Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 241135

Area Forecast Discussion
National Weather Service Huntsville AL
635 AM CDT Sat Jun 24 2017

For 12Z TAFS.


.NEAR TERM...(Today)
Issued at 409 AM CDT Sat Jun 24 2017

The remnants of former Tropical Depression Cindy, now over the
northern Mid Atlantic region was heading to the north and east,
after being picked up by the northern stream yesterday. Despite the
"core" of this system was now well northeast of the Tennessee Valley,
lots of residual moisture present was resulting in widespread clouds
and scattered showers. Even a lone thunderstorm with intermittent
lightning that formed near Florence an hour or so ago was moving
towards the greater Huntsville area. Under cloudy skies, rather mild
conditions prevailed across the central Tennessee Valley with night-
time lows in the low/mid 70s, and light/variable winds.

A somewhat drier trend will take place after daybreak today, as a
cold front now lurking across the region continues moving further
to the south. Despite the passage of the front, lots of post frontal
lower level moisture present will keep some chance of showers and
thunderstorms in the forecast, mainly this morning. Rain chances
should diminish from north to south this afternoon as the front
pushes further to the south and drier/cooler air to our north
filters in.

Went cooler than guidance for highs today, given extensive clouds
and showers lurking around the region, and the cooler air moving in.

.SHORT TERM...(Tonight through Monday)
Issued at 409 AM CDT Sat Jun 24 2017

Rather deep troughing for this time of year will dig southward across
the eastern CONUS into early next week. This trough and surface
Canadian high pressure building southward will bring cooler
conditions across the Tennessee Valley to start the first full week
of summer. High temperatures should range 5-7 degrees below norms
for Sunday and Monday. We stayed below guidance and with previous
continuity, with highs both days only in the lower 80s. Average highs
both days are around 90 this time of year. Corresponding low temps
will also be "chilly" for late June, down into the upper 50s to
around 60 --- with running seasonable averages around 69.

Even with more sun and drying opportunities on Sunday and Monday,
plenty of residual moisture from the recent bout of heavy rains
will remain. Forecast dewpoint values will be a few degrees cooler
than night time lows, which should for the most part keep fog
formation minimized. However those more sheltered spots could be
affected by late night fog. Did not include fog in the short term
period at this time with limited confidence on it occurring.

.LONG TERM...(Monday night through Friday)
Issued at 409 AM CDT Sat Jun 24 2017

Relatively quiet and mild wx conditions will start this part of the
forecast period for the cntrl TN Valley, as a large ridge of high
pressure out of the nrn/mid Plains/Midwest states continues to build
sewd into much of the SE region. Large upper trough pattern from the
Great Lakes into the wrn Gulf region will also continue to translate
ewd towards the Atlantic coastal states. The combination of the sfc
high approaching the local area coupled with cooler air below H7
mixing sewd into the region will result in some unseasonably cooler
air continuing into the new work week for the cntrl TN Valley. Highs
both Mon/Tue look to remain predom in the lower 80s, while overnight
lows from Mon morning thru Wed morning trend mainly in the upper
50s/lower 60s for most locations (normal highs are near 90F while
lows are arnd 69F). With high pressure settling into the mid TN
Valley/mid Atlantic states and the upper trough axis giving way to
weak upper ridging out of the Plains states gradually shifting ewd,
skies should become mostly clr/partly cloudy into mid week.

A gradual warming trend is then xpcted to develop across the area
starting Wed, as the sfc high translates ewd into the mid Atlantic
waters and upper ridging quickly traverses over the cntrl/ern Gulf
states. Afternoon highs Wed look to rebound more into the mid/upper
80s while early morning lows Thu increase back into the mid/upper
60s. Iso/sct showers/tstms return for the latter half of the forecast
period, as a fairly deep sly flow regime below H5 develops and Gulf
moisture spreads nwd into the mid TN Valley. This should also result
in weak isentropic lift developing over much of the region, thereby
providing an additional focus mech for showers/tstm development, to
go along with convection driven by latent heating. This general trend
should continue thru the end of the work week, with overall temps
remaining near seasonal.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 635 AM CDT Sat Jun 24 2017

A frontal boundary across the Tennessee Valley will slowly move
southward during the course of today. Remaining showers and embedded
thunderstorms associated with this front will move southward with the
front, ending across the forecast area by the late morning. Given
on-going shower activity in the vicinity of KHSV, maintained VCSH
with a possible brief reduction to MVFR for the start of the TAF.
Additional showers are unlikely at KMSL. Winds will become northwest
in the 5-10kt range this afternoon. Winds should decrease under
scattered, VFR ceilings this evening, as high pressure from Canada
settles southward across the Tennessee Valley.





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