302
FXUS63 KGLD 010749
AFDGLD

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

.KEY MESSAGES...

- A marginal to enhanced risk for severe thunderstorms continues
  for the region Wednesday afternoon and evening. Isolated
  storms possible in the afternoon east of Highway 83 in
  northwest Kansas where large hail, damaging winds and perhaps
  an isolated tornado will be possible. Storms will become more
  widespread Wednesday night with large hail and locally heavy
  rainfall becoming the primary hazards.

- Severe storms possible next Monday in eastern portions of the
  area.

- Elevated to near critical fire weather possible Monday and
  Tuesday of next week.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 200 PM MDT Tue Apr 30 2024

Cold front has moved out of the area this afternoon with gusty
northwest winds in its wake. Those winds will gradually diminish
through the late afternoon and early evening. Tonight, a weak
wave embedded in the southwest flow aloft combined with low
level upslope at the surface might result in a few isolated
showers, mainly overnight, from northeast Colorado into
southwest Nebraska. However, confidence is low and most models
are dry. Low temperatures will be in the 40s.

Clouds will increase Wednesday morning with moisture return from
the southeast. By 18z expecting most if not the entire area to
be socked in with low to mid level clouds with east to southeast
winds. Weak impulse in the southwest flow aloft comes across in
the afternoon with warm front likely south of the area. With
persistent easterly winds north of the warm front, clouds may
persist well into the afternoon. This will impact not only
thunderstorm chances, but temperatures. Convective allowing
models not in the best agreement on where storms will initiate.
The HRRR has a couple of isolated supercells initiating after
21z near southeast corner of the area moving northeast, and
additional develop towards 00z in northwest corner of the area
near the secondary cold front. NAMnest on the other hand keeps
the area in the cool, cloudy and capped all day with more of a
stratiform light drizzle or light showers. The NAM does show
plentiful elevated instability and shear, but never taps into
it. The NAM keeps surface temperatures in the upper 40s to lower
50s all day in most of northwest Kansas and southwest Nebraska,
a solution that cannot be completely discounted. Given all the
uncertainties, confidence in severe risk and temperatures is
low.

Wednesday night, upper heights continue to fall/cool with
approach of main upper trough. Surface cold front will continue
to plow southeast and should be through the forecast area by
06z. There will be a risk of severe storms during the evening
with the stronger forcing. NAM finally shows elevated convection
developing late in the evening which taps into MUCAPE in excess
of 1000 j/kg and up to 3000 j/kg in eastern areas with deep
layer shear of around 50 kts. The HRRR shows a similar
environment during that time with elevated storms and a
favorable combination of MUCAPE/shear that would suggest a risk
for large hail. HREF shows lows probabilities of 6-hour rainfall
amounts of greater than 1 inch at 06z across mainly southwest
Nebraska, which is consistent with the HRRR which shows 1-2 inch
amounts along the Kansas/Nebraska border area and the NAM which
shows a bullseye of around 1 inch in the same general area.
Storms will be moving at a fairly decent clip of 10-20 kts, so
appears to be more of a heavy rain threat than flash flood
threat. Storms continue to move east overnight, with perhaps a
lingering risk for severe hail between 06-09z east of Highway
25, before moving out after 09z. Low temperatures will be in the
40s.

After morning clouds, Thursday will be mostly sunny with highs
in the 60s. Widely scattered light showers will be possible
Thursday evening in western areas with a weak wave coming across
in the zonal flow aloft. However, with no instability to work
with and little moisture, impacts will be minimal. Lows Thursday
night will range from the upper 30s to lower 40s.

Zonal flow continues on Friday with another open wave coming out
of Colorado in the afternoon. Convection should initiate on the
higher terrain to the west with forecast SBCAPE values of less
than 500 j/kg. Showers and isolated storms continue east into
Friday night, possibly merging into a large area of light to
occasionally moderate rain. GFS and ECMWF show 12-hour
precipitation amounts by 12z Saturday morning of between a
quarter and a half inch. High temperatures will be in the lower
70s and low temperatures will range from the low to mid 30s in
northeast Colorado to the lower 40s in north central Kansas.

&&

.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...JN
LONG TERM...CC
AVIATION...99