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fxus64 khun 201827 

Area forecast discussion
National Weather Service Huntsville Alabama
127 PM CDT Tue Aug 20 2019

Near term...(tonight)
issued at 127 PM CDT Tue Aug 20 2019

Visible imagery and radar indicates that the preferred areas of
convective development are along the Cumberland Plateau and brindley
plateau/mtns at this hour. There is also development in the deeper
moisture and higher cape field across middle Tennessee into Kentucky. These storms
should remain to our north this evening. Will continue to carry a
low pop into this evening, primarily for our higher terrain locations
and south of the Tennessee River, much like the hrrr indicates. Will leave
the heat advisory in place for now. The large scale mesoscale convective system now in the
southeast corn belt and lower Ohio Valley will make progress southeast
into Kentucky and northern Tennessee overnight. It is less clear if this system
will reach into southern Tennessee or north Alabama per short range model runs.
Will carry a very low pop in southern Tennessee and far northeast Alabama late

Short term...(wednesday through thursday)
issued at 127 PM CDT Tue Aug 20 2019

At this point, confidence is too low to carry much more than a slight
chance or chance pop on Wednesday. The possible MCS, remnants or
outflow boundary may slip into southern Tennessee or far north Alabama on
Wednesday, but may also tend to mix out quickly and lift back
northward. The GFS solution suggests a more defined mesoscale convective vortex than the NAM
hovering over southern Tennessee through Wed afternoon. At this point, will
carry a chance pop during the afternoon, weighted heavier northeast
and east portions of our forecast area. If this feature is realized
and persists as the GFS suggest into Wed night, will have to make
further adjustments. If the NAM is correct, a more diffuse feature is
noted with less precip coverage Wed afternoon into Wed night. At this
point, heat index values will remain below advisory levels.

As the ridge breaks down further aloft and flow becomes more westerly
across the MO into Ohio valleys, there is more doubt on whether the
next mesoscale convective system on Wed night will dive south into the Tennessee Valley on Thursday.
The frontal system may also tend to stay further north on Thursday,
concentrating thunderstorms along it well to our north. Will keep
pops in mid chance range on Thursday, and elevate our temperatures a
bit more into the 90s from suggested model blends.

Long term...(thursday night through monday)
issued at 127 PM CDT Tue Aug 20 2019

Weak frontal boundary is still expected to drift swd into the cntrl
Tennessee Valley by the end of the work week, although the latest global
model suites are a little slower with the progression of the sfc
boundary. The front will still be aided by a broad/weak upper trough
axis moving sewd into the region. As such, sct/num showers/tstms
should develop during the day Fri along the weak boundary as it
settles more into the area. Given the depth of the moisture profile
by the end of the week, brief heavy downpours/localized flooding
issues will certainly be a concern over areas that see multiple
storms. This GOES along with the threat for gusty outflow winds with
any heavier showers/tstms. The front is xpcted to meander across the
area into the weekend period, with again sct/num showers/tstms
possible on Sat. These rain chances will certainly continue sun into
Mon, although they may not be quite as high, as the front drifts a
little more to the south. With the increase in cloud cover/rainfall,
afternoon temps are not xpcted to be quite as hot compared to the
first of the week, with highs more in the mid/upper 80s. Overnight
lows look to remain predom in the upper 60s/near 70f.


Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1129 am CDT Tue Aug 20 2019

VFR flight weather conditions are expected through the period. There
is a low probability of thunderstorms this afternoon and early this
evening, but too low to include in either taf. Also, patchy late
night River Valley fog is also possible, but mainly in northeast Alabama
and not affecting the terminals.


Hun watches/warnings/advisories...
Alabama...heat advisory until 9 PM CDT this evening for alz001>008-016.



Near term...17
short term...17
long term...09

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