Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 200538
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1138 PM CST Tue Feb 19 2019

.SHORT TERM...(Tonight through Friday)
Issued at 400 PM CST Tue Feb 19 2019

The Winter Storm Warning is still on track for tonight into
Wednesday morning (with some slight adjustments to timing). Model
consistency has increased further with this morning`s runs,
painting a large swatch of 6+ inches of snow across most of
eastern Nebraska and southwest Iowa.

Diffluent mid level flow across the Plains ahead of deep trough
extending from Montana to New Mexico was inducing widespread lift
from western Oklahoma into Nebraska this afternoon. Somewhat dry low
level air was limiting the radar echos in our region to mostly
virga north of Omaha, with light snow occurring over south of the
city.

Through this evening, snow should efficiently spread from south
to north as strong lift overspreads the area. Cross sections and
forecast soundings suggest pockets of conditional instability
where convective snows could occur for several hours from late
evening through early morning. Thus snow rates of 1-2 inches per
hour are possible. A consensus of model output suggests
widespread 5 to 9 inch snowfall amounts are likely, but could see
some totals over 10 inches where convective bands set up.

Winds will average 5 to 15 mph through the evening, favoring an
easterly direction overnight then turning northerly Wednesday morning
before becoming westerly Wednesday afternoon. Also, will likely see
a gradual temperature increase overnight with most areas holding in
the lower to middle 20s through Wednesday morning. Not much of a
rebound Wednesday afternoon given new snow cover, despite some
afternoon sunshine.

Thursday will be the "break" day between wintry systems in the
Plains. For our region this will entail afternoon highs that
range from the upper 20s to mid 30s. Mostly sunny skies in the
morning will give way to increasing clouds through the day as
moisture streams in above 500 mb.

The next weather maker (upper trough) for our region will be
moving through the Southwest U.S. Friday. As this occurs, a
region of diffluent flow and weak isentropic assent should develop
over the Plains, returning the chances for precipitation to the
region. The precipitation chances will stick with us Friday night
as southerly flow ahead of a developing surface low in the lee of
the Rockies brings significant mid/low level warming. Models are
in reasonably good agreement with this trend. Hence the forecast
favors a chance for light snow Friday morning, transitioning to a
rain/snow mix Friday afternoon then mostly rain Friday night.

.LONG TERM...(Saturday through Tuesday)
Issued at 400 PM CST Tue Feb 19 2019

The upper trough over the Southwest is forecast to eject into the
Plains and deepen during the day on Saturday. As this occurs a
strong surface low is projected to develop in the lee of the
Rockies, then push to the northeast. Current models are in
remarkably good agreement on the track of the surface low, taking
it through Kansas, Missouri and then into the Great Lakes. While
adjustments in the this track are likely, confidence in this
system being a significant weather maker for our region is High.
Current thinking suggests mostly rain Saturday morning, turning to
snow Saturday afternoon as the surface low tracks to our
southeast. Significant snow accumulations of +6 inches,
blowing/drifting snow and strong winds all look possible at this
time. There appears to be at least some potential for blizzard
conditions. Those with weekend plans should continue to monitor
this system closely as impact appear likely.

Generally improving conditions Sunday, as the trough lifts to the
north and east. Temperatures will remain cold with prevailing
northwest winds.

The longwave trough that has been stuck over the Western U.S. for
the last couple weeks doesn`t appear to be going anywhere next
week. This will lend itself to the continuation of an active and
cold pattern, as shortwaves continue to eject from the larger
longwave trough and track across the Plains. This could bring snow
back to the region Monday or Tuesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1135 PM CST Tue Feb 19 2019

Band of moderate to heavy snow moving through the TAF sites at
this time, but should be clearing KLNK within the hours, and
KOMA/KOFK within a couple of hours. Visibility in this band 1/2
mile, but improving to 3/4 to 1 1/2 miles. Snow eventually ends by
14-16z from south to north.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Winter Storm Warning until noon CST Wednesday for NEZ012-015-018-
     034.

     Winter Storm Warning until 9 AM CST Wednesday for NEZ011-016-017-
     030>033-042>045-050>053-065>068-078-088>093.

IA...Winter Storm Warning until noon CST Wednesday for IAZ043-055-056.

     Winter Storm Warning until 9 AM CST Wednesday for IAZ069-079-080-
     090-091.

&&

$$

SHORT TERM...Dergan/Albright
LONG TERM...Albright
AVIATION...DeWald


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