Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 200548
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1148 PM CST Fri Jan 19 2018

.SHORT TERM...(Tonight through Monday)
Issued at 335 PM CST Fri Jan 19 2018

The main forecast issue is in regards to the winter storm system
that will affect the area Sunday into Monday. Freezing drizzle is
expected to develop over parts of the area Saturday night, which
will need to be monitored as we get closer. Right now that is not
expected to have a large impact, but things could change.

Mid level shortwave energy will be moving into the southwestern
United States tonight and that will be better sampled in the upper
air network this evening and Saturday. A couple of things noted
from the 12z upper air maps this morning included the following.
A broad area of height falls at 500 mb stretched from CA into
Saskatchewan and Manitoba at 12z this morning. At 850 mb, mild air
was noted over much of the plains, with 850 mb temperatures from
8 to 16 degrees C.

Tonight, expect variable clouds, mainly high clouds, with lows in
the 20s. Saturday should be dry with highs in the 40s.

Things start to change Saturday night, with drizzle or freezing
drizzle developing as low level moisture increases. Chances are
highest across southwest IA and southeast NE. The main upper
level support by early Saturday evening will still be back over
the southern and central Rockies, and the surface low with this
system is expected to move from southeast CO into the OK
panhandle Sunday morning. Surface temperatures will be critical
for precipitation type, but temperatures are currently expected to
warm above freezing in all of the area Sunday.

Kept the timing of our Winter Storm Watch as it was, but did add
some counties on the western side. Axis of heaviest snow is
expected to be from western NE into northeast NE/southeast SD,
northwest IA and southern MN. We will closely monitor that and
adjust if needed. Snow amounts could reach 6 inches or more in the
watch area and winds gusting to around 40 mph will be strong
enough to create considerable blowing and drifting snow Sunday
night into Monday morning. Current mid level mixing
ratios/specific humidities average about 3 g/kg with about 12 to
18 hours of moderate to strong upward vertical motion. See our
WSW product for more details. Some light snow could linger
through into Monday afternoon, but mainly in western IA. Highs
Monday should mostly range from around 30 to the mid 30s.

.LONG TERM...(Monday night through Friday)
Issued at 335 PM CST Fri Jan 19 2018

The period from Tuesday through Friday morning is expected to be
mainly dry with highs in the 30s and 40s. Lows will be mainly
teens and 20s. Our next chance of rain and snow arrives Friday
afternoon.

 &&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1047 AM CST Fri Jan 19 2018

VFR conditions are expected through the period. Light southerly
winds will swing around to the northwest late tonight and into
Saturday morning, as a weak cold front drops into the area.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1137 PM CST Fri Jan 19 2018

VFR conditions with variable high clouds. Low level moisture will
be on the increase late Saturday afternoon and Saturday evening.
Should see IFR clouds increasing from the south.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Winter Storm Watch from Sunday afternoon through Monday morning
     for NEZ011-012-015>018-030>033-042-043-050-065.

IA...None.
&&

$$

SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Zapotocny


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