Area Forecast Discussion
Issued by NWS Tulsa, OK

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FXUS64 KTSA 122330 CCA

Area Forecast Discussion
National Weather Service Tulsa OK
526 PM CST Thu Jan 12 2017

MVFR to IFR ceilings will continue to overspread eastern Oklahoma
and western Arkansas Tonight with precipitation developing later
tonight into Friday. Freezing rain or drizzle will affect the
northeast Oklahoma TAF sites later tonight into Friday morning. Rain
will be predominate elsewhere.


.PREV DISCUSSION... /Issued 409 PM CST Thu Jan 12 2017/

The arctic airmass has overspread most of the area...with
temperatures in the 30s across NE OK to the 70s in far SE
OK. The 12z OUN sounding revealed the true shallow nature of
this cold air...with the sub freezing depth less than 1500
feet. As we often see...the bulk of the numerical models did
a poor job resolving this low-level cold air...although the
latest NAM12 and higher resolution NAM-WRF appear to have a
reasonable handle (although they might not be cold enough)
and we have followed their thermal profiles very closely for
this forecast.

Areas of light precipitation should begin to develop this
evening just north of the arctic front...then spread north
later tonight into northeast OK/northwest AR. Steady wet-bulbing
will bring surface temperatures down through the night...with
areas of light freezing drizzle or freezing rain developing
generally along and north of the I-44 corridor toward daybreak.
Have issued a freezing rain advisory for this area...and have opted
to extend it just a bit farther south into parts of NE OK and
NW AR. Will allow the initial freezing rain advisory to expire
tomorrow at 18z as surface temperatures rise just above freezing.
Obviously this will need to be monitored very closely...and expect
some short-fuse updates with later forecasts.

Areas of the north of I-44 are expected to remain below freezing
or very near freezing for an extended period from later tonight
into Sunday morning. While continuous freezing rain is not
expected...there will be periodic bands of light freezing rain
through this period. An ice storm warning has been hoisted for
Pawnee...Osage...Washington and Nowata counties...where around a
quarter to half inch of ice accumulation is possible. Locally
heavier amounts near three-quarters of an inch will be possible
especially in northwestern sections of Pawnee and Osage counties.
There are some indications that the precipitation will have a
convective element...which could result in brief/rapid ice
accumulation. There is the possibility that parts of the warning
area could rise above freezing Friday and Saturday afternoon...but
for simplicity sakes will run the ice storm warning from Friday
morning through early Sunday morning. Areas near the I-44 corridor
will be under another freezing rain advisory during this time
as well.

Temperatures will finally warm well above freezing by Sunday in
advance of a strong upper low moving through the southwestern
states. The upper low will eject into western TX/western KS
Sunday night into Monday...with a large area of showers/isolated
thunderstorms moving through the forecast area. Instability should
remain low...but strong wind fields could result in a few severe
storms. Locally heavy rainfall will be a good possibility as well.

Rainfall should be exiting to the east later Monday/Monday night
with generally quieter weather anticipated for the remainder of
next week.


OK...Freezing Rain Advisory from midnight tonight to noon CST Friday
     for OKZ057-058-060>065.

     Freezing Rain Advisory from 6 PM Friday to noon CST Saturday for

     Ice Storm Warning from 6 AM Friday to 6 AM CST Sunday for

AR...Freezing Rain Advisory from midnight tonight to noon CST Friday
     for ARZ001-002.



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