Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 112104
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
304 PM CST Wed Jan 11 2017

.SHORT TERM...(This evening through Thursday)
Issued at 303 PM CST Wed Jan 11 2017

Chances for light snowfall through this evening and temperatures
overnight will be the primary focus of the short term period.  Radar
trends as of 20z show developing snowfall across much of the western
and northern Sandhills, but dry air continues to limit most of the
precipitation from hitting the ground. This should be overcome by
late afternoon and evening as mid-level ascent increases. Expecting
snowfall to become more concentrated by this evening as recent
hrrr/rap solutions forecast show an area of enhanced mid-level fgen
moving out of southwest Wyo/southern Neb Panhandle and kicking
northeast across the central tier of the CWA. Light snowfall may be
observed as far south as Interstate 80 in southwest Nebraska if mid-
level dry air can be overcome.

Precipitation chances quickly push east of the forecast area
overnight as an area of surface high pressure slides eastward across
South Dakota. Expecting the coldest air to remain north of our area,
but the forecast still favors temperatures slightly below guidance
given clearing skies and the chance for a fresh layer of snowfall
over parts of the area. Going with single digits above and below
zero with the coldest readings in northwest Nebraska.

Quiet conditions will be seen on Thursday as surface high pressure
dominates the weather pattern over much of the Central and Northern
Plains. With nearly zonal flow aloft the cold front stalls out in
Kansas. This will keep the CWA under the influence of a shallow
Arctic airmass with below normal temperatures.

.LONG TERM...(Thursday night through Wednesday)
Issued at 303 PM CST Wed Jan 11 2017

As upper flow becomes southwest Thursday night into Friday, a
disturbance in the southern stream flow will bring a slight
chance for snow to the north central zones. Little if any
accumulation expected.

The airmass will modify by Friday as surface winds become light
southerly and highs moderate into the mid to upper 20s.

A closed upper low will cross Baja Mexico, to the south of Arizona
on Saturday as an upper ridge extends from the southeastern U.S.
into the southern Plains. The system will take on a negative tilt
Saturday night and Sunday as it moves into eastern New Mexico. This
will draw Gulf moisture northward into Nebraska by Sunday. The
closed low associated with the system will move into western
Kansas Sunday night, into eastern Nebraska Monday. Likely snow
chances Sunday night into Monday across the southeast. Medium
range models have made an adjustment a bit further northwest. It
appears a well defined deformation zone will develop from eastern
Colorado into northwest Kansas and southwest Nebraska and extend
northeast through central Nebraska.

A look at model soundings favor snow as the main precip type. Some
sleet may mix in Sunday night in eastern areas. Otherwise snow is
expected. Given an anomalously high precipitable water value near
six tenths of an inch at North Platte Sunday evening, heavy snow
is possible. Snow ratios should be low however near 10 to 1.
Accumulating snow around an inch is possible along a line from
Ogallala through Bassett, with more significant snowfall amounts
to the southeast. Due to a sharp gradient, little if any snow is
forecast across the northwest half of the forecast area. Northerly
winds should increase Sunday night into Monday to 10 to 20 mph,
which could cause some blowing snow issues.

Snow chances should come to an end Monday night as system fills
and lifts into the western Great Lakes. The upper flows is
forecast to become fairly zonal by Wednesday with temperatures
potentially warming into the lower 40s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1125 AM CST Wed Jan 11 2017

Primary concern through the next 24 hours will be the chance for
snowfall and IFR conditions across northwest and north central
Nebraska this afternoon and evening. Model guidance continues to
show a band of snowfall developing in the Panhandle and pushing
east this afternoon, impacting KVTN. Confidence is high in MVFR
cigs/visbys by mid-afternoon and into the evening. The snowfall is
expected to be light, but IFR conditions are possible at times.
Conditions are expected to improve by early in the overnight hours
as VFR returns to the forecast through Thursday morning.

Further south, including KLBF, cloud cover will increase later
this afternoon, however model guidance has consistently kept cigs
VFR generally around 5 kft this evening. Current obs show cigs a
little lower than forecast, currently around 2 kft at KOGA.
Trends will need to be monitored and adjustments made include MVFR
cigs in the TAF if necessary. Clearing skies are expected
overnight.

&&

.HYDROLOGY...
Issued at 153 PM CST Wed Jan 11 2017

The North Platte River above Lake Mcconaughy has seen elevated
river levels above action stage due to minor ice jamming the past
several days at Lewellen and Lisco. Cold temperatures have arrived
today and will continue through Friday, which could increase ice
jamming concerns. Will continue an RVS for both sites until the
ice issues are fully resolved.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...Martin
LONG TERM...Roberg
AVIATION...Martin
HYDROLOGY...Roberg



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