533
FXUS63 KGLD 192033
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
233 PM MDT Thu Sep 19 2024

.KEY MESSAGES...

- Dangerous fire weather conditions and significant reductions
  in visibility assoc/w blowing dust would accompany such a wind
  shift, if present.

- Showers and thunderstorms will develop over much, or all, of
  the Tri-State area this weekend as a potent upper level low
  tracks eastward across the Rockies and Central Plains. An
  instance of flash flooding or river flooding is possible,
  mainly Saturday afternoon through Sunday morning. Barring a
  significant change in the evolution of the upper wave, severe
  weather is unlikely in the Goodland CWA.

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

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 232 PM MDT Thu Sep 19 2024

Across the Tri State region this afternoon, skies are sunny as high
pressure continues a transition through the area. Temperatures as of
100 PM MDT are ranging in the mainly in the 80s with some upper 70s
in portions of northeast Colorado. With much of the forecast area
still on the east side of the surface ridge, the gradient remains
northerly with gusts up to 20-25 mph in spots. Areas in Colorado are
lighter and should transition to light/variable by sunset.

The main wx concerns for the short term period will be the potential
for near critical to locally critical fire wx conditions over
portions of northeast Colorado for Friday afternoon, increased
rw/trw chances late Friday into the upcoming weekend. Weekend precip
chances may bring locally heavy rainfall that could bring about
flooding concerns.

The latest RAP40 500mb analysis is showing zonal flow aloft as a
large ridge resides over the lower two thirds of the country.
Guidance carries this ridge slightly south and east on Friday,
allowing for a transition to SW flow aloft.

At the surface, high pressure working through the area tonight will
provide tranquil conditions as winds will be light, but will slowly
transition to southerly by Friday morning as the ridge moves east of
the area. There will be an inverted trough setting up over eastern
Colorado that will begin to enhance the southerly flow, especially
over our Colorado counties. This gradient, combined with dry
conditions setting up on southerly flow, will create increased fire
wx concerns for portions of northeast Colorado. Please refer to the
Fire Weather section below for more information. Winds may also
create some blowing dust concerns and will have to be monitored.

There will be a weak shortwave that rounds the northern periphery of
the upper ridge Friday night moving up into Kansas. The
aforementioned trough to the west will also shift east Friday
evening. 20% chance of rw/trw is possible for areas along/east of
Highway 83. Weak instability and the NamNest is showing some
scattered potential towards the 06z Saturday timeframe.

Going into this weekend, guidance brings a closed upper low slowly
out of the Desert SW and slowly into the central Rockies. The ridge
to the east will slow the progression of the system towards the
Plains region after 18z Saturday. 700/850mb low ahead of the 500mb
parent will slide east through the CWA Saturday night into Sunday
morning. Guidance brings the 500mb low slowly E/NE through the CWA
through Sunday, clearing east going into the evening hours.

The result of this system and is slow trek across the area, will be
a 36-hour period of persistent steady rainfall with rw/trw. The
latest WPC QPF for this time remains fairly closer to previous
forecast with the potential for a range from 1.30-1.70 inches area-
wide. This steady rainfall combined with some localized
thunderstorms could bring amounts exceeding 2 inches. This could
create some localized flooding concerns that may affect areas
river/streams. This will have to be monitored for potential flood
watch. WPC does have the entire CWA under a Marginal Risk for
excessive rainfall. Gusts could approach the 25-35 mph on the
backside of the exiting system Sunday/Sunday night.

For temps, highs Friday in the upper 80s to lower 90s will give way
to 70s and 80s on Saturday. Going into Sunday, mainly 50s to lower
60s are expected as CAA brings in a nice round of cooler temps(850
mb temps during the day range around +5c). Overnight lows tonight
will range in the 50s, 50s/60s Friday night, but for the upcoming
weekend, mainly 40s Saturday night and for Sunday night, mid to
upper 30s in Colorado and along the border, with lower 40s east of
there. Areas Highway 27 and west may have to be watched for a
potential Frost Advisory.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Issued at 101 PM MDT Thu Sep 19 2024

For the extended period, the latest runs of the GFS/ECMWF both show
a cutoff 500mb set up in the Desert SW, allowing for NW flow aloft
initially. By midweek, amplified ridging occurs allowing for a
return to SW flow aloft, with the low still over the southwest
portion of the country. The two models do differ some on the
placement of the system during this time.

At the surface, high pressure will set up east of the area, with an
inverted trough over eastern Colorado. As the upper low swings south
through the Rockies on Mon-Tue, there is a 20-30% chance for rw/trw
to occur. Guidance has the pop chances out to the Highway 25
corridor, but should be focused closer to inverted trough although
it does shift a bit E/SE going into Tuesday. There is a weak
shortwave that could work into the upper ridge midweek, but after
the precip chances through Tuesday evening, the rest of the week is
mainly dry.

850 temps through Tuesday top off around +20c, increasing into the
20s midweek as the upper ridge becomes more assertive over the
Plains region. This will allow for a slow increasing temp trend, if
only by a few degrees from Monday`s to Friday`s highs.

For temps, the Tri State area will see mainly 70s for highs each
day. There could be some locales during the day Monday/Tuesday that
may only see the upper 60s. Tuesday`s numbers will be highly
dependent on how fast cloud cover breaks to allow mostly sunny skies
during the afternoon hours. Overnight lows will range mainly in the
40s each night, warmest areas east of Highway 25. Thursday night
could have low 50s stretch as far west as Highway 25, but cloud
cover/wind dependent.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 929 AM MDT Thu Sep 19 2024

With high pressure transitioning through the area during the
forecast period, VFR conditions are expected. Both terminals
(KGLD/KMCK) will see northerly winds around 10-20kts through
about 22z this afternoon, then becoming light/variable. By 07z
Friday, KGLD will see S/SE flow around 10kts. KMCK will see a
longer period of light/variable conditions, then becoming SE
around 10kts by 15z Friday.

&&

.FIRE WEATHER...
Issued at 232 PM MDT Thu Sep 19 2024

Across much of our northeast Colorado on Friday afternoon, RH
values are expected to drop into the mid teens to the lower 20s.
There is an inverted trough over eastern Colorado that will
strengthen by the afternoon hours, creating southerly gusts
around 25-30 mph. This will create near critical to localized
critical fire wx conditions, especially over western portions of
Kit Carson and Cheyenne counties. This will have to be
monitored for potential red flag conditions/warning by next
forecast shift.

&&

.HYDROLOGY...
Issued at 232 PM MDT Thu Sep 19 2024

An efficient 850mb LLJ is expected to start setting up around
21Z Friday and continue until Sunday morning. 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 Friday evening,
intensifying Saturday afternoon, and begin weakening Sunday
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 couple tenths of rain with the potential (~25%)
of seeing 2+ 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 flooding being slightly high at
around 20%.

There could result in a precipitation range from 1.30-1.70" with
localized higher amounts in convection.

&&

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

&&

$$

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