Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 130841
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
341 AM CDT Fri Oct 13 2017

.SYNOPSIS...
Issued at 339 AM CDT Fri Oct 13 2017

At 08z...Northeast winds continued across western Nebraska, and were
still gusting to 25 mph across southeastern zones. Scattered light
showers continued in Sheridan and Cherry county. Mainly sprinkles
occurring. Temperatures ranged from 45 to 50 across western
Nebraska.

&&

.SHORT TERM...(Today and tonight)
Issued at 339 AM CDT Fri Oct 13 2017

An upper trough currently digging across the Pacific Northwest will
track east into central Utah through central Montana by late
tonight. A cold front has already pushed through northwest Kansas
through northwest Iowa. There remains scattered light rain showers
across the northwest including Sheridan and Cherry county. These
showers are forecast to lift northeast out of the area by 12z this
morning, for a dry day today. Partly to mostly cloudy skies early
this morning will become mostly sunny by afternoon. Surface winds
behind the front will veer to the east and southeast today as 850 mb
temperatures warm slightly to 8-10C. Again used the CONSMOS for
highs today, which also are near the warmer MAV guidance highs.
Highs across the forecast area should be very uniform from 61-63
degrees.

For tonight, the upper trough will advance into western Wyoming and
eastern Montana. An inverted surface trough will develop from
eastern Colorado into the central Dakotas, providing a persistent
light south to southeast wind. Higher dewpoints will be advected
into the area, especially across the southeast where lower to mid 40s
will occur. While dry conditions are expected this evening, cloud
cover will increase. Then after midnight, a 30 percent chance for
showers in Sheridan and northwest Cherry county, with a slight
chance southwest into central zones. Weak isentropic upglide
increases after midnight, with stratus expected to develop. Fog will
also be possible, especially southwest Nebraska, where deeper dry
air aloft will be present. Introduced patchy fog across southwest
Nebraska after 09z. Another reason shower chances were kept mainly
slight chance, is that the best focus for showers and thunderstorms
to reside from central Kansas into southeast Nebraska, which will be
in vicinity of the stalled front and low level jet south of that
area.

.LONG TERM...(Saturday through Thursday)
Issued at 339 AM CDT Fri Oct 13 2017

An H5 trough quickly traverses the central/northern Plains this
weekend and is replaced by a building ridge over the Southwest U.S.
and southern Plains. Nebraska spends most of next week in broad
northwest to quasi-zonal flow aloft. At the surface, a deepening low
over KS and cold front push east in conjunction with the upper
trough, followed by a 1032mb high. Midweek, a couple sfc lows
centered to the north and south of the area drag weak troughs.

Saturday... Models are in fair agreement with bringing the cold
front through the forecast area by 18z and the upper trough axis by
00z. Kept schc to chc -RA in the morning due to moistening southerly
low level flow, weak isentropic upglide (most evident at 295K), and
forcing and lift associated with the front. Extended patchy fog
through 15z to account for light southeast winds (synoptically
favorable) and SREF probabilities. Precip in the afternoon will be
primarily contained to northern Neb, where the shortwave provides
the best mid level forcing and moisture. Temperatures and winds are
the primary forecast challenges concerning this system. Max temps
are highly dependent on fropa timing. GFS and ECM spreads range from
the lower 50s to upper 60s, and MET guidance also differs from MAV
quite a bit. Didn`t stray too far from the general model blend for
this forecast package. Increased wind speeds toward the stronger
MET/MAV/Cons MOS, now showing peak gusts over 30 kts. The tightest
sfc pressure gradient has shifted north toward NE/KS border Sat
aftn, suggesting 2 mb/hr rises. Winds at H85 approach 40 kts, which
much of it could easily be mixed toward the surface due to post-
front momentum transfer. Concurrently, the 1.5 PVU racing across the
Sandhills reaches 550mb and the H3 jet streak across eastern Neb
strengthens to 130 kts.

Sunday thereafter... A warming and drying trend will take place with
the help of the building H5 ridge and a persistent WAA scheme at
H85. NAEFS ensembles suggest H5 and H7 heights over 90%ile and PWAT
below 10%ile of climo norms Tuesday. Bumped max temps up a degree or
so midweek to agree with the warming MEX and ECE guidance (mid/upper
70s). Moisture remains hard to find with dew points in the 30s and
40s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1127 PM CDT Thu Oct 12 2017

A cold front continues to cross the area tonight, with north
winds gusting to near 20 kts behind the front. Otherwise expect
SCT to BKN mid level clouds with VFR all areas. An isolated shower
cannot be ruled out but most areas should remain dry.


&&

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

$$

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



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