Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 221947

Area Forecast Discussion
National Weather Service Huntsville AL
247 PM CDT Fri Sep 22 2017

.NEAR TERM...(Tonight)
Issued at 245 PM CDT Fri Sep 22 2017

Today is the first day of fall and it sure does not feel like it out
there with highs approaching the 90 degree mark. Combine those values
with upper 60 degree dewpoints and it still feels a bit like summer
outside. Normals for this time of year are in the lower 80s. The high
that was to our west has slowly shifted through the day and is
positioned to our north. This and the lack of any real forcing has
limited convective activity. Based on last few images of GOES-16 and
NASA SPoRT CI product there are a few storms trying to develop over
northern GA and these could sneak westward into NE AL later this
afternoon. There is also another weak convergence axis located over
Franklin/Lawrence counties and could see an isolated storm form over
there as well. So, have held onto low end PoPs for the area through
sunset. After that point any activity that does form should quickly

Patchy dense fog will be possible again in the same favored valley
locations. Otherwise, most of the area will see clear skies with lows
dropping into the mid 60s.

.SHORT TERM...(Saturday through Sunday night)
Issued at 245 PM CDT Fri Sep 22 2017

Models are in pretty good agreement in bringing the low that has been
located over NC/SC westward across the TN Valley on Saturday. This
might provide enough additional forcing for isolated to scattered
storms to form. NCAR ensembles, NSSLWRF, and other hires guidance are
all showing scattered storms moving from east to west across the
area. Model soundings indicate around 1,000 J/kg and with little in
the way of shear storms may be more pulse like and produce gusty
winds up to 40 mph. Highs in the afternoon will be similar to today
with highs in the mid to upper 80s.

For Sunday, the weak lift associated with the low will be to the west
of the area. We might see an isolated storm along the MS/AL border
but think chances are too low to include in the grids at this time.
Expect a rinse and repeat for high temperatures with values in the
upper 80s, close to 90 degrees.

With the near persistent pattern, fog will likely occur in the
favored valley locations each night.

.LONG TERM...(Monday through Thursday)
Issued at 245 PM CDT Fri Sep 22 2017

The extended portion of the forecast begins Monday morning with the
inverted trof in place over the SE moving quickly E/SE and becoming
absorbed by TC Maria. As a result, a generally dry but warm forecast
is on tap through the end of the week as a cold front approaches the
area from the NW. Though much of the convection early in the week
will be confined to locations well S/W of the CWFA, an isolated
shower/storm is possible, especially for Franklin/Colbert/Lawrence
Counties through Tuesday, as these counties will be the closest in
proximity to what little makes it this far N.

As an upper ridge builds into the region for the middle of the week
ahead of the approaching cold front, temperatures will climb back
into the upper 80s to lower 90s in a few spots. Thankfully the
dewpoint temperatures being in the lower/middle 60s will help keep
the Heat Index values at bay (only in the lower/middle 90s instead
of in excess of 100 degrees).

Longer-range models are advertising the first real Fall cold front
pushing across the area Thursday/Friday. The ECMWF/GFS have
different solutions regarding this fropa, with the ECMWF the more
dry solution, and the GFS by far the wetter solution (developing an
upper wave along the front and producing a bit more rainfall for
here and points E into the Carolinas). At this point, with northerly
winds ahead of the cold front, am not anticipating much in the way
of moisture return ahead of the front for the CWFA. This should
translate to dwindling showers/storms along the front itself, with a
mostly dry fropa expected for late next week. The bigger story will
be the temperatures in the wake of the front. They`re expected to
drop down into the upper 60s/lower 70s for highs next weekend, with
morning lows falling into the 50s. Depending on your model of
choice, some middle 60s for highs may occur, and morning lows may
fall into the upper 40s. This is more wish-casting at this point,
but it`s definitely a step in the right direction for more
traditional Fall temperatures for this time of year.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1143 AM CDT Fri Sep 22 2017

Generally light and variable winds will prevail thru the TAF period
at both KMSL/KHSV terminals. Aside from a few cu developing this
aftn, skies will remain mostly clear, with patchy fog again
developing between midnight and daybreak. MVFR conds (Vsbys ~4SM)
during this time will quickly return to VFR shortly after sunrise.
Otherwise, for Saturday, expect scattered cu arnd 5kft across the
area, which will dissipate shortly after sunset Saturday evening.




NEAR TERM...Stumpf

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