Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 232349

Area Forecast Discussion
National Weather Service Huntsville AL
649 PM CDT Wed Aug 23 2017

For 00Z TAFS.


.NEAR TERM...(Tonight)
Issued at 242 PM CDT Wed Aug 23 2017

Quiet and slightly below normal temps prevail across the cntrl TN
Valley this Wed afternoon in the wake of a cold frontal passage
earlier today. Drier air associated with the boundary is making its
way swd into mid TN and should begin to filter into the local area by
the onset of the evening hrs. Lingering low/mid sct cu across much of
the area should begin to diminish with the influx of drier air this
evening. Temp trends currently in the lower/mid 80s should quickly
lower this evening into the 70s and eventually into the lower 60s
for most locations by early Thu morning.

.SHORT TERM...(Thursday through Friday night)
Issued at 242 PM CDT Wed Aug 23 2017

Quiet and tranquil conditions will prevail across the mid TN Valley
thru the end of the work week, as a strong area of high pressure
builds ewd across the Midwest/OH Valley regions. Afternoon temps
look to remain slightly below seasonal trends Thu/Fri, with highs
mainly in the mid 80s for most areas while overnight lows Thu
night/Fri night remain in the lower/mid 60s. Moisture below H7 may
begin to creep back into the region Fri night, as low level winds
begin to veer toward the SE/E.

.LONG TERM...(Saturday through Tuesday)
Issued at 242 PM CDT Wed Aug 23 2017

Weak northwest flow will persist aloft on Saturday, with surface
winds generally to the east-northeast as high pressure builds along
the east coast. Moisture will be somewhat limited across the local
area, however there might be just enough to see some very isolated
showers and thunderstorms during the afternoon hours.

An upper level low will begin to dig southward and into the Upper
Midwest on Sunday, tracking southeastward in a more broad upper
trough extending across much of the eastern CONUS. Weak shortwaves
in the northwest flow aloft will move through the TN Valley on
Sunday, as greater moisture begins to lift northward across the
region. This will bring a greater coverage of showers and
thunderstorms during the day, though still scattered in coverage.
The TN Valley will generally remain under the influence of the broad
upper trough through the first half of next week, keeping diurnally
driven thunderstorms in the forecast for Monday and Tuesday.
Meanwhile, Harvey will meander around the SE TX coast through the
weekend and then lift northward and towards the TN Valley early next
week. It should be noted that models have come into much better
agreement in terms of the timing of Harvey`s movement (though some
timing and placement discrepancies remain), with the first impacts
to the local area expected as early as next Tuesday night. While
there may be periods of greater thunderstorm coverage, given the
uncertainties on where and how quickly Harvey tracks, will keep
scattered thunderstorms in the forecast through the extended period.
It`s still a bit early to look at the overall impacts to the local
area, but heavy rainfall does appear likely across portions of the
TN Valley during the latter half of next week.

Temperatures through the period will remain just below normal for
late August. The combination of northwest flow/low upper heights and
cloud cover will keep afternoon highs in the lower to mid 80s.
Meanwhile, overnight lows will generally cool into the 60s.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 649 PM CDT Wed Aug 23 2017

Lower level cumulus clouds across the Tennessee Valley were on a
dissipating stage with early evening cooling. However, broken mid and
high altitude clouds associated with a weak upper disturbance and
from convection to our west continued to stream across much of the
region. Those clouds should dissipate during the overnight. High
pressure building towards the region from the north will bring VFR
weather for the TAF period. Northerly winds around 5KT this evening
should become light from the south during the later evening and
overnight, then become NE 5-10KT after daybreak Thursday.





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