Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 141724
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1124 AM CST Sat Jan 14 2017

.SYNOPSIS...
Issued at 328 AM CST Sat Jan 14 2017

Upper level low pressure well defined in water vapor imagery early
this morning just off the SoCal/Baja coast. Weak lead PV anomaly
moving into southern AZ, and weaker system also progressing across
the Dakotas. Moisture ahead of the system streaming northeastward
from the southwest U.S. and does have a connection to tropical
convection located in the eastern Pacific. A glance at observed
sounding data shows total column moisture values nearing
climatological maxes for this time of year in portions of the
southern Plains, so moisture likely won`t be a problem for this
system. Closer to Nebraska, mainly mid and high clouds across the
area currently with a few echoes showing up on radar indicating
mid clouds and possibly virga as cloud bases are around 12K ft.&&

.SHORT TERM...(Today and tonight)
Issued at 328 AM CST Sat Jan 14 2017

For today, will see mid and high clouds continue to increase across
the southern portion of the area. Main upper low will begin to track
eastward across Baja into northern Mexico. Large area of
condensation and cloud development, and eventual precipitation will
occur across the southern Plains today which will ultimately serve
to build the downstream ridge ahead of eastward moving upper low.
All this leads to the system taking on a negative tilt which is
important when considering the further development of the system.
However a dry forecast for western NE today and highs slightly
warmer temps despite some cloud cover.

Tonight, main push of low level moisture on track to move in toward
daybreak Sunday morning through the southern High Plains. Even
though moisture values are high there will still be some dry air in
the mid levels initially. Hence will include the potential for light
freezing rain/drizzle in far southeast Frontier county around 6 AM
Sunday morning. Conditions deteriorate after that. Low temps coldest
in the north where less cloud cover remains overnight.

.LONG TERM...(Sunday through Friday)
Issued at 328 AM CST Sat Jan 14 2017

The upper level low will be rounding the base of the long wave
trough Sunday morning, and begin it`s northeastward turn from
northwest Mexico toward the central plains. Due to such a far
southward position initially, a robust amount of subtropical
moisture will be drawn northward into the central plains ahead of
the system. This will set the stage for widespread freezing rain
and snow. Most models (minus the GFS) have locked on to a track
which places at least the southeast half of western and north
central Nebraska under the gun for a decent amount of
precipitation. A warm layer aloft will be present Sunday into
Sunday night which will keep the precipitation as freezing rain or
perhaps sleet, but colder temperatures aloft by late Sunday night
into Monday will allow the precipitation to change to all snow.
Snow could become heavy for a time within a deformation band,
which most likely appears would set up along a line from roughly
O`Neill to Broken Bow to North Platte. This is where several
inches of snow could accumulate, with lesser amounts northwest of
this area. Prior to the snow, some ice accumulation of one tenth
to one quarter of an inch could also accumulate. Will keep the
winter storm watch going and mention all these hazards.

Mid to late week a nice warm up is in store, with highs well into
the 40s and 50s. This will be welcome, melting any ice
accumulation and significantly reducing any snowpack.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1122 AM CST Sat Jan 14 2017

VFR conditions are light winds are expected to prevail across
much of western and north central Nebraska through the next 24
hours. Only forecast concern will be the threat for light freezing
rain in southwest Nebraska Sunday morning. At this point,
confidence is not high enough to include any mention of -FZRA in
the KLBF TAF as the better chances look to hold off until after
18z.

&&

.HYDROLOGY...
Issued at 328 AM CST Sat Jan 14 2017

Frazzle ice continues to impact area streams and rivers.  The North
Platte River above Lake Mcconaughy has seen fluctuations due to
minor ice jamming the past several days, most notably at Lewellen
and Lisco.  Warmer temperatures helped alleviate some of the ice
issues early this week, but colder temperatures have returned.  Will
continue a RVS for Lewellen until the ice issues are fully
resolved and upgrade if needed.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Sunday afternoon through Monday
afternoon for NEZ007>010-025>029-036>038-057>059-069>071.

&&

$$

SYNOPSIS...Stoppkotte
SHORT TERM...Stoppkotte
LONG TERM...Taylor
AVIATION...Martin
HYDROLOGY...Roberg



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