teens Sunday morning. 

The strong winds and drier air rushing into the area will really help
to evaporate moisture off of the roads. We can probably expect some
patchy black ice where water has pooled but most road/concrete
surfaces should be okay. The focus then turns to the potential for
any wintry precipitation overnight. Current radar, satellite, and
observations indicate a narrow band of snow is occurring on the back
side of the strong upper low. This low is currently north of
Nashville and moving fairly quickly E/NE away from the area. Because
the system will be pulling away from the area we should start to lose
some of the lift that is supporting these light snow showers near
Memphis, TN. In addition to the loss of lift, drier air working in
above this shallow moisture layer may result in a shrinking band of
precip as it moves towards northern Alabama and southern middle
Tennessee. With that in mind have reduced PoPs a bit overnight but
think we'll still end up with some flurries or light snow showers. We
do not expect any accumulations for much of the area. The exception
to that is in the higher terrain across southern middle TN and far NE
AL where a light dusting is possible on grassy and elevated surfaces. 

We will be monitoring the radar trends closely to see if the current
band of light snow in western TN holds on as it moves towards the
area. Another update before midnight is possible if that were to
occur. 

.SHORT TERM...(Sunday through Monday)
Issued at 325 PM CST Sat Jan 19 2019

With the upper low/trough axis lifting newd into the OH Valley Sun
morning, some very limited moisture may result in a few flurries
tomorrow morning, but this should only last a couple of hrs. Clouds
will then begin to diminish later in the day, as strong high pressure
builds into the Midwest/OH Valley states. With lingering NW winds
around 10-15 mph coupled with perhaps higher gusts, temps may 
struggle to get much higher than the lower 30s across srn mid TN and 
the mid 30s over north AL. Wind chill values only look to climb into 
the mid/upper 20s for most of the area later in the day Sun.

Quiet and cold wx conditions are then xpcted Sun night into Martin
Luther King Jr Day, under mostly clr skies. Lows Sun night look to 
fall well into the lower 20s, with temps then perhaps rebounding into
the lower/mid 40s during the day Mon, as the sfc high north of the 
area begins to translate ewd.

.LONG TERM...(Monday night through Friday)
Issued at 325 PM CST Sat Jan 19 2019

A moderating trend in the wx/temps is then xpcted to gradually begin
Mon night into Tue, as the sfc high moves into the nrn/mid Atlantic
states. This should allow low level flow to veer more to the ESE, and
allow moisture to begin spreading back into the area. Rain chances
also look to return later in the day Tue, as another deep upper
trough axis moves into the Plains states. A potent sfc low associated
with this next upper trough looks to lift into the Great Lakes, with
an attendant cold front stretching swwd into the srn Plains/west Gulf
Coast. There remains some spread in the latest global model runs with
the handling of this next system, with the 12Z ECMWF still the more
progressive solution. In any case, the lead cold front should sweep
thru the area during the day Wed, with rainfall then beginning to
taper off from the west Wed night. Total rainfall amounts with this
next system look to be around 2-2.5 inches. Colder air spreading into
the region with this next system following the passage of the front
Wed coupled with some lingering moisture may result in a wintry mix
or changeover to light snow late Wed night into Thu. Some light 
accum around a quarter inch or so are possible, but this will be 
dependent on the influx of drier air into the region as the upper 
trough moves across the Gulf states and a potential second sfc wave 
lifts newd away from the area with the passing front. High pressure 
out of the srn/mid Plains will then build into the region late in the
work week, with quiet and seasonably cool conditions xpcted Thu/Fri.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 520 PM CST Sat Jan 19 2019

The cold front has pushed through both terminals with winds shifting
to the W/NW. Expect wind gusts between 25 to 30 kts overnight. Winds
begin to diminish after 12z Sunday with gusts dropping below 20kts.
Cigs have lowered in the wake of the front with bases down to 1,000
to 1,500ft. Brief lowerings to 800ft are possible through 02z. There
is still some uncertainty but a brief change over to a rain/snow mix
is possible after midnight. No accumulations are expected.


&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Wind Advisory until 7 AM CST Sunday for ALZ001>010-016.

TN...Wind Advisory until 7 AM CST Sunday for TNZ076-096-097.

&&

$$

NEAR TERM...Stumpf
SHORT TERM...09
LONG TERM...09
AVIATION...Stumpf


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at weather.gov/huntsville.