179
FXUS63 KGLD 120808
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
208 AM MDT Mon Aug 12 2024

.KEY MESSAGES...

- Dense fog is possible through roughly 10 AM MDT/11 AM CDT
  across the area. Dense Fog Advisory in effect through the
  previously mentioned time.

- Low confidence for severe weather occurring Monday
  afternoon/evening over the west half of the forecast area.

- High rainfall chances Monday night.

- Rain chances continue through most of the week and
  temperatures gradually warm.

&&

.UPDATE...
Issued at 1251 AM MDT Mon Aug 12 2024

With visibilities dropping to half a mile in Wray, CO already
decided to go ahead and issue another area wide Dense Fog
Advisory through 10 AM MDT/11 AM CDT. With the lingering showers
over NW Kansas it may be a while before the visibilities begin
to drop, but conditions should decrease rapidly similar to what
they did yesterday.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 204 PM MDT Sun Aug 11 2024

Latest upper air analysis shows the ridge over the Great Basin.  The
flow over the ridge is almost zonal.  Within the flow are small
scale short wave troughs.  The strongest of these troughs is over
Eastern Wyoming.  Satellite imagery shows cumulus clouds forming
ahead of this trough.  Further east a large area of stratus
continues to be in place over the Plains.

For the rest of today the current storm activity over Southeast
Wyoming will continue to progress east-southeastward.  As the storms
move southeast they will encounter higher instability and deep layer
shear.  As such, am expecting the storms to increase in intensity.
Models show a single supercell forming over far Northeast CO, moving
southeast along the dry line into the forecast area.  If this does
happen there may be a potential for a tornado to occur given the
source for surface vorticity along the boundary.  If this does
happen the supercell will be entering the forecast area during the
latter half of the afternoon.

This evening the supercell, assuming it does form, will continue to
track southeast along the corridor of instability along the dry
line.  The eastern border of the instability corridor may be the
west edge of the cloud cover.  The storm should weaken as surface
heating ends.  However the supercell can overcome the increasing
stability for a time, but should eventually end before late evening.
Later on storm activity should continue into KS with the upper level
short wave trough.  As the trough moves over the central part of the
forecast area it will begin to fill, which should cause storm
activity to wane. Am not anticipating any severe weather during the
latter half of the evening given the large dew point depressions
above the inversion.

Meanwhile another area of concern will be over Central CO where a
cluster of thunderstorms should move through from another upper
level short wave trough.  This activity will be much less organized
due to the upper level short wave trough being less intense.  As
this activity continues east it should weaken near the KS/CO border
where the instability ends.  Main threat with this activity will
likely be damaging wind gusts.

A cold front will move through behind the storm activity.

Later in the night the storm activity may increase in coverage as
the upper level short wave trough moves over the LLJ nose in Central
KS.

Toward sunrise fog will return to most of the forecast area.
Locations east of the CO border will generally be favored for
visibility of less than a half mile.

Monday will be warmer than today despite the cold front passage.
This is mainly due to no cloud cover.  The afternoon looks to be a
similar pattern to today; an upper level short wave trough
approaches from the west bringing storm activity with it.  Also like
today, instability will be best over Eastern CO, but mostly west of
the forecast area.  If strong to severe thunderstorms form west of
the forecast area, they may move into the forecast area then weaken
due to the more stable environment.

Monday night another strong upper level short wave trough moves over
the forecast area.  Models agree for the high rainfall chances.
However, am concerned the is based on plentiful moisture overhead
and the assumption an upper level short wave trough will move
through; which has happened in this pattern already. However the
ECMWF and GFS ensembles have high probability of atleast .1" and
atleast .5" of rainfall occurring. Currently there is no good reason
to not have high chances other than the concern that models are too
high with the rainfall chances.  Am thinking the rainfall activity
will end up being lower in coverage than what is currently being
forecast.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 207 AM MDT Mon Aug 12 2024

Troughing looks to continue on Wednesday as we watch another wave
move off of the Front Range. Will need to again monitor for fog
development on Wednesday morning as moisture will remain in
place. It currently looks to be warmer with highs near normal
(assuming the fog can lift during the morning hours) with highs
currently forecasted in the mid 80s to low 90s. As mentioned
above will be watching another wave resulting in another round
of showers and storms for the area. Severe weather is possible
with mainly damaging winds along the main cluster. If a discrete
storm can form ahead of the cluster then 2+ inch hail will
again be possible as upper level winds remain very strong around
60-70 knots (confidence in that scenario is currently low).
Heavy to torrential rain in slow moving storms is again possible
with slow corfidi vectors in place.

Thursday looks to see a weak front move across the area which will
be the focus for additional showers and storms during the afternoon
hours. High temperatures again look to be in the mid 80s across the
area but could be lower if the front moves through quicker which
some ensemble members do suggest to be a possibility.

Late week and into the weekend looks to see ridging redevelop across
the Intermountain west. This will lead to warmer temperatures
with highs in the 90s returning but depending on the positioning
of the ridge will continue to lead to daily showers and storms.
The heat may be short lived however as some signals for another
strong trough to move through the northern Plains/Great Lakes
region ushering in some cooler air again.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1105 PM MDT Sun Aug 11 2024

A few thunderstorms will continue around KGLD terminal through
the overnight hours, before LLJ veers and forcing weakens after
09z. While IFR conditions appear likely once storms dissipate
and low levels stabilize, outflow and a few gravity waves seem
to be keeping low levels mixed just enough for areas to clear
out briefly. Think this break will be short lived and expect IFR
conditions to develop rapidly after 08z, impacting both TAF
sites. Reduced flight categories will continue through the
morning hours before ceilings begin to lift after 18Z. While
another round of precipitation is expected tomorrow night,
confidence too low in impacts to include at end of TAF period.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Dense Fog Advisory until 10 AM MDT /11 AM CDT/ this morning
     for KSZ001>004-013>016-027>029-041-042.
CO...Dense Fog Advisory until 10 AM MDT this morning for COZ090>092.
NE...Dense Fog Advisory until 10 AM MDT /11 AM CDT/ this morning
     for NEZ079>081.

&&

$$

UPDATE...KMK
SHORT TERM...JTL
LONG TERM...Trigg
AVIATION...JRM