Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 201757

Area Forecast Discussion
National Weather Service Goodland KS
1157 AM MDT Fri Oct 20 2017

.SHORT TERM...(Today and tonight)
Issued at 1145 AM MDT Fri Oct 20 2017

A lee cyclone will deepen in eastern CO as shortwave energy over
the PAC NW progresses east toward the northern Rockies. Marginal
destabilization is expected along/east of Hwy 283 late this
afternoon into tonight as 10-12C H85 dewpoints advect poleward
beneath a pronounced elevated mixed layer (characterized by H7-H5
lapse rates of 8.0 C/km) via strengthening southerly flow on the
eastern periphery of the lee cyclone in western KS. Given a
significant amount of convective inhibition and relatively weak
upper forcing prior to cold fropa ~12Z Sat, expect dry conditions
to persist. Strong southerly winds are expected along/east of
Highway 283 this afternoon/evening, becoming sustained at 25-35
mph with gusts up to 50 mph. Although winds should decrease with
loss of insolation by ~00Z, GFS forecast soundings suggest a
shallow (1500-2000 ft) mixed layer may develop beneath the EML
east of Highway 283 around 03Z, when low-level (1000 ft AGL)
southerly flow nocturnally strengthens to ~50 knots. As a result,
a second maxima in winds/gusts may occur east of Hwy 283 this
evening. Wind gusts of 45 to 55 mph cannot be ruled out, though
this is more likely to occur south/east of the GLD CWA (e.g.
Dodge City, Hays, Russell). Expect highs this afternoon in the
lower 80s and lows tonight ranging from the lower/mid 40s in
eastern CO (where the cold fropa will occur prior to 12Z) to the
upper 50s/lower 60s in the far east where southerly flow will
persist all night.

.LONG TERM...(Saturday through Thursday)
Issued at 258 AM MDT Fri Oct 20 2017

Saturday morning the cold front will move through.  Northwest winds
will not increase too much until mid morning when the warming
temperatures allow some of the low level jet behind the front to mix
to the ground.  Winds will be strongest in the morning then
gradually decline in the afternoon.  The strongest winds will be
over the west 2/3s of the forecast area.  The windy conditions and
low relative humidity values may lead to a fire weather concern. See
fire weather section for further information.

There will be a slim chance for rainfall in the early morning over
Yuma County between the front and the upper level short wave trough
following the front.  Lift with the upper level short wave trough
will trigger a line of storms just east of the forecast area, but
Graham County may catch the west edge of the storms that develop.

Saturday evening the winds will become light.  With a colder, drier
air mass in place lows will be near normal.  Dew points will be in
the teens and low 20s.  With conditions looking favorable for
radiational cooling, am thinking the lows may be too warm.  If this
is the case, a freeze watch may be needed for counties east of the
Colorado border where a hard freeze has yet to happen for this
growing season.

Sunday/Sunday night warm air advection will warm temperatures
compared to Saturday.  Winds will be light to breezy.  Dry northwest
upper level flow will move over the forecast area behind the trough
from Saturday.

An active and dynamic pattern will prevail Monday through Thursday
with alternating periods of near normal to above normal temperatures
and generally dry weather. Northwest flow aloft will dominate on
Monday, gradually becoming northerly as we head into Tuesday. This
will be in response to a cold front that will push through the
region late Monday night and early Tuesday morning. Due to lack of
antecedent moisture advection, this passage will likely be dry and
windy. I increased winds on Tuesday beginning around mid morning as
pressure rises will be a bit sharp on the trailing side of lowered
heights associated with a deep trough to our east. Could see gusts
approaching the 40 to 45 mph range with 20 to 25 mph sustained north
to northwest winds. Also adjusted temps down slightly from guidance
as very strong CAA will prevail through the day.

The upper flow will shift back to westerly as we go into Wednesday
with weak high pressure briefly traversing the central High Plains.
Another cold front will push through the area on Thursday and once
more we will not have much moisture to work with as this happens.
There will be only a slight chance of precipitation as the front
moves across the region; however, breezy conditions are expected as
a sharp pressure gradient will trail the frontal passage. This front
could bring widespread freezing temperatures to the region; however,
a hard freeze is not likely as of today`s guidance.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1145 AM MDT Fri Oct 20 2017

VFR conditions will prevail through the TAF period at the GLD/MCK
terminals. Southerly winds will increase to 15-25 knots with gusts
up to 30-35 knots this afternoon and early evening. Breezy
conditions will persist until ~midnight, after which winds should
decrease to ~10 knots as a lee cyclone progresses into southwest
NE and northwest KS. Winds will veer to the northwest and increase
to 20-30 knots with gusts to 35-40 knots in the wake of a dry cold
frontal passage Sat morning (11-17Z). Northwest winds will
decrease to 15-20 knots at the end of the TAF period 18-21Z Sat


Issued at 1145 AM MDT Fri Oct 20 2017

NW wind gusts of 25-35 mph are expected in the wake of a cold
frontal passage in eastern CO during the day Sat as dewpoints
fall into the teens while temps remain nearly steady in the 50s.
Minimum RHs of 20-25% are expected for the majority of the
day. RHs as low as 15% will be possible by late afternoon when NNW
winds will begin to decrease. With a temporal disconnect between
the lowest RHs and strongest winds, confidence is low that
critical fire weather conditions will occur for more than an hour
or two.




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