Area Forecast Discussion
Issued by NWS Dodge City, KS

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FXUS63 KDDC 202346
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
546 PM CST Wed Feb 20 2019

...Updated Aviation Section...

.SHORT TERM...(This afternoon through Thursday night)
Issued at 1135 AM CST Wed Feb 20 2019

Sunshine returning to SW KS as of midday, as subsidence behind
yesterday`s departing system clears the remaining stratus.
Visible satellite imagery clearly shows snow cover across the
NW 1/2 of SW KS from Monday`s snowfall, and the eastern zones
from Tuesday`s snowfall. Temperatures will moderate back well into
the 30s for most zones, well above freezing, although areas with
snowpack will be held back several degrees. Areas without snow
near Oklahoma will reach the lower 40s this afternoon. A clear sky
will continue into this evening, as light winds gradually trend
SEly. SE winds will continue to increase modestly tonight, gusting
to near 20 mph by sunrise Thursday, along with increasing cirrus.
Expecting temperatures to fall quickly into the teens and 20s
after sunset this evening, and then hold steady in the teens and
20s overnight with increasing cirrus and SE winds.

Thursday...noticeably milder. SW flow aloft will continue to
intensify, in response to a powerful 530 dm closed low over the
Great Basin. Mid/high clouds will be increasing Thursday, but warm
air advection will begin as well, with 850 mb temperatures
rebounding to the +4 to +5C range. This supports afternoon
temperatures well into the 40s, with again several degrees
reduction over snowpack. Areas near Oklahoma absent snowcover will
achieve lower to mid 50s. Mid layer clouds and SE winds will both
be increasing Thursday, in response to leeside cyclogenesis
organizing in SE Colorado. Models suggest there may be some
sprinkles from the mid level clouds, and pressure gradients will
support 20-25 mph sustained SE winds by afternoon. So although it
will certainly be milder, the SE winds will be brisk and chilly.
Models suggest there may be some sprinkles from the midlevel
clouds Thursday afternoon, but opted to keep a dry forecast in the
grids.

Thursday night/Friday morning will again be noticeably milder
compared to recent nights, as continued SE boundary layer winds,
thickening clouds, moisture advection and areas of stratus/fog all
work against radiational cooling. Upper 20s/lower 30s will be
common Friday morning with stratus/fog, and with many areas
failing to fall to freezing.

.LONG TERM...(Thursday night through Wednesday)
Issued at 212 PM CST Wed Feb 20 2019

...Quick-Hitting High Impact Snow/Blowing Snow Possible
Saturday...

Intense closed 500 mb low near Las Vegas at sunrise Friday is
consistently forecast by all model guidance to be in east-central/
NE New Mexico, at sunrise Saturday. As the system approaches on
Friday, moisture advection is expected to spread stratus/fog and
areas of light drizzle/rain/wintry mix mainly across the eastern
counties. Despite continued warm air advection on SE winds, thick
cloud cover is expected to hold most locations in the 40s Friday
afternoon, with 50s across the SW zones where more sunshine is
probable. Gulf moisture is expected to be fully available to this
system as it arrives on the plains Saturday morning.

Models have displayed excellent consistency from run to run, and
with each other, regarding the expected storm track Saturday. In
fact, 12z ECMWF is essentially a carbon copy of its previous 00z
run. So forecast confidence is high that the storm will produce
impacts, and the storm track confidence is increasing. With a
strong surge of warmth/moisture ahead of the advancing cyclone,
expect all precipitation to begin as rain for all zones Friday
night. Some thunder is certainly conceivable near the Oklahoma
border. Currently, have rain/snow line marching to about US 83
around 6 am Saturday, reaching Dodge City about 8 am Saturday,
and through most of SW KS by early afternoon. As colder air is
drawn into this strong system, progged to be on a near ideal track
for SW KS, conditions are expected to deteriorate rapidly from
west to east Saturday morning. The period 6 am - noon Saturday
will experience the strongest lift, with most models cranking out
QPF of 0.6-0.8" in just that 6 hour period. Increased pops for
this time period above the forecast builder to near 100%. Snow
production just after phase change should be quite dramatic, with
a few hours of 1-2 inch/hour rates. As the associated surface low
tracks to near Medicine Lodge by around noon, NW winds will become
intense as the snow is falling, with models consistently progging
850 mb winds of 50-60 mph. Loaded the strongest ConsMos guidance
into the wind grids, and expect gusts of that magnitude during the
intense snowfall rates. That is to say, blizzard conditions appear
likely for much of the CWA for several hours Saturday. This will
be a wetter, more compacted snow, falling on wet grounds from
previous rains, but still placed plenty of blowing snow in the
grids especially across the NW zones. Wet snow sticking to trees
and powerlines may also create additional impacts with power
outages possible. If many model solutions verify, travel will be
dangerous to impossible across portions of SW KS Saturday.
WPC/ECMWF guidance both show a maximum in snowfall centered
near/around Garden City (QPF about 1.3") with about the first 25%
falling as rain. For now, accepted the forecast builder solution
of 4-6" snow amounts roughly from Garden City to Hays. Very
progressive nature of the cyclone will work against much higher
snowfall amounts, with limited residence time of admittedly
intense forcing. Snow will wrap up quickly from west to east late
Saturday, with all pops zero after 6 pm Saturday. Accepting this
timing in the grids, barring any slowing down of the storm`s
expected rapid ejection.

Gave serious consideration to a winter storm/blizzard watch on
this shift. Models continue to consistently place SW Kansas in the
path of highest impacts Saturday. The flip side of that is: ANY
deviation in the cyclone`s track (north or south) could diminish
the expected impacts (or move them to another portion of the CWA).
Models prog significant CAPE across W TX Saturday morning, and
have seen instances in the past where Texas convection lures
cyclones on a more southerly track. That said, it would require a
very large southward shift in order to remove all winter
impacts/hazards from all of SW KS. There are also thermodynamic
uncertainties regarding how much QPF is lost as rain before snow
reaches each location. Given the uncertainties, will punt on the
watch decision to the next 1-2 shifts. Will opt for a special
weather statement, and continue to hit hard on social media, to
get the ball rolling and increase awareness. Those planning travel
across the plains Saturday are urged to monitor the forecast
closely, and be ready to make alternate plans.

Sunday through Wednesday look thankfully quiet under uneventful
zonal flow aloft. Spent little time looking at the model blend
output past Saturday`s potential impacts.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 532 PM CST Wed Feb 20 2019

Light winds will occur through the first 9 to 12 hours of this
forecast before gradually increasing out of the southeast toward
daybreak Thursday. The NAM model suggests some fog development and
even some low ceiling in a corridor of stratus from 09-15Z
Thursday, however this is the only model really suggesting this,
and upstream moisture is not all that great across Oklahoma, so
for now will be keeping all terminals in VFR for this entire TAF
period.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  20  48  31  47 /   0  10   0  10
GCK  19  47  30  47 /   0   0   0  10
EHA  20  54  30  56 /   0   0   0  10
LBL  22  52  33  56 /   0   0  10  10
HYS  17  40  29  42 /   0  10  10  30
P28  20  44  31  44 /   0  10  10  30

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Umscheid


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