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Area forecast discussion...updated 
National Weather Service North Platte NE
632 am CDT Tuesday Apr 21 2015

Short term...(today and tonight)
issued at 355 am CDT Tuesday Apr 21 2015

An Arctic cold front across North Dakota will back into the forecast
area this afternoon producing some cloudiness. The front will continue
to move south and west tonight. By 12z Wednesday a small area of
high pressure has settled over ncntl Nebraska which should produce
lows in the 20s. By this time...the models suggest any cloud
cover would lie across the Panhandle and southwest Nebraska which
would hold up lows in the lower 30s.

Highs today rise into the 60s ahead of the front with 50s north
of the front along Highway 20.

The midlevel cloud cover across cntl/southeastern Nebraska early this morning
is associated with 700mb frontogenesis. The rap moves these
clouds southeast and then drops a second batch of clouds into northern
Nebraska as early as 15z which hang around most of the day and then
move south and west tonight. The radar returns across North
Dakota move east of the forecast area in the NAM model while the hrrr
shows too much dry air in the lower levels for anything more than
sprinkles this afternoon and tonight.

Long term...(wednesday through monday)
issued at 355 am CDT Tuesday Apr 21 2015

Surface high pressure quickly follows the cold front and will
slide southeast of the area early in the day on Wednesday with
southerly winds developing. Despite southerly winds...cool air
aloft...850 temperature from 3c east to 8c west...and even with sun and
good mixing...highs in the upper 50s and lower 60s. Meanwhile an
upper level low lifts towards the desert SW. Models also show a
weak system ahead of the main low...pushing across the Southern
Plains.

A second wave ejects from the main low and arrives to the
southern/Central Plains Wednesday night into Thursday. Marginal lift
into SW Nebraska may result in a few light showers initially. A better
chance arrives later in the day on Thursday after we get some
heating. Models increase convective available potential energy to a few 100 j/kg and lifted index
values around zero or slightly negative. Generally thing activity will
be some showers and a few rumbles of thunder here or there.

By Friday the main low will be crossing The Rockies. Moisture
continues to increase ahead of the low and Friday looks to see a
wave or two of showers to rotate through the area. Better
moisture lift associated closer to the low...which favors higher
probability of precipitation across SW Nebraska.

A second wave...clipper...quickly follows for the weekend. Should
see a brief break in the activity before the second wave
arrives...although timing the break is difficult due to model
differences. Forecast does retain low probability of precipitation and expect this to
change in the coming days as the lull in activity becomes more
clear. At this time models are in favor of the dry period to
occur sometime Saturday...earliest is the Gem/GFS...while later
is favored by the European model (ecmwf).

The next wave should be east of the area to start the work week
dry and mild.

&&

Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 630 am CDT Tuesday Apr 21 2015

The middle level clouds across South Dakota will spread south through the
forecast area today and exit south and west tonight. VFR is
expected all areas during this time.

&&

Lbf watches/warnings/advisories...
none.
&&

$$

Short term...cdc
long term...masek
aviation...cdc

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