Winter Weather Advisory 4, NWS Omaha, NE

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1110 PM CST Sat Jan 23 2021

...Updated Aviation Forecast Discussion...

.DISCUSSION...
Issued at 330 PM CST Sat Jan 23 2021

Snow currently moving through most of southeast NE and western IA,
moderate in some locations with visibility down to 1/2 mile at
times in the heavier pockets. This has allowed roads to quickly
become snow covered across southeast NE with a quick dusting
already noted on webcams. NEDOT currently indicating many roads
partially to fully snow covered from Ashland southwestward. The
concern remains that on the back edge of the snow, which likely
exists from about Columbus southward to Beatrice, we lose the deep
saturation for snow and we transition to several hours of
freezing mist/freezing drizzle. This is already occurring as
evidenced by most recent observations across central NE with
widespread visibility 1-3 miles. This will result in a light
glaze of ice across much of the region this evening and overnight,
thus the reasoning for the expansion earlier of the winter
weather advisory earlier today. While the snow amounts are light,
it's the icing that we were concerned with compounding any travel
this evening. Snow amounts are mostly less an inch, but amounts
higher than an inch are forecast to the northeast of Omaha up to a
couple of inches.

The freezing mist gradually ends overnight with dry weather
expected Sunday.

Focus then shifts to a major winter storm that is expected to
impact the region Monday. Models remain in very good agreement
highlighting snow developing by daybreak Monday, mostly
along/south of Interstate 80 and continuing through early Tuesday.
With an expected closed low surface track to the south of Kansas
City, this puts portions of our forecast area in the favored track
for heavy wet snow, especially as a trowal/deformation zone sets
up from northeast KS through southeast NE, northwest MO and
southern IA. Current snowfall forecasts remain consistent from 6
to 10 inches, and in fact, some models suggest 10 to 13 inches
or even higher appear possible. After coordination with other NWS
offices and WPC earlier today, we did issue a winter storm watch
12z Monday through 12z Tuesday for heavy snow, along/south of
Interstate 80. The Interstate corridor has the highest potential
for uncertainty as the range could be 3-5 or 5-8, but would be
leaning toward the higher end amounts this time for south
periphery of the LNK/OMA/CBF metro areas. Our official peak forecast
range will mention 7-13" near Falls City. Snowfall rates Monday
afternoon could easily be 1-2" per hour. There is some
indication that there could also be marginal mid level
instability, and if that occurs, thudnersnow couldn't be ruled out
south of I80 as well. Northeasterly winds will increase to 15 to
30 mph, with higher gusts.

The second piece of this system moves across the area Tuesday into
Tuesday night, now about 12-18 hours earlier than previously
thought. Some lingering snow is possible into early Wednesday
morning, but the remainder of the extended forecast should be dry.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1110 PM CST Sat Jan 23 2021

Radar and surface observations suggest that any light freezing
drizzle has become quite patchy with some potential for a brief
period of light snow at KOFK within the next hour or two.
Otherwise, precipitation potential at KOMA and KLNK appears to
have diminished with prevailing MVFR ceilings expected overnight
into Sunday morning. IFR ceilings at KOFK could linger through the
overnight hours at KOFK. Light and variable winds currently being
observed will switch to the north at 5 to 7 kt within the next few
hours.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until 3 AM CST Sunday for NEZ033-034-044-
     045-051>053-066>068-089-090.

     Winter Storm Watch from Monday morning through late Monday night
     for NEZ052-053-065>068-078-088>093.

     Winter Weather Advisory until midnight CST tonight for NEZ011-
     012-015>018-030>032-042-043-050-065-078-088.

IA...Winter Storm Watch from Monday morning through late Monday night
     for IAZ069-079-080-090-091.

&&

DISCUSSION...DeWald
AVIATION...Mead

Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
348 PM CST Sat Jan 23 2021

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-241200-
Monona-Harrison-Shelby-Pottawattamie-Mills-Montgomery-Fremont-
Page-Knox-Cedar-Thurston-Antelope-Pierce-Wayne-Boone-Madison-
Stanton-Cuming-Burt-Platte-Colfax-Dodge-Washington-Butler-
Saunders-Douglas-Sarpy-Seward-Lancaster-Cass-Otoe-Saline-
Jefferson-Gage-Johnson-Nemaha-Pawnee-Richardson-
348 PM CST Sat Jan 23 2021

This Hazardous Weather Outlook is for portions of southwest
Iowa...west central Iowa...east central Nebraska...northeast
Nebraska and southeast Nebraska.

.DAY ONE...Tonight and Sunday

Areas of snow moving through the area late this afternoon into
early evening. The snow will transition to a period of freezing
drizzle through the remainder of the evening and early overnight.
Snow amounts should remain less than 2 inches, and icing amounts
up to one tenth of an inch could occur after the snow ends. Many
roads could become slick and hazardous through the evening. Thus,
a winter weather advisory is in effect for portions of eastern
Nebraska through tonight.

.DAYS TWO THROUGH SEVEN...Sunday night through Saturday

Confidence remains high that a significant winter will impact
southeast Nebraska and southwest Iowa on Monday. Current
indications suggest that several inches of snow will be possible
for southeast Nebraska and southwest Iowa along and south of
Interstate 80 where a winter storm watch is in effect. From 6 to
10 inches of snow are forecast, and some areas across southeast
Nebraska could see 10 to 13 inches. Lighter amounts, and possibly
little accumulation is expected for northeast Nebraska. Additional
light snow is forecast for Tuesday into Tuesday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1111 PM CST SAT JAN 23 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1109 PM     SNOW             4 NE BOYS TOWN          41.31N 96.08W
01/23/2021  E1.0 INCH        DOUGLAS            NE   PUBLIC

            NEAR 108TH AND FORT.

&&