Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 200457

Area Forecast Discussion
National Weather Service Norman OK
1057 PM CST Mon Feb 19 2018

Aviation discussion for the 06 UTC TAFs is below.


Have low confidence in the TAFs.

At KOKC and KOUN, believe conditions will worsen to MVFR by
08 UTC. South to southeasterly surface winds are expected at KOKC
by 06 UTC. Went with a later time of -TSRA (11-15 UTC), but storm
timing, if -TSRA happens at all, remains uncertain. IFR (possibly
LIFR) conditions and a wind shift to the north will likely occur
1-6 hours behind a cold front passage 12-17 UTC. Improving conditions
can be expected after 18 UTC.

AT KSPS and KLAW, think conditions will become MVFR by 08 UTC,
then improve to VFR again 10-14 UTC. Went with a later time
of -TSRA (11-14 UTC), but storm timing, if -TSRA happens at
all, remains uncertain. Brief MVFR/IFR conditions could briefly
occur with cold front passage 15-19 UTC, but did not mention due
to confidence.

KHBR, and KCSM, think VFR conditions will mainly occur before cold
front passage 12-17 UTC, though brief MVFR/IFR conditions could
occur especially near KCSM where surface winds may be variable and
tricky near a front. Brief MVFR or lower conditions will likely
occur just after cold front passage as well. Chances for -TSRA
remain too low to mention. Confidence is high that VFR conditions
will occur after 18 UTC.

At KPNC, worsening conditions are expected now through 14 UTC
with IFR/LIFR conditions expected. Airport minimums may be met as
well before 14 UTC. Went with -TSRA 11-14 UTC, but storm timing,
if -TSRA happens at all, remains uncertain. -PL and -FZRA could
occur as well, but did not mention due to low confidence of
occurrence. Improving conditions are expected after 14 UTC along
with increasing northerly surface winds.

At KWWR and KGAG, conditions will worsen to IFR/LIFR before 12
UTC, then improve. Chances of -SHRA/-TSRA remain too low to
mention at this time.



.PREV DISCUSSION... /issued 725 PM CST Mon Feb 19 2018/

Front moved further south than previously forecasted so have made
some adjustments to grids to account for this further south
position. It does appear that the front has stalled or at least
very nearly stalled. Front is forecast to lift back north
overnight the question is how far north. The 18Z NAM12 seems to
have the best handle on current front position, etc. This model
shows the front moving north to a line near Stillwater to
Cheyenne. This position is not as far north as other models.
Moisture will also spread back northward which could lead to an
area of fog development.

Showers/storms will remain possible the rest of this evening and
overnight. It appears that the better chance for precipitation
will increase overnight,especially in SE parts of the fa. Some
freezing rain may also be possible in far northern parts of the
fa. Temperatures could drop to around freezing in this area and
with the front not forecast to move that far north then
temperatures have a chance to still be freezing when precipitation
moves into the area. However, if the front moves further north
than forecasted freezing rain will not occur.

So adjusted temperatures, winds, and dewpoints to account for the
current and forecast position of the front. Lowered PoPs in some
areas for this evening. Also added a mention of fog and a chance
for freezing rain.




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