Winter Storm Warning 1, NWS Norman, OK

Area Forecast Discussion
National Weather Service Norman OK
1047 PM CST Mon Jan 27 2020

...New AVIATION...

.SHORT TERM...
(This Evening through Tuesday Night)
Issued at 316 PM CST Mon Jan 27 2020

We are converting the Winter Storm Watch to a Winter Weather
Advisory with this package. Areas of 1-3 inches of wet snow are
forecast, with some locations around 4 inches possible in far
northwest Oklahoma, specifically Harper County. But there is still
some question about the timing of the transition to snow and the
duration of accumulating snow, and where the heaviest banding will
set up.

The longwave trough approaching the area tonight continues to
amplify with plenty of low-level moisture having moved into the
area today. Cold air will be a relatively late arrival and will
begin moving into the area after midnight as the surface low
shifts east-southeast across west Texas into north Texas. QPF
amounts are rather healthy and look like will be enhanced somewhat
from the enhanced vertical motion northwest of low-level
frontogenesis progged in the 925/850 mb layer. The question is
when sufficient low-level cooling arrives to make a changeover to
snow and how long the heavy snowfall will occur. We will likely
see 1 to 3 inch amounts in the advisory area with some potential
for 4 inches in far northwest. Decided to keep it with an advisory
for now since some of the QPF will be falling as rain or a mix
instead of pure snow, but will be watching the trends in the low-
level thermodynamics closely.

Precip will decrease from west to east Tuesday, but will still
have precipitation chances linger in the eastern part of the area
into Tuesday evening.

&&

.LONG TERM...
(Wednesday through next Sunday) Issued at 321 PM CST Mon Jan 27
2020

An upper ridge will be building on Wednesday, as our weather system
moves off to the east.  A couple more shortwave trough will be
meandering through at the end of the week.  The shortwave on
Thursday will taking another southern track across northern Texas.
Both medium range models have a good handle on the timing and track,
but now differ in precipitation and forcing. The ECMWF is showing
weak forcing and little moisture return, and keeping the QPF
generally south of the Red River while the GFS is a little more
aggressive with stronger vorticity/vertical motions, a moisture
return, and more widespread QPF. With hardly any midweek moisture
return likely this far north, any weather activity should remain
across Texas. For now will continue to stick with the previous
forecast and ECMWF solution by keeping low POPs for light rain
restricted to just a couple of our counties in western north Texas.
On Friday, a second short wave digging Central High Plains will push
a dry and weak downslope cold front across our area.

This weekend, a large amplitude ridge of high pressure will be
building across the entire southwestern U.S. and extending to the
Southern Plains. West winds will bring in dry and mild air off the
higher plains, keeping temperatures well above seasonably normal.
Sunday could see highs in the lower to mid 70s.

&&

.AVIATION...
(06Z TAFS)
Issued at 1026 PM CST Mon Jan 27 2020

Most areas will quickly drop into MVFR category early in the
forecast with a drop to IFR overnight. These conditions are
expected to continue through much of the day and into tomorrow
evening. Winds will come around to the north during the day
tomorrow and become quite gusty.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  40  42  29  45 /  90 100  60   0
Hobart OK         36  43  26  49 /  90 100  20   0
Wichita Falls TX  47  52  32  51 /  60  70  30   0
Gage OK           28  36  20  46 / 100 100  10   0
Ponca City OK     32  36  25  41 /  50 100  60   0
Durant OK         48  53  37  48 / 100 100  70  10

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Winter Weather Advisory until 6 PM CST Tuesday for OKZ004>007-
     009>011-014>017.

TX...None.
&&

SHORT TERM...30
LONG TERM....08
AVIATION...30

Hazardous Weather Outlook...UPDATED
National Weather Service Norman OK
422 PM CST Mon Jan 27 2020

OKZ004>048-050>052-TXZ083>090-282230-
Harper-Woods-Alfalfa-Grant-Kay-Ellis-Woodward-Major-Garfield-
Noble-Roger Mills-Dewey-Custer-Blaine-Kingfisher-Logan-Payne-
Beckham-Washita-Caddo-Canadian-Oklahoma-Lincoln-Grady-McClain-
Cleveland-Pottawatomie-Seminole-Hughes-Harmon-Greer-Kiowa-Jackson-
Tillman-Comanche-Stephens-Garvin-Murray-Pontotoc-Coal-Cotton-
Jefferson-Carter-Johnston-Atoka-Love-Marshall-Bryan-Hardeman-
Foard-Wilbarger-Wichita-Knox-Baylor-Archer-Clay-
422 PM CST Mon Jan 27 2020

This hazardous weather outlook is for portions of northern...
western...central...and southern Oklahoma...and western north
Texas.

.DAY ONE...Through Tonight...

.Winter Weather...
A winter storm is expected to impact northwest Oklahoma after
midnight tonight where accumulating snow may create significant
impacts on roads by daybreak Tuesday. A winter weather advisory is
in effect.

.Thunderstorms...
Isolated non-severe thunderstorms will be possible over the
southern-half of Oklahoma and all of western north Texas tonight.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday...

.Winter weather...
Accumulating snow is possible across northern and northwestern
parts of Oklahoma. Accumulations could be enough to have
significant impacts to travel. A winter weather advisory is in
effect for Tuesday. Snow accumulations of 3 to 6 inches are
possible. Farther south and east, rain may mix with or change over
to snow late Tuesday with little or no accumulations.

.Thunderstorms...
Isolated non-severe thunderstorms are possible Tuesday across
southern Oklahoma and western north Texas.

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