817
FXUS63 KGLD 011721
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1121 AM MDT Wed May 1 2024

.KEY MESSAGES...

- A few surface based thunderstorms may develop in northeast CO
  late this afternoon. An isolated marginally severe storm is
  possible, mainly between 4-7 PM MDT. A brief landspout cannot
  be ruled out.

- Elevated thunderstorms may abruptly develop along/north of
  I-70 in northwest KS and southwest NE late this evening. A few
  severe storms capable of producing large hail are possible,
  mainly between 10pm-2am CDT. Storms will rapidly exit the
  region (into south-central and southeast NE), thereafter.

- Scattered thunderstorms are anticipated to develop over
  portions of northeast CO and northwest KS Friday afternoon.
  Severe storms capable of producing damaging winds are
  possible, mainly late Fri aft/eve, when storms may increase in
  coverage and track SE toward southwestern and south-central KS.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 430 AM MDT Wed May 1 2024

Overview: An upper level low near the Canada/US border (invof
Alberta-Saskatchewan-Montana) will remain near-stationary in
this period.. advancing ever-so-slightly eastward into
Saskatchewan Thu-Thu night. Meanwhile, robust shortwave energy
presently situated invof the Oregon/Idaho border (on the
southern periphery of the aforementioned upper low) will
progress eastward into WY this aft/eve.. then northeastward into
the Dakotas (on the eastern periphery of the upper low) Thu-Thu
night.

Today-Tonight: Challenging temperature forecast. Expect highs
ranging anywhere from the upper 50s to lower-mid 70s.. warmest
in eastern CO and far southern portions of the area
(Greeley/Wichita counties), coolest east of Hwy 83 and north of
I-70.. where low stratus will rapidly develop late this morning
and persist through the day.

Convection allowing guidance suggests that a few surface- based
thunderstorms may develop within a marginally unstable `return-
flow warm sector` in northeast CO late this afternoon (~21-01
UTC) -- presumably in association with low-level convergence,
aided (perhaps) by a southeasterly /upslope/ component to low-
level flow -- as upper forcing will be well- removed from
northeast CO in the aforementioned time frame.

Convection allowing guidance suggests that elevated
thunderstorms may abruptly develop along and north of the I-70
corridor in northwest KS and southwest NE late this evening (~04
UTC).. as southerly to easterly low-level (~850 mb) flow /warm
advection/ strengthens over the region.. overrunning a
cool/stable near-surface airmass.. in the presence of moderate
instability (1000-2000 J/kg MUCAPE) and 40-50 knots of effective
deep layer shear. With this in mind, expect a potential for
elevated supercells capable of producing large hail.. mainly
along/north of I-70 in the ~04-07 UTC time frame. Storms will
rapidly abate and/or exit the region into south-central and
southeast Nebraska around or shortly after ~07 UTC.. as low-
level warm advection abruptly terminates.

Thu-Thu night: Benign weather. Expect a clearing trend late
tonight and Thu morning, followed by mostly clear skies and
light northerly to easterly winds during the day, with highs in
the 60s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Issued at 149 AM MDT Wed May 1 2024

The area is under southwesterly flow aloft at the start of the long
term period with low pressure centered over Saskatchewan/Manitoba on
into Ontario, upper level ridging building across the western CONUS,
and our next low pressure system coming into view off the coast of
the Pacific Northwest. At the surface, a front is forecast to push
through during the Friday afternoon-Friday evening timeframe. With
this, expecting gusty southerly winds shifting northerly and
shower/storm chances up to ~50-70% working in from the west with QPF
ranging generally from a quarter to three-quarters of an inch,
locally higher amounts possible.

Heading into the weekend, upper level ridging will build back in
with flow becoming briefly zonal before approach of the next system
has flow returning southwesterly. A disturbance skirts south of the
area, then east on Sunday, and with the low level southeasterly flow
allowing for increased moisture into the area, at least expect to
see some increased cloud cover but also some shower/thunderstorm
chances (up to around 20-30%).

Guidance is coming into somewhat better agreement with regards to
timing/placement of the early week system. Latest deterministic
guidance shows the upper low centered in vicinity of the Great Basin
Sunday evening before crossing the Rockies throughout the day Monday
within an upper level trough becoming negatively tilted. Still
monitoring potential for multiple hazards with this system,
including gusty southerly to southwesterly winds ahead of it and
associated increased fire weather concerns/possible blowing dust
concerns. Additionally will be looking at the potential for strong
to severe thunderstorms across eastern portions Monday afternoon-
evening where the dryline is forecast to set up with instability
reaching around 1000-2000 J/kg and 0-6 km shear values in the 50-70
knot range. A frontal passage will then sweep through the area, with
gusty post-frontal winds into Tuesday. Again will be looking at
potential for fire weather concerns.

For temperatures, highs are forecast generally in the low-mid 70s
Friday, mid 60s to lower 70s Saturday before warming into the 70 to
low 80s thereafter. For low temperatures, the forecast calls for low-
mid 30s to middle 40s Saturday morning, low-mid 40s Sunday morning,
middle 40s to middle 50s Monday morning, and 40s Tuesday, Wednesday
mornings.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1118 AM MDT Wed May 1 2024

MVFR ceilings likely to prevail at both KGLD and KMCK through
the afternoon, though a brief improvement to VFR possible at
KGLD in mid afternoon. Tonight, scattered to numerous showers
and thunderstorms will develop with an upper level disturbance.
Both terminals likely to be impacted by  lower ceilings and
rain. There is also a slight risk for hail with any stronger
thunderstorm. Convection expected to end around 06-07z, but low
ceilings persisting through the overnight. A return to VFR
expected at both terminals early Thursday morning.

&&

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

&&

$$

SHORT TERM...BV
LONG TERM...CC
AVIATION...024