Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 111728
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1128 AM CST Thu Jan 11 2018

.SHORT TERM...(Today through Saturday)
Issued at 314 AM CST Thu Jan 11 2018

Winter weather has overspread most of the area and will reach the
rest shortly. Subjective 00Z upper-air analysis indicates upper-
level troughing broadly from SK to MT/WY, NE panhandle through the
CO/KS border, and then southward through eastern NM toward far west
TX. 500mb height falls were as high as 160m in west TX, with a broad
expanse of 30m+ falls reaching the MS River valley. A 160kt upper-
level jet extended from western BC through ID/NV, with 130kt
rounding the base of the trough into west TX. Distinct cold front
was evident at 850mb, as sub-0C air had descended into WY/SD/far
northwest NE, with temps below -25C into northeast MT. The 850mb
cold front at 00z extended from northern ON through northeast MN to
the IA-SD-MN border area to central NE and toward a secondary low
centered in northeast NM. Surface low at 08Z was centered in western
OK and also in the western UP of MI/northern WI. The cold front
extending between the low centers had passed through KICL-KAFK-near
KMHK by 0830Z, likely just approaching KFNB, and sub-freezing
temperatures lagged about 50-ish miles behind the front.

Several areas of precipitation were underway at 08Z. A band of
snowfall moving through central NE was just reaching northeast NE,
but radar trends exhibit some weakening. A smattering of
precipitation was developing ahead of that line, roughly along and a
county or two either side of Interstate 80, and precipitation at
least was beginning as a mix of freezing drizzle, sleet, and snow.
Further south, rain extended across northeast KS to northwest MO,
just clipping southeasternmost NE, and into south central IA.
Precipitation will continue to progress eastward, turning to all
snow over the next few hours. Short-term models have come to some
agreement with the GFS/NAM solutions on a band of snow extending
from central to southwest IA, southeasternmost NE, and into
northeast KS, where frontogenetic lift is maximized. Weak stability
is still not ideally located over the frontogenetic zone, likely
among the factors in the lower snow totals. In that band, a 50-ish
mile wide swath of snow totals of 3-5" should fall. Elsewhere, a
dusting to 2 inches of snow is possible, with higher snow totals
closer to the main band. The combination of light snow, light
freezing drizzle/icing, and gusty winds with sharply falling
temperatures is enough to maintain the current advisory even in
areas that are not expected to see under an inch of snow, at least
for now. Will continue an advisory in the southern areas that should
see more snow, too, with stronger wording for blowing snow and white-
out conditions this morning into early afternoon as the heaviest
snow falls while winds are around 25-30 mph.

Winds will diminish this evening, easing the blowing snow concerns
for areas that do get enough snow for it to blow around. With lows
tonight in the single digits either side of zero, and winds around 5-
10mph, wind chills will fall to around -10 to -18F everywhere - not
quite cold enough for an advisory, but substantially colder than the
last few days. A shortwave will drop through the northern Rockies
and into NE/KS on Friday afternoon and evening, prompting another
round of light snow. Amounts should be in the quarter inch to inch
range across the area, with the higher amounts likely in northeast
Nebraska. Did bump POPs in northeast NE, as the potential looks high
enough for a likely mention. Behind that wave, temperatures get
another cold push for Saturday. Lows on Saturday morning again will
be in the single digits either side of zero, but with light winds,
the wind chill forecast is not as cold as it looked a day or two
ago.

.LONG TERM...(Saturday night through Wednesday)
Issued at 314 AM CST Thu Jan 11 2018

Yet another fast-moving wave could produce another light snow
dusting on Saturday night into Sunday morning, with maybe a half
inch currently in the forecast if it materializes. A short-lived
brush with moderating temperatures is forecast for Sunday with some
mid-level warming, but another rather substantial cold air push will
arrive on Sunday evening. There has been reasonable consistency in
some light precipitation along the cold front as it pushes through
the area, especially as it reaches the KS-MO border areas, and have
increased POPs there. Behind that cold front lies the coldest
weather of this particular cold snap, with lows Monday night
forecast to be well below zero everywhere and with wind chills of -
15 to -25 everywhere. Moderation will begin on Tuesday but will take
some time to overcome the cold air in place. Highs should return to
the upper 20s to around 30 on Wednesday and should crack freezing on
Thursday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1123 AM CST Thu Jan 11 2018

Radar trend over the last couple hours indicate just a matter of
time now before SN moves out of ERN NE and into W-CNTRL IA.
Activity will continue to dissipate at KLNK/KOMA and expect
conditions to improve to VFR toward 20Z. As for KOFK, MVFR cigs
will likely hang on until 21Z with conditions improving to VFR.
VFR conditions prevailing then the remainder of the fcst pd.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until noon CST today for NEZ045-051>053-
     066-067-089.

     Winter Weather Advisory until 3 PM CST this afternoon for NEZ068-
     090>093.

IA...Winter Weather Advisory until noon CST today for IAZ055-056-069-
     079.

     Winter Weather Advisory until 3 PM CST this afternoon for IAZ080-
     090-091.

&&

$$

SHORT TERM...Mayes
LONG TERM...Mayes
AVIATION...DEE



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