Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 241129

Area Forecast Discussion
National Weather Service Huntsville AL
629 AM CDT Mon Jul 24 2017

For 12Z TAFS.


.NEAR TERM...(Now through Today)
Issued at 337 AM  CDT Mon Jul 24 2017

A couple outflow boundaries from earlier convection in Middle TN
continue to push south through the central CWA this morning. KHSV
observed a wind gust to 31 KT from the north along this boundary as
it moved through. This boundary, currently moving through Cullman
Co., has been the source of a large area of showers with a few
embedded thunderstorms. For the rest of the morning, expecting a few
more storms to initiate along the boundary, mainly south of HWY 72,
but gradually decrease in coverage, leaving behind a few showers as
day breaks. For the areas that clear out quickly from the showers,
patchy fog will likely linger through sunrise.

For the rest of today, with plenty of moisture and instability in
place again, expect another round of scattered thunderstorms this
afternoon. Northern zones, including the TN counties could see a
better shot of some potentially stronger storms today as a weak short
wave with a slightly enhanced area of vorticity rotates through the
Ohio Valley and parts of the TN Valley. Models soundings from S.
Middle TN suggest slightly more instability thanks to more favorable
mid level lapse rates compared to southern zones. However, overall
coverage expected to be greater in the southern zones given higher
available moisture.

.SHORT TERM...(Tonight through Wednesday)
Issued at 337 AM CDT Mon Jul 24 2017

A weak, stalled surface boundary will remained draped across the
Ohio Valley. This will help keep seasonably warm and moist
conditions in place through mid week. We`ll see the start of a break
in this pattern late in the period as the boundary to the north
starts to drift south helping to filter in some slightly drier air.
While scattered thunderstorms will remain in the forecast, PoPs will
slightly decrease each day from north to south. However, with a steady
decrease in rain chances through Wednesday, temps will be able to
rebound to the low the mid 90s given less cloud cover. Not expecting
heat like we had a few days ago, as dew points should stay in the low
70s, but the heat index could push 100 each day, especially near and
west of the I 65 corridor.

.LONG TERM...(Wednesday night through Sunday)
Issued at 337 AM CDT Mon Jul 24 2017

The latter half of the work week is looking to end on a wet note,
with an H5 ridge holding tight over the Desert SW/Intermountain
West, placing the HUN CWFA in NWrly flow (thanks to a departing trof
to the E). This setup will pinwheel a disturbance toward the area,
rounding the base of the trof to our E, bringing a cold front to the
area on Friday/Saturday. Both the GFS/ECMWF are showing at least
isolated to scattered showers and storms on both Thursday and Friday
afternoons ahead of this feature. The GFS is by far the more
progressive of the two, with both a stronger front pushing across
the area on Friday into Saturday, and a quicker ending of the precip
just after sunrise Saturday morning.

Given good run-to-run model consistency with the more progressive
pattern, have trended the temps/PoPs toward the GFS again this
shift. This should translate to temps a few degrees cooler than
we`ve seen here recently, only topping out in the middle/upper 80s
in the afternoons, after starting out in the middle 60s this

The `drier` air filtering into the area post-fropa will be short-
lived, however, as the subtropical high retrogrades Wwrd off the SE
FL coast. The recently-departed upper disturbance will begin to
meander W/NW back into the area, bringing moisture/unsettled weather
by Sunday night and especially into Monday/Tuesday. This should set
the stage for more showers and thunderstorms as we begin the new
work week.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 630 AM CDT Mon Jul 24 2017

Shower and thunderstorm activity from earlier this morning has
diminished. There remains a weak shower just north of MSL at the
moment that is slowly sagging south but weakening. Expecting VFR
conditions to generally prevail today but thunderstorms will again be
possible this afternoon/evening. For now, kept TS wording out of the
forecast given the anticipated widely scattered nature of the
storms. Any storm activity should be ending in the 0-2Z timeframe
before patchy fog develops during the early morning hours.




NEAR TERM...Barron

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