Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 170522
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1122 PM CST Sun Feb 16 2020

...Updated Aviation Forecast Discussion...

.DISCUSSION...
Issued at 312 PM CST Sun Feb 16 2020

Forecast Summary:

Colder temperatures and a couple of chances for light
precipitation are forecast through mid week. Then we should see
warming once again for next weekend.

This afternoon through Monday:

Clouds thinned out this morning allowing for plenty of sunshine this
afternoon. And along with southwesterly winds, temperatures had
risen into the 50s in all but far northern parts of Nebraska and
west central Iowa.

The mild temperatures of this afternoon will be heading downward as
we approach mid week as a couple of low pressure systems drop
through the region. The first will track across the Northern Rockies
tonight then through eastern Nebraska and western Iowa Monday
afternoon. Warm advection ahead of this system will lead to
increasing cloud cover overnight, with modest isentropic upglide
helping saturation of mid then low levels as the night goes on.
Weak forcing suggests at least some precipitation should fall
across mainly the northern half of our CWA from after midnight
through about noon before we are in subsidence region of exiting
wave. Mild temperatures tonight combined with increasing clouds
and cooler air lagging behind system suggest most precipitation
will fall as rain across our CWA. Forecast soundings do indicate
snow in our north, but with warm grounds, not expecting much
accumulation.

Winds turn northwesterly later Monday morning with modest cooling to
follow. However with temperatures remaining near or above freezing
overnight, we should see a rebound into the 40s for most of our area
before cooler air invades for the afternoon.

Tuesday through Wednesday:

With temperatures beginning a downward trend behind Monday`s system,
a strong shortwave is scheduled to rotate through the region Tuesday
and Wednesday. Airmass behind attendant cold front should drop
temperatures well below mid-February normals, especially on
Wednesday when 1047mb surface high pressure will settle into Iowa.
850 temperatures drop into the -10 to -15C range across our CWA,
indicating highs in the 20s are all we can hope for Wednesday.

Ahead of mid level shortwave trough, forcing under right entrance
region of 110kt upper level jet inducing upglide over cool surface
air will drive light snow formation across our northern CWA
beginning Tuesday night and continuing through Wednesday while
slowly sinking south. Forecast soundings cool sufficiently to deepen
dendritic growth zone on Wednesday indicating a relatively efficient
snow-producing environment. However mixing ratios are low, generally
1 g/kg or less, and forcing is weak, so not expecting snow to pile
up very quickly. A consensus of model output concurs with this
evaluation, point to an inch or two favoring the northern half of
our forecast area.

Thursday through Sunday:

A warming trend continues to be advertised for late this week into
the weekend. Mid level heights begin to rise Thursday as mid level
shortwave trough swings east. Southwest surface flow sets up
Thursday afternoon, but cool surface temps will be slow to scour
out. Still, highs back into the 30s should be realized Thursday.
Warming continues into the weekend as 850 temps swing back into the
5-8C range by Saturday, suggesting highs in the 50s once again. By
Sunday, models diverge on mid level low tracking through the region.
GFS rotates low northeast through Kansas, spreading a swath of rain
across much of our area. The ECMWF tracks the low through the
Southern Plains, keeping precipitation south of our area. Have
split the differences in this regard and kept a small chance for
perception for Sunday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1120 PM CST Sun Feb 16 2020

VFR conditions initially with light southeast winds, which
eventually become northwest and increase to 12 to 24 knots by
17-19z. Wind gusts diminish by 18/00-02z. Could be a few rain
showers that affect the sites through the first 12 hours. Also
could see MVFR ceilings at KOMA 19-02z.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

DISCUSSION...Dergan
AVIATION...DeWald



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