Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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606
FXUS64 KOUN 012349
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
549 PM CST Thu Dec 1 2016

.DISCUSSION...
00Z TAFs.

&&

.AVIATION...
The weak surface boundary across northwest Oklahoma will slowly
move southeast tonight and Friday morning. The backing of the
winds ahead of the front will be more of a gradual backing than
what the TAFs may indicate where the old BECMG transition might
have been more appropriate. Conditions will mainly be VFR with
MVFR conditions developing late in the forecast period in the
southwest /mainly KSPS/ as low clouds and showers begin to spread
into the area.

&&

.PREV DISCUSSION... /issued 256 PM CST Thu Dec 1 2016/

DISCUSSION...
The current forecast challenge is precipitation and low temperatures
over the weekend.

The seasonably cool and dry weather will come to an end tomorrow as
an upper level low moves in. Fairly high confidence in precipitation
spreading over the CWA Friday night through Saturday. The question
that comes up is in regard to precipitation type across northwest
Oklahoma Saturday morning. Model blends want to bring surface
temperatures down to freezing or just below in that region. However,
these blends incorporate bias corrected grids which may not be
appropriate for the weather regime change. GFS and ECMWF raw data
are trending 5 to 7 degrees warmer than the blend. The more recent
NAM guidance is trending cooler than previous runs, though still a
bit warmer than the blend. Trended on the warmer side using a raw
model blend, leaving out bias corrected guidance. Left a small
region of rain/snow mix in far northwest Oklahoma, but not
expecting any kind of accumulation.

A second round of precipitation is expected Monday morning as the
low lifts back out. Timing does not look to be concurrent with the
low temperatures to present any risk of frozen precipitation.

After this, models begin to diverge greatly. ECMWF lags a full 24
hours behind the GFS in the timing of a low mid week next week. This
will bring in a strong blast of cold air, but the front looks to be
fairly dry.

Day

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  34  56  43  47 /   0  20  60  70
Hobart OK         32  54  42  46 /   0  40  70  60
Wichita Falls TX  40  56  45  47 /   0  40  70  80
Gage OK           27  51  36  43 /   0  20  60  50
Ponca City OK     33  55  40  48 /   0  10  50  50
Durant OK         40  60  46  48 /   0  10  70  90

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&

$$



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