Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 172313

Area Forecast Discussion
National Weather Service Goodland KS
513 PM MDT Tue Oct 17 2017

.SHORT TERM...(Today through Wednesday)
Issued at 1130 AM MDT Tue Oct 17 2017

Through Tonight: A very dry/stable airmass (PWAT ~0.25" per 12Z
DDC sounding) will prevail over the region. A small amplitude
wave located upstream in Wyoming at 16Z (per WV imagery and
mesoanalysis data) will track ESE through Nebraska this
afternoon/evening and into MO tonight. Variable winds will become
S/SW at ~10 knots in western KS late this aft/eve as the
aforementioned shortwave progresses into western NE and a lee
surface trough develops over eastern CO. With the above in mind,
expect clear skies with 0 chance for precipitation.

Wednesday: A robust shortwave moving onshore the PAC NW this
afternoon will track rapidly east across the Canadian Rockies into
Saskatchewan/Manitoba tonight and Ontario during the day Wed.
Subsidence (in the wake of the shortwave progressing east across
southern Canada) will result in surface pressure rises over the
northern Rockies/Upper Midwest Wednesday morning, driving a weak
back-door cold front southward through western NE into western KS
by early afternoon, with winds shifting to the north and
increasing to 12-17 knots. With the above in mind, expect clear
skies and 0 chance for precipitation. Weak SFC-H85 CAA should
result in cooler temperatures north of I-70 Wed afternoon,
particularly in southwest NE and northeast CO where highs are
unlikely to exceed the lower 70s. Expect highs ranging from the
mid 70s (I-70 west of Colby) to upper 70s/80F (south of I-70/east
of Colby).

.LONG TERM...(Wednesday night through Tuesday)
Issued at 229 PM MDT Tue Oct 17 2017

Main forecast issue will be winds in advance and behind cold front
late Friday night into Saturday with secondary issue of temperatures
from Wednesday night into Friday. Satellite is showing a
progressive/zonal to near zonal flow from the Pacific into the
western Atlantic.

Wednesday night...the first in a series of shortwave troughs moves
through in southwest flow aloft. However, forecast soundings are
showing a deep dry layer so a continued dry forecast will continue.

During the later half of the night, the surface ridge behind the
front will be moving into the area and bring light winds to the area
especially in the eastern portion. So lowered the mins accordingly.

Thursday through Friday...continued southwest flow aloft with
shortwaves moving through in a very dry air mass. So a continued dry
forecast will continue. As surface ridge pulls to east on Thursday
and next lee trough develops, gradient tightens and 3 hour pressure
falls near 5 mb support breezy winds, mainly in the western half. So
adjust winds up a little.

Gradient tightens along with increasing winds and warm air advection
during Thursday night. Models commonly underdo this. So expect a
rather mild night for this time of year. Based on latest model data
and collaboration, increased the winds and low temperatures.

On Friday the gradient looks like it lessens over the area. However,
area has dry low layers with steep lapse rates so would expect some
mixing down of the stronger southwest winds. Model data and
collaboration resulted in raising the winds during the day. Also
with the downslope winds and increased warm air advection, raised
the maxes a little from what the blend gave me.

Friday night through Tuesday...Right rear quadrant moves through the
area late Friday night into early Saturday. This is at the same time
a shortwave trough and strong cold front move through the area.
Gradient along with very high pressure rises behind the front
support using consmos for the winds as they become windy/very windy.
That and collaboration resulted in the loading of consmos.

The dry layer is not as deep during the day Saturday, however there
is still too much air in place to allow any precipitation to occur.
The dry forecast through the entire period looks in good shape.

Also model output has come into agreement through the period with
keeping the flow progressive with numerous open waves. At the end
of the period a sharp ridge develops over the western portion of
the country with a trough developing in the Great Lakes region.
This will leave the area in northwest flow aloft and open to
colder air masses.

Based on the available data, what the blend gave me through the
period, outside of the winds, looked reasonable and made no changes
anywhere else.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 513 PM MDT Tue Oct 17 2017

VFR conditions will prevail through the TAF period at KGLD and
KMCK terminals. Prevailing winds should remain below 10kt through
12Z. A cold front moves into the region from Nebraska into Kansas
Wednesday morning, with winds shifting to the north and increasing
during the day. Gusts 18-22kt will be possible, with the
strongest at KMCK.




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