Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 022054

Area Forecast Discussion
National Weather Service Huntsville AL
254 PM CST Fri Dec 2 2016

.NEAR TERM...(Tonight)
Issued at 233 PM CST Fri Dec 2 2016

Nearly zonal flow aloft continues this afternoon across the area
along with with surface high pressure as a trough develops over
southern Arizona. A surface low is developing over Mexico in response
to the digging trough which, combined with the southwesterly flow
aloft, is sending cirrus into the area. The cirrus will continue to
thicken overnight which will keep lows from bottoming out too low.
But with light winds and weak cold advection, lows will still drop to
the lower to middle 30s.

.SHORT TERM...(Saturday through Monday Night)
Issued at 233 PM CST Fri Dec 2 2016

The previously mentioned trough continues to deepen on Saturday
with the surface low continuing to strengthen and move northeast.
Broad isentropic lift and strong warm advection occurs ahead of the
low and is developing precip/low clouds to our southwest by Saturday
afternoon. However, the surface high that moved off to the east
remains locked in with winds remaining from the east-northeast at
this time. It looks like by around 00z, the warm advection aloft
should force fairly rapid saturation to the surface with light,
stratiform precipitation beginning southwest to northeast. Highs on
Saturday will be cooler than Friday, in the lower 50s.

For Sunday, it`s a real messy pattern aloft especially in regards to
where any of the boundaries will settle at and what QPF we get as a
result. The latest GFS and ECMWF seem to settle the boundary to the
south which is where the heaviest rain would end up with the NAM
pushing one wave to our north and the next just over us. Gut feeling
is that with the strong high to the northeast, even with the quick
saturation overnight, the northeast winds and surface high will keep
the boundary and the heaviest rain to the south but it`s still to far
out to determine these mesoscale features. Highs will be similar to
Saturday, in the lower 50s.

The boundary settles across the southeast states with weak lift and
warm advection from the southwest still continuing leading to more
light stratiform precipitation overnight Sunday night. This will
keep lows above normal, in the middle 40s.

The trough finally gets moving on Monday and quickly advances into
Texas with the surface low over Louisiana by Monday afternoon.
Southwesterly flow keeps the moisture and rain over the area ahead
of the surface low. This will help keep highs warmer, in the upper
50s. The upper low opens to a wave and the surface low moves through
Monday night with surface winds finally shifting around to the
southeast with dew points quickly rising from the lower 50s to the
upper 50s. This could produce 1-2 inches of rain between 00-12z
Tuesday. Lows will have little room to drop and will only be in the
lower 50s Monday night.

Overall, from Saturday afternoon through Monday night could be around
1 to 3 inches with locally higher amounts likely.

.LONG TERM...(Tuesday through Thursday)
Issued at 233 PM CST Fri Dec 2 2016

Rain will taper off throughout the day on Tuesday from west to east
as the upper-level low sling shots off to the northeast. Conditions
will be dry on Tuesday night but short lived as the next system
builds across the West.

The trough will amplify across the Plains on Wednesday with a
trailing arctic cold front. The cold front now looks like it will
approach the TN Valley by late Wednesday/early Thursday. There`s a
slight chance of rain on Wednesday, but the best chance of rain
will be Wednesday night into Thursday with the front. Timing of the
front is still uncertain, thus kept all rain in the forecast and did
not put in any flurries or rain/snow mix in at this time. Also, tried
to split the timing between the GFS and ECMWF, so precip should be
out before the cold air filters in. One thing the models do agree on
is cooler temps. Behind the front, in combination with cold
air advection and decreasing clouds, temps will drop into the lower


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1124 AM CST Fri Dec 2 2016

VFR conditions and winds of 5-10 knots are expected through the TAF





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