628
FXUS63 KGLD 170957
AFDGLD

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

.KEY MESSAGES...

- Windy today 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 TUESDAY/...
Issued at 353 AM MDT Tue Sep 17 2024

Overview: A modest upper level ridge will prevail over the
central CONUS at the beginning of the long term period (Thu-
Fri). Long range guidance suggests that a potent upper level
wave.. presently situated offshore the coast of British
Columbia.. will amplify and dig southward along the Pacific
Coast today and Wed, stall invof central California on Thu, then
gradually progress east across the Intermountain West (Fri-Fri
night) and central Rockies/High Plains (Sat-Sun).

Thursday: Clear skies and unimpeded insolation assoc/w the
upper ridge over the region will foster dry conditions and above
average temperatures, though.. a short period of breezy (15-20
mph) N winds and modest cold advection (assoc/w the passage of a
weak surface to 850 mb /SFC-H85/ trough Thursday morning) could
temper highs to some degree. Expect light/variable winds with
temperatures ranging from ~82-92F during the afternoon, coolest
in northeast CO.

Friday: Upper level flow will back to the SW and strengthen
late Fri and Fri night.. as the aforementioned upper wave
progresses east across the Intermountain West. Forecast
soundings suggest that deep vertical mixing and strengthening
mid-level flow may yield breezy SW winds and exceptionally dry
conditions over portions of the area late Fri afternoon..
particularly in eastern CO and adjacent KS border areas.. where
a period of critical fire weather conditions is possible.
Isolated high- based convection cannot be ruled out during the
late afternoon, mainly south of I-70 where marginal high-based
instability (~100-250 J/kg MLCAPE) may be present invof a modest
low-level convergence zone /dryline. Very low confidence with
regard to whether or not viable high-based convection will
develop in the Goodland CWA.

Sat-Sun: With a progressive upper wave progged to track east
across the region this weekend.. expect cooler temperatures and
well-above average chances for precipitation (in the form of
scattered to widespread convection).. mainly Saturday afternoon
through Sunday morning. Forecast specifics -- severe weather
potential, in particular -- will highly depend upon the
evolution and track of the upper wave/low.

&&

.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...Vincent
AVIATION...KAK