Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 252351
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
651 PM CDT THU AUG 25 2016

.SYNOPSIS...
Issued at 234 PM CDT Thu Aug 25 2016

At 20z the synoptic setup was highlighted by a broad upper level
trough over much of the western two-thirds of the conus, and a
strong but low amplitude ridge of high pressure centered over the
southeast US. Fast quasi-zonal flow aloft was in place between these
two features, extending from the Central Plains and into the Great
Lakes towards southeastern Canada. At the surface a slow moving
frontal boundary extended from the Great Lakes region through the
Ozarks and into Oklahoma/Texas, with a weak low pressure center
analyzed in northwest Missouri. Surface high pressure and a cool,
dry airmass was in place to the north of the front which includes
the local forecast area. Temperatures in the CWA were generally in
the 70s, with 60s beneath expansive cloud cover in northwest
Nebraska.

&&

.SHORT TERM...(This evening through Friday)
Issued at 234 PM CDT Thu Aug 25 2016

Quiet conditions are expected through the remainder of the afternoon
and evening as an area of surface high pressure slides east through
the Dakotas. A shortwave trough pushes into the Central Rockies
early Friday morning. Increasing DPVA aloft will slowly aid in the
development of a lee side low over eastern Colorado, which will turn
our winds southeasterly as the low level mass fields begin to
adjust. Latest model guidance has trended drier and backed off
from any fog potential for early Friday morning. Although
southeasterly winds are favorable for fog development in the
Platte River Valley over southwest Nebraska, the initial moisture
advection will be relatively weak as the winds transport recycled
air around the aforementioned surface high. In addition, both the
GFS and the NAM advertise upper level clouds streaming into the
area overnight, which may keep temperatures a few degrees warmer
than previously thought.

Precipitation chances begin to increase over western Nebraska by mid
to late morning Friday as 500mb height falls spread east over the
Central Plains. Better low level moisture will advect in the area as
a stalled front to our south begins to surge north. Have introduced
likely pops by late afternoon as most models begin to push a line of
showers and storms out of the Panhandle and across the Sandhills
region. A strong to severe storm isn`t out of question, mainly in
our Panhandle counties where low level moisture pooling in the
vicinity of a lee side surface trough will result in dewpoints
around 55F, beneath modest mid-level lapse rates and 30+ kts of
shear. The cool airmass and lack of daytime heating will limit
instability, and the potential will diminish as low level CIN
increases with eastward extent.

.LONG TERM...(Friday night through Thursday)
Issued at 234 PM CDT Thu Aug 25 2016

The models are in good agreement with passage of shortwave trough
and system Friday night. Kept near previous pops, except lowered
pops a bit after midnight, with eastward progression of the
system.

The northern stream trough is not as amplified as was previously
on Saturday. This will result in a dry day with mostly sunny skies.
Highs will return to near normal in the low 80s Saturday.

A long sustained upper ridge will begin to build in Sunday and
persist through at least Thursday. Western Nebraska will remain on
the periphery of the upper ridge with subtropical moisture
available. This will keep a slight chance for thunderstorms
during the evening and overnight Sunday through Tuesday, then
chances should shut off entirely as upper ridge axis translates
westward over the Central Plains. Highs in the upper 80s/near 90s
Sunday through Wednesday warm into the lower 90s by Thursday.
Potential exists for an upward trend in these highs, given
anomalously strong upper ridge building in.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 651 PM CDT Thu Aug 25 2016

Mid and high clouds will be on the increase later tonight.
Ceilingswill range from 10000 to 15000 FT AGL. Skies will become
overcast Friday afternoon with CIGS ranging from 5000 to 8000 FT
AGL. There will be an increased threat for thunderstorms as well,
particularly at the KLBF terminal. The greatest threat for
thunderstorms is from 20Z through 24Z Friday. Visbys may fall off
to 4SM at the KLBF terminal.

&&

.LBF Watches/Warnings/Advisories...
None.
&&

$$

SYNOPSIS...Martin
SHORT TERM...Martin
LONG TERM...Roberg
AVIATION...Buttler


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