Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 131121

Area Forecast Discussion
National Weather Service North Platte NE
621 AM CDT Tue Apr 13 2021

.SHORT TERM...(Today through Wednesday)
Issued at 359 AM CDT Tue Apr 13 2021

The primary concern for the short term will revolve around breezy
conditions this afternoon and the potential for precipitation
into tomorrow morning.

Currently, the area continues to be under the influence of a large
upper trough centered over Minnesota. Flow aloft remains largely
zonal while low level flow is northwesterly. Surface high pressure
continues to slowly spill into the area from the northwest. An upper
low is slowly moving southwest through the Intermountain West and
will be the primary focus for much of the forecast period.

For today, expect breezy conditions yet again across portions of
north central Nebraska. H85 flow remains around 25-35kts across the
area this morning, though will weaken through the day as the low
over the Upper Midwest finally begins to move off to the east.
However, flow will remain elevated across north central Nebraska at
least through this afternoon, and mixing should promote a few gusts
up to 40mph. Winds will weaken with southwestward extent this
afternoon, with portions of southwest Nebraska looking at winds
largely below 20mph. Temps remain near to just above freezing at
H85, and will lead to another day of highs in the upper 40s to 50s.
Shortwave ridging passes overhead through the afternoon and keeps
things quiet.

By late tonight, flow aloft begins to transition southwesterly and
will mark the start of a more active pattern into the weekend.
Isentropic ascent increases on the 295-310K surfaces as moist
advection begins in earnest. With this increased moisture, clouds
will build in overnight, and a good portion of the area will be
overcast by tomorrow morning. Forecast soundings indicate good top-
down saturation through the night, though dry air in the lowest few
kilometers should keep precip at bay through most of the night.

Increased advection and upslope flow should spark at least some
precipitation over the higher terrain off to the west. Steering flow
could bring this precip into the western CWA by early tomorrow
morning. However, low level dry air is slow to erode with eastern
extent so not expecting much in the way of accumulations with this
and it will likely remain west of Highway 83. There appears to be a
brief lull in precip tomorrow afternoon before the parent wave
finally begins to eject eastward. Clouds will keep things a little
cooler than today, though persistent WAA leads to highs in the 40s
to low 50s.

.LONG TERM...(Wednesday night through Monday)
Issued at 359 AM CDT Tue Apr 13 2021

The parent low begins to eject into the Plains Thursday morning and
mark the beginning of a longer duration precipitation event through
Friday evening. Isentropic ascent increases and precip should begin
from west to east by late Wednesday night. With this initial push
happening overnight, rain/snow to all snow is the expect precip
types. QPFs don`t look overly heavy through Thursday afternoon
(generally <0.1") and temps initially hover very near freezing. This
leads to rather low SLRs expected (near 6-7:1) and any accumulations
should be on the lighter side into Thursday morning. A transition to
a more mixed mode and then all liquid is expected late Thursday
morning. The heaviest precip looks to fall between midnight Thursday
to late Friday morning. Forecast soundings indicate a potential
transition back to mixed/all snow type given diurnal cooling. This
will be the best window for snow accumulations, though SLRs again
remain on the lower side and any snow that does fall will do so on
rain soaked ground. Still, a couple of inches of wet snow may
accumulate on grassy and elevated surfaces mainly west of Highway
83. Additionally, lapse rates begin to steepen in the lowest few
kilometers through Friday afternoon and could lead to a brief period
of more showery precip. Confidence remains low in this and trends
will need to be monitored for impacts to potential totals. The
system begins to finally pull away by Friday evening and precip
should taper off by midnight Saturday. In total, accumulations look
to be the highest over southwest Nebraska, where ~0.75" can be
anticipated. Amounts taper off from southwest to northeast, where
<0.1" is possible across portions of north central Nebraska.

Confidence wanes in the wake of the late week system, with model
solutions diverging. Will defer to later forecasts to pin down any
additional low-end precip chances early next week given large spread
in timing/strength of our next potential weather system.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 621 AM CDT Tue Apr 13 2021

Wind will be the main aviation weather concern again today. The
highest speeds will affect the northern terminals (KVTN) where
northwest winds gust to near 30 kts late this morning and much of
the afternoon. Farther south (KLBF), most gusts should remain
under 20 kts. Meanwhile, some areas of low/mid clouds across the
far north will break up this morning, but thicker mid/high clouds
in the southwest may stick around. Overall, VFR is anticipated
through Wednesday morning. Perhaps the exception would be far
southwest (KOGA to KIML) around daybreak tomorrow when a stratus
deck builds in with some light rain or snow showers.




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