663
FXUS63 KGLD 211859
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1259 PM MDT Fri Jun 21 2024

.KEY MESSAGES...

- Continued very windy today with 20%-30% chances for afternoon
  and evening thunderstorms, mainly along/north of I-70, some
  of which could become severe(Yuma/Dundy/Hitchcock counties).

- Weekend looks to remain hot with highs in the 90s. Could be a
  few thunderstorms Sunday afternoon/evening.

- Skeptical regarding how quickly the upper level ridge
  retrogrades west going into next week. Depending on where the
  ridge is will dictate where storms will move through.

- If ridge is delayed, the arrival of the hottest temperatures
  will be delayed too.

- Chances for storms each day next week.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 312 AM MDT Fri Jun 21 2024

Across the region this morning, skies are mainly clear, except for
lingering clouds north from exiting precip, and some mid/high clouds
over southern portions of the area. As of 100 AM MDT, temperatures
are ranging in the 60s and 70s. With a surface low sitting off to
the southwest of the CWA, and a front sitting over the extreme
northern portion of the area, persistent southerly flow is occurring
for most. Areas along/north of Highway 34 are seeing an easterly
fetch in the vicinity of the boundary.

Weather concerns for the short term period will focus on the hot
conditions each day with above normal temperatures, strong southerly
flow over the area today/tonight and the threat for showers and some
thunderstorms(some may be strong to severe for portions of the area
later today/this evening).

Currently for today/tonight, the latest RAP40 500mb analysis and mid
level water vapor imagery are showing a broad elongated ridge over a
good portion of the eastern U.S. and with the western extent of this
ridge extending into central/southern Plains, the Tri State area is
seeing SW flow aloft. The aforementioned surface low sitting over
eastern Colorado will shift eastward through the afternoon/evening
hours, combining with a shortwave that works over the
western/northern periphery of the upper ridge, and will trigger
chances for convection with about 15-20% chance near I-70 and
increasing to about 30-40% from Highway 36 and points north
especially NW zones.

The remnant front to the north will also aid in focusing convection
as the entire complex lifts E/NE later this afternoon into the
evening hours. SPC is carrying a Marginal Risk for severe storms for
Yuma county in Colorado extending east into Dundy and Hitchcock
counties in Nebraska. Best instability will be located closest to
the front/low combo, but with daytime heating drying out lower
levels ahead of expected activity later today, guidance is having
inverted-v soundings around the 21z-03z timeframe, giving DCape
values 1000-1400j/kg on top of PW values that increase form an inch
in the west to around 1.5" in the east. While hail can`t be ruled
out with any storms that do develop, wind could be the main threat
along with locally heavy rainfall. Bulk of activity will clear the
CWA by 06z Saturday per latest CAMs, with some scattered showers
thereafter through 12z Saturday.

Before seeing an increase in convection, the southerly gradient
ahead of the low passage will afford the area gust potential into
the 40-50 mph range by midday into the evening hours, tapering off
from west to east as the flow shifts to the northwest.

Guidance continues to shift the upper ridge westward into the
upcoming weekend, allowing for SW flow aloft to become zonal both
days. Dry conditions are expected to persist over the area Saturday,
with a weak shortwave passage on Sunday. This system will track east
over the northern extent of the ridge. 15-20% pops for isolated
rw/trw over western areas during the day, tapering off over NW
Kansas during the evening hours. Other than these storms chances,
hot weather will persist area-wide.

For temps, highs today will range in the lower to mid 90s. On
Saturday, upper 80s to mid 90s are expected, and for Sunday, a range
mainly in the upper 90s with a few spots around the 100F mark.

Heat indices for the most part will range at or below forecasted
highs, however, on Sunday a few spots east of Highway 25 will start
to see readings approach the low 100s.

Overnight lows tonight will range mainly in the 60s west of Highway
83. East of there, upper 60s through the mid 70s. Lower to mid 60s
Saturday night will give way to mainly mid to upper 60s on Sunday
night. Some locales across Graham and Norton counties will only drop
to around 70F.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 1252 PM MDT Fri Jun 21 2024

This part of the forecast will be greatly influenced by the
upper level ridge. Models have the ridge entrenched over the
Southern Plains, centered over TX. With the ridge south of the
forecast area, models have zonal flow over us. Within the zonal
flow, upper level short wave troughs move overhead almost daily.
This may lead to precipitation chances for us.

However am skeptical of the ridge being centered over TX before next
week starts.  Models have been moving the ridge west too fast, which
is to be expected when the ridge is a blocking high pressure.  For
this reason am doubtful the ridge will scoot west as quickly as
currently forecast.  A delay in the ridge moving west should cause
the upper level flow over the forecast area to be more from the
southwest than the west.  This would influence where storms will
track across the forecast area, and affect how hot the forecast area
becomes.  If the ridge does end up being slower to move west, the
hot air under it will stay more to the east.

Even though models have upper level short wave troughs moving
through the flow over the forecast area, am thinking the storm
coverage should be on the low side.  This is more reflective of a
summertime pattern in which storms are isolated to scattered at
best.

If the current forecast is on track, there may be a brief
respite from heat midweek as a weak cold front moves through.
However high temperatures rebound by the end of the workweek.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1117 AM MDT Fri Jun 21 2024

Generally VFR conditions will be observed at both KGLD and KMCK,
but strong winds, made worse with storms this afternoon and
evening, will make for some tricky conditions. Models are
having a difficult time figuring out exactly what is going to
happen over the next 8 hours, but we are currently expecting two
waves of storms. The first will form around 21Z and move away
from the TAF sites by 0Z. The second wave, the wave with higher
confidence, will impact KGLD around 1Z and should stay south of
KMCK. This second wave is expected to produce strong winds as it
progresses eastward. If any of the stronger cells moves overhead
of either TAF site, heavy rainfall will reduce visibility
significantly. The heavy rain is the only concern for IMC
throughout the period. Later in the period, winds will weaken
and become northwesterly.

&&

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

&&

$$

SHORT TERM...JN
LONG TERM...JTL
AVIATION...CA