Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 240955

Area Forecast Discussion
National Weather Service Goodland KS
355 AM MDT Mon Apr 24 2017

.SHORT TERM...(Today and tonight)
Issued at 354 AM MDT Mon Apr 24 2017

Latest upper air analysis shows zonal flow behind the exiting short
wave ridge with smaller short wave troughs within the flow.  At the
surface a trough was approaching the Tri-State Area from the west.
Ahead of the trough south winds were still breezy, while west of the
trough winds were slower.

Today south winds will turn to the northwest behind the surface
trough as it moves through the forecast area.  Winds will be
strongest in the morning due to the low level jet mixing down behind
the trough.  In the afternoon winds will decline as the low level
jet weakens.  Later this afternoon an upper level short wave trough
will approach from the west. Ahead of the trough the environment
will begin to saturate above 10k ft. over NW Yuma and Dundy counties,
which may lead to some rainfall.  Meanwhile highs will be warmer
today due to the WAA behind the surface trough.

Tonight the upper level short wave trough will move across the rest
of the forecast area.  The strongest lift will occur overnight, but
the environment above 10k ft. will dry out as a cold front moves
through.  Behind the front the first 5k ft. will saturate under the
upper level short wave trough north of I-70.  This will be a better
setup for drizzle than rainfall due to the shallow saturated layer.
The lift from the short wave trough may be strong enough and the
saturated layer deep enough to possibly produce precipitation mainly
north of Highway 36.

.LONG TERM...(Tuesday through Sunday)
Issued at 354 AM MDT Mon Apr 24 2017

Tuesday there may be some lingering drizzle in the morning as the
upper level short wave trough exits.  In the afternoon another upper
level short wave trough will approach from the west.  At the surface
the cold front will lift back north as a warm front and stall just
west of the KS/CO border, under the upper level short wave trough.
This will provide a focus for rain development into the evening.
Further east have much less confidence in rainfall occurring.
Forecast rainfall chances look a bit too high given the lack of
upper level lift.  Not too sure what the model consensus and near
term models are taking into account to generate rainfall.  Only
favorable factor is the steep temperature lapse rates in the first
5k ft. to support some rainfall development, but am not very
optimistic about that. Believe only rainfall in the afternoon will
be near the KS/CO border near the cold front and approaching upper
level short wave trough.

Tuesday night rainfall chances increase along and west of the KS/CO
border as the upper level short wave trough deepens.  Rainfall
chances will decline as the front and short wave trough move south.
Have low confidence of any rainfall occurring to the east due to a
lack of upper level lift and a drier environment.  Not sure why
model consensus had around 40% chance for rain. Maybe some models
are producing  drizzle with the backdoor cold front that moves
through.  Anyway, the front will be fairly strong. Behind it the
surface pressure gradient will tighten and a shallow mixed layer
will develop that will allow the low level jet to mix down, both
contributing to breezy winds. The CAA behind the front may cause the
rainfall to be mixed with snow late in the night. Am skeptical of
this since the rainfall should be ending by this time if not already
over. Despite lows falling into the 30s, am not anticipating any
frost forming due to the cloud cover.

Wednesday highs will be even cooler than Tuesday due to the cold
front passage.  North winds will be strongest in the morning then
decline as the low level jet declines.  The day will be dry for the
most part due to subsidence inbetween the exiting upper level trough
and the next one approaching from the west.

Wednesday night a weak upper level short wave trough will move
through from the west.  The environment will saturate above 5k ft.
but the short wave trough will be too weak to produce any rainfall.
Am surprised models didn`t produce any rainfall given the rainfall
chances Tuesday and Tuesday night in drier air with much less lift.
Despite lows in the 30s, do not foresee frost occurring due to the
cloud cover.

Thursday through Sunday

Northwest flow aloft shifts to a broadly cyclonic flow over the
central high plains region on Thursday and Thursday night as the
initial short wave trough in the series of waves rotating through the
western U.S. moves east of the Rockies. Latest model runs show this
pattern becoming more amplified than previously expected as the
trajectory of the short wave troughs entering the back side the
deepening upper trough are now going deeper into the U.S. southwest
or into the northern sections of Mexico before recurving back to the
north as they move move east of the Rockies and lift out across the
plains states.

The ECMWF remains the more progressive in the timing and position of
the main upper low that develops as it moves through the 4-corners
region mid day Saturday and quickly reaches the far southwest
portion of Minnesota by mid day Sunday.  The GFS is further south
and less progressive with the movement of the upper low as it tracks
through Arizona and New Mexico Saturday evening, and through the
Texas panhandle region into central Oklahoma by mid day Sunday. Tend
to prefer the the deeper and slower GFS somewhat, and have continued
the trend of taking the higher pops and QPF further south and
cooling the temperatures, but have strayed slightly from the gridded
solutions loaded form the Superblend by going with even cooler
temperatures on Saturday along with an overall slight increase in
pops late in the week through Saturday.  With either solution, should
see the system lift out of the region through the day on Sunday.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1030 PM MDT Sun Apr 23 2017

For KGLD and KMCK, vfr conditions expected through the period.
Southerly winds gusting 25-30kts expected at KGLD from taf
issuance through about 11z while at KMCK winds generally from the
southeast near 12kts. From 12z-22z winds steadily veer to the
southwest, west then northwest through the morning into early
afternoon with gusts near 30kts expected as a cold front moves
through. After 22z winds continue to veer to the north, northeast
and east at speeds under 10kts. KMCK could see a shower near/over
the terminal in the 02z-06 timeframe.




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