790
FXUS63 KGLD 230517
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1017 PM MST Fri Nov 22 2024

.KEY MESSAGES...

- Warm weather continues through Sunday.

- Some patchy fog is possible towards sunrise Saturday for areas
  along/east of Highway 83.

- Weather pattern change Sunday afternoon toward cooler
  temperatures.

- Wintry precipitation forecast for the Tri-State Area Wednesday
  into Thanksgiving Day, however details remain murky.

&&

.UPDATE...
Issued at 1016 PM MST Fri Nov 22 2024

Based on the latest runs of the HRRR and NAM12, have opted to
slightly increased the coverage of fog in the east from the
10z-15z Saturday timeframe. The focus for the fog will be the
front/boundary currently draped over the eastern portion of
region. Light winds, some moisture convergence along the front
and tight T/Td spreads could bring about some patchy fog for
locales along/east of Highway 83, especially from Red Willow
county in Nebraska down to eastern portions of Norton and
Graham counties in Kansas.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 146 PM MST Fri Nov 22 2024

Latest upper air analysis shows a ridge over the Plains.  To the
north and east of the ridge were large expanses of cloud cover.

Tonight through Sunday the upper level ridge will dominate the
weather pattern.  Highs will be rather warm for this time of year.
Southerly winds will be light to breezy.  Sunday afternoon a weather
pattern change will occur as an upper level short wave trough will
move through the Plains from the west.  A cold front will accompany
the trough, bringing cooler weather with it.

Aside from the warmer, dry weather, fog may form over parts of
Norton and Red Willow counties where weak moisture advection will
occur tonight.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 146 PM MST Fri Nov 22 2024

The main focus for this period will be the winter weather coming mid
week next week.  The models continue to be in rather good agreement
with this precipitation event considering this is still nearly a
week out.  All three models have westerly flow over the Plains with
a trough over Canada and another short wave trough moving over the
Great Basin.  However the Canadian model has almost zonal flow over
the Plains, while the other two models (GFS and ECMWF) both have a
more pronounced short wave trough over the Great Basin.  The ECMWF
version is deeper than the GFS.

The ensembles all agree with the higher chances for precipitation
occurring Wednesday night into Thursday, which seems more reasonable
given the speed of the approaching short wave trough.  Conversely
the latest forecast has the best chances for Wednesday.  Slower
timing seems more reasonable too based on the models deepening
the trough over the eastern CONUS and strengthening the ridge to
the west during this time; both of which will serve to slow
down the eastward progression of the upper level short wave
trough.

However the more concerning aspect of this is the overall look of
the upper level flow over the Plains.  There is a stronger jet flow
over the Northern Plains then a branch off of the jet stream caused
the by short wave trough over the central Great Basin.  This pattern
resembles split flow, which typically directs the precipitation
north and south of the forecast area.  The forecast area could still
receive precipitation, however most of the precipitation would be
directed elsewhere if the pattern continues hold.

If the split flow pattern does not direct precipitation elsewhere
there is a potential for a band of higher precipitation amounts to
occur. The type of precipitation in the band will depend on where
the band forms, ahead or behind the cold front.

The latest forecast has snow being the dominate precipitation type.
The precipitation type will greatly depend on when the cold front
moves through, and the strength of the cold air advection. This was
well outlined in the prior forecast discussion.  The latest data is
showing some saturation occurring ahead of the cold front, with the
bulk of the saturated air moving in behind the front.  (A similar
trend is seen with the wet bulb zero heights.) This would support
more snow occurring during the day than rain.  However this can all
change in the coming days.

Another minor upper short wave trough will move through the Plains
late next week. If this happens it looks to be a quick moving round
of snow in the northwest flow at this point.

List of acronyms:
GFS - Global Forecast System
ECMWF - European Center for Medium-range Weather Forecasts

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 908 PM MST Fri Nov 22 2024

For KGLD, with high pressure east of the terminal and a surface
trough developing over eastern Colorado, looking for VFR
conditions to persist during the forecast period. Winds, will be
west-southwest around 10kts, become briefly light/variable from
15z-20z, then south around 10kts.

For KMCK, with the terminal near a frontal boundary as well as
exiting high pressure, winds will remain light/variable through
about 20z Saturday then becoming southeast around 10kts. Right
now, VFR conditions are expected but will be monitoring for
some fog potential for the next forecast update at 12z
Saturday.

The visibility sensor is currently down at KMCK. Technicians
are aware of the issue. For now amendments are not scheduled
(AMD NOT SKED) for the TAF site until the sensor has been
repaired.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.

&&

$$

UPDATE...JN
SHORT TERM...JTL
LONG TERM...JTL
AVIATION...JN