628
FXUS63 KGLD 170905
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
305 AM MDT Tue Sep 17 2024

.KEY MESSAGES...

- Windy Tuesday with southerly winds gusting 35 to 50 mph
  during the afternoon hours.

- Severe weather is forecast for the area this afternoon and
  evening with wind gusts generally up to 75 mph, a few
  instances of large hail, and maybe a spinup tornado.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 303 AM MDT Tue Sep 17 2024

Current observations show clearing skies as the last of the storm
activity continues to shift further east into Central Kansas. Winds
near the surface have lightened to around 10-15 mph from the
south/southeast.

For today, another warm and windy day is forecast ahead of an
advancing upper low/trough. For the daytime hours, mostly sunny
skies should allow temperatures to warm to around 90. The pressure
gradient is forecast to tighten as the day goes on and allow winds
to increase to 20-30 mph. However, the continued slight shift of the
upper trough more to the north and with a faster motion is weakening
the forecast flow in the low to mid levels. Guidance is now
suggesting that the 850-700mb layer is going to have speeds more
around 30-35 kts which would keep the gusts a tad bit lower. Have
tuned the grids to match this with gusts now generally between 30
and 45 mph. There should still be an area or two that sees a gust
near 50 in the west, as long as good mixing occurs. With the surface
moisture advection from the southeast and continued moisture
streaming in the mid levels from the southwest, dewpoints are
forecast to generally be in the 50`s and 60`s which will prevent
critical fire weather conditions. Still will probably be a bad day
for burning though with most of the area having persistent dry
conditions and the gusty winds.

This afternoon and evening, the upper trough is forecast to begin
more of a north/northeasterly track and push into the North/Central
Rockies. This will begin to push the center of the lower surface
pressure off the Front Range and pull the center north into Nebraska
and the Dakotas. This should pull the better forcing and winds for
storms to the north with it. However, the area should still see
storms move through with storms firing up along the higher terrain
in Eastern Colorado and with the surface field evolving to have
southeasterly winds and southwesterly winds creating a surface
convergence zone as the low moves east. With plenty of moisture
available, the issue is not so much if the area will have storms
(though gusting out could weaken storms before they get to the
eastern half of the area), but if the storms will be severe and how
strong. Locales closer to the low (northwestern parts of the area)
are forecast to have winds push 60kts in the cloud layer where as
locales further south are closer to 45-50 kts. Combining this with
DCAPE around 1200 J/KG and downshear vectors around 45-50 kts, there
is a good signal for storms to produce gusts generally to 65 mph.
However, any storm in the greater flow (currently forecast as the
counties near the Tri-State border) could see wind gusts push 75 mph
if not 80 mph. This looks to be the bulk of our severe hazard this
afternoon and evening as clusters and lines move through from west
to east. However, given the moist environment and chance for
additional convergence zones, isolated to scattered storms may form
ahead of the main line. If these storms form, there will be a
slightly increased risk for hail around one to two inches in
diameter. the main inhibitor is that effective shear is generally
forecast to be 30 kts or less so storms would have to be long lived
and/or modify the environment to produce better shear and develop
supercells. Within the expected mainline, the storm motion should be
too fast and shear too low to support large hail development.
Finally, it is worth mentioning that there is a low threat for a
tornado or two in either the main line or discreet storms. The
favored area looks to be along the Colorado border where discreet
storms have a higher chance of forming. If winds near the surface
become more southeasterly, the south to southwest lower level flow
will have winds veer and create low level shear to allow for a
spinup. QLCS tornadoes look to be unlikely as the 0-3km shear vector
is forecast to be more parallel instead of perpendicular to the line
of storms.

Tonight, storms are forecast to move out and dissipate as the upper
trough and lower pressure shift further north and east. This will
begin to weaken our flow and allow winds to lower through the night.
With lowering winds, clearing skies, and drier air moving in behind
the system, lows could drop into the 40`s in the west while the east
is more likely to stay in the 60`s.

Tomorrow, another warm day is forecast as broad troughing continues
and with no cooler air mass moving into the area. Highs should warm
to near 90. Winds are forecast to be lower as the upper low
continues to push off to the north and the next upper low/trough
develops near the West Coast. This has winds forecast around 10-15
mph with maybe a few gusts to 25 mph. This could allow for briefly
critical fire weather conditions in Eastern Colorado with drier air
moving into the area and lowering RH into the teens. Otherwise,
mostly sunny skies are forecast with the drier air forecast to
be over most of the area. There is a low chance for a storm or
two east of Highway 83 with a broad area of low pressure
providing some convergence zones. If the dry air does not move
most of the moisture out, a few afternoon/evening storms may
fire off. Tomorrow night would have lows ranging from the 40`s
in the west where it is drier, to 60`s in the east with the
higher dewpoints. Skies should be clear with winds around 5 to
10 mph.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 200 PM MDT Mon Sep 16 2024

Upper low in the Four Corners to start the period on Friday will
move into the central Rockies on Saturday and into the central
plains on Sunday. Northwest flow will then follow for early
next week on the back side of the system as it lifts into the
northern plains.

Precipitation chances Friday through Sunday will be the primary
forecast concern. Will start with southwest flow on Friday ahead
of the main system. Embedded waves and a frontal boundary will
combine for scattered showers and storms. Best moisture and
instability look to stay just southeast of the area, with more
of a dry southwest flow further north. If that holds, severe
chances will be low due to limited instability, though wind may
still be a concern with the high based storms. Cold front moves
through Friday night through Saturday morning (the usual timing
differences in the models), but by mid day Saturday should see a
post frontal regime across the area with breezy northeast winds.
Main upper low will move out of the Rockies Saturday afternoon
or Saturday night, accompanied by good chances for
rain/isolated thunderstorms. Severe storms not expected due to
the cooler/stable conditions. However, some signals in the
models for locally heavy rainfall, but exactly where the best
chances will occur uncertain due to the model differences in
track, strength and timing of the system. Precipitation chances
may linger well into Sunday depending on how fast the system
lifts out. A dry northwest flow will follow on Monday.

Temperatures remain above normal on Friday with upper 80s to
lower 90s. Quite a large range in temperatures in the models
for Saturday through Monday, with the ECMWF slower/warmer
overall compared to the wetter/cooler GFS solution. The blended
forecast essentially yields temperatures near normal, with highs
in the 70s to lower 80s and lows in the 40s and 50s.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1130 PM MDT Mon Sep 16 2024

For KGLD & KMCK... VFR conditions are forecast through the
period. Main concerns are the strong surface winds through most
of the day and thunderstorms during the late afternoon and
evening hours. Winds are expected to increase through the day
which will end the LLWS at KMCK. Starting as early as 21Z, but
likely around 00-04Z, a line of storms is forecast to move
through from west to east. These storms may be severe with
mainly wind gusts to 50-60 kts and maybe some large hail. Once
the storms pass, winds will begin to lower through the remainder
of the night.

&&

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

&&

$$

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