964
FXUS63 KGLD 302315
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
515 PM MDT Tue Apr 30 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 /SATURDAY THROUGH TUESDAY/...
Issued at 200 PM MDT Tue Apr 30 2024

Saturday will be dry with shortwave ridging in the southwest
flow. High temperatures will be in the upper 60s. Models are
mixed regarding precipitation chances on Sunday. Next
disturbance in the southwest flow passes well to the south in
the GFS solution, but the ECMWF has a weaker, broader wave with
a few showers/isolated storms further north. Confidence is
rather low, but blended model did put in some 20 to 30 pops for
the area during the afternoon and evening. Instability continues
to be weak, so severe storms not expected. Temperatures warm
into the 70s to lower 80s with lows Sunday night in the upper
40s to middle 50s.

On Monday, the main trough ejects across the Rockies and a deep
closed low will develop over the northern Rockies/adjacent
plains by Monday afternoon. Most of the local area appears to
get dry slotted on that track with a fire weather risk should
stronger winds develop. Dry line trailing south across the High
Plains may reside in eastern portions of the area Monday
afternoon. Models show moderate instability along and east of
the dry line with deep layer shear of 50-70 kts, parameters
sufficient for a risk of severe storms including supercells.
Uncertainty at that time range on location of the dry line is
high and will likely fluctuate until the models can settle on a
solution. High temperatures will be mainly in the 70s and lows
in the 40s.

Should be on the dry and breezy side of that system for Tuesday
with highs in the 70s and lows in the 40s. May see another day
of fire weather concerns with afternoon humidity minimums
approaching 15-20% along with the breezier conditions.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 515 PM MDT Tue Apr 30 2024

KGLD...VFR conditions are expected through at least 14z. A
northerly wind around 10kts at taf issuance will veer to the
east overnight with speeds generally below 11kts. On Wednesday,
east-southeast winds slowly increase through the day, gusting up
to 25kts or so. Sub VFR cigs in stratus are possible in the
16z-20z timeframe and if the NAM model is correct, linger
through the rest of the taf period. HRRR/GFS boundary layer
relative humidity show the stratus (marking the location of a
dry line) lifting to the northeast so at this time the late
afternoon forecast of cigs is uncertain. Presently, am not
expecting any precipitation through the period.

KMCK...VFR conditions are expected through about 20z. A
northwest wind gusting up to 25kts at taf issuance will subside
below 10kts by 02z with winds veering to the east at speeds
under 10kts overnight. On Wednesday, easterly winds gusting up
to 25kts are expected. From 20z-24z, sub VFR cigs are expected
in stratus. Will need to watch for a few showers in the vicinity
of the terminal in the 08z-12z timeframe and again after 18z.

&&

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

&&

$$

SHORT TERM...024
LONG TERM...024
AVIATION...99