Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 261143
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
643 AM CDT Mon Jun 26 2017

.SHORT TERM...(Today and tonight)
Issued at 355 AM CDT Mon Jun 26 2017

Sensible weather highlights in the short term include: slight
chances for showers/isolated thunderstorms today; highs in the mid
70s to lower 80s (generally slightly below seasonal normal values);
and light northeasterly breezes today. NtMicro RGB imagery shows low
clouds/stratus creeping northward from northwest KS/extreme
southeast NEB into southwest NEB and south central KS. Appears to be
limited to mostly stratus across the NEB/KS border with patchy fog
more prevalent in KS based on surface plot. Elsewhere, a few areas
of mid-level clouds are present across north central NEB and the
Sandhills. Latest water vapor imagery continues to show cyclonic mid-
level flow across the Central and Northern Plains with little in the
way of disturbances upstream in the flow outside of a disturbance in
the Middle Missouri Valley that is tracking southeast. Meanwhile, an
upper level ridge extends from the Southwest US into the Northern
Rockies and Northern Intermountain West to Alberta. At the surface a
weak trough lies roughly w-e across central NEB. Broad high pressure
encompasses the Northern Plains and extends south into the
Middle/Lower Mississippi Valley.

Stratus will continue to progress northward and is expected to make
it just into the southern portions of the Loup River basin then
diminish through mid and late morning. There could be some patch fog
development as well. The surface trough will continue to sag
southward and be south of the local forecast area by late
morning/early afternoon with north or northeast winds then
prevailing. Northerly flow will help keep highs mild with cooler air
in place overhead. Slight chances for showers/isolated thunderstorms
mainly along and south of the Interstate 80 corridor this afternoon
with chances diminishing by late afternoon to early evening. Low
confidence associated with chances this afternoon given the weak
forcing and setup. Decreasing sky cover this evening followed by
increasing high clouds and some mid-level clouds across southwest
late tonight.

.LONG TERM...(Tuesday through Sunday)
Issued at 355 AM CDT Mon Jun 26 2017

Upper level low centered just east of the central British
Columbia/Alberta line will lift east into far western Saskatchewan
on Tuesday.  Extending south from the low is a trough that dips into
the Great Basin.  The trough will follow a similar path, but across
the northern US Rockies and eventually breakdown a Plains ridge.  At
the surface, a broad lee low from NOCO north into eastern MT will
rapidly deepen while surface high pressure builds east across the
Ohio RVR valley.  Southerly return flow off will strengthen and
transport TDs in the upper 50s to lower 60s across the Sandhills by
mid-afternoon on Tuesday.  The atmosphere is shown to become
increasingly unstable as strong surface heating combines with
cooling aloft /from a lead sw/ with the latest projections
suggesting SBCAPES Tue afternoon in excess of 2.5 kj/kg from SW NE
northeast into the Dakotas.  Storms are expected to initiate along a
strengthening baroclinic zone over the high plains.  Initial modes
suggest the potential of multi and supercells capable of very large
hail.  The latest proximity soundings indicate a large contribution
of CAPE in the HGZ across western Neb Tuesday afternoon.  SFC T-TD
spreads show the potential of greater than 30F over the high plains,
so severe wind will be also be possible.  The convection will
eventually develop into one /or more/ convective complexes as the
storms encounter a 50KT LLJ over west central Neb.  The prospects of
much needed widespread rainfall is looking good. Unfortunately, the
forward speed and marginally supportive PWATS would suggest a good
soaker will not occur for most locations, but a few spots may see
rain amounts of an inch or greater.

The upper low will effectively flatten the ridge, leaving zonal flow
across the forecast area through at least the end of the work week.
Additional low amplitude waves are shown to spark off convection
within the region.  The greatest coverage of storms will be Thursday
afternoon into Friday.  Thermal and wind profiles show the potential
for additional strong or severe storms then with the best chances
for the central Sandhills and points south.  These storms should
grow upscale into a complex bringing measurable rainfall to many
areas.

The Canadian upper low will get evicted and dive south across the
northern plains on Friday before getting absorbed by a Great Lakes
trough on Saturday.  Ridging will build into western Canada, though
a low amplitude wave will undercut the wave and bring storm chances
for next weekend.  Confidence in this is rather low, but will watch.

The active pattern will keep temperatures at or slightly below
seasonal norms through the extended.  Highs in general will top out
in the 70s and 80s, with lows in the 50s and 60s.  Tuesday appears
to be the warmest day in the extended as upper ridging becomes
established and breaks down to the east.  A few 90 degree readings
will be possible across sw Nebraska and possibly the eastern
Panhandle.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 627 AM CDT Mon Jun 26 2017

Satellite imagery shows low stratus, ceilings 600-1000 ft AGL,
extending north from parts of southwest NEB into the Interstate
80 corridor and across the South Loup River. Patchy fog is
present as well. Only modest restrictions to visibility so far
(lowest is 2SM at KOGA) with web cams showing fog as well.
Improvement in sky cover will take place mid-late morning with
mostly sunny skies prevailing this afternoon. Winds will gradually
shift across southern NEB and become north/northeast by mid to
late morning. Slight chances for showers/isolated thunderstorms in
the afternoon along and south of the Interstate 80 corridor.
Mostly clear skies this evening with clouds increasing gradually
late tonight over western NEB (mainly mid- and high-level clouds).
LLWS conditions become a concern tonight associated with
developing low-level jet. More confident in LLWS conditions at
KVTN terminal/northern NEB than KLBF terminal/southern NEB. Thus
no mention of LLWS in the KLBF TAF at this time.

&&

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

$$

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


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