526
FXUS63 KGLD 011220
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
620 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 /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 545 AM MDT Wed May 1 2024

GLD: VFR conditions are expected to deteriorate to MVFR late
this morning and early this afternoon, further deteriorating to
IFR and possibly LIFR at/around sunset (~02Z) this evening.. in
association with stratus. While showers/storms cannot be ruled
out invof the GLD terminal late this afternoon (~22-02Z), at
this time.. the majority of convective activity is anticipated
to be confined further north. Expect conditions /ceilings/ to
improve to VFR near the end of the TAF period.. 06-12Z Thu.
Easterly winds at ~10 knots will veer to the ESE and increase
to 15-25 knots late this morning.. further veering to the SE
this afternoon. Winds will shift to the N or NE at 15-25 knots
this evening, backing to the NW and decreasing to 10-15 knots
near the end of the TAF period as a lee cyclone in southeast CO
weakens and progresses eastward across southern KS.

MCK: VFR conditions are expected to deteriorate to MVFR (in
association with stratus) this afternoon, further deteriorating
to IFR and possibly LIFR around or shortly after sunset
(02-04Z) this evening. Showers and thunderstorms are possible
late this evening into tonight.. mainly in the 04-07Z time
frame. Expect conditions /ceilings/ to improve to VFR near the
end of the TAF period.. 09-12Z Thu. NE winds at ~10 knots will
veer to the E or ESE and increase to 15-25 knots late this
morning and persist through the afternoon. Winds will back to
the NE or N at 15-25 knots this evening and persist overnight..
decreasing to ~10 knots by the end of the TAF period.

&&

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

&&

$$

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