Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 241555

Area Forecast Discussion
National Weather Service Huntsville AL
1055 AM CDT Sat Jun 24 2017

.NEAR TERM...(Rest of Today)
Issued at 1055 AM CDT Sat Jun 24 2017

Near term guidance is in agreement that a mid-level vort max in the
wake of the remnants of TC Cindy will continue to weaken and spread
rapidly into NC/SC today. This will occur within confluent 500-mb
flow between a subtropical ridge centered off the east coast of FL
and a compact trough digging southeastward across the upper MS
valley. As a result of the gradual decreasing trend in large scale
ascent throughout the day, precipitation redevelopment is not
anticipated in the wake of lingering showers currently departing our
southeastern counties. POPs have been decreased and weather grids
have been adjusted accordingly based on this reasoning. The max
temperature forecast is a little more complicated...and dependent on
the scattering of low/mid-level cloud cover currently in place across
the region. Assuming that subsident vertical motions are sufficient
to result in partial clearing of these clouds, highs will likely be a
few degrees warmer than originally anticipated, and afternoon temps
have been increased by a degree or two for most of the CWFA.

.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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