Area Forecast Discussion
Issued by NWS North Platte, NE

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680
FXUS63 KLBF 231204
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
704 AM CDT FRI SEP 23 2016

.SYNOPSIS...
Issued at 338 AM CDT Fri Sep 23 2016

The H5 pattern has become amplified across the western CONUS over
the past 24 hours. An area of low pressure was present over
northern Nevada with a deep trough of low pressure extending south
into northern portions of Baja California. Downstream of the
trough, a ridge of high pressure extended from the central and
northern plains into eastern portions of the Northwest Territories
of Canada. Across the srn tier of states, high pressure was
anchored across the Arklatex. At the surface, low pressure was
located over eastern Colorado with a warm front extending east
along the Kansas/Nebraska border into South Central Nebraska. The
front then was located from south central Nebraska into east
central Nebraska in the vicinity of Fremont Nebraska. South of the
front, southerly winds and mild temperatures were seen. North of
the front, areas of fog were present with some visibilities down
to a quarter mile or less. With this in mind, decided to issue a
dense fog advisory until 9 AM CDT for a strip of counties from
Custer north to Keya Paha and eastern Cherry. Visibilities are
expected to improve quickly this morning as the warm front lifts
north.

&&

.SHORT TERM...(Today and tonight)
Issued at 338 AM CDT Fri Sep 23 2016

Today and tonight...Over the next 24 hours, fog this morning and
precipitation chances later today and tonight are the main
forecasting challenges. For today: Low pressure will deepen off to
the west of the forecast area, over eastern Wyoming. East of this
feature, a warm front will lift north across western and north
central Nebraska today which will give a boost to temperatures
this afternoon. Highs will reach the upper 80s to near 90 as the
warm front and surface low pushes into South Dakota. By evening,
the low will begin to track to the northeast into northern South
Dakota. This will force a cold front through the forecast area
overnight. Ahead of the cold front, thunderstorms are expected to
develop as a lead disturbance aloft lifts north northeast into the
central plains from the central Rockies. Thunderstorms will track
quickly to the north northeast this evening. At this time, based
on the frontal timing, the best chances for storms is in the
eastern panhandle through the early evening hours. As for the
threat for severe storms, there is ample bulk layer shear to
support severe storms development tonight, however CAPE is meager
on the order of 1000 to 1500 J/KG. Deep layer shear increases
further to around 70 KTS later this evening...which may shear
apart any weaker storms. storms may have a hard time overcoming
the increased shear given the meager amount of CAPE especially
during the late evening and overnight hours. With this in mind,
thunderstorm chances will decrease east of the panhandle overnight
with only slight chances along and east of highway 83. Overnight
lows will range from the lower 50s in the west where some clearing
is expected, to the mid 60s in the east.

.LONG TERM...(Saturday through Thursday)
Issued at 338 AM CDT Fri Sep 23 2016

In the medium range...the models depict a solution in which a long
wave trough will advance from the central/northern Rockies across
the High Plains. The trough will pull a cold front across the state
of Nebraska Saturday afternoon/evening which will cool temperatures
back to seasonal or slightly below seasonal norms for the weekend
and early next week.  The models show mainly dry conditions for the
weekend, except for the possibility of a shower or storm across the
eastern periphery of the cwa Saturday where the presence of a warm
front and favorable upper jet dynamics meet.  If storms occur...it
should be before noon when diurnal heating will be challenged...thus
widespread strong or severe storms are not anticipated. The warm
front is shown to exit to the east early afternoon as the mean
trough and associated sfc low advance southeast across the Dakotas
leaving the dry and cool post frontal conditions.  Will have to
watch for the prospects of a frost early Monday for locations along
and west of highway 61...and possibly the Platte system through
Lincoln County. At this point the guidance suggests mid to upper 30s
as winds stay breezy through the overnight.  Will monitor. Otherwise
the models came into better agreement early to mid next week as the
trough advances northeast through the Great Lakes and rising heights
associated with a building ridge spreads east across the Plains. A
gradual warming trend is thus expected. Mid and late week, the
solutions still point however to a piece of energy in the southern
stream that retrogrades west from the mean longwave trough back
across the southwestern states. Both the GFS and EC then carry the
energy northeast across the Central Plains late week, which would
provide for increasing chances of showers/storms.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 705 AM CDT Fri Sep 23 2016

A warm front will lift north across western and north central
Nebraska this morning. As this feature lifts north, low clouds
will dissipate by mid morning across northern Nebraska. High
cloudiness will remain in place over the next 24 hours with
scattered cigs of 25000 ft agl. Clouds will increase this evening
with an increased threat for thunderstorms tonight. The greatest
threat will be from 03z to 09z tonight and will be handled at both
terminals with a prob30 group. winds will be from the south at 15
to 25 KTS today, diminishing to under 15 kts tonight.

&&

.LBF Watches/Warnings/Advisories...
Dense Fog Advisory until 9 AM CDT /8 AM MDT/ this morning for
NEZ005>010-025>029-038.

&&

$$

SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Jacobs
AVIATION...Buttler



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