Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 172106

Area Forecast Discussion
National Weather Service North Platte NE
406 PM CDT Sat Mar 17 2018

Issued at 221 PM CDT Sat Mar 17 2018

Surface ridge of high pressure that extends through the central
Plains builds east tonight for a return to an active, wet
weather pattern Sunday through early Tuesday.


.SHORT TERM...(This evening through Sunday)
Issued at 221 PM CDT Sat Mar 17 2018

Tonight the stratus over the north central slowly erodes then will
see a return westward overnight. Southerly winds return moisture
and the boundary layers moistens up with clouds on the increase.
Forecast challenge will be how low clouds will reach and the areal
coverage for fog. For now expect areas of fog generally east of a
line from Merriman to Brewster and Broken Bow. The fog and clouds
will hang tight through mid morning Sunday. Temperatures tonight
will drop into the upper 20s north central to middle 30s in the
west. Sunday models are in good agreement where considerable
cloudiness will limit heating for the day with temps reaching into
the middle 40s far north to upper 50s in the far southwest.
Sunday afternoon a few showers may develop but remain on the light

.LONG TERM...(Sunday night through Saturday)
Issued at 221 PM CDT Sat Mar 17 2018

Primary forecast challenge revolves around the tomorrow night-Monday
time frame where rain, snow, and/or wintry mix are expected, along
with a low-end chance for thunder late Sunday. Otherwise, a warming
trend starts Wednesday with temperatures Thursday and Friday
expected to be about 5-15 degrees above seasonable normal values.

Guidance continues to be in decent agreement with a shortwave trough
ejecting from the Four Corners region Sunday. This shortwave will
become negatively tilted and will track into the Southern High
Plains by Sunday evening with a closed low developing near the OK
Panhandle. The closed low will then track into the Middle
Mississippi Valley Monday afternoon. Meanwhile, lee cyclogenesis is
anticipated across eastern CO Sunday with the surface low moving
eastward to southeast KS/northeast OK area by Monday morning.
Current thinking is the setup will be one of a rain-snow/mix.
Moisture appears sufficient with decent transport based on WCB and
the evolution of MTVs, 290-295 K, Sunday-Sunday night. While the
atmosphere is a warm environment based on thermodynamic profiles,
current thinking is dynamic cooling with lift/ascent and wet-bulb
profile evolution will support a changeover to snow from nw-se
overnight. Of which, generally a rain/snow mix is anticipated by
Monday morning over portions of the southeast-third of the local
forecast area. Additionally, lift may be shallow given omega
profiles and lower-tropospheric frontogenesis. As such, the
combination of this lift and relatively warm profiles support a
lower SLR compared to climo. Current thinking for snowfall amounts
is 2 to 4 inches in the eastern Panhandle and far northwest NEB with
lesser amounts going into far western NEB. Elsewhere, generally an
inch or less is expected. Further, don`t think p-type will be an
issue compared to the most recent winter event given saturation and
ice in-cloud thus freezing rain/sleet mention was minimal.
Otherwise, elevated instability supports some low-end mention of
thunder across the far southwest NEB area early on Sunday evening.

Little change to forecast Tuesday and beyond, especially with
respect to the large scale pattern. A broad upper-level ridge will
be in place across the western CONUS Tuesday extending from the far
Southwest US to the Pacific Northwest/Northern Intermountain West.
While there are minor disturbances/waves rotating through the
periphery of the upper-level ridge Tuesday-Tuesday night, forecast
was kept dry. Western NE will stay under northwest flow aloft
through Wednesday with the ridge then moving east to the eastern
Central and Northern Plains by Thursday. Overall, temperatures are
expected to warm up beginning Wednesday with above-normal highs
anticipated Thursday and Friday. Guidance then shows the ridge
braking down Friday-Friday night supporting at least low-end chances
for precip within that time period.


.AVIATION...((For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1246 PM CDT Sat Mar 17 2018

A range of cloud coverage this afternoon as stratus remains
entrenched across the central and clearing slowly in the west.
Models in fair agreement with next system moving out on the plains
where boundary layer moisture will create a challenge with ceiling
heights lowering after midnight to MVFR conditions across the
north and possibly into LIFR conditions east of a line from
Merriman to Broken Bow through 15Z. For the west and southwest
low confidence as clouds will be on the increase with how low
ceilings will go in question with VFR conditions overnight into
Sunday morning for now.




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