Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 161751
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1251 PM CDT Mon Apr 16 2018

.SYNOPSIS...
Issued at 352 AM CDT Mon Apr 16 2018

At 08z...Surface high pressure extended from eastern North Dakota,
through central South Dakota, central Nebraska, and central Kansas.
A winter storm system centered near Chicago continues to affect the
Great Lakes region and advance slowly east. Mainly cloudy skies
continued east of Springview through Burwell. Clear skies prevailed
across much of western Nebraska. Temperatures mainly ranged in the
mid teens central Sandhills, the the mid 20s far western Sandhills.
Beneath cloudy skies, the eastern areas were in the upper 20s. North
Platte has tied the record low, while Valentine and Broken Bow were
each two degrees from tying a record low as of 08z.

&&

.SHORT TERM...(Today and tonight)
Issued at 352 AM CDT Mon Apr 16 2018

An upper ridge axis will move into western Nebraska today. As a
western trough moves into the Great Basin, surface low pressure will
deepen over the Front Range, as high pressure extends from the
Missouri Valley into the southern Mississippi Valley. Southeast
winds will increase across western Nebraska in response to this.
Winds increase to 15 to 25 mph across the western third of the area,
to 5 to 15 mph in the east. Morning stratus will slowly errode in
the east, as high clouds increase this afternoon across the west.
temperatures were raised a few degrees from previous forecast, due
to increased mixing, and mostly sunny skies into this afternoon.

For tonight, mid and high clouds increase after midnight. The upper
trough will move into western Wyoming and eastern Utah late tonight.
A southeast wind will continue at 5 to 15 mph overnight.
Temperatures not as cold from the mid to upper 20s northeast, to
around 30 across the west.

.LONG TERM...(Tuesday through Sunday)
Issued at 352 AM CDT Mon Apr 16 2018

The passage of two main upper lows/troughs and associated surface
systems highlights the forecast challenge over the next week.

Tuesday and Wednesday... The sfc low emerges on the CO/WY high
plains early Tue, curves southeast along the NE/KS border, then
turns northeast toward DSM by Wed PM. Aloft, the GFS and ECM are in
general agreement with a trough digging and taking on a slight
negative tilt, and closing a low off over NE/SD. Meanwhile, a 100kt+
H3 jet streak brushes SW Neb. With the upper low deepening and
taking a northerly track, north central Neb is placed in the main
deformation zone. Some differences remain in the model suite with
temps (H85 temps ranging from 0C to -4C), which could play a big
role in ptype. Forecast soundings suggest ice initiation in the
cloud layer due to deep saturation, but much of the thermal profile
is warmer than the DGZ. Lift and fgen are strong at times as the low
passes, but being colocated with the DGZ is relatively brief.
Overall, leaning toward a rain/snow mix for much of the event as
lows only reach near 30F, with a few hours of all snow. Snow
probability increases for north central Neb where temps are slightly
cooler and precip rate will be higher. WPC is trending toward higher
snow accumulation potential, but with uncertainty in thermal
profile, hedged toward lower end of plumes and kept generally 1-3"
east of VTN to BBW. Regardless of accumulation, a couple concerns
exist with this event. The first being ice potential with rain in
the evening then temps falling below freezing. The second is wind,
where any snow Wed AM could be blown and greatly reduce visibility.
Will need to monitor for possible Winter Wx Advisory.

Thursday and beyond... The next closed low is progged to cross the
southern/central Plains Friday into Saturday. The 16/00z model suite
suggests a slightly faster moving system with the amount of cold air
still in question. Confidence remains relatively low for snow
accumulation as it appears to be daytime rain and nighttime mix/snow
event.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1250 PM CDT Mon Apr 16 2018

Overall, quiet aviation conditions expected through Tuesday. High
pressure over the region will allow dry weather and mostly clear
skies to continue. Clouds begin to increase towards late Tuesday
morning as the next disturbance is forecasted to move into the
region on Tuesday evening. There is also a chance for some low
level wind shear across both terminals Monday night.

&&

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

$$

SYNOPSIS...Roberg
SHORT TERM...Roberg
LONG TERM...Snively
AVIATION...Kulik



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