535
FXUS63 KGLD 011037
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
437 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 THURSDAY 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 /FRIDAY 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 /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1020 PM MDT Tue Apr 30 2024

KGLD...VFR conditions are expected through 16z. A northeast wind
under 10kts at taf issuance will slowly veer to the east through
sunrise. From 12z-16z, east-southeast winds slowly increase with
gusts up to 30kts. From 17z-01z, east-southeast winds continue
to produce gusts up to 25kts or so. The possibility remains that
stratus will move over the terminal from the east-southeast,
creating sub VFR cigs. The cigs may move off to the northeast or
remain over the terminal so a period of cigs just above VFR
level are included at this time. After 01z, winds back to the
northeast and north, gusting up to 30kts. Stratus that may have
moved northeast and away from the terminal will quickly move
over the terminal causing sub VFR cigs through the end of the
taf period. An approaching upper level trough will bring an
increasing chance for elevated showers and thunderstorms to the
terminal after about 02z. It is possible that severe
thunderstorms could impact the terminal with the primary hazard
being large hail.

KMCK...VFR conditions are expected through about 19z. A
northeast wind under 10kts at taf issuance will slowly veer to
the east at similar speeds through sunrise. From 15z-19z, east
winds increase with gusts up to 25kts. From 20z-01z, east winds
gusting up to 25, maybe 30kts continue with sub VFR clouds due
to stratus reaching the terminal from the south. There could be
a few rain showers as well around or over the terminal but
confidence in that is low. After 02z, winds shift to the
northeast with gusts up to 25kts. Sub VFR cigs continue along
with some fog/mist. Elevated thunderstorms will be possible and
similar to KGLD, severe thunderstorms are possible with large
hail the primary hazard.

&&

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

&&

$$

SHORT TERM...Vincent
LONG TERM...CC
AVIATION...99