867
FXUS63 KGLD 021110
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
510 AM MDT Tue Jul 2 2024

.KEY MESSAGES...

- Chance for storms today, mainly along and south of Highway 40.
  There could be a severe storm or two with wind gusts up to 70
  mph.

- Wednesday, there is the potential for a significant severe
  weather day for the area. Storms are forecast to move west to
  east across the area with the potential to produce hail up to
  3 inches, wind gusts up to 75 mph, and a tornado or two. There
  are a few scenarios where storm coverage is instead limited
  and weak.

- Breezy to gusty 4th of July; albeit a bit cooler.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 218 AM MDT Tue Jul 2 2024

Current observations show a few showers in Eastern and Western
portions of the area while an upper trough and low continue to shift
east over the area. Dense fog has also been reported over McCook
with nearby counties seeing slight reductions in visibility. This
patchy fog will likely affect most counties along and north of I-70
with the calm winds and moist air in place. If it weren`t for the
cloud cover, most of the area might already be in dense fog. With
the clouds forecast to linger, fog will remain somewhat limited with
dense fog being patchy. Fog should clear a few hours after sunrise
with increasing temperatures.

For the remainder of today, cloud cover is forecast to slowly burn
off for Eastern portions of the area with partly cloudy skies over
the rest of the area. With the cloud cover and upper trough axis
swinging through the area, cooler temperatures in the 80`s are
forecast. A few storms are possible this afternoon, but would mainly
favor Eastern Colorado and south of Highway 40. The front is
forecast to be well south of the area which will be the focus for
most of the storms today. However, some storms are forecast to move
in from the higher terrain in Colorado, especially if the lower
pressure lingers in East-Central Colorado. This would provide the
area`s primary chance for severe storms with wind gusts up to 70 mph
possible. There is a 15% chance for storms across the rest of the
area north of Highway 40 with high moisture availability, but the
lack of forcing that is forecast would likely keep the rest of the
area clear.

For tonight, most of the area should see partly cloudy skies with
light winds. Along and south of Highway 40 may continue to see
storms develop in similar fashion to the past few nights. As such,
the severe threat should be near zero by midnight. Lows are forecast
to be in the upper 50`s to 60`s. Fog will be possible again,
especially east of Highway 25 with light easterly winds and
relatively moist low level air.

Tomorrow, a more active day is forecast as another trough axis
swings through the Rockies and Northern Plains. Temperatures may be
a few degrees cooler than the prior day with the continued troughing
aloft and possible cloud cover through the day. As the next trough
advances, low pressure is forecast to develop in Eastern Colorado.
With moisture availability forecast to remain fairly high, storms
are forecast to develop in Eastern Colorado and push east across the
area. In most forecast soundings, CAPE is forecast to be above 2000
J/KG, mid level lapse rates around 8 C/KM, and effective shear
around 45-55 kts. These conditions would favor very large hail with
initial storms or supercells with analogs suggesting hail to 3
inches. However, the strong winds higher up, increasing downshear
vectors, and increasing shear would likely favor storms clustering
or becoming linear and moving across the area. With downshear
vectors forecast to reach 55-65 kts and similar winds in the higher
levels of the clouds, winds up to 75 mph are possible. Even that may
be a little underdone and will need to be watched. As for tornadoes,
low level shear and SRH isn`t forecast to be that high, but with the
overall shear in the environment being high and the potential for
both supercells and a line of storms, a tornado or two is possible.
Storms could start as early as 19Z (1pm MT), but the more likely
time period is around 21Z through about 3Z (3pm-9pm MT). There is
some suggestions (namely the Nam 3k and some GEFS ensemble members)
that storms will struggle to maintain themselves as they move east.
This looks to be more likely in scenarios where convection is
ongoing during the day and/or increased cloud cover from prior
storms limits the instability in the environment. In this case,
storm and severe chances would lower quite a bit east of Eastern
Colorado.

Tomorrow night is forecast to be similar to previous nights, where
temperatures largely remain in the 60`s and storm chances /
increased cloud cover remain present over the area due to the high
moisture availability.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 100 AM MDT Tue Jul 2 2024

Thursday...an upper level low pressure area is forecast to move
east-southeast across the northern plains with the flow aloft from
the west-northwest. Guidance continues to advertise a generally dry
day with a 20%-30% chance for thunderstorms during the night across
the southwest 1/2 of the forecast area as a weather system per 700-
500mb relative humidity moves through from the northwest. Otherwise,
we`re looking for breezy north winds during the day as surface high
pressure strengthens from the north. High temperatures are forecast
to be below normal in the upper 70s to middle 80s, spot on with
850mb temperature bias` over the past week or so. Low temperatures
fall into the lower to upper 50s.

Friday...the forecast area is forecast to be under northwest flow
aloft, in between low pressure to our north and east and a
strengthening ridge to our west. Similar to Thursday, it appears per
GFS/ECMWF/GEM 700-500mb relative humidity forecasts that another
weather system skirts the far southwest 1/3-1/4 of the forecast area
during the afternoon and early evening hours, potentially supporting
a 20% chance of thunderstorms. Presently, pops are limited to the
Flagler area. High temperatures are forecast to remain below normal
in the lower to middle 80s, in great agreement with GFS/ECMWF/GEM
850mb temperature bias` from the past week or so. Low temperatures
are forecast to be in the middle 50s to lower 60s.

Saturday...not much change in the general 500mb pattern when
compared to Friday. There is some agreement from the GFS/ECMWF/GEM
models that another weather system will move through the area during
the afternoon through late evening/overnight hours, supporting 20%-
30% chances for showers and thunderstorms. GFS/ECMWF/GEM 850mb
temperatures rise a few degrees, supporting high temperatures in the
upper 80s to lower 90s. Low temperatures are forecast to be in the
middle 50s to lower 60s.

Sunday...500mb pattern remains similar to Friday and Saturday.
GFS/GEM models are in fair agreement bringing another weather system
into western parts of far eastern Colorado during the afternoon,
supporting a 20% chance for thunderstorms. This system continues
moving southeast through the remainder of the forecast area
overnight with 20%-30% chances for thunderstorms. High temperatures
are currently forecast to be in the 85-90 degree range. This could
be a bit warm given GFS/ECMWF/GEM 850mb temperatures supporting
highs about 5F to 7F cooler. Low temperatures fall into the middle
50s to lower 60s.

Monday...the 500mb pattern shows no signs of significant change when
compared to the prior few days. That is also reflected in the
thunderstorm forecast with 20% chances during the typical afternoon
and overnight hours. High temperatures look to be near normal in the
middle 80s to lower 90s with low temperatures in the upper 50s to
lower 60s.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 502 AM MDT Tue Jul 2 2024

For KGLD... VFR conditions are forecast through the period. With
winds out of the north/northwest, am not as concerned with the
possibility for fog or low stratus clouds this morning. There
may be a storm or two that moves in around 21-03Z, but chances
are currently around 10%. Storms are more likely about a county
south of the terminal. Similar to the previous nights, will have
to watch for nocturnal convection and fog, but neither is high
enough confidence at this time. Winds should become light
overnight.

For KMCK... VFR conditions are forecast for most of the period,
though am currently watching for fog/low stratus to develop
around sunrise. After 15Z/16Z, the threat for stratus should
end. During the afternoon and evening hours, there could be a
pop up thunderstorm, but chances are lower than 10%. The next
hazard to keep an eye on will be the potential for fog again
tonight. Will need to see if any storm outflows have an effect
on the fog potential.

&&

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

&&

$$

SHORT TERM...KAK
LONG TERM...99
AVIATION...KAK