FXUS64 KHUN 230818

Area Forecast Discussion
National Weather Service Huntsville AL
218 AM CST Thu Nov 23 2017

.NEAR TERM...(Today)
Issued at 218 AM CST Thu Nov 23 2017

Happy Thanksgiving from the HUN midnight crew! Latest water vapor
images are showing an upper trough digging into NW MS with cirrus
clouds streaming along and ahead of it. Locally, light winds and
clear skies have set up great radiational cooling conditions with
2AM temps in the middle 20s to lower 30s. Dew points are in the mid
to upper 20s so the temps should continue to fall another few
degrees. A few cirrus clouds may impact us early this morning but
shoudln't impact the temps. The trough will move through this
afternoon but won't do much to the sensible weather. Behind it, a
steep ridge and surface high pressure will quickly build in. This,
combined with the mostly sunny skies, will push highs into the
middle to upper 50s, even under the northwest flow.

.SHORT TERM...(Tonight through Saturday Night)
Issued at 218 AM CST Thu Nov 23 2017

Another fantastic radiational cooling night is forecast for tonight
but with slightly warmer 850mb temps and a moisture surge from the
southeast, lows will be slightly warmer, in the upper 20s to middle
30s. As the surface high shifts east on Friday, winds at the surface
turn southwesterly, helping warm highs in to the lower 60s and lows
in the lower 40s. A weak trough will move through on Saturday but
the low levels of the atmosphere remain pretty dry. This front
should only bring an increase in mid to high level clouds Sat and
then start to clear out again Sat night. The cooler northwest flow
will drop lows Sat night into the middle to upper 30s.

.LONG TERM...(Sunday through Wednesday)
Issued at 218 AM CST Thu Nov 23 2017

Another strong dome of high pressure out of the Plains states will
begin to build ewd into the SE region by the start of Sun, in the
wake of a cold frontal passage earlier in the weekend. Any lingering
cloud cover from the earlier frontal passage should also be quickly
exiting to the SE, as drier air below H5 begins to stream into the
cntrl TN Valley. The influx of cooler air should also be fairly
brief, with lows perhaps falling close to the freezing mark Sun
night, before a gradual warming trend begins going more into the new
work week. Highs look to climb back toward the 60F mark on Mon, with
lows that night trending more in the upper 30s/around 40F, as the
sfc high begins to translate ewd into the mid/srn Atlantic Basins.

With the sfc high exiting to the E, Gulf moisture may be able to
stream back into the region Tue into Wed, given the development of a
return flow pattern. Highs on Tue also look to rebound more into the
mid 60s, before the influx of cloud cover out of the W begins Tue
night. The latter half of the global model runs are still suggesting
another cold front dropping into the region around the middle of next
week, as an upper trough pattern quickly moves ewd across the Plains
states. There is some timing discrepancies between the latest ECMWF
and GFS, with the GFS the faster solution with the frontal passage by
some 12-24 hrs. Persistence would keep this next cold frontal passage
in the late Tue/Wed time frame. Given some moisture return back into
the area coupled with some weak dynamic lift along the oncoming sfc
boundary, the next chc of rain/showers still looks to be in the late
Tue thru Wed evening time frame. Any rainfall should then quickly
make its way to the SE by Thu with the passage of the cold front as
another strong dome of high pressure out of the Plains states builds
ewd into the region.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1045 PM CST Wed Nov 22 2017

No changes to previous aviation forecast reasoning. VFR conditions
will prevail at the HSV/MSL terminals thru the period. However, an
upper-lvl disturbance embedded within NW flow aloft will track across
the region late tonight, bringing an increase in ci clouds by
09-12Z. Another upper-lvl wave will push sewd tomorrow, with sct
ac/ci expected during the late morning/early aftn hours. NNE flow
will remain elevated in the 5-10 knot range this evening, but should
diminish to 3-5 knots after Midnight. Winds will remain light, but
back to NNW after sunrise tomorrow. If winds diminish sufficiently
after Midnight, patchy fzfg may develop btwn 08-13Z in ne AL river
valleys, but this is not expected to impact either terminal at this





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