Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 290836

Area Forecast Discussion
National Weather Service Goodland KS
236 AM MDT Sat Apr 29 2017

.SHORT TERM...(This evening through Saturday)
Issued at 216 PM MDT Fri Apr 28 2017

Latest upper level analysis shows a closed low over the central
Rockies. Ahead of the closed low southwest flow was pulling higher
moisture onto the High Plains. At the surface a cold front was
near the I-70 corridor. Behind the front northeast winds were
gusting up to 30 MPH.

Tonight the cold front will slide south through the rest of the
forecast area in the evening. Any lingering thunderstorms will be
pushed south with the front. Meanwhile frontogenesis and
isentropic lift will develop over the forecast area, with the
lift/frontogenesis strongest over the southeast portion of the
forecast area. At the surface rain will change to snow from west
to east as temperatures cool. The higher snowfall amounts for the
night will occur after midnight when the lift/frontogenesis will
be strongest.

Saturday morning there will be a lull in the precipitation
intensity. Light precipitation will continue as weak frontogenesis
and isentropic lift continue. In the afternoon a stronger band of
frontogenesis and isentropic lift will develop over the southeast
half of the forecast area, causing precipitation intensity to

Snow will change back to rain generally north of I-70 and east of
Highway 83, but how quickly this change-over occurs is highly
dependent on temperature. If temperatures are a couple degrees
cooler than forecast, snow will persist longer through the day
before changing to rain, if it changes over.

Saturday night through Sunday the main snowfall event will occur
as strong, deep isentropic lift and repeated rounds of
frontogenesis move over the southeast half of the forecast area.
Snowfall amounts are actually lower Saturday night than what they
should be based on the lift due to a dry pocket of air moving
north over the area. As precipitation ends from west to east
Sunday afternoon, the snow may change to rain as warmer
temperatures move in behind the storm system.

Sunday morning into early afternoon strong to possibly high winds
will occur mainly east of the Colorado border and west of Highway
83 on the back of the storm system. Considered issuing a high wind
watch, but confidence was too low at this time to warrant a
watch. Am expecting gusts of 55 MPH in this part of the forecast
area, but a few gusts near 60 MPH can`t be ruled out.

Snowfall for this storm system will come in two different rounds.
The first round will begin tonight and last through Sunday evening
for counties in the winter storm warning, with next round starting
Saturday night in watch area and lasting through Sunday evening.
Due to the change- over of rain to snow being dependent on
temperatures there will be a sharp cut- off between the higher
snowfall amounts and the lower snowfall amounts along the Highway
36 corridor up to McCook. Could have gone either way including
Cheyenne County KS in the warning, but decided to play it safe and
include them since current forecast has 7 inches in the far
southern part of the county. If temperatures are a couple degrees
cooler for the forecast area, snowfall amounts will be higher.
Already cooled temperatures a couple degrees below most models,
but that may have not been enough.

Looking at CIPS Analog analysis, this event is similar to the
April 2, 1988 and the April 12, 1994 events which both had close
to a foot of snowfall with them. Current forecast has close to a
foot of snow south of I-70.

Impacts with this storm system will be tree limbs breaking and
possibly power lines being blown down from the weight of the
heavy wet snow combined with the strong winds. As such people
should make preparations for no power during the storm. The cold,
wet conditions, with wind chills in the teens and 20s, will be
very hard on newborn livestock.

.LONG TERM...(Tuesday through Friday)
Issued at 235 AM MDT Sat Apr 29 2017

During the long term period chances for precipitation will be
Tuesday into Wednesday afternoon. There will be a trough that will
dip down into Colorado and the High Plains that will bring moisture
to the region. Current guidance shows rain showers possible through
that period, but does not have much for instability. So, there was
no mention of storms. This could possibly change, but if it does
severe storms are not likely.

Thursday and Friday will dry out with the exiting of that low
pressure system to the east. Upper level flow shifts to the
northwest, with a strong ridge in place over the western CONUS.

Temperatures during the period will be in the 50s Tuesday and
Wednesday. Then increase to the 60s on Thursday and the 70s on


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1119 PM MDT Fri Apr 28 2017

At KGLD...IFR and occasional VLIFR conditions will continue
through the TAF period. Ceilings will be the main driver of the
flight category. Light snow overnight and Saturday morning will
reduce visibility to between 3-5SM. A rain snow mix may develop
Saturday afternoon as temperatures warm slightly, but change back
to all snow after sunset. Surface winds will be gusty out of the
northeast to north.

AT KMCK...precipitation will be slow to develop, and may hold off
until Saturday morning. Temperatures will be warm enough so that
when it does develop it will be rain or a rain/snow mix. There may
be a lull in the precipitation Saturday afternoon, then pick up in
earnest Saturday night as the upper system approaches. Ceilings
will be mostly IFR, but might improve to MVFR at times Saturday
afternoon, before lowering again Saturday night. Surface winds
will be gusty out of the northeast to north.


KS...Winter Storm Warning from 7 PM this evening to 7 PM CDT Sunday
     for KSZ002>004-014>016-029.

     Winter Storm Warning until 6 PM MDT /7 PM CDT/ Sunday for KSZ001-

CO...Winter Storm Warning until 6 PM MDT Sunday for COZ091-092.

NE...Winter Storm Warning from 7 PM this evening to 7 PM CDT Sunday
     for NEZ080-081.



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