Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 202321
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
521 PM CST Tue Feb 20 2018

.SHORT TERM...(This evening through Wednesday)
Issued at 318 PM CST Tue Feb 20 2018

Latest satellite imagery shows predominantly clear skies overhead
with a nice line of separation noted between fresh snow-covered
ground and little-no snow across far northwest KS into south
central NEB. Latest water vapor imagery shows an amplified long
wave trough affecting much of the western CONUS and high pressure
offshore the southeast CONUS.

Our sensible weather concern revolves around wind chills tonight
into tomorrow morning. While skies are clear presently overhead,
current thinking is some clouds will make there way into southwest
NEB overnight. However, think these clouds will only have minor
impacts on temperatures overnight. Latest mesoanalysis and MSAS
analysis shows surface high pressure currently over the Northern
High Plains extending into NEB. Surface high pressure will slide
eastward overnight to southeast SD/northeast NEB. Meanwhile, winds
currently 10-15 MPH will lessen through mid evening becoming
light to calm though breezes will persist across northern NEB.
These light breezes with fresh snow cover and cold temperatures
necessitated wind chill warnings and advisories for portions of
northern NEB, coldest across northern Sheridan and western Cherry
(wind chills as low as 35 below zero). Further, the forecast lows
were modified towards the cold-end with respect to the forecast
envelope given the fresh snow. Lows are forecast from about 2
below to 18 below zero, coldest in the extreme northwest.
Tomorrow, despite mostly sunny skies, temperatures will remain
well below-normal with highs largely 15 to 20 degrees below
seasonable normal values. Otherwise, quiet and fair conditions
will prevail.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 318 PM CST Tue Feb 20 2018

Beginning 00z Thursday. A long wave trough centered over the Great
Basin will be the primary player in our weather through Saturday
before swinging through the plains on Sunday. This will promote a
gradual warming trend with near seasonal temperatures expected by
Sunday for the Sandhills and surrounding areas. Precipitation
chances will be tied to a series of shortwaves, first of which
arrives on Thursday. The previous shift noted that saturation in
the lower levels are less than ideal, but shown to increase as the
wave passes through. The models are keying on the development of
precipitation generally in two areas. First is in an area of
strengthening h5-7 FGEN across western portions of our CWA while
weak upglide is maximized. We expect light snow to develop and
expand northeast from southwest Nebraska through the central
Sandhills after 12z. The second area of stronger FGEN develops
across our southeast and extends northeastward after 18z. Both
areas show temperatures support of snow with some weak instability
in the form of neg-EPV. Snow rates on the order of a half inch
per hour would be possible under convective enhancement.

The shortwave pulls to the east as the long wave cruises across
the Rockies. Increasing qg with strong FGEN banding associated
with the long wave will begin the next round of snow to the
forecast area. The main area of potential looks to be squarely
across southwest Nebraska up through north central Nebraska.
Better moisture and stronger combination of lift will promote
moderate accumulations, which most will fall as snow. Temperatures
may be supportive of a brief period of rain or wintery mix, so
will need to monitor closely.

Westerly flow will follow the departing wave with a slight warm up
for late week and early next week. Precipitation chances look to
be slight at best days 6-7 until the next potential wave sets up
mid or late week next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 521 PM CST Tue Feb 20 2018

VFR conditions the next 24 hours at the KLBF and KVTN terminals.
Mainly SKC conditions tonight and Wednesday. Light and variable
winds tonight will be southerly on Wednesday at less than 10 kts.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Wind Chill Warning until 10 AM CST /9 AM MST/ Wednesday for
NEZ004-094.

Wind Chill Advisory from 11 PM CST /10 PM MST/ this evening to
10 AM CST /9 AM MST/ Wednesday for NEZ005-006-008.

&&

$$

SHORT TERM...ET
LONG TERM...Jacobs
AVIATION...Roberg



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