089
FXUS63 KGLD 300921
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
321 AM MDT Thu May 30 2024

.KEY MESSAGES...

- Strong/severe thunderstorms possible the next few days with
  all modes of severe weather possible along with excessive
  rainfall that could produce flooding/flash flooding.

- A bit drier with less shower/thunderstorm coverage Sunday
  through Wednesday with afternoon temperatures well into the
  80s. Lower to middle 90s are forecast Sunday and Tuesday.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 130 PM MDT Wed May 29 2024

Tonight...showers and thunderstorms are forecast to move into parts
of far eastern Colorado in the 5-6 PM MDT timeframe aided by
sufficient moisture in the 850-500mb layer, modest instability and
modest 250mb jet divergence. These isolated to scattered
thunderstorms will move toward Highway 25 by 03z, increasing in
coverage east of Highway 25 after midnight. Primary hazards through
midnight look to be large hail, damaging winds and perhaps some
locally excessive rainfall. The 06z-12z GFS and prior runs of the
HRRR were showing signs in the 0.5-1km wind speeds of a potential
blowing dust threat associated with any convection moving into the
far southern/southwestern zones from southeast Colorado (generally
00z-02z timeframe). After midnight, the threat becomes locally
excessive rainfall that could produce flooding/flash flooding.

Low clouds and likely some fog will be present a few hours prior to
sunrise Thursday morning. Dense fog cant be ruled out.

Low temperatures are forecast to be in the lower 50s to lower 60s.

Thursday-Thursday night...lingering morning showers and
thunderstorms east of Highway 25 in the morning look reasonable
given sufficient moisture in the 850-700mb layer despite mid level
dry air moving overhead. During the mid afternoon, looking at 20%-
30% chances for showers/thunderstorms east of Highway 27 with
continued chances through late afternoon with focus then shifting
toward far eastern Colorado as the next weather system moves in.
Overnight, this feature, aided by sufficient lift, instability and
upper jet divergence moves generally to the east although specifics
are a bit more difficult to pinpoint. High temperatures are looking
to be in the middle 70s to lower 80s with low temperatures in the
upper 40s to upper 50s.

Friday-Friday night...we`ll have 20%-40% chances for showers and
thunderstorms although a bit more specific timing would be east of
Highway 25 in the morning and early afternoon as Thursday nights
wave moves through. The next weather system moves into far eastern
Colorado during the late afternoon hours then east across the
remainder of the area through midnight before moving southeast and
out of the area. High temperatures are forecast to be in the lower
to middle 70s with low temperatures in the lower to middle 50s.

Saturday-Saturday night...shower/thunderstorm chances increase in
the afternoon from the west and southwest (20%-40% chance) then east
and out of the area near sunrise Sunday morning with continued 20%-
40% chances. High temperatures rise into the lower to middle 80s
with low temperatures in the middle 50s to lower 60s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Issued at 320 AM MDT Thu May 30 2024

The long-term pattern looks to remain zonal with an upper-level low
pressure system moving along the U.S./Canada border, maybe in the
northern row of states. This would lead to diurnal pop-up showers
and storms, but nothing very organized. The CMC-NH is showing the
low pressure system moving over the Tri-State area and becoming
cutoff Wednesday and lasting into the weekend. This seems highly
unlikely (<5% chance of occurrence), but if this does occur we could
see persistent storms and showers until it moves out.

RH values look to lower into the teens in southwest on Sunday and
Tuesday afternoon. This does increase fire weather concerns, but
winds do not support critical fire weather.

Temperatures will be fairly warm with highs in the mid 80s to mid
90s. Low temperatures will remain in the mid 50s to low 60s.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1003 PM MDT Wed May 29 2024

Showers and storms continue to move across each terminal
bringing with MVFR visibilities. This is forecasted to continue
through the first few hours of the new TAF period. Continue to
have concern for patchy dense fog across the area around sunrise
similar to this morning, so confidence isn`t overly high in
exact locations but do feel it is worth including as tempo.
stratus may linger across eastern portions of the area
especially KMCK; appearing more likely that status should be
clear of the KGLD terminal. Another round of potentially severe
storms is again forecast for tomorrow.

&&

.HYDROLOGY...
Issued at 358 AM MDT Wed May 29 2024

Highly efficient moisture return has already began and will continue
into the end of the workweek with aid from the 850 mb LLJ. This
moist conveyor belt will cause PWATS to increase above 1 inch
starting Wednesday and potentially remain that way until Sunday. The
highest values will be in the eastern CWA, but the majority of the
Tri-State area will have a good chance (70%+) at seeing PWATS above
1 inch. Throughout this active pattern, a high melting layer is also
expected, generally 11,000-15,000 feet agl.

Tuesday evening saw 2-3+ inches of rain in Cheyenne county Colorado,
and a few other locations in eastern Colorado. This rain did not
cause any flooding, but it will make it easier for flooding to occur
over the next few days. Locations that received heavy rainfall are
not fully primed for flooding (SAC-SMA soil saturation is around 30-
45% in these area), but will become susceptible to flooding sooner
than normal.

Based on what the CAMs are showing, the southern cluster of storms
would be a slower mover and larger in size, meaning based on its
projected path (south of I-70 across the CWA) and potential for
heavy rainfall, it will need to be watched closely for flash
flooding.

Thursday is currently the best day for training storms to create
heavy rainfall that could lead to rate-driven flash flooding and
duration-driven areal flooding. Friday and Saturday are also at risk
for flooding potential due to a combination of efficient rain
producing storms and potentially multiple days of heavy rain
saturating the soil.

Current confidence in localized flooding occurring through Saturday
is around 25-45%. Confidence in widespread flooding is about
20%.

&&

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

&&

$$

SHORT TERM...99
LONG TERM...CA
AVIATION...Trigg
HYDROLOGY...CA