Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 232355
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
555 PM CST Thu Feb 23 2017

.SHORT TERM...(tonight through Sunday)
Issued at 220 PM CST Thu Feb 23 2017

...Major winter storm still on track to affect the region through
Friday...

Forecast overall remains on track for a major winter storm to
affect the region tonight into Friday. Some complications for the
expected weather include a chance of thunderstorms this evening
across southeast Nebraska and southwest Iowa, which will include a
severe threat with some hail possible. Second compounding factor
will be a changeover from rain to snow, where that initially sets
up, and how fast it moves southeast through time. Northeasterly
winds will continue to increase to 20 to 30 mph through time, with
gusts 30 to 40 mph possible. One of the major changes that we
have made with the upcoming package is to include a slightly
faster changeover from rain to snow based pm Rap model trends.

A couple of notes regarding QPF, the GFS model came in a little
lower, while the SREF and NAM models perhaps a little higher,
which both indicate up to 12 inches or more from northern NE
through northern IA. The ECMWF as not as high, similar to the GFS.
Blending all of that together, combined with input from WPC.
Overall, forecast snowfall amounts have not changed significantly
from the previous package. We are still forecasting 6 to 10 inches
for the northern half of the forecast area, from 2 to 5 along and
either side of Interstate 80, and an inch or less in southeast
Nebraska.

Concerning our current package of winter weather headlines, we
anticipate no major changes with this package, although we may
adjust the start time of the last group of headlines. We feel the
the overall alignment and message of expected impacts looks good
with current products in effect. We do have very strong winds
forecast with this system, and will continue to mention near
blizzard conditions expected with 1/2 mile visibility along with
blowing snow and possibly drifting. However, just not confident
we`ll see widespread 1/4 mile visibility for 3+ hours, thus have
no plans to upgrade any of the area to a blizzard warning at this
time.

Snow accumulation rates will be winding down significantly Friday
afternoon, tapering to flurries, and ending altogether before
midnight. Due to recent warmth, soil temperatures are running in
the mid to upper 40s. This will easily be overcome by expected
rates.

Impacts to travel will eventually develop. Near blizzard
conditions are expected across northeast NE and northwest IA.
Travel may eventually become impossible over parts of of the area.

Quiet weather expected on Saturday. Another weather system brings
a chance of small snow and rain south of I80 on Sunday, with the
GFS a little more robust than the ECMWF.

.LONG TERM...(Sunday night through Thursday)
Issued at 220 PM CST Thu Feb 23 2017

Another quick moving weather system moves through the region on
Tuesday. Again, the GFS is more robust with this than the ECMWF,
but we will have a chance of snow and rain in the forecast. And
one more system may graze our northern counties on Wednesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 555 PM CST Thu Feb 23 2017

Precipitation has switched over to snow at KOFK, and periods of
moderate to heavy snow are expected to continue through the
evening with gusty north and northeast winds. Lighter snowfall and
some blowing snow is then expected late tonight and into Friday
with IFR conditions continuing. Scattered TSRA are still expected
at KLNK/KOMA this evening, with some possibility of a sleet and
rain mixture near the end around 06Z. We then expect a dry period
into the night with continued IFR conditions. The snowband is
likely to move into KLNK/KOMA around 08-10Z and continue through
the day on Friday with IFR conditions expected through the day.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Winter Storm Warning from 3 AM Friday to midnight CST Friday
     night for NEZ034-044-045.

     Winter Weather Advisory from 3 AM Friday to midnight CST Friday
     night for NEZ050>053-065>067.

     Winter Storm Warning from 10 PM this evening to midnight CST
     Friday night for NEZ015-032-033-042-043.

     Winter Storm Warning until midnight CST Friday night for NEZ011-
     012-016>018-030-031.

IA...Winter Storm Warning from 3 AM Friday to midnight CST Friday
     night for IAZ043-055.

     Winter Weather Advisory from 3 AM Friday to midnight CST Friday
     night for IAZ056-069-079.

&&

$$

SHORT TERM...DeWald
LONG TERM...DeWald
AVIATION...Boustead


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