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000
FXUS64 KTSA 161149
AFDTSA

Area Forecast Discussion
National Weather Service Tulsa OK
549 AM CST Wed Jan 16 2019

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
MVFR ceiling heights should slowly rise this morning becoming VFR at
most locations this afternoon, however overcast conditions will likely
persist. As upper disturbance approaches tonight, lower cloud deck
is expected with LIFR ceilings late tonight, including the potential
for patchy dense fog. Scattered areas of light rain and/or light
drizzle also possible across northwest Arkansas late tonight in
association with disturbance / WAA regime.

&&

.PREV DISCUSSION... /Issued 255 AM CST Wed Jan 16 2019/

DISCUSSION...
Forecast focus remains squarely on the strong storm system set to
move through Friday night and into Saturday, with strong
thunderstorms, accumulating snow, significantly colder temperatures,
and low wind chills all possible. Models continue to struggle with
consistency in timing and the eventual path of the surface and
upper level features, and as such, low confidence remains in the
details surrounding this event.

Presently, low stratus deck continues across most of the forecast
area, with expansion of the cloud deck likely to lead to at least
mostly cloudy skies most locations by daybreak. Expect cloudy
skies to persist for much of the day as low level moisture expands
ahead of a fast moving disturbance that will push through the
region tonight. Have kept toward the lower end of guidance for
temperatures today due to the expected cloud cover. Showers and/or
drizzle will be possible overnight as the disturbance moves
through. Clouds should diminish some behind the disturbance,
resulting in highs expected to be a few degrees warmer than
today.

Cloud cover will increase again from the west during the day
Friday as the stronger system approaches, with the initial rain
still expected to hold off until the afternoon. Isolated
thunderstorms ahead of the approaching cold front still look to be
a good bet, especially across southeast Oklahoma, given forecast
instability. Any strong thunderstorm potential should be limited
to areas near the Red River, where CAPEs of 500-1000 J/kg are
currently forecast. With the current models trending slower, the
thunderstorm potential will linger into early Saturday morning.
This slower trend will also delay the onset of any notable wintry
precipitation until after daybreak Saturday. It continues to look
like most areas will see rain with a transition to snow, although
there still looks like there could be a narrow buffer time frame
when freezing rain/sleet could be possible. Accumulations of
either will be negligible with snow dominating in the wintry
precipitation department. Besides the slower model trend, there is
also a more southerly trend than the 15/00Z suite, more like the
15/12Z suite. If this trend holds, this could place the maximum
amounts in eastern Oklahoma farther south than the Kansas border
and perhaps similarly in northwest Arkansas. For now, will go with
a broad brush 2 to 3 inch area north of I-40 given the difficulty
in pinpointing where any snow band might set up. Precipitation
remains likely to move out by early Sunday morning.

With regards to the expected cold temperatures, the cold air
intrusion does not look quite as strong this morning as it did 24
hours ago. Forecast temperatures from Saturday night into early
next week will be a few degrees higher this cycle but not
significantly so. The likelihood of single digit wind chills late
Saturday night and early Sunday morning remains high.

There will be a good warmup early next week immediately ahead of
the next system set to move through Tuesday and into Wednesday.
This system will have some winter weather potential as well,
although details with this one are even more uncertain than the
weekend system.

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&

$$


AVIATION.....12