Area Forecast Discussion
Issued by NWS Goodland, KS

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000
FXUS63 KGLD 200914
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
214 AM MST Tue Feb 20 2018

.UPDATE...
Issued at 940 PM MST Mon Feb 19 2018

Narrow northeast to southwest oriented band of moderate to heavy
snow with Burlington and Saint Francis automated observations at
1/4sm +SN. Have expanded the Winter Weather Advisory to include
locations currently located within the band of snow with
additional accumulations of several inches. At present time not
expecting Winter Storm Warning criteria from being met but will
continue to monitor. Yuma county still looking good to meet Wind
Chill Advisory criteria based on recently updated temps and winds.

UPDATE Issued at 710 PM MST Mon Feb 19 2018

Current forecast for tonight looks in pretty good shape. Did
remove mention of blowing snow given winds in the 10 to 15 mph
range.

Convective looking showers starting to increase in coverage across
the western 1/2 to 1/3 of the area where weak elevated instability
and little cin forecast from a batch of moisture in the 850-500mb
layer through midnight. This batch of moisture and elevated
instability weakens around 09z then dissipates by sunrise.

Current snowfall forecast looks good but will have to watch where
any bands set up for possibility of axis shifting a bit from
current forecast location.

Based on current temperatures and dewpoints I did follow the
latest ruc/hrrr which has a good handle on things compared to
observed readings. Doing so lowered temperatures quite a bit from
previous forecast. Wind chill advisory criteria (-15F to -24F)
looks to be met in Yuma county which is already under a Winter
Weather Advisory.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 236 PM MST Mon Feb 19 2018

Forecast problem will be snowfall amounts tonight. Light snow has
fallen most if not the entire day over the northwest half of the
forecast area. This is despite the saturated air mass being below
700 mb. Not only was there ice in the column at the bottom of the
sounding according to the upstream 12z soundings but the dendritic
zone is at or near the surface. So the minor weak lift we have
received all day has allowed light snow or flurries to occur.
Accumulations so far have been near a half or below. The main change
for this air mass during the night will be for it to move over the
southern portion of the area and deepen over the remainder of the
area, especially in the northwest portion.

For tonight...Models are showing elevated Cape during the evening
over the western half of the area. But would not be surprised to
see this moving into the east overnight. I say that because
negative low and mid level theta-e lapse rates stay over the
western half of the area through the evening and then slowly
transition east through the rest of the night. So felt confident
to add isolated thunder to most of the area into the overnight
hours.

Right rear quadrant of upper jet starts affecting the northwest half
of the area during the mid and late evening. That area moves very
little during the night. Also strong mid level trough/baroclinic
zone and frontogenetic forcing follow this same path. High
resolution guidance has been very consistent through the day in
producing some bands of higher intensity snowfall near or over the
northwest corner. After running through all the parameters, I came
up with 3 to 5 inches of snow in the northwest corner, Yuma and
Dundy counties, for tonight. So went ahead and have hoisted a Winter
Weather Advisory for the night. The winds will be strong enough
enough that some patchy blowing snow will be possible, even a little
outside the area. Evening shift will have to watch if higher
snowfall amounts and the advisory need to be changed.

Also something else to watch for. Current forecast shows wind chills
dropping into the 10 to 15 below zero range in the northwest corner
as well.

For Tuesday...Above mentioned wind chills are in the northwest
corner during the morning. The mid level trough line stays to the
west the entire day. Models continue mid level lift and favorable
theta-e lapse rates over the area with the deepest moisture profile
over the northwest half. Baroclinic zone at 700 mb also remains over
the area. Above mentioned upper jet moves very little during the day
and is still affecting the southeast half of my area by the end of
the afternoon. Am thinking the models are ending snowfall to soon
and light snow or flurries could continue the entire day. Night
shift will have to look to see if this needs to be expanded or
increased.

Cloud cover, snowfall, snow cover, and an arctic air mass will keep
things cold with expected high temperatures near or below the
guidance blend.

.LONG TERM...(Friday through Monday)
Issued at 214 AM MST Tue Feb 20 2018

Going into Friday...weak surface ridging is set up over the region
during the daytime hours...w/ an inverted surface trough developing
over SE CO. This trough does develop out ahead of a larger
shortwave...and will shift east off the central Rockies Friday night
into Saturday across the CWA. Some model timing differences but the
shortwave pushes east of the CWA during the afternoon hrs Saturday
allowing for dry conditions for the remainder of the weekend into
the beginning of next week. Another weaker shortwave does move over
the region Monday morning.

For the Friday night/Saturday morning timeframe...track of the
surface trough/low just south of the CWA with the upper support
transitioning over the CWA...will give the region a round of
precipitation...with light snow as main p-type based on latest temp
profiles. Best enhancement will be focused along and north of
Interstate 70. Looking for potential 1-2" of snowfall here with an
inch or less south of the Interstate. As temps increase during
morning Saturday...any leftover moisture will transition to light
rain before ending.

Temps in the extended will see and increasing trend during this time
w/ highs starting off Friday in the upper 30s to low 40s...then
increasing to around 50F by next Tuesday. Overnight lows will range
from the upper teens thru the mid 20s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 915 PM MST Mon Feb 19 2018

KGLD, mvfr-ifr cigs/vis from taf issuance through about 13z with
winds from the northeast near 11kts. Northeast to southwest
oriented band of light to moderate snow will impact the terminal
before weakening. After 14z vfr conditions expected. Winds begin
the period from the north around 13kts with some possible gusts
before veering to the northeast around 10kts by 00z then almost
due east near 6kts after 02z.

KMCK, mvfr/ifr cigs/vis from taf issuance through about 15z with
winds from the north to northeast near 12kts. Northeast to
southwest oriented band of light to moderate snow should impact
the terminal before weakening. After 16z vfr conditions expected.
Winds begin from the north to north-northwest near 14kts with some
gusts. After 23z winds fall below 12kts from the north and after
02z expect a light northeast wind 5kts or so.


&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Winter Weather Advisory until 5 AM MST /6 AM CST/ early this
     morning for KSZ001-002-013.

CO...Winter Weather Advisory until 5 AM MST early this morning for
     COZ090>092.

NE...Winter Weather Advisory until 5 AM MST /6 AM CST/ early this
     morning for NEZ079-080.

&&

$$

UPDATE...99
SHORT TERM...BULLER
LONG TERM...JN
AVIATION...99



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