Area Forecast Discussion
Issued by NWS Tulsa, OK

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FXUS64 KTSA 181038

Area Forecast Discussion
National Weather Service Tulsa OK
438 AM CST Mon Dec 18 2017



Difficult aviation forecast for the next few hours. Erosion of the
low cloud deck from the west that was occurring a few hours ago
has largely stopped, with low clouds even back building west in
satellite data. As such, fog, especially dense fog, is becoming
increasingly unlikely at the terminals. The exception may be MLC
where surface obs indicate that low clouds and lower visibilities
are climbing northward into southeast Oklahoma. Because of this,
will include a tempo group for IFR visibility and lowered ceiling
through 15Z at MLC, with MVFR ceilings continuing through 18Z.
Ongoing IFR/MVFR conditions at the remaining 7 terminals should
improve 15-16Z, with VFR conditions prevailing through 03-06Z. IFR
conditions will again be likely at the eastern Oklahoma terminals
and MVFR at the northwest Arkansas terminals thereafter.


.PREV DISCUSSION... /Issued 356 AM CST Mon Dec 18 2017/

Stubborn low clouds continue to cause forecasting headaches, and
may continue to do so at least off and on for the next few days.
Where skies have cleared just west of our forecast area, dense
fog quickly developed. As such, have kept some mention of fog this
morning in the western part of the forecast area in case we start
seeing some breaks in the cloud cover.

A westerly component to the low level flow should allow at least
some partial clearing today, perhaps initially in the higher
terrain areas of southeast Oklahoma and northwest Arkansas given
the shallowness of the moisture. This should allow temperatures to
warm into the upper 50s to lower 60s.

Low clouds are likely to overspread the area again tonight, which
will keep overnight temperatures on the mild side. An upper level
storm will move across the area late Tuesday and Tuesday night,
bringing widespread rain to at least the southern part of the
forecast area. Rain chances will drop off to the north.

Mild to warm weather will continue through Thursday, with Thursday
likely to be the last warm day for quite some time. An initial
cold front will sweep south across the area Thursday night and
early Friday, with the possibility for a few showers to develop
near and north of the front. Temperatures will fall to below
normal levels behind this front, but will not be overly cold

A secondary surge of even colder air will arrive over the weekend,
and there are some hints in the data that a band of light snow
could sweep across the area behind this front. The models differ
on the timing, location, and intensity of this snow band, so for
now will just introduce low pops for Saturday night and Sunday
with very light amounts. Temperatures behind this front Sunday and
Monday may struggle to reach freezing in some places.

Generally went between the warmer GFS MOS and cooler NAM MOS for
temperatures the next couple days given the uncertainties with low
cloud coverage.




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