Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 252035

Area Forecast Discussion
National Weather Service Goodland KS
235 PM MDT Tue Apr 25 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 234 PM MDT Tue Apr 25 2017

Main forecast issue will be chance of precipitation through tonight.
Satellite showing a slow moving/closed off low over Wyoming.
Satellite and height fall analysis shows the southern end this
trough extending from this low has begun and will continue split off
and dig to the south.

Nam and Ecmwf were doing a little better than the Gfs and Canadian
on the upper level jet. The Canadian and Nam were starting the best
with the mid levels. Other output is tending to have features/lower
heights too far east.

For tonight...a few things to note that required some changes to the
previous forecast. First the 12z DDC sounding show a very deep and
dry air mass that will advecting into the area ahead of the upper
low over Wyoming and southern extension of that low. The southern of
portion of this trough is shown by the model output to be
splitting/cutting off further south and west than indicated

The high resolution output picked on that with keeping the northeast
portion of my area dry through tonight. So removed the pops from
that area. There is still enough mid level lift along with a
secondary/weaker left front jet segment that will affect the
southwest portion of the area from later this afternoon through the

As a result, reduced pops a little over the central of the area.
Maintained or increased pops slightly in the far west per the
output and reasoning given above. Most of the precipitation will
be done by late evening with only a lingering chance in the far
south that will end a few hours after midnight.

For Wednesday...ridging aloft and drier conditions will prevail
across the area for this period. Will have more sun but the air mass
will be cooler. Overall the temperatures will be a little cooler
than what is occurring today.

.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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