Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 170851
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
351 AM CDT Tue Apr 17 2018

.SYNOPSIS...
Issued at 350 AM CDT Tue Apr 17 2018

At 08z...Surface low pressure extended from central Wyoming into
eastern Utah. This was in response to an upper trough pushing across
the Great Basin. Meanwhile surface high pressure extended from
Minnesota down through Missouri. Across northwest Nebraska, skies
were mainly clear, with some cirrus clouds across southwest into
central and eastern Nebraska. Temperatures mainly ranged in the low
to mid 30s.

&&

.SHORT TERM...(Today and tonight)
Issued at 350 AM CDT Tue Apr 17 2018

An upper trough will advance onto the Central and Northern High
Plains by late this afternoon. As an inverted surface trough moves
east today, southeast winds 10 to 20 mph will switch to the
northwest after 21z across the far southwestern zones. The winds
will increase to 25 to 35 mph with gusts to 50 mph possible into
this evening for areas mainly south of a line from Lisco through
Paxton and Hayes Center. Highs today will warm up the most across the
far southwest zones reaching the mid 60s, with upper 60s in a few
locations. Southeast winds to the north and east will bring highs
from the mid 40s north central with mid to upper 50s central
Sandhills. As the upper trough moves in, increasing chances for rain
to develop from the northwest Sandhills into central areas toward 7
pm cdt.

For tonight, the upper trough will exhibit a slight negative tilt
and close off across eastern portions of nctrl Nebraska after
midnight. There will be modest instability over central Nebraska
that an isolated thunderstorms or two possible. Rain chances likely
this evening over most of nctrl Nebraska, with only a slight chance
in the southwest. Cooling temperatures late evening and overnight,
will bring a changeover to light snow across nctrl Nebraska. Light
accumulations mainly on grassy surfaces from a dusting up to an inch
area possible. Amounts over an inch are possible in Boyd county
after midnight. Northwest winds will overspread the forecast area
overnight, with the strongest wind across the southwest half of the
forecast area from 25 to 35 mph, with some gusts to 50 mph possible
in the evening. Low temperatures from the low 30s north and west, to
33 to 35 degrees southeast.

.LONG TERM...(Wednesday through Monday)
Issued at 350 AM CDT Tue Apr 17 2018

Nebraska sits under the influence of two main upper lows over the
next week. In between the systems, a brief ridge builds over the
Plains late week. Temperatures moderate some over the next few days,
but remain below normal.

Wednesday... The upper and sfc lows as well as a PV anomaly work
east across the Upper Midwest, but conditions stay breezy for
western Neb. A steep pressure gradient and 40kt+ flow at H85 will
combine for gusts near 40mph in the afternoon. Trended toward the
stronger ConsMos to highlight the potential. Precip wise, have a few
snow showers far north central Neb. through 15z, then schc rain in
the afternoon. Not expecting much moisture as mid level fgen weakens
and isentropic downglide resumes in the lower levels. Went with a
general MAV/MET/ECS blend for highs to result in mid 40s north
central to near 60F SW.

Thursday... A fairly mild day is in store relatively speaking
(widespread 50s, a few 60s) as H85 flow turns south/southeasterly
and weak WAA takes over. Would go warmer, but upslope flow combined
with a deep moisture plume from the Desert Southwest (as indicative
on WV imagery) suggests thickening clouds.

Friday and Saturday... The 17/00z model suite shows a more southerly
trend with the upper low and slightly less moisture advecting into
Neb. In addition, the thermal profile is trending warmer. H85 temps
struggle to drop below 0C and overnight lows barely hit freezing. At
this rate, the bulk of the precip will fall as rain with brief
periods of rain/snow mix at night. The potential for accumulating
snow seems to be falling with each model run.

Sunday and beyond... A sfc high pressure builds onto the central
Plains as flow aloft turns southwesterly to quasi-zonal. Temps
moderate once again to near normal values with mainly fair
conditions.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1050 PM CDT Mon Apr 16 2018

Aviation concerns revolve around LLWS conditions early on then
ceilings and rain chances. Latest satellite imagery shows high
clouds streaming from northeast CO to northeast NEB. Latest KLNX
VWP at 500 m (1640 ft) AGL shows south southeast winds around 50
kts. As such with surface winds out of the southeast generally
8-12 kts some LLWS conditions are expected overnight given speed
aloft and minor directional differences. An upper height of about
1500 ft AGL and winds of about 45-55 kts at the top of the wind
shear layer are expected with conditions improving during the
early morning. Regarding stratus, current thinking is some could
still develop, however, confidence is lower regarding areal
coverage and impacts. Stratus development more likely towards late
tonight-early morning tomorrow across north central NEB and the
Sandhills with ceilings becoming VFR then tomorrow afternoon.
Otherwise, rain chances increase after 18Z across northwestern
NEB then spread south and east in the evening with best chances
across northern NEB in the evening. Isolated thunderstorms will
be possible across portions of the southern Sandhills late
afternoon-evening, however, confidence is low. A changeover to
snow or a wintry mix is then expected mid-late evening across
parts of western NEB.


&&

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

$$

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



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