Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 251157

Area Forecast Discussion
National Weather Service North Platte NE
657 AM CDT Sun Jun 25 2017

.SHORT TERM...(Today and tonight)
Issued at 355 AM CDT Sun Jun 25 2017

Main sensible weather highlights today include: mild highs in the
70s  about 6 to 12 degrees below seasonal normal values, a mix of
partly to mostly sunny skies, and slight chances for precipitation
early today and after midnight tonight. Latest water vapor imagery
shows cyclonic flow aloft over the Central and Northern Plains with
a mid-level trough over much of the central and northeast CONUS.
Elsewhere, a broad mid-level ridge extends from the southwest US to
offshore the West Coast to British Columbia. Multiple disturbances
are embedded within the flow and are apparent over southern
Manitoba, western Saskatchewan, and the Upper Great Lakes with a
weaker disturbance moving southeastward across southern SD/northeast
NEB. Mid-level clouds have increased and blossomed since midnight
across the northern NEB Panhandle through the Sandhills with
ceilings generally around 9-12 kft. Regional radar display shows a
swath of modest returns stretching from near east central WY into
the northern NEB Panhandle into northwest NEB. However, don`t think
much is hitting the ground besides sprinkles, if that, given dry
lower troposphere (below 700 hPa).

Slight chances for light precip early today mainly across the
southwest provided enough saturation occurs in the lower-levels with
modest upward moisture transport and low-level warm air advection.
Confidence remains on the lower-end and may materialize more so as
sprinkles than measurable precipitation. Otherwise, clouds will
affect most areas early on until gradually improvement occurring mid-
late morning. However, clouds are expected to stick around in
extreme southwest NEB and this coincides with cooler high
temperatures compared to elsewhere across western NEB. Tonight,
slight chances for showers/isolated thunderstorms mainly after
midnight outside the eastern NEB Panhandle given amplifying low-
level warm advection and a weak disturbance tracking across. While
instability is weak, a few rumbles of thunder cannot be ruled out.

.LONG TERM...(Monday through Saturday)
Issued at 355 AM CDT Sun Jun 25 2017

Beginning 12z Monday. We`ve seen for several days now multiple
models indicate an area of weak FGEN, center along H7, that would
promote the production of precipitation from the eastern Panhandle
southeast through Frontier county on Monday.  With no strong source
of low moisture and rather weak forcing, the projected rainfall
amounts are anticipated to be light, at most a few hundreths.  There
are suggestions from the latest GFS and NAM of weak tropospheric
instability across southwest Nebraska, so a few CG strikes or
marginally strong storms would not be out of the question, but
severe storms are not anticipated Monday.  Highs on Monday are once
again dominated by the predominate northwest flow and cool high
pressure to the east.  Highs largely in the 70s are expected, but a
few low 80s are possible for SW Nebraska.

Attention then turns to a mid level low that will dive southeast
from the Gulf of Alaska into Central British Columbia and eventually
settle along the central Alberta/Saskatchewan border.  Trailing the
low is a trough that dips well into the Great Basin.  This
low/trough will allow for the eastward progression and de-
amplification of the mid level ridge with the full breakdown to the
east occurring late Tuesday. While the ridge is in place across the
Plains, southerly return flow will rule with good to strong moisture
return expected. The latest consensus has trended a bit west with
the 60F Tds, now along and even west of highway 83 mid afternoon
Tuesday. Instability is shown to increase as the ridge breaks down
and a lead disturbance races eastward toward the plains. The latest
projections show moderate instability in place with more than
sufficient shear to promote sustained updrafts. Large hail and a
severe wind threat will be likely as storms develop upscale into a
complex Tuesday evening.  At this point the most likely initiation
will be over the eastern high plains with the upscale growth
occurring in the vicinity of the central Sandhills. This projection
would provide for beneficial rainfall for much of the CWA.

The model runs from 24 hours ago hinted at the possibility of
enhanced range fire risk Tuesday.  The current runs contradict the
risk, suggesting sufficient moisture to keep critically low RH well
west of the forecast area.  Fuels are still not yet ready for RFW
issuance, but the latest high plains drought monitor indicates a 22%
increase in abnormally dry conditions across the state. The greatest
increase is centered along Highway 83 from Lincoln County north
through Cherry County.  If Tuesday`s rain chances come to fruition
it would definitely help ease some concerns through the Independence
Day Holiday.

As the low wobbles north of the Canadian border, largely zonal flow
will remains over much of the contiguous US.  The models show
several impulses/speed max that will provide for additional
precipitation chances for parts of the CWA.  The first arriving
Wednesday evening into early Thursday and then again Thursday
afternoon into Friday. Strong or severe thunderstorms will once
again be possible owing to favorable shear and instability.
Temperatures through the period look to remain seasonal, or at times
cooler than average for most locations.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 628 AM CDT Sun Jun 25 2017

Local radar display shows a swath of modest returns across
central portion of the eastern NEB Panhandle to south central NEB
producing sprinkles to light rainfall. While surface obs reports
have been limited to a trace of precipitation, web cams show wet
pavement that appears indicative of measureable precipitation
across portions of southwest NEB and the southern Sandhills.
Otherwise, ceilings range from 6-12 kft across western NEB and
winds are light (less than 5 MPH).

Showers will continue to affect portions of southwest NEB through
the morning. A dry afternoon and evening should prevail with
slight chances for showers then returning after midnight across
western and north central NEB. VFR conditions should prevail
through the TAF period.




LONG TERM...Jacobs
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