Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 290055 AAB

Area Forecast Discussion...UPDATED
National Weather Service Huntsville AL
755 PM CDT Wed Jun 28 2017

.NEAR TERM...(Tonight)
Issued at 755 PM CDT Wed Jun 28 2017

As the sun sets, the few or scattered cumulus are dissipating across
north AL and southern TN. High clouds fanning northeast from the
Gulf Coast region will begin to clip our southern north AL counties
this evening. Deep convection which developed at the northern fringe
of deeper moisture is showing signs of diminishing in west central
into central AL. Short term model trends, including the HRRR still
suggest convection trying to enter north AL around daybreak. Any
activity will be isolated, so have maintained a 20 PoP generally
south of the TN river. However, I have delayed the PoP until after
09z. Otherwise, the forecast grids look good and few other changes
are needed at this time.

.SHORT TERM...(Thursday through Friday)
Issued at 301 PM CDT Wed Jun 28 2017

A return of the above noted moisture and instability will bring an
unsettled end to the work week. Scattered shower/thunderstorm chances
should be across the region Thursday morning as deeper moisture
returns. Upped the ante with likely shower/t-storm chances during the
afternoon, as an upper level system moves across the region from the
southwest. As of now, only "general" thunderstorms intensity wise
are expected with the usual gusty winds, locally heavy rainfall and
sudden lightning strikes. Precip water amounts per the NAM/GFS creep
up into the 1.5 to 2 inch range by Thursday afternoon; which
definitely could support gusty winds, frequent lightning and heavy

Rain chances should reduce somewhat Thursday night as the system
passes to our northeast. Still keep some chance of rain in the
forecast given an already unstable atmosphere and past convection.
Business picks up more during Friday, as yet another passing upper
level system provides lift to an already unstable environment, with
more numerous showers/thunderstorms - especially Friday afternoon.

.LONG TERM...(Friday night through Tuesday)
Issued at 301 PM CDT Wed Jun 28 2017

The extended forecast will be unsettled and warm. As we head into
the weekend, an upper level ridge spread across the eastern Gulf and
into the Atlantic will stream moisture into the region and a trough
swinging into the Great Lakes will send a series of disturbances
through. On Saturday, shear will be weak (10-20kts), but as CAPE
values get up to 1-2,000 J/kg, there could be a few strong
thunderstorms. However with the amount of cloud cover expected by
Saturday afternoon instability could be limited. Saturday`s highs
will be in the mid 80s with a heat index in the lower 90s and an
overnight low only cooling down towards 70 degrees.

These main synoptic features will weaken by Sunday but seem anchored
heading into the beginning of the work week. Additional disturbances
combined with daytime heating will provide a lingering chance of
showers and thunderstorms. Temps will warm into the upper 80s/around
90 degrees with overnight lows in the lower 70s. With 70 degree
dewpoints still in place, heat index values also increase from
low/mid 90s on Sunday to the mid/upper 90s on Tuesday.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 541 PM CDT Wed Jun 28 2017

VFR flight weather conditions should last through most of if not all
of tonight. Low and mid level moisture will increase late tonight
into Thursday which will lead to scattered to broken layers between
015-025agl (possible MVFR) and 040-100agl (VFR). Scattered to
numerous showers and a few thunderstorms are expected to develop by
late morning into the afternoon hours. Have included VCSH at both
KMSL and KHSV after 14Z for now, but may need to include
thunderstorms in future updates when coverage and timing are more





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