Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 170458
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1158 PM CDT Sat Sep 16 2017

.SYNOPSIS...
Issued at 315 PM CDT Sat Sep 16 2017

Upper low over eastern MT continues to lift northeast into ND with
lead PV anomaly over western SD early this afternoon. Another PV
anomaly located across southern WY will also be pulling northeast
tonight. At the surface weakening high pressure across NE as
pressure falls increase across the western High Plains. Cold front
that came through the area last evening now located across
central KS into eastern MN, cutting through far southeast NE. Mid
level cloudiness atop lower clouds remains across north central
NE, with light echoes on radar waning.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 315 PM CDT Sat Sep 16 2017

Height rises over the central Rockies behind the exiting upper
level low over the northern Plains will induce a more zonal flow
over the lee of the Rockies this evening. This will promote
surface pressure falls over the High Plains and a resulting return
flow prior to advancing high pressure to come later overnight.
This will result in upslope flow further west and a mid level warm
advection pattern and associated isentropic lift this evening.
Mid level cloudiness and isolated to widely scattered rain showers
should develop this evening/overnight as per the HRRR. Will
include some cloud cover in the western and southwestern portion
of the area tonight for this. While not a big deal from a
precipitation perspective, the cloud cover should keep the
southern portion of the area from dropping into the 30s overnight
assuming it happens as expected. This is as a result of surface
high pressure dropping south and settles in over the central part
of the state early Sunday morning. Recent MOS guidance has warmed
overnight lows a few degrees in the south due to cloud cover in
the south as discussed, but remains fairly constant further north
and west where mid 30s are likely. Patchy frost possible there.
Did include patchy frost in the northwestern areas which was also
in prev forecast.

As previously mentioned area of upper height rises moves in to the
northern Plains during the day Sunday broader surface pressure falls
develop over the lee of the Rockies. This will set up a return low
level flow through the day. Cloud cover is not consistent in the
models with more precip shown in the HRRR in the morning, after a
cool start. Atmospheric return flow increases during the day and low
level moisture returns into the High Plains. This, combined with
southwesterly flow aloft will bring an elevated mixed layer and
available mid level instability which is indicated by a narrow area
of CAPE in the Panhandle by afternoon. Morning precip should weaken
and went with a mainly dry forecast after that.

.LONG TERM...(Sunday night through Saturday)
Issued at 315 PM CDT Sat Sep 16 2017

An active week ahead as a large upper level trough digs south
through the western portions of the United states. Our region will
remain on the eastern periphery of the upper trough with
southwest flow aloft to dominate for the first half of the week,
then a more south-southwest flow aloft for the second half of the
week as the trough digs farther south into the southwest U.S.

The first chance for rain will be Sunday night into Monday morning.
Strong mid level warm air advection and increasingly moist southerly
low level jet, will lead to significant destabilization in the mid
levels of the atmosphere. Looks like a decent set up for elevated
thunderstorm development, and have this covered in the forecast with
some fairly decent pops.

Another shot for rain enters the picture late Tuesday afternoon and
Tuesday night. This looks most likely for northern Nebraska, which
will be in closer proximity to a decent wave moving across the
Dakotas. SPC continues to highlight northern Nebraska for potential
severe during this time. Moisture, instability and shear look decent
and agree some stronger storms are possible and will highlight in
the Hazardous Weather Outlook.

A cold front will scour out the moisture for Wednesday through
Thursday night and expect dry conditions during this time. For
Friday into the weekend, rain/thunder chances will increase, as both
quality low level moisture and upper level dynamics become favorable
for precipitation development. Certainly could be some stronger
storms as dew points rise into the 60s and south-southwest flow
aloft increases as the upper trough approaches from the west.

Temperature wise, it is looking like a fairly warm week, with highs
ranging from the mid 70s to mid 80s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1158 PM CDT Sat Sep 16 2017

Expect increasing high level cloudiness overnight with scattered
to broken CIGS of 10000 to 12000 FT AGL on Sunday. There is a
small threat for showers across southwestern Nebraska early
Sunday. Since coverage is expected to be isolated at best, will
forgo mention of shras in the 06z TAF fcst. For Sunday night,
there will be an increased threat for showers and thunderstorms
but this is expected to be after 06z Monday.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SYNOPSIS...Stoppkotte
SHORT TERM...Stoppkotte
LONG TERM...Taylor
AVIATION...Buttler



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