239
FXUS63 KGLD 231525
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
925 AM MDT Sat Aug 23 2025

.KEY MESSAGES...

- Showers and thunderstorms may develop over portions of the
  area late tonight and early Sunday morning. Strong storms
  capable of producing small hail and locally heavy rainfall are
  possible.

- Severe storms are possible Sunday afternoon and evening in the
  Kansas and Colorado border area.

- Rain chances and cooler weather are forecast to continue
  through most of the upcoming week.

&&

.UPDATE...
Issued at 255 AM MDT Sat Aug 23 2025

Scattered showers and isolated thunderstorms will continue
through early this morning before moving out to the east. After
morning clouds, will see partly sunny skies in the afternoon
with highs in the upper 70s to lower 80s. Models show afternoon
convection hugging the Front Range but not making any eastward
progress, so will keep it dry. Tonight, models generally show it
dry in the evening, then elevated convection developing towards
06z in the Tri-Border area and expanding in coverage overnight
across most of northwest Kansas and southwest Nebraska. MUCAPE
will be around 500-1000 j/kg and shear around 30-35 kts through
the overnight. Primary hazard with stronger storms will be hail,
mostly small, but can`t completely rule out quarter sized or
slightly larger. Raw model output suggests locally heavy rain
possible, between 1" and 2", but HREF not very supportive of a
flooding threat, so may just end up with some beneficial rain.
Rain chances continue well into Sunday morning. Lows will be in
the mid to upper 50s.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 1210 PM MDT Fri Aug 22 2025


A cold front is slowly sagging into the area from the northwest
where rain showers are already ongoing along the I-80 corridor;
an associated 500mb shortwave is also in place across southern
Wyoming along with a developing surface low across eastern
Colorado. As you can tell there are a ton of features at play in
the next 24- 36 hours which will lead to a varying forecast of
potential outcomes. There is one thing for sure is that there
will be rainfall, but the overall coverage, amounts, and severe
potential are still in question unfortunately even at this range
of the forecast. The reason for this is due to so many
variables at play there is no one single deterministic or CAM
that is handling the current location of all of these features
the best. With that said this forecast is currently strictly
ensemble based off of the ECMWF at least for rainfall chances
and the 15Z RAP as it is initializing the current features the
best.

Confidence is increasing in convection developing along the
Front Range and the Palmer Divide this afternoon aided by the
500mb jet and the low, the question is how far east will this
survive as this will depend on how the low evolves; a more
compact low will keep the bulk of the rainfall to the west and a
more elongated low which is currently developing should extend
the rainfall to the east quicker. Now comes into play the speed
of the front as well, as the front progresses to the south. An
axis of CAPE of 1500-2000 j/kg and 30-35 knots of shear will be
in play along the front as it progresses to the south which
should be after 23Z which will be our peak time for severe
weather this afternoon. There will be the potential for some
supercell structures in this environment with the main concern
for large hail residing along and north of Highway 36. The key
to our severe weather potential will be how widespread is the
rainfall which would limit overall instability due to competing
updrafts. Current thinking is that a window for severe weather
will be in place from 6pm-10pm MT then as we turn into more of
an upslope regime behind the front with northeasterly winds this
will help promote more showers and non severe storms;
confidence in that is around 60%.

Now is where the scenarios come into play, if the evening
storms and coverage of rainfall doesn`t come to fruition then as
we turn more into the upslope/isentropic enhanced regime
overnight the atmosphere won`t be as worked over and we may have
a severe threat with damaging winds and large hail overnight as
well, confidence in that scenario is around 25%. There is also
a scenario where very little to nothing happens and the upslope
flow leads to dense fog with the climatologically favored
northeast flow across the entire area (15% chance.

An overall strong signal for a swath of 1-2 inches of rainfall
is seen in ECMWF ensembles which favors locales north of I-70.
The RAP is also showing strong isentropic lift across the I-70
corridor overnight as well which would line up well with the
timing of the heavier signal of rainfall seen in the ECMWF
ensemble; so will be interesting to see if that area shifts to
the south a little bit on the 12Z run as the only run available
for this package was the 06Z. Not overly concerned for flooding
but wouldn`t be surprised if there was an instance or two of
nuisance flooding as PWATs increase to 1.4-1.5 and Corfidi
vectors range from 15-28 knots which supports some training
potential. It is worth noting that at least the past two runs of
the HREF suggest a 10% chance of 3+ inches of rainfall targeted
west of Highway 59 across Yuma, Kit Carson and Cheyenne
counties in Colorado so there is some support for locally
heavier rainfall.

Finally into Saturday, guidance has trended a little cooler
which isn`t overly surprising as cloud cover may be entrenched
across the area for the majority of the day. The way Saturday
plays out is completely dependent on how the overnight hours pan
out. HRRR suggests another 500mb trough moving through the area
after 12Z Saturday morning which if we are limited on storm
chances tonight may lead to a severe threat in the morning
should this materialize. RAP and NAM indicate a much weak wave
but would be the focus for the next round of precipitation with
the chances increasing south of I70 as it interacts with the
front which appears to stall out. A brief reprieve of
precipitation may occur NW to SE across the area during the late
afternoon hours through the evening as some drier air again
pushes in. Saturday night 850mb upslope flow again returns to
the area increasing rainfall chances for the area.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 1253 PM MDT Fri Aug 22 2025

Starting the extended period, Sunday and Monday at this time
appears to be the relative highest chance for rainfall for the
area as the upper level ridge that has been across the area for
the past several days shifts to the west and eventually breaks
down. Severe weather may be possible each day, but at this time
Sunday appears to be more favorable as bulk shear significantly
increases to 35-50 knots due to a developing surface low across
eastern Colorado which will also push some warmer air back into
western portions of the area due to downsloping winds. A surface
high will be in place across eastern portions of the area
keeping showers and some embedded storms in place but limiting
any severe potential over that way; the key question that will
need to be resolved is how far west will that feature set up
which will limit the coverage of severe weather potential during
the afternoon. A better wave comes off of the mountains during
the late afternoon/evening hours Sunday leading to a potential
MCS developing. Increasing PWATS to 1.7 and slower storm motions
will then lead to an increasing concern for flooding especially
for any areas that receive heavy rainfall or multiple rounds of
rainfall over the next few days. Rainfall is then forecast to
continue through the morning hours on Monday before ending.
Additional rainfall may occur during the afternoon and evening
hours due to the continued upslope flow but the better forcing
will lie south of the area.

Tuesday and through the remainder of the week, monsoonal flow
continues to feed into the Rockies as we see more waves from a
trough off of the western coast leading to the continued chances
for showers and storms. Surface high pressure across the
Midwest stalls out and continues to keep the cooler air in
place. Temperatures may need to be raised a little especially
across western portions of the area if subtle surface lows are
able to develop which will again bring in downsloping winds
occur; at this range that signal is so minute that being able to
pick out a specific day is unreasonable so will leave the
forecast as is for now. Towards the latter portion of the week
the high pressure slowly pushes to the east allowing the area to
warm back up some into the 80s but would not be surprised if
our active pattern continues as a more progressive upper air
pattern ensues.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 925 AM MDT Sat Aug 23 2025

GLD: Occasional MVFR or borderline MVFR-IFR ceilings remain
possible through the duration of the morning. VFR conditions
are anticipated to prevail this afternoon and evening. Showers
and thunderstorms may develop over portions of the area tonight
into Sunday morning (~06-15Z Sun), though.. confidence in both
thunderstorm development and coverage is presently too low to
warrant explicit mention with the 18Z TAF issuance. Light (~6-12
knot) NE winds will gradually veer to the E and SE (this aft)
and SE to S (this evening).. remaining light throughout the TAF
period.

MCK: Showers and thunderstorms may develop over portions of the
area tonight into Sunday morning (~06-15Z Sun), though..
confidence in both thunderstorm development and coverage is
presently too low to warrant explicit mention with the 18Z TAF
issuance. Otherwise, VFR conditions are anticipated to prevail
through the TAF period. Light (~6-12 knot) NE winds will veer to
the E and SE this afternoon.. perhaps becoming variable, at
times. Variable or light easterly to southerly winds are
expected this evening through the remainder of the TAF period.

&&

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

&&

$$

UPDATE...024
SHORT TERM...Trigg
LONG TERM...Trigg
AVIATION...Vincent