950
FXUS63 KGLD 201855
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1255 PM MDT Fri Sep 20 2024

.KEY MESSAGES...

- Briefly critical fire weather conditions are possible today
  in eastern Colorado.

- Showers and thunderstorms will develop over majority of the
  Tri-State area this weekend. Severe weather does not look
  likely, but there is a slight concern for flooding.

- Low temperatures in the mid to upper 30s are forecast for
  eastern Colorado by Monday morning.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 323 AM MDT Fri Sep 20 2024

This morning, a high pressure system over Texas is extending a
ridge over the Great Plains and Midwest. This will create mostly
clear skies for majority of the day, allowing temperatures to
warm into the low 90s. Winds will be south- southwesterly
throughout the day. In the far western CWA, around the Joes to
Flagler, CO area, the winds are expected to mix out surface
moisture and drop RH values to around 15% for a couple hours.
The winds will have picked up at this time and gusts around
25-30 kts are expected, briefly leading to localized critical
fire weather conditions. For more information, see the fire
weather section below.

Starting around 19-21Z this afternoon, a shortwave is forecast
to fire off some storms south of the CWA. Majority of this
precipitation will occur outside of the Goodland CWA, however,
Gove, Wichita, and Greeley counties could (~15% chance) see some
light showers late this afternoon. There is a low (~15%) chance
that lingering showers or sprinkles could last through the
night in the far eastern CWA. The best chance for showers over
there would be after 6Z Saturday.

Looking at isentropics, there is a well define moisture
boundary at 315K around the 19-23Z timeframe near the Tri-State
border. This feature could set off an isolated storm or two this
afternoon, but confidence is only around 10-15% this will
occur.

Overnight tonight, the pattern gets a bit more interesting as
the 850mb LLJ will kick up to around 30 kts, moving Gulf
moisture into the area. A shortwave ridge will move back over
the area, clearing out the skies by morning. A low pressure
system near the Four Corners will be moving northeast to stir up
the atmosphere throughout the day Saturday. Lows look to drop
into the low 50s in the northwestern CWA where the winds will be
weaker and skies will be clear, but in the southeast, mid 60s
are forecast where the cloud cover will linger most of the
night.

Saturday morning, the aforementioned low will be crossing over
the Rockies, but will extend a shortwave trough over the
southern CWA to cause some warm-front type showers. This
shortwave will push out the ridge from overnight, allowing
clouds to form across a large portion of the CWA. The shortwave
will also cause a broad cold front to move in from the
northwest, shifting winds as it move in. The new northerly winds
and additional cloud cover look to bisect the area, causing a
fairly strong thermal gradient to setup. In the northwestern
CWA, temperatures will be capped in the lower to mid 70s, but
southeast of the front, mid 80s are forecast.

Around 21Z Saturday, 500mb vorticity increases and begins
moving northward, indicating a start to the widespread forcing.
This forcing will cause showers and storms to form across
majority of the area with the precipitation lasting until Sunday
morning. Severe weather does not look likely (<5% chance) due
to a lack of instability, but deep shear and strong forcing
could cause a storm to over preform.

Saturday night, the low will move over the CWA causing
widespread precipitation. For more information about the rain,
see the hydrologic discussion below. Overnight lows will drop
into the 40s.

Sunday morning and into the mid-day, the low will be moving out
of the area to the east-northeast. The following pressure rises
will cause the rain to cease in the west around 15Z with
lingering showers in the east likely until around 18-21Z.
Northerly winds and clouds will keep temperatures capped to the
50s for the area. The skies are expected to clear in the
evening, allowing efficient overnight cooling.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 1255 PM MDT Fri Sep 20 2024

The latest extended guidance from the GFS/ECMWF do start off the
period on Monday consistent showing a 500mb shortwave trough sliding
southeast through the central Rockies. The models then do break off
as to the evolution of the system as it slides to our S/SW. The GFS
carries the system through the Kansas area as an open wave Monday
night into Tuesday morning, followed by amplified ridging coming
eastward through the Rockies. This will provide the CWA with mainly
dry conditions for most of Tuesday onward. The current ECMWF however
allows the shortwave to move slower into Tuesday, forming a cutoff
low over northern Texas then lifting northeast towards the southern
Kansas border late in the week.

The latest NBM guidance does take into account both models initially
as the trough approaches the CO/KS border Monday night with a 15-30%
chance for precip. Highest pops closest to the Colorado tapering off
into the central CWA. It does look like the consensus is for the
cutoff system to occur then slide south of the CWA Tue-Tue night,
keeping a 15-20% chance over S/SW zones into Tuesday night. This
does follow previous runs yesterday at this time, so will stick with
this consistency for now. The bulk of the QPF will stay south of the
area closest to the formed cutoff low. Late Thursday into Friday as
the system lifts northeast, the northern periphery of the system
could bring enough moisture into eastern zones that could trigger a
few rw/trw(15-20%).

For temps, upper 60s to lower 70s expected for highs Monday and
Tuesday due to expected clouds/rain, will give way to mid 70s
Wednesday, trending warmer to the upper 70s and lower 80s for most
for next Thursday and Friday as the aforementioned upper ridge works
east off the Rockies and southerly surface flow persists area-wide
these days. Lows in the 40s Monday night will trend warmer as well
with upper 40s west into the mid 50s east for the end of next
week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1104 AM MDT Fri Sep 20 2024

For KGLD & KMCK... VFR conditions are forecast through the
period. There is a less than 10% chance of storms this afternoon
and evening with the forecast keeping storms well southeast of
the airports. The low level jet is forecast to develop tonight
across the area around 03Z and persist until around 12-15Z when
a front passes through the area. Winds will then shift from out
of the south, to out of the north and strengthen to 20-25 kts
with gusts to 35 kts. A few sprinkles may occur at the very end
of the period.

&&

.FIRE WEATHER...
Issued at 323 AM MDT Fri Sep 20 2024

This afternoon, in western Kit Carson and Yuma counties,
southwesterly winds are expected to pick up. Sustained winds around
15-20 kts with gusts up to 25-30 kts are expected. These winds will
work to mix in drier air, lowering RH values into the mid teens
across eastern Colorado. In the area mentioned above, local RH
values around 14% are expected for an hour or two. Widespread, long
duration critical fire weather conditions are not expected.

If the winds over perform and extremely dry air mixes down to the
surface, we could see some locations meet Red Flag criteria.
Confidence in the current forecast is moderate, around 60-70%,
meaning there is about a 30% chance three hours of critical fire
weather conditions could occur in the far western CWA.

&&

.HYDROLOGY...
Issued at 323 AM MDT Fri Sep 20 2024

An efficient 850mb LLJ is expected to set up around 21Z Friday-0Z
Saturday and continue until Sunday morning/mid-day. This LLJ will
provide a moist conveyor belt from the Gulf of Mexico into the High
Plains. As mentioned above, an organized low pressure system will
move into the region Saturday, creating a moderately strong forcing
mechanism to start precipitation.

Precipitation looks to start in the eastern CWA early Saturday
morning, intensifying Saturday afternoon, and begin weakening Sunday
morning/mid-day before moving out of the area by Sunday evening.
Between 21Z Saturday and 18Z Sunday, nearly the entire Tri-State
area will see at least a few tenths of rain with the potential
(~25%) of seeing 1.25+ inches in that timeframe. If the higher
amounts do occur, especially in the eastern CWA, there will be
increased flooding concerns. Concerns for flash flooding are low
(<10%) with the potential for areal or river flooding being slightly
higher at around 20%.

Throughout the entire event, locations along and southeast of a line
from Wallace, KS to Norton, KS can expect to see 0.9-1.6 inches of
rain, with pockets of 3+ inches being possible. Locations west and
north of that line will receive less precipitation, likely around
0.4-1 inch of rain, with some pockets up to 1.75 inches.

&&

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

&&

$$

SHORT TERM...CA
LONG TERM...JN
AVIATION...KAK
FIRE WEATHER...CA
HYDROLOGY...CA