Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 301227

Area Forecast Discussion
National Weather Service North Platte NE
727 AM CDT TUE AUG 30 2016

Issued at 352 AM CDT Tue Aug 30 2016

H5 analysis from earlier this evening had very weak mid level
flow across most of the CONUS with a strong northern stream
extending from the Pacific Northwest states, east to the northern
Great Lakes and New England. Further south, most of the CONUS was
under the influence of two areas of high pressure. Very weak mid
level flow was present across the central and southern plains
tonight. No surprise that convection which has developed earlier
this evening and overnight has moved little. As of 3 AM CDT, an
area of thunderstorms remained anchored over Wheeler county.
Radar estimates are between an inch and two inches per hour with
this cluster of storms. Flash flood guidance however remains high
with 3 hrly guidance amounts upward of 5+ inches. As of 3 AM CDT,
we are half way there with radar estimating 2-3 inches over
Wheeler county. Elsewhere, skies were mostly cloudy overnight
with some isolated showers present over southwestern Nebraska. In
these areas only trace to five hundredths of an inch were
reported. Under mainly cloudy skies, 3 AM CDT temperatures ranged
from 63 at Valentine to 69 at O`Neill.


.SHORT TERM...(Today and tonight)
Issued at 352 AM CDT Tue Aug 30 2016

Over the next 24 hours, precipitation chances will be the main
forecast concern. Abundant low and mid level moisture will
continue to stream into southern and eastern Nebraska from the
southern plains today. Abundant cloudiness will limit highs to
the lower to middle 70s in the south and southeastern CWA today.
Highs will reach the lower 80s over northern Nebraska where
sunshine will be more prevalent. With a very weakly capped
environment in place today, weak surface heating will lead to the
development of thunderstorms. Based on the latest NAM12, HRRR and
WARW solutions, the greatest chances for precipitation will
generally be in the southern half of the forecast area. This is
in the vicinity of an area of enhanced mid level frontogenesis
which shows up nicely in the 00z NAM12 solution from earlier this
evening. Steering flow will be very weak as well, so there is the
threat for isolated areas of heavy rain. Right now, potential
coverage of heavy rain will be isolated at best, so not
anticipating any flooding concerns right now. Since coverage is
expected to be isolated, will keep mention of heavy rain out of
the forecast, however am planning on hitting this in the HWO. As
for pops, will continue to mention scattered coverage, as there
will be alot of competing updrafts given the weakly capped
environment this afternoon and evening. Finally, there is the the
threat for fog later tonight into Wednesday morning. The latest
MET and MAV guidance is indicative of fog development over
southern Nebraska tonight. However, the latest NAM12 solution
does have an abundance of mid and high level moisture tonight
across the southern half of Nebraska. That being said, if enough
cloudiness can develop and persist over the area tonight, fog may
have a hard time developing. For now, will plan on leaving this
out of the forecast. Lows tonight will range from the lower 50s
in the west to upper 50s in the east and south.

.LONG TERM...(Wednesday through Monday)
Issued at 352 AM CDT Tue Aug 30 2016

Wednesday will continue to see a chance across far sw Neb for
showers and thunderstorms with the plume of Pacific/Gulf moisture
streaming north along the southwestern plains then turning to the
east. Lingering chances for precip generally south of the
interstate, however it may end up being just stratus with the
showers remaining in KS. At the surface a large area of high
pressure across central Canada will draw cool Canadian air across
the northern plains. Some of this cool air will make its way to
western Nebraska beneath the upper level ridge. This will limit
warming on Wednesday as moisture easterly/southeasterly flow will
keep highs in the lower 80s which is seasonal.

The upper level ridge will build across the southern/high plains
to end the week, however this will battle the cool air which
continues to rotate around the large area sfc high pressure that
drifts east to Hudson Bay to the Great Lakes. The mid level lift
shifts south with a dry end to the week, although nocturnal fog
may become more of a factor as models hint at reduced
visibilities. Even with the rich BL moisture fog has been limited
the past few nights so will hold off and wait for some higher
probs in the ensemble guidance.

As the sfc high shifts east over the weekend allowing for a
slight warmup. Meanwhile an upper level low/trough moves across
the pacific northwest and the ridge shifts more to the Miss Rvr
valley. A sfc trough will develop along the front range and bring
a chance for storm development. Temps will be seasonal to
seasonally warm.

A cold front is advertised by the models Sunday night into Monday
with cooler conditions for Monday. Will have to monitor the
timing as highs likely to struggle into the lower 70s behind the
front as cool Canadian air brings a taste of fall.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 727 AM CDT Tue Aug 30 2016

For the KLBF terminal: Expect broken to overcast skies over the
next 24 hours. Ceilings will range from 5000 to 12000 FT AGL
today, increasing to 25000 FT AGL Tuesday evening. Rain showers
will be possible this afternoon with isolated coverage expected.
For the KVTN terminal: Expect scattered to broken CIGS of 25000 FT
AGL over the next 24 hours.


.LBF Watches/Warnings/Advisories...


SHORT TERM...Buttler
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