Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 211946

Area Forecast Discussion
National Weather Service Norman OK
146 PM CST Tue Jan 21 2020

Challenging forecast in the short term as precipitation moves across
the region tonight into tomorrow. Strong height falls and warm air
advection will provide strong forcing for ascent, most pronounced
across western Oklahoma before midnight, and across central and
eastern Oklahoma after midnight tonight. With southerly flow in the
low-levels, temperature profiles will be dependent on evaporational
cooling effects to sufficiently cool the column to support snow.
Models have trended slightly warmer across the board with the most
recent runs, but are still supportive of some snow across parts of
central and northern Oklahoma.

It appears the most likely time for snow will be within the first 4-
6 hours of precipitation onset as moderate to heavy rates work to
cool the column, and temperature profiles become isothermal along
the O C line. Where surface wet-bulb temperatures are near or below
freezing, a couple hour period of moderate to heavy snow appears
possible. This is most likely to occur across northern Oklahoma
early tomorrow morning, roughly north and east of an Enid to
Stillwater line. Up to an inch of wet snow accumulation is
possible for these areas, mostly on grassy surfaces. South and
west of there, precipitation type is more uncertain as temperature
profiles and surface temperatures are slightly warmer. These
areas, including the OKC metro, will likely see mostly rain with a
brief burst of snow possible if temperatures can sufficiently
wetbulb down. Little to no snow accumulation is expected for these
areas. Southwestern Oklahoma and western north Texas should
remain all rain through the duration of the event as temperature
profiles remain above freezing.

After the initial wave of heavier precipitation moves out of the
area tomorrow morning, temperatures should continue to warm and
precipitation type should just be rain. Expect rain showers to
continue for central and eastern Oklahoma through the day as the
upper shortwave crosses the region, with rain chances tapering
from west to east by late afternoon.


A somewhat active synoptic pattern will continue over the
weekend, bringing us a few weak fronts (keeping temperatures
seasonable) and a few chances for precipitation.

The first chance for rain in the long term will be mainly across
southern Oklahoma and north Texas as a shortwave passes through in
conjunction with some moisture return. With no front in play and
marginal moisture, chances will remain fairly low.

Monday is showing a little bit of downslope flow that may enhance
temperatures and winds during the afternoon. This seems to be
reflected in the blended MaxT grids. Raised Winds slightly.

The next significant chance for rain in the long term looks to be
next Tuesday / Wednesday with a more potent upper level system and
associated cold front as well as adequate moisture. Some isolated
thunderstorms may also be possible Tuesday afternoon.



.AVIATION... /issued 1157 AM CST Tue Jan 21 2020/

Conditions will deteriorate throughout the forecast period Tuesday
night into Wednesday. Southerly surface winds will increase and
become gusty Tuesday evening. Precipitation chances will increase
as a widespread line of showers enter the area Tuesday evening
move west to east. Ceilings are expected to plummet overnight,
with widespread IFR and LIFR conditions possible after 06Z. Slight
snow chances is possible within northern and central Oklahoma.



Oklahoma City OK  36  44  38  51 /  80  60  50  10
Hobart OK         37  53  35  54 /  80  40  20   0
Wichita Falls TX  40  53  41  56 /  80  50  30   0
Gage OK           35  53  31  52 /  80  20  10   0
Ponca City OK     34  42  34  49 /  80  70  50  10
Durant OK         35  43  39  53 /  80  80  60  30


OK...Winter Weather Advisory from midnight tonight to 9 AM CST
     Wednesday for OKZ007-008-013-020.



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