Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 241801
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1201 PM MDT Fri Mar 24 2017

.UPDATE...
Issued at 1201 AM MDT Fri Mar 24 2017

High Wind Warning has been cancelled as downward trend in obs
matching short range and 12Z guidance has continued. Main surface
low center is transitioning south and east and this will continue
to shift axis of better mix layer winds out of our CWA (and these
are already below criteria based on VAD wind profiles). While
58mph or higher wind gusts are no longer expected, we may still
see some gusts to 50 mph near showers/isolated thunderstorms this
afternoon. This will be covered in HWO.

UPDATE Issued at 1055 AM MDT Fri Mar 24 2017

Cancelled Winter Weather Advisory early. We are getting reports of
snow in western Cheyenne County Colorado, but accumulations are
minimal. Web cams along I-70 are only showing very light precip.
Winds are substantially lighter than originally anticipated and
due to the wet nature of the snow (where it is occurring) we are
not seeing blowing snow. I could see 1-2" of slushy snow
accumulation in eastern CO, but this will be mainly on grassy
surfaces and below advisory criteria as well.

In other parts of our CWA I extended rain/snow mix mention
further east. Web cams in Nebraska show light accumulations on
grassy surfaces and we had a report of sleet/light snow in
Cheyenne county KS where air temps are hovering around 39. This
should predominantly be rain for most locations, but there is
still a chance that a light slushy layer of snow develops further
east on grassy surfaces due to convective showers/isolated
thunderstorm cooling the BL.

Regarding High Wind Warning: So far we have only received an
isolated 60 mph report, with other locations remaining just below
criteria. It appears best chance for stronger winds will be near
showers/isolated thunderstorms, and 12Z guidance has shown a
downward trend in mixed layer winds even compared to 00Z guidance
(which was already lower than 24hr ago). HRRR still shows
potential gusts around 50kt mainly in our west near the CO state
line mating region where better pockets of precip are occurring.
Even with the HRRR this trend is shown to decrease after 18Z. The
plan is to monitor over the next few hours and consider
cancellation early if these trends continue.

&&

.SHORT TERM...(Today through Sunday night)
Issued at 427 AM MDT Fri Mar 24 2017

Main focus will be active weather into tonight. Satellite showing an
amplified pattern from the eastern Pacific into North America.
Strong slow moving closed slow spinning over southeast Colorado will
be the main weather make early on.

For Today/tonight...In short have kept the current highlights.
However, there are caveats/uncertainties with that part of the
forecast. First the wind. Models have backed off on the winds. This
may be because the low is a little slower to move into the area and
takes a slightly more southerly path. Am not certain of the lower
winds since the models did not have surface low associated with the
upper system strong enough. Day shift will have to assess again.

Am also having doubts about precipitation coverage, especially
further south and east in my area, and the phase in the far west.
First model output has had the band associated with the overnight
precipitation too far south and east and consequently does not have
the dry slot far enough north and west. Of all the output, the Hrrr
appears to have the best handle on this. This keeps the brunt of the
precipitation in the northwest third to half of the area with very
little precipitation in the far south and east.

Models also have the temperatures not warm enough and dewpoints not
high enough, especially in the far west. Currently Limon is at 32
degrees with light snow, and Flagler is at 42 degrees. The thing
that could change this is the current and forecast
thunderstorms/instability going on. Thunderstorms could lower the
temperatures to start snow. Wpc has far western Kit Carson and
Cheyenne counties with the highest snowfall totals which fits with
our current forecast. Also forecast soundings would support the
phase change is this area as well.

So kept the current snowfall forecast for the far west. Also since
it does not look like it will get cold enough further east per
temperature forecasts and forecast soundings, took the rain line a
little further west. Also per the note above, currently we are still
getting isolated thunderstorm development, and elevated cape
forecasts would support that across the entire area. So have kept
isolated thunderstorm mention across the entire area through the day.

Precipitation should end near or shortly after midnight.

For Saturday/Saturday night...Did not have a lot of time to deal
with this period due to ongoing active weather. Models/blend bring
in a low chance of precipitation after midnight Saturday night. That
looks reasonable with good model agreement. Also kept temperatures
for this period as well.

For Sunday/Sunday night...Again not a lot of time to spend on this
period. Also not a lot of model agreement on this period. The blend
gave me high chance to likely pops. At this time cannot dispute
that due to lack of time and model disagreement. Definitely looks
like the area will get something just not sure of the chance. As a
result did not change any of the grids the blend gave me.

.LONG TERM...(Monday through Thursday)
Issued at 239 AM MDT Fri Mar 24 2017

The main story during the extended period is rain chances due to a
potentially strong system heading towards the Plains midweek.
Temperatures remain near to above normal for much of the region.

The period starts out dry on Monday with an upper ridge between
Sunday`s departing wave and the incoming system to the west. A warm
day with highs in the low/mid 60s is anticipated.

A deep upper trough develops over the west coast and moves into the
desert southwest Monday night. The trough closes off and tracks east
across northern Texas and Oklahoma through Thursday. This system
brings rain shower chances to the region Monday night through the
end of the period. Wednesday night and Thursday, chances are
confined to the southern and eastern portions of the area as weak
ridging builds in behind the exiting system. There are still
discrepancies with how this system will evolve and precipitation
chances depend on its track. Will continue to monitor.

Temperatures cool off slightly Tuesday through Thursday, with highs
in the upper 50s to low 60s. Lows stay in the 30s throughout the
extended.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1131 AM MDT Fri Mar 24 2017

Rain possibly mixed with snow at times, and a few thunderstorms
will continue to move across NW Kansas and SW Nebraska this
afternoon before decreasing in coverage this evening/late tonight.
Confidence was not high enough to include mention of thunder at
either TAF site as current trends have been for this activity to
remain west of both terminals (can`t rule it out completely
though). IF Cigs and occasionally IFR vis have occurred at both
terminals and will remain possible through the middle of the
afternoon. A few models are showing the potential for MVFR
conditions to linger through Saturday morning. Currently model
consensus is VFR conditions returning late this evening, and this
was favored for this TAF update.

Strongest winds will remain in the afternoon, with northerly
winds decreasing below 12kt by the later part of the evening as
the main surface low pressure area shifts south and east of the
region.


&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

UPDATE...DR
SHORT TERM...BULLER
LONG TERM...JBH
AVIATION...DR



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