Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 242317 AAA

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
617 PM CDT Mon Oct 24 2016

Issued at 259 PM CDT Mon Oct 24 2016

H5 hand analysis this morning had an amplification of
the ridging across the Rocky mountains of Canada and the CONUS. This
ridge extended well north into northern portions of British
Columbia, Alberta and Saskatchewan. Upstream of the ridge, a closed
low was noted approximately 400 miles west of Portland Oregon.
Height falls along the west coast were limited east of this feature
with 50 meter falls noted at Medford Oregon and San Francisco
California. East of the ridge, a closed low was located over western
portions of Labrador Canada with a trough extending south into New
England and the Canadian maritimes. Height falls east of this low
were most pronounced over Newfoundland with 100+ meter falls located
on that island. Across the central and northern plains, ridging
continued to dominate the weather pattern, however, a decent shortwave
located over southern California ATTM will cross the desert
southwest overnight, and will suppress the ridging across the central
and southern plains for Tuesday. At the surface, high pressure was
located over Minnesota, with a surface low located over central
Montana. Southerly and southeasterly winds have increased this
afternoon with wind speeds of 10 to 20 MPH common across western and
north central Nebraska. Other than a few high clouds drifting in
from the southwest and west, skies were mainly clear this afternoon.
Temperatures as of 3 PM CDT were in the lower to middle 60s across
western and north central Nebraska.


.SHORT TERM...(This evening through Tuesday)
Issued at 259 PM CDT Mon Oct 24 2016

A quiet evening across central Nebraska is forecasted as the upper
level ridge remains in place across the western US. The main story
for tonight will be the potential for fog development across south
central Nebraska as a weak trough slides across the region. Fog will
start off patchy, beginning mainly in the low lying river valleys
around 3am before spreading eastward. Fog has the potential to
become dense, mainly after 6am, with visibilities approaching a half
mile to one mile. Areas with the densest fog will be along and
southwest of a Broken Bow to Hyannis line. At this time, no fog
advisories are expected, however, this will be something we will be
watching overnight as visibilities begin to drop.

A moist boundary layer and light winds will inhibit fog from
dissipating quickly. Currently expecting fog to stick around,
especially in low lying regions, through much of the morning. Even
after fog dissipates, stratus and low cloud ceilings will keep
conditions cloudy through Tuesday. There is then a slight chance of
some shower and thunderstorm development late Tuesday afternoon.
Current models have pushed the majority of the activity further
eastward. Therefore, Tuesday should remain dry for most locations in
our forecast area, with the exception of Wheeler, and eastern Boyd
and Holt counties. Even these locations only have about a 20 percent
chance of seeing any shower development.

.LONG TERM...(Tuesday night through Monday)
Issued at 259 PM CDT Mon Oct 24 2016

Mid range...Tuesday night through Thursday...In the mid range, the
lingering threat for precipitation Tuesday evening along with
temperatures Wednesday through Thursday are the main forecast
challenges. For Tuesday night, the H7 trough axis will approach the
far northeastern portion of the CWA by 00z Weds. This feature will
clear the area during the 03z to 06z time frame Wednesday,
effectively ending the threat for pcpn by midnight Tuesday evening.
Low clouds may linger in the eastern forecast area overnight, but
the threat for fog/low clouds should end after midnight, as the
boundary layer winds take on a westerly component. Some low level
moisture will remain in place behind the exiting trough of low
pressure, along with clouds, so a mild night is expected with lows
in the lower to middle 40s. On Wednesday, ridging aloft will begin
to build into the central Rockies. However, H85 temps are not
expected to surge upward until Wednesday night. That being said,
with H85 temps in the teens, highs will reach the lower 70s. On
Wednesday night, ridging will build east into the central and
northern plains. By Thursday, H85 temps will reach the upper teens
to around 20C. With westerly winds in place, highs will reach the
upper 70s to near 80 in the southwest. Record highs for Valentine
and North Platte are both 85 degrees Thursday. ATTM, based on the
latest forecast, we should be 5 to 8 degrees below these records.

Thursday Night through Monday...Temperatures will be the main
forecast concern in the extended forecast. As was the case
yesterday, a cold front will track across the central and northern
plains sometime late in the week. The GFS has this feature passing
through Nebraska Thursday Night, while the EC is 36 hours slower,
forcing this feature through the forecast area on Saturday. With the
model differences, forecast temperatures Friday could vary widely
based on model choice. In fact, H85 temps in the 12z EC soln for
Friday afternoon are well into the lower 20s C, which would equate
to the lower to middle 80s for highs. Middle 80s would break records
for North Platte and Valentine Friday. The GFS solution is about 10C
cooler at H85 for Friday. That being said, chose to stick with the
model blend for temps Friday. By Saturday, the models do come into
better agreement with their temps as the EC forces a decent cold
front through the area. Even with the cooler air, highs Saturday
will range from the upper 50s in the northeast, to near 70 in the
southwest, which is still above climatology for this time of year.
The cool down will be short lived however, as ridging builds back
into the central plains for Sunday into Monday. Highs will rebound
back into the upper 60s to 70s for Sunday and Monday. With respect
to lows Friday Night through Sunday Night, they were lowered from
the superblend soln. This was done for two reasons, 1) Our airmass
will be dry during the period, so lows in the 40s seem overdone and
2) Lows in the lower 40s are 10 to 15 degrees above climo. With no
strong moisture advection, no clouds and fairly light winds, we
should easily be hitting the 30s for lows each night.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 617 PM CDT Mon Oct 24 2016

Nearly all models indicate fog and widespread LIFR/IFR developing
09z- 17z Tuesday morning. Confidence is high this will develop
affecting areas along and near highway 83 south of highway 20.

MVFR is expected 17z-21z east of highway 83 as the fog lifts and
a weak frontal boundary moves through Wrn Neb and into Ncntl Neb.
VFR is generally expected all areas east of highway 83.




LONG TERM...Buttler
AVIATION...CDC is the U.S. government's official web portal to all federal, state and local government web resources and services.