Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 261720 AAA

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
1220 PM CDT Sun Mar 26 2017

.SHORT TERM...(Today and tonight)
Issued at 401 AM CDT Sun Mar 26 2017

The main forecast concerns in the short term period include: fog
this morning and late tonight; precipitation chances today; and
high temperatures. Latest surface plot shows sites reporting
reduced visibility as fog spreads towards the central Sandhills
and southwest NEB. Visibilities have deteriorated the worst at
KTIF, KONL, and KIML where visibility are sub-one mile. Areal
coverage of fog with visibility less than one mile appears to be
more patchy with visibility greater than one more widespread
based on web cams and surface obs. Latest satellite imagery shows
high clouds obscuring stratus/fog over much of western and north
central NEB.

Residual moisture in the boundary layer from previous rain,
modest dew points, and light southeast winds and weak upslope
flow are providing support for formation and development of fog
across north central and southwest NEB. Anticipate the trend of
deteriorating visibilities to continue to spread across southwest
NEB and west across much of the Sandhills, especially as
temperatures drop to the dew point. Main concern is how prevalent
fog with visibility 1/2SM or less will be. Current thinking is the
areal coverage of 1/2SM or less visibility will not be
significant enough based on SREF probabilistic products and latest
deterministic guidance. In addition, visibilities are expected to
vary in intensity though areal coverage of fog will be greater
than patchy. Further, boundary layer turbulence is suspected
to be elevated that will act to limit formation of 1/2SM or dense
fog. Fog/stratus is expected to lift/dissipate across much of the
area by mid-late morning. However, cloudy skies will prevail
today with cooler conditions expected compared to yesterday.

Latest water vapor imagery shows a northern and a southern stream
trough. Of which, the southern stream short wave trough will exit
the Four Corners region and eject into the OK Panhandle mid-late
morning today. The positive PV anomaly will then continue to
track swiftly across OK and the Southern Plains. Cyclogenesis is
expected there with a surface low developing in the vicinity of
the TX Panhandle/OK Panhandle. North of the system, slight
chances-chances for showers will be present across mainly western
NEB today with chances decreasing this afternoon as the low
develops. A potential fly in the ointment exists with respect to
today`s highs wherein precipitation and cloudiness could cause
temperatures to be on the warm side. This will need to be
monitored. As the low moves eastward across the Southern Plains
tonight and weak high pressure noses into the local forecast area
from the Upper Mississippi Valley, the threat for fog returns
late tonight-tomorrow morning.

.LONG TERM...(Monday through Saturday)
Issued at 401 AM CDT Sun Mar 26 2017

Few changes have been made to the going forecast. For early Monday
morning, light winds and a moisture rich environment from previous
rain will provide favorable conditions for some patchy fog across
the southern and eastern forecast area. Otherwise, high pressure
build into the region on Monday bringing drier conditions to north
central Nebraska. Temperatures return to the upper 50s and low
60s. Clouds increase late Monday as the next system approaches the

A developing low pressure system will move off the Rockies on
Tuesday night and slide across the south central Plains on
Wednesday. For the most part, north central Nebraska will be along
the northern fringe of this system. However, warm air will be
plentiful and precipitation will remain as rain for most of the
system. There is a slight chance of precipitation mixing with snow
early Wednesday morning across the eastern Panhandle and Pine
Ridge region. Any snow that develops will have a difficult time
accumulating on a fairly warm and wet ground. Have left out
accumulations at this time.

The system will continue to move eastward across Kansas and
Missouri on Wednesday and Thursday. Precipitation is anticipated
to continue through impact the forecast area through early
Thursday for the entire forecast area. There`s another chance for
some rain/snow mix on Thursday morning, this time along and west
of the US-83 corridor. Again, no snow accumulations are expected
as the boundary layer environment will be too warm to support snow
accumulations. By Thursday afternoon, the precipitation line will
begin to move eastward across Nebraska. By late Thursday
afternoon, areas east of US-83 will be the only locations still
seeing rain.

Upper level ridging returns behind the departing low, bringing dry
conditions to the central US for the end of the week and into
the first part of next weekend. High temperatures remain steady in
the 50s through the week, with overnight low temperatures ranging
from the upper 30s to low 40s.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1220 PM CDT Sun Mar 26 2017

Moisture is expected to increase tonight across Wrn and Ncntl
Nebraksa. The short range models suggest a return to LIFR
conditions in fog and low CIGS. The radiation conditions for fog
appear uncertain since the moisture will be fairly deep which
does not support the escape of heat necessary for fog. The
forecast is very tentative with marginal visibility and MVFR cigs.
Any breaks in the mid level cloudiness could support areas of
dense fog. Flight conditions...whatever they are Monday
morning...should improve after 14z.




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