Area Forecast Discussion
Issued by NWS North Platte, NE

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367
FXUS63 KLBF 251735
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1235 PM CDT SUN SEP 25 2016

.SYNOPSIS...
Issued at 350 AM CDT Sun Sep 25 2016

A highly amplified H5 pattern remains in place across the CONUS
and Canada overnight. High pressure was anchored off the coast of
California with a ridge extending north to off to the coast of
British Columbia. Further east, a trough of low pressure extended
from western portions of the Northwest Territories of Canada
south to the four corners. Within this trough, a closed low was
located north of the Black Hills. Downstream of this trough, high
pressure was anchored around the confluence of the Ohio and
Mississippi rivers. Ridging extended north of this high into
western Ontario and southwestern portions of Hudson Bay. Down
stream of the ridge a closed low was located over Labrador Canada
with a trough extending south into the Canadian Maritimes. At the
surface, a strong cold front extended from far northeastern
Nebraska into north central Kansas. Westerly winds were present
behind the front and much drier air has pushed into western and
north central Nebraska overnight. Readings as of 3 AM CDT, ranged
from 51 at Valentine to 56 at O`Neill. Dew points had fallen into
the lower 40s.

&&

.UPDATE...
Issued at 902 AM CDT Sun Sep 25 2016

Current surface observations across northern Nebraska and
especially South Dakota support the need to increase wind speeds
across the cwa. A blend of the 25.06z consall with the previous
forecast nudged our wind forecast values up 3-5kts.

&&

.SHORT TERM...(Today and tonight)
Issued at 350 AM CDT Sun Sep 25 2016

Over the next 24 hours temperatures will be the main forecast
concern. A decent pressure gradient will develop today across the
forecast area, as surface low pressure tracks into northern
Minnesota, while strong high pressure builds east of the Wyoming
Rockies. H85 winds will reach 25 to 30 KTS later this afternoon
and with plenty of sun and surface heating, we should see
efficient mixing to that level with surface wind speeds of 20 to
30 MPH this afternoon. Highs today will reach the mid to upper
60s. High pressure will build into the panhandle and southwestern
Nebraska overnight tonight. With very dry air in place, lows will
bottom out in the 30s across the forecast area tonight. Lows
tonight utilized the cooler MET guidance given the expected light
west northwesterly winds and the surface high being located over
swrn Nebraska by 12Z Monday morning. This location was a slight
shift from yesterday`s model runs which had the High further
north in the Nebr. Panhandle. This shift facilitated colder
temperatures for southwestern and west central Nebraska for
tonight. That being said, overnight lows will be in the lower 30s
along the Interstate 80 corridor and western sandhills tonight.
This will lead to patchy frost with possible areas of frost in
low lying areas tonight. In all likelihood, we will need some
kind of frost headlines for tonight. At this time, plan to hold
off on headlines just yet and would like to see if the high
trends further south with today`s model runs. If this were the
case, we would have to add some frost wording to the forecast in
the far swrn CWA for tonight. For now, will hit this hard in the
HWO and on social media. Right now, locations west of a line from
Cody, to Mullen to Arnold will see the best chances for frost
tonight where lows are forecast in the lower to middle 30s. The
exception will be across Chase, Hayes and Frontier counties where
lows will be in the upper 30s.

.LONG TERM...(Monday through Saturday)
Issued at 350 AM CDT Sun Sep 25 2016

Early in the week an upper level closed low will drift across the
Great Lakes week as ridge across the west will slowly expand
across the high plains. After the chilly morning start, highs
Monday rebound close to seasonal averages, lower to mid 70s with
sunny skies.

The expanding ridge overhead will result in a warmup for Tuesday
and Wednesday. Surface high pressure will settle across the
plains with models in good agreement with dry conditions through
mid week.

Low confidence for the end of the week and into the weekend as
the closed low across the east moves in varying speeds/locations
pending which model solution you choose. The ripple effects from
the low is causing some significant model differences over the
high plains. In general models do break down the ridge to some
point which should result in a slight lowering of temps although
the degree of cooling is in question and forecast will blend the
cooler EC with the more mild GFS. Also seeing some pacific
moisture surging across the southern plains. This will result in
pops returning to the forecast although will keep them low at
this time.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1235 PM CDT Sun Sep 25 2016

VFR anticipated through the 18z forecast period for all western
and north central Nebraska terminals as the guidance shows the
region under the influence of high pressure. Northwesterly winds
will gust in excess of 30kts at times this afternoon...but weaken
and back to the west overnight as the atmosphere decouples.

&&

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

$$

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



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