Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 151736

Area Forecast Discussion
National Weather Service North Platte NE
1136 AM CST Thu Feb 15 2018

.SHORT TERM...(Today and tonight)
Issued at 339 AM CST Thu Feb 15 2018

The main sensible weather concern revolves around some very light
snowfall across northern NEB late morning-afternoon and moderate
breezes today. Latest satellite imagery shows a veil of mid- and
high-level clouds across the southwestern half of NEB, elsewhere
low- to mid-level clouds are present across the northern NEB
Panhandle into far southwest SD. Regional radar display shows some
light returns in the Panhandle, however, nothing is reaching the
ground. Latest water vapor imagery shows a shortwave trough
digging into central CA and the Central Great Basin, elsewhere a
weaker disturbance is over the Central Plains moving downstream.

Current thinking is this disturbance moving into the southwest
CONUS will continue east and lift into the Central Rockies later
today then on east. The combination of large scale forcing for
ascent and lower-level lift with modest moisture in place should
be conducive for some very light snowfall there. Otherwise, highs
will be cooler as colder air filters in along with limited
insolation with mostly cloudy skies. Highs will largely be 10-20
degrees cooler than yesterday, except towards extreme southwest
and south central NEB. Moderate breezes expected today also with
decent low-level cold air advection anticipated. BUFKIT soundings
show potential for upper level winds to mix down with gusts up to
30 MPH, peaking late today-early evening. Winds expected to then
lessen late evening on. This with colder air moving in and
clearing skies expected late tonight should help lows read 5 to 15
degrees below seasonable normal values, generally in the single
digits above zero with the coldest readings expected in the
extreme northwest.

.LONG TERM...(Friday through Wednesday)
Issued at 339 AM CST Thu Feb 15 2018

The long range solutions remain fixed in the synoptic scale in
that the overall pattern will transition from northwesterly on
Friday to southwesterly early next week. This is in response to a
dipping northern stream that will develop a trough over the
western CONUS and ridging to our east. There remains uncertainty
on the timing and amplification of the trough, but the ensembles
and the latest operational output are closing the gap and coming
into at least a general agreement. They suggest after a dry
weekend, POP chances will increase across the Plains and northern
Nebraska early next week. That being said, the operational models
still are at odds in the mesoscale and differ on the intensity and
location of the measurable precipitation. Thus at this point, an
overall blend of the latest guidance is a good starting point.

A post frontal modified Arctic airmass will be atop the forecast
area starting off the extended. The area of high pressure will
not linger though as westerly downsloping flow Friday forces the
high to the east. Temperatures are forecast to gradually warm
through the weekend with expected highs in the 30s and 40s
Saturday and 40s and 50s Sunday. Sunday evening the harsh reality
of winter returns when the digging western CONUS upper trough
forces a cold front across the forecast area. As it sits now,
light or moderate QPF will be possible along the primary forcing
of the mid-level front, which drops into northwest Nebraska early
Monday morning. Depending on the model of choice precip amounts
vary, but the general idea suggest the baroclinicity/front drops
south across the CWA on Monday as the atmosphere becomes
increasingly unstable in the post Arctic frontal environment.
Again, depending on the model, measurable snowfall will occur over
most western, northern and possibly central portions of the
forecast area before the FGEN become increasingly frontolytic over
south central/eastern portions of the cwa. Light snow chances
will linger through mid- week given the location of the upper
trough and a southwest tap.

With this set up, most of the moisture will be lost over the
various mountains to our west and southwest, which is good, they
need it. But, even a tenth or two tenths of an inch QPF could
produce significant fluffy snow accumulations given a high SLR in
the Arctic airmass.

As for temperatures next week, well below normal temperatures are
forecast Sunday night through Tuesday with gradual warming mid
week and beyond. Sub-zero lows return Tuesday and Wednesday
morning over northern Nebraska, and depending on the fresh snow
pack, bitterly cold lows will be possible. Wind Chill headlines
are possible Monday, Tuesday and Wednesday mornings. As the
forecast sits now, Tuesday morning readings should fall well below
minus 20 for much of the CWA with the possibility of minus 30 or
cold across our north. This may change, but stay tuned.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1136 AM CST Thu Feb 15 2018

Ceilings will continue to lower this afternoon across western and
north central Nebraska as a cold front passes through the area.
MVFR ceilings at the KVTN terminal will persist through the early
evening hours and may even dip below 1000 FT AGL this afternoon.
Lower ceilings will combine with light snow with visbys around a
mile at the KVTN terminal from 20z to 24z this afternoon.
Conditions and ceilings will improve this evening with VFR conds
expected. For the KLBF terminal: Some MVFR ceilings are possible
early this evening with CIGS down to 2000 FT AGL. VFR ceilings are
expected after 03z this evening with clearing expected overnight.




LONG TERM...Jacobs
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