Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 282322 AAA
AFDLBF

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
622 PM CDT Fri Apr 28 2017

.SYNOPSIS...
Issued at 340 PM CDT Fri Apr 28 2017

H5 analysis this morning has a long wave trough of low
pressure over most of the CONUS with the exception of the eastern
seaboard. Within this longwave trough, several closed lows and
shortwaves were noted. Closed lows were noted over southeastern
Alberta and southwestern Saskatchewan, western Ontario, and northern
Utah. Shorwaves were noted over western Nebraska, northern Kansas,
and central Oregon. The shortwave over western Nebraska-colocated
with an H7 low and very strong mid level frontogenesis, has led to
rain and snow across the forecast area overnight into today.
Snowfall rates around an inch per hour were common in the areas
where radar returns were most intense. Based on highway cameras,
snow accumulations were generally confined to grassy and elevated
surfaces, as roadways remained wet for the most part. However, some
slushy spots have developed along highways 2 and 92 from Merna to
Hyannis and Arthur respectively. This is expected to improve this
afternoon thanks to a high sun angle and to a decrease in snowfall
intensities.

&&

.SHORT TERM...(This evening through Monday)
Issued at 340 PM CDT Fri Apr 28 2017

Tonight through Monday...The main forecast challenge
in the short term is the threat for snow Saturday night into early
Sunday, along with the threat for precipitation. For tonight:
Surface high pressure will nose into Wyoming and the Nebraska
panhandle overnight, forcing drier air into western and north
central Nebraska from the northeast. Mid level lift will weaken and
be forced west and south of this area overnight, effectively ending
precipitation across the forecast area. On Saturday, an H5 low will
begin to cross New Mexico, emerging onto the Texas panhandle
Saturday evening. Light precipitation will lift north from western
Kansas into southwestern and southeastern portions of the forecast
area on Saturday. With temperatures expected to be in the upper 30s
to around 40 Saturday afternoon-which coincides with the onset of
precipitation, ptype is expected to be all rain attm. Could see
some wet snow mix in as well but no impacts are expected. By
Saturday night, the H5 low will lift into southwestern Kansas.
Initial deformation precipitation will begin to lift into south
central Nebraska, impacting the southeastern forecast area late
Saturday night into Sunday morning. Temperatures will be favorable
for snow, in the southeastern forecast area Sunday morning based
on wet bulb zero hts. After collaboration with the neighbors to
the east and south, decided to hoist a low confidence winter storm
watch for Frontier county. Snow amounts will be on the light side
and probably not even worthy of an advisory at this point,
however, strong northwesterly winds are expected to develop
Sunday, making for some miserable conditions Sunday morning where
the snow flies. By Sunday afternoon the low will lift into central
and northeastern Kansas with the deformation band of
precipitation impacting southeastern through northeastern portions
of the forecast area. Qpf`s will be highest during the Sunday
afternoon period. Wet bulb zero hts are expected to run 1000 to
1500 FT AGL underneath the heaviest pcpn per the 12z GFS, so am
not too excited about significant snow accumulations. Also the
diurnal timing of peak pcpn in the afternoon doesn`t favor heavy
accumulating snows. We may see periods of moderate to heavy snow
in the east Sunday afternoon, however with a high sun angle and
temps in the mid to upper 30s forecast, it will be hard to
accumulate anything other than on grassy and elevated surfaces,
and that should be minimal. As mentioned before, strong surface
low pressure will develop over northeastern Kansas into western
Iowa Sunday afternoon and Sunday night, which will produce some
strong winds across the eastern half of the forecast area. ATTM,
went ahead and increased winds toward the CONSALL guidance. With
no cold air advection noted across the eastern cwa, and cloudy
skies, we may have a difficult time mixing those strong 50kt H85
winds down to the surface. The upper level low and surface low
will lift into Iowa Sunday night with precipitation lingering in
the northeastern cwa through early Monday morning. With
temperatures falling, the best threat for accumulating snow will
be in the northeastern forecast area Sunday evening. Fortunately
by then the strongest deformation will shift into northeastern
Nebraska and southeastern South Dakota.

.LONG TERM...(Monday night through Friday)
Issued at 340 PM CDT Fri Apr 28 2017

Monday night through Friday...Temperatures will begin
to moderate quickly behind the exiting low with highs in the 50s
expected for Monday. Temperatures will moderate slightly into the
lower 60s for Tuesday and Wednesday as the long wave trough
remains anchored across the eastern 2/3rds of the CONUS. This
feature will shift east on Thursday with highs reaching the mid
and upper 60s on Thursday, followed by mid 70s on Friday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 621 PM CDT Fri Apr 28 2017

MVFR cigs should continue to shrink southward this evening. The
SREF which has performed resonably well over the last 2 days
suggest they will drift south of I-80 and become stationary across
Swrn Neb overnight.

The next storm system will begin to affect Swrn Neb Saturday
afternoon. MVFR cigs and -SHRA are expected to begin lifting north 18z-
00z. This would impact areas generally south of I-80. VFR is
expected elsewhere.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Saturday evening through Sunday evening
for NEZ071.

&&

$$

SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC



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