133
FXUS63 KGLD 182218
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
418 PM MDT Tue Aug 18 2026

.KEY MESSAGES...

- Severe chances continue through the end of the week. Coverage
  will be somewhat limited by weak forcing, but environmental
  parameters support at least a marginal risk of severe storms
  each day with damaging winds and large hail the main hazards.
  A few supercells will be possible Wednesday and Thursday with
  increasing wind shear, which could also produce brief
  tornadoes.

- Near normal temperatures through Wednesday, then above normal
  for the end of the week.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 100 PM MDT Tue Aug 18 2026

Shortwave trough rotating around the Four Corners ridge will
result in thunderstorm chances tonight. CAMs show initiation
occurring in northeast Colorado by around 02z and quickly
spreading east into areas generally north of Interstate 70
through 04z with additional lift provided by a southwesterly low
level jet. Instability will initially be limited, resulting in
mostly high-based updrafts and a wind threat, but as they move
further east MUCAPE rapidly increases to 1500-2500 j/kg in
Kansas and Nebraska. Deep layer shear will be around 50 kts. So,
in addition to the wind threat, clustering storms may also pose
a large hail threat through the late evening and overnight
hours. Surface-based CIN appears too high to support a tornado
threat as storms will likely be elevated. CAMs show storms
gradually weakening after about 09z as they continue to move
east.

Ridge begins to amplify on Wednesday over the Great Basin and
western Rockies. Appears to be another embedded wave in the
northwest flow over the plains which initiates convection in
northeast Colorado around 22z. REFS shows generally weak
instability of up to 1500 j/kg, but there are pockets of
stronger instability of up to 2500 j/kg generally south of
Interstate 70. Deep layer shear is excellent in the northwest
flow at around 45 kts. The environment would be supportive of
supercells capable of large hail, damaging winds and perhaps a
tornado. Coverage may be somewhat limited by the relatively weak
forcing, but best chances appear they will be south of
Interstate 70 through the evening hours.

Upper ridge continues to strengthen Thursday over the Great
Basin. Instability is similar to Wednesday afternoon, but with a
slight decrease in deep layer shear to around 35 kts with the
stronger ridge. Should see another shortwave trough moving
through in the afternoon and evening with widely scattered
thunderstorms developing. NBM currently shows best chances east
of Highway 25 in Kansas and Nebraska through about 06z before
moving east and out of the area.

The ridge continues to dominate on Friday, but with a notable
shift eastward and centered over Colorado. Nonetheless, eastern
parts of the area, generally east of Highway 25, will once again
see weak to moderate instability develop and 30-50 kts of deep
layer shear on the eastern periphery of the ridge. Assuming some
kind of embedded wave rotation around the ridge, will see some
low chances for afternoon and evening thunderstorms in those
areas.

Temperature trends for the period are near normal tomorrow, but
warm to above normal for both Thursday and Friday as the ridge
builds.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Issued at 225 PM MDT Tue Aug 18 2026

Ensemble guidance continues to be in support of ridging at 500-mb
overhead through the duration of the long term period. At the same
time, a 500-mb shortwave trough looks to be traveling
anticyclonically around the ridge, with a high amplitude 850-mb
trough at its leading edge. There are indications that a surface low
will be able to form across the High Plains in association with this
850-mb feature, and move over or just south of the forecast region
Saturday and Sunday.


***Saturday/Sunday***

Southerly flow underneath the ridge alongside solar heating looks to
favor hot conditions Saturday and Sunday, with highs forecast in the
mid to upper 90s, and possibly low 100s in some spots. In addition,
GEFS 850-mb height guidance is in support of a high across portions
of Eastern Texas during this period, which would prevent moisture
from entering the southerly return flow. This is expected to promote
dry conditions across portions of East-Central Colorado and West-
Central Kansas, where relative humidities (RH) may drop into the
lower 20s to upper teens. While RH values are forecast to be a bit
low, fire weather conditions are not yet expected either Saturday or
Sunday, as wind gusts are not favored to exceed 25 mph except in Kit
Carson and Yuma Counties in Colorado, where wind gusts may reach the
25-30 mph range. Still, LREF guidance shows that RH values have less
than a 20% chance of meeting criteria for critical fire weather
conditions (less than 15% RH) across nearly the entire forecast
area. Confidence in a Red Flag Warning being needed is less than 5%
both Saturday and Sunday.

Forecast guidance continues to suggest that showers and
thunderstorms are also possible during this period in association
with convergence from the surface low pressure. Even so, NBM 24 hr
precipitation guidance shows a 1 in 3 chance or less across the
forecast area both days for greater than 0.1 inches of precipitation
to be experienced. Any storms that develop are not expected to be
severe, as LREF guidance shows a 2 in 3 chance or better that sfc-
500mb wind shear will be below 30 kts. Currently, the greatest
concern with these showers is that they may be able to produce dry
lightning, particularly across East-Central Colorado where RH values
are lowest, and NBM guidance shows the highest chances of showers
occurring.


***Monday/Tuesday***

As the surface low moves well south of the forecast area, a weak
cold front may lower temperatures a couple of degrees into the low
to mid 90s. Chances for precipitation increase a little bit during
this period, especially on Monday when NBM 24 hr precipitation
guidance shows a 40-60% chance of receiving greater than 0.1 inches
of rain across portions of Eastern Colorado. This would be in
association with a cold front. The risk for severe storms continues
to be low, as LREF guidance shows similar probabilities for wind
shear as Saturday and Sunday. RH values look to improve as well, as
temperatures drop a little, and easterly winds across portions of
Central and East Kansas feed slightly higher dew points into the
forecast area. This would reduce risks for critical fire
weather.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 415 PM MDT Tue Aug 18 2026

Main aviation concern for both KGLD and KMCK will be
thunderstorm chances tonight. Latest models show showers and
storms moving out of Colorado after about 04z then moving into
northwest Kansas and southwest Nebraska by 06z. Chances will
continue through the overnight hours with several rounds
possible. Potential impacts include erratic and gusty winds as
well as visibility reductions due to rain. A return to VFR
should occur by 12z as storms move out of the area.

&&

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

&&

$$

SHORT TERM...KAK
LONG TERM...Davis
AVIATION...024