Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 251757

Area Forecast Discussion
National Weather Service Goodland KS
1157 AM MDT Tue Apr 25 2017

Issued at 1141 AM MDT Tue Apr 25 2017

Just completed an update. The main change was to adjust pops for
this afternoon into tonight. 12z DDC sounding showing a very dry
air mass to advect into the area. Latest trends show no
precipitation over or near the east/northeast portion of the area.
Based on the DDC sounding and the Hires output indicating no
precipitation, the removed pops for the rest of today into tonight
for the northeast portion of the area.

Also the high resolution output has pulled the main area of
precipitation further west with the far west and southwest having
the highest chance of precipitation. This matches well with the
strongest mid level output and weak left front quadrant of jet. So
raised the pops in the far west.

Also made slight adjustments on todays high temperatures. Cloud
cover is thinning a little more than expected and temperatures,
especially in the east are getting very close to the previous
forecast high temperatures.


.SHORT TERM...(Today and tonight)
Issued at 409 AM MDT Tue Apr 25 2017

Latest upper air analysis shows a long wave trough over the CONUS
with a smaller trough moving east onto the High Plains.  Ahead of
this trough storms have been ongoing, some with moderate rainfall.
Accompanying the trough was a cold front.  Along and behind the
front a second round of storms were moving east.  The rain activity
has remained along/north of Highway 36 where the environment is
saturated deeper.

Today there will be some lingering precipitation in the morning over
the northeast corner of the forecast area ahead of an upper level
short wave trough moving through.  Soundings show a shallow
saturated layer in the first 10k ft, so am expecting this to be more
drizzle than rain. This afternoon the cold front that moved through
before the morning will retreat back north west of the KS/CO border.
Meanwhile another upper level short wave trough will approach from
the west.  Rainfall chances will increase as the trough approaches
in the afternoon. Highs will be cooler than yesterday due to CAA and
cloud cover.

Tonight the upper level short wave trough will move over the stalled
front in the evening, producing the best chance for rainfall.
Average storm motion along the front will be almost stationary,
which may lead to heavy rainfall.  The main source for storm
movement will be the upper level short wave trough.  To the east the
first 10k ft. will continue to be saturated over the east half to
third of the forecast area.  With weak lift moving over top ahead of
the short wave trough, drizzle may occur.  Rainfall chances will
shift south with the front and associated upper level short wave
trough. The trough axis will move through during the overnight hours
bringing any lingering rainfall to an end.  Due to the CAA lows will
fall into the 30s but am not expecting any frost development because
of the cloud cover.  Even though the forecast mentions rain mixing
with snow overnight, am doubtful of this since the precipitation
will be ending as temperatures become cold enough to support snow.

As the cold front heads south tonight a secondary cold front will
move through from the north.  Accompanying this front will be a low
level jet.  The CAA behind the front will allow a shallow mixed
layer to develop and mix some of the low level jet winds to the

.LONG TERM...(Wednesday through Monday)
Issued at 409 AM MDT Tue Apr 25 2017

Wednesday will be dry due to subsidence overhead.  Highs will be
similar to today.  North winds will be strongest in the morning due
to the low level jet overhead and the shallow mixed layer in place.
Winds will decline in the afternoon as the low level jet weakens.

Wednesday night a weak upper level short wave trough will move
through in the zonal flow.  This trough will not be strong enough
and the environment too dry to generate more than clouds.  The cloud
cover should prevent any frost from forming since lows will be
in the 30s.

Thursday another stronger upper level short wave trough will move
through from the west.  The environment saturates as the trough
moves over the area.  However the east half of the forecast area
currently looks to have a deeper saturated environment than the west
due to somewhat drier air being circulated in around the upper level
trough as it moves through.  At the surface a warm front will be
near Cheyenne County CO and Greeley County.  Am expecting isolated
thunderstorms along and slightly north of the front with showers
elsewhere.  Highs will be similar to Wednesday.

Thursday night the upper level short wave trough deepens over the
forecast area, producing an even better chance for rainfall.  After
midnight dry air begins to circulate in from the southwest causing
rainfall to end from southwest to northeast.  The rainfall should
end before temperatures cool enough to support snow.

Friday through Monday

An extended period of precipitation is expected from late Friday
through Saturday night as a strong low pressure system moves east of
the Rockies and across the plains.

The upper short wave trough rotating out of the main upper trough to
the west lifts out of the forecast area on Friday while the main
trough continues to deepen over the Central Rockies and
Intermountain Region. Rain will subside briefly early Friday before
additional rain begins to spread across the forecast area later
Friday in association with the stronger system approaching the

Friday night and Saturday a 140kt jet max on the back side of the
upper trough drives the low center through the 4-corners region and
the base of the trough further south towards northern Mexico.
Saturday night the jet max rotates around the base of the trough
with the entire trough moving east of the Rockies by early Sunday
and the low center lifting out over Iowa by late Sunday.

Friday night the rain spreading across the area will mix with and
change to snow over mainly the western sections of the forecast area
as temperatures drop into the lower to middle 30s. Expect a change
back to all rain during the day on Saturday with a rain and snow mix
returning Saturday evening as temperatures drop into the lower 30s.
As the low pressure system lifts out across the plains states
Saturday night, precipitation is expected to start tapering off
after midnight.

As generally higher pressure moves across the region on Sunday and
Monday, expect dry conditions with temperatures returning to near
normal with highs in the 60s and lows around 40.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1141 AM MDT Tue Apr 25 2017

For Kgld...Through the rest of the afternoon, into the late evening
hours, vfr conditions are expected along with northeast winds of
around 15 knots. Showers will begin moving close to the sight
later this afternoon into this evening. However, model output is
not clear on how far east this precipitation with more guidance
keeping further west of the sight. So chose only to put in
vicinity showers. In the 03z to 05z time frame mvfr conditions
will develop and the winds will shift to the north at 17 knots
with gusts to near to 25 knots. Even when conditions become vfr
around 09z, those gusty winds will continue until 13z. After 13z
the winds will be sustained near 14 knots.

For Kmck...Through the first half of the period, mvfr conditions
are expected with occasional vfr conditions expected during the
mid afternoon hours. Shortly after 06z, vfr conditions will return
for the remainder of the period. North winds will increase to near
17 knots with gusts to near 25 knots. Those winds will stop
gusting around 14z with the sustained winds remaining near 16
knots through the rest of the morning.




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