Area Forecast Discussion
Issued by NWS Huntsville, AL

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465
FXUS64 KHUN 250841
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
241 AM CST Sat Nov 25 2017

.NEAR TERM...(Today)
Issued at 241 AM CST Sat Nov 25 2017

A weak upper level trough is moving through the Ohio Valley this
morning with a surface low dragging a cold front down to the south.
The front, as of 2AM, looks to be stretching through SE MO and
Central AR and will be moving east through the morning hours. Some
very light radar returns are showing up with pretty high cloud
bases, the lowest seen on observations is around 9000ft and only one
station reporting any rain. Moisture with this system is limited
with saturation only occurring above 700mb. This is also where all
the lift is confined too so an increase in clouds is really the
only impacts we will see. I did add occasional sprinkles to the
forecast as the front moves east but confidence isn`t high on even
this occurring. Looks like the front will be through NW AL by 1PM,
Huntsville by 3PM and out of NE AL around 6PM. Given the cloud
cover, highs today will be slightly cooler than yesterday, in the
lower 60s.

.SHORT TERM...(Tonight through Monday Night)
Issued at 241 AM CST Sat Nov 25 2017

Surface high pressure and a drier northwest wind quickly builds in
behind the front tonight along with clearing skies. Dew points won`t
bottom out just yet which will keep lows in the middle 30s.

Sunny skies will prevail for both Sunday and Monday under strong
high pressure and northwest flow aloft. Sunday will feel the effects
of the front with highs only in the upper 50s. Temps will warm
into Monday as mid level ridging starts to build with highs in the
lower 60s. Sunday night will see freezing temps again before warming
back into the middle 30s by Monday night.

.LONG TERM...(Tuesday through Friday)
Issued at 241 AM CST Sat Nov 25 2017

Upper ridging will maintain its hold on Tuesday, with high pressure
at the surface. Under ample sunshine, temperatures will warm into
the lower to mid 60s. A relatively strong upper level cutoff low
will be spinning towards the ArkLaTex region early Wednesday
morning, with weak southwest flow over the TN Valley. At the
surface, high pressure along the eastern seaboard will be weakening
and shifting eastward, with east-southeast flow veering to the
south. A cold front will trail south from its parent low over the
Mid Mississippi Valley and approach the forecast area during the day
on Wednesday. Temperatures will warm into the lower to mid 60s
during the day, with increasing clouds keeping overnight lows in the
lower to mid 40s.

The front will move east of the Mississippi River late Wednesday and
be on the doorstep of the TN Valley on Thursday morning. Given the
southerly flow ahead of the front, moisture return will be
sufficient to bring light showers across the TN Valley as the front
and upper low move through the region. Forecast models are still
roughly 12 hours apart on the timing of when the front makes its way
through the TN Valley, with the GFS continuing to be the faster
solution. The upper system is expected to weaken as it shifts east,
with the cutoff low opening into a wave as it moves east of the
Mississippi River. Given the weakening upper forcing and support,
the slower ECMWF seems to be more reasonable. But, with it being a
few days away, will continue to follow closely to the blends and cap
precip chances at around 40 percent generally on Thursday. Although
moisture will increase enough to bring scattered showers, the
atmosphere will be too stable for thunderstorms with this system.
Temperatures on Thursday will be a couple of degrees cooler than
those on Wednesday due to the clouds and rain, with highs in the
upper 50s to lower 60s.

The front will clear the area by Friday morning, with northerly flow
advecting cooler and drier air into the region. Despite abundant
sunshine, temperatures will remain in the mid to upper 50s Friday
afternoon, with overnight lows dropping into the lower 30s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1122 PM CST Fri Nov 24 2017

VFR weather should continue for the TAF period. Weak high pressure
east of here will provide light southerly winds into the overnight.
A cold front is forecast to move in a NW-SE manner across the region
during Saturday afternoon (~18Z at KMSL and ~20Z at KHSV), with
winds becoming NW after the front passes. Given dry air either side
of the boundary, showers are unlikely with the frontal passage. A
plume of thickening high altitude moisture should produce broken to
overcast high clouds on Saturday.


&&

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

$$

NEAR TERM...LN
SHORT TERM...LN
LONG TERM...73
AVIATION...RSB


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at weather.gov/huntsville.



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