Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 252321
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
621 PM CDT SUN SEP 25 2016

.SHORT TERM...(This evening through Monday)
Issued at 201 PM CDT Sun Sep 25 2016

Tonight and tomorrow. Temperatures remain the primary forecast
concern over the next 24 hours. The pressure gradient is shown
to relax across the forecast area tonight as a surface low tracks
north of the Great Lakes and high pressure builds over the high
plains and eventually south into western Kansas. The wind will
relax and back to the west overnight, which will aid in cooling
off temperatures. The latest guidance continues to suggest frost
potential across our western zones, southwest Nebraska and along
the Platte river system overnight, with lows in the lower to mid
30s. The guidance did however trend slightly warmer from previous
runs, which introduces some uncertainty in the forecast. But given
the location of the surface high tomorrow morning /western
Kansas/, clear skies and light winds, a good radiational event is
expected. Will issue a frost advisory for the aforementioned areas
with the forecast package...but note that localized /patchy/ frost
is likely rather than a widespread frost.

Clear skies and light winds across the Sandhills region will greet
the new work week and lead to a pleasant day. Highs will be
seasonal with guidance indicating lower to mid 70s cwa wide. With
the region being under the influence of high pressure at the
surface and aloft, precipitation chances are nil over the next 24
hours.

.LONG TERM...(Monday night through Sunday)
Issued at 201 PM CDT Sun Sep 25 2016

Monday Night through Wednesday: The main challenge in the time
period was temperatures. Otherwise, no major concerns with
sensible weather as dry conditions and mostly clear skies prevail
and wind stay light (less than 15 mph). Monday we start to warm
with highs then rising into the upper 70s and lower 80s Tuesday
and Wednesday. Low will be in the upper 30s to lower 40s and
largely mid to upper 40s Monday Night and Tuesday Night,
respectively. The latter is about 3-6 degrees above normal while
highs Tuesday and Wednesday will be 6-12 degrees above their
seasonal normal values.

The large scale pattern aloft will feature a broad trough over the
Midwest US with a 500 hPa closed low over the Upper Great Lakes
and a ridge that will be located over the Intermountain West into
the Northern Rockies at the start of the period. The trough will
move gradually eastward and fill in from Tuesday onward with the
trough then being located from Quebec to Southeast US by late
Wednesday. Meanwhile, the ridge will shift east and expand across
the Plains Wednesday with generally weak heights rises occurring
over the forecast area. The approaching ridge Tuesday then
expanding overhead Wednesday will result in dry conditions and a
warm up. Wherein temperatures at 850 hPa will rise into the lower
20s (C) to mid teens (C) west to east. This combined with decent
mixing and ample insolation will be conducive for warmer than
normal high temperatures and low temperatures Tuesday-Wednesday.
Surface high pressure will rule across the Southern and Central
Plains Tuesday with a weak lee side trough expected to develop
near the Front Range. Surface high pressure then continues to
dominant Wednesday.

Wednesday Night through Sunday: Guidance continues to show
variability and differences in solutions with the large scale
pattern, although the GFS has trended some towards the ECMWF in
the handling of the trough/closed low over the eastern CONUS
Thursday-Friday. Overall, confidence begins to wane from Friday
onward into the weekend. In general, the aforementioned ridge over
the Plains is expected to break down some beginning late Thursday,
however, there continues to be appreciable differences with how
fast this occurs. Of note, the GFS maintains a weak ridge over the
Southern and Central Plains this weekend while the ECMWF is faster
in breaking down the ridge and advancing the trough from the
western CONUS eastward. Current thinking is that high temperatures
will trend downward some Thursday and Friday, albeit they are
still anticipated to be above their seasonal averages. Slightly
above normal highs are then expected to continue through the
weekend. Lows will stay above normal. Otherwise, Thursday Night-
Friday will be the next opportunity for precipitation as a
disturbance in the flow moves affects the forecast area, however,
confidence is low given model difference at this time.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 620 PM CDT Sun Sep 25 2016

Clear skies will continue across western Nebraska the next 24
hours. Northwest winds will quickly decouple early this evening,
then remain light northwest around 5 kts or less overnight. On
Monday, light northwest winds in the morning will generally remain
at 12 kts or less in the afternoon.

&&

.LBF Watches/Warnings/Advisories...
Frost Advisory from 4 AM CDT /3 AM MDT/ to 8 AM CDT /7 AM MDT/
Monday for NEZ004-022>024-035-036-056>059-069-094.

&&

$$

SHORT TERM...Jacobs
LONG TERM...ET
AVIATION...Roberg



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