939
FXUS63 KGLD 300800
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
200 AM MDT Sun Jun 30 2024

.KEY MESSAGES...

- Low confidence with regard to thunderstorm development
  tonight and Sunday night.

- Much cooler highs Sunday due to cloud cover all day.

- Hot weather returns Monday behind a warm front. However highs
  are not as hot.

- Chances for storms each day, mainly during the evening.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 216 PM MDT Sat Jun 29 2024

Latest upper air analysis shows nearly zonal flow over the
central Plains. Pockets of higher water vapor were moving
through this flow, leading to cloud cover. At the surface winds
were breezy from the northeast. A surface high pressure was
located over Wyoming.

For the rest of the afternoon the surface high pressure will
slide southeast across Nebraska, causing the winds to turn to
the southeast. As the high pressure approaches winds will
decline.

This evening a weaker upper level short wave trough will move
over the forecast area from the west. The latest model runs have
slightly delayed the arrival of the upper level short wave
trough. (This is in line with the delayed trend in storm arrival
of the last few days.)

Models are now keeping the cold front well south of the
forecast area during the night. However the low level jet will
strength over the front and into the forecast area. This will
provide low level moisture advection ahead of the approaching
upper level short wave trough. Both the NAM and RAP models are
suggesting elevated instability will be present with in this
part of the forecast area. In addition there does look to be a
weak LLJ nose over the southern part of the forecast area. Am
thinking scattered storms should form ahead of the approaching
upper level short wave trough around midnight, then gradually
spread east-northeast ahead of the short wave trough. Storms
will be moving around 15 MPH, which may lead to heavy rainfall
given the precipitable water values of over an inch in that part
of the forecast area. The storm activity may last well into
Sunday morning.

At this time confidence for severe weather occurring over the
southern part of the forecast area is low (30%). This is due to
the midlevel lapse rates being around 6C/km and deep layer shear
being 25-30kts. Strong thunderstorms seem more likely in this
environment. If severe thunderstorms were to form, quarter size
hail would be the main threat. The highest elevated instability
will be around midnight. This threat area may shift north or
south, however the latest model run has shifted the elevated
instability south.

Meanwhile the continued moisture advection from the LLJ will
bring in low clouds from the south. These will start from the
CO/KS border then gradually expand eastward through the
overnight hours. The surface high over Nebraska will also aid in
advecting moisture over the forecast area.

Sunday morning the upper level short wave trough will continue
to move across the southeast part of the forecast area. Elevated
instability will continue to decline. Storm activity should be
east of Graham County by noon, if not before.

Sunday afternoon an upper level short wave ridge will move in
from the west. By this time the surface high pressure will be
Central Nebraska into Central Kansas. Moisture advection will
continue. Soundings show atleast a broken, if not overcast cloud
deck over the forecast area through the day. The exception will
be East Central CO where the moisture advection will be less,
allowing the clouds to break up during the afternoon. Lowered
highs a few more degrees for the afternoon, mainly east of CO.
The 25th percentile high temperature forecast is in the low/mid
70s for this part of the forecast area. Based on this the
current forecast seems representative.

Sunday night another upper level short wave trough will move in
from the west. By this time the ridge has shifted more to the
west, pushing the upper level flow slightly more to the north.
During the evening there may be some low level convergence from
the LLJ over the northwest part of the forecast area as the
short wave trough moves through. This convergence then shifts to
the northern part of the forecast area, moving with the upper
level short wave trough. Models show deep layer shear of 40 kts
and midlevel lapse rates around 7C/km. The current data supports
the potential for storms to become severe given the elevated
instability could occur. However, the elevated instability is
highly dependent on how warm will 800- 700mb layer be and how
high will the dew points be in that layer. The HREF has not
strong storms in the forecast area at this point. For now this
bears watching as strong to severe elevated thunderstorms could
occur. However confidence is low (20%) for them to occur given
how much could change with the small details regarding the low
level temperature and moisture advection.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 200 AM MDT Sun Jun 30 2024

Tuesday...the forecast area will be in between an upper level trough
moving through the area with an upper level ridge centered over the
southeast United States. Moisture, mainly in the 700-300mb layer
will move across the area from the southwest during the day then
west-southwest during the night. PWAT values of 1-1.7" during the
day slowly decrease into the 0.9-1.3" range overnight. It appears
we`ll have just a 20% chance for thunderstorms across parts of far
eastern Colorado in the afternoon with a 30%-50% chance overnight.
High temperatures are forecast to be in the middle 80s to lower 90s
with low temperatures in the upper 50s to middle 60s.

Wednesday...there is fairly good agreement between the GFS/ECMWF/GEM
models in bringing a weather system through the area from the west
during the typical mid to late afternoon hours through much of the
overnight hours. Presently, we have 20%-30% chances for afternoon
thunderstorms, peaking in the 30%-50% range during the evening
before decreasing from west to east. With evening GFS PWAT values of
0.70-1.0" and storm motions of 25 to 30 mph, the threat for
excessive rainfall should be rather low. High temperatures are
forecast to be in the middle 80s to lower 90s with low temperatures
in the middle 50s to middle 60s.

Thursday...an upper level low pressure area is forecast to move east-
southeast across the northern and central plains with the flow aloft
from the west-northwest. It appears that we`ll have a weather system
move through during the overnight hours from the northwest with 30%-
40% chances for thunderstorms. GFS PWAT values arent terribly high
in the 0.8-1.1" range with storm motions generally around 25 to 30
mph. High temperatures are forecast to be in the middle 80s to lower
90s with low temperatures in the middle 50s to lower 60s.

Friday...the forecast area should be under northwest flow aloft with
some ridging moving on to the west coast. Although we currently have
20% chances for thunderstorms across the entire area during the
night, the better chance of that could be across the southwest 1/3-
1/2 of the area as weather systems move off the Colorado front
range, moving toward the southeast. With PWAT values around 0.80"
across the entire area, only light amounts of rainfall are possible.
GFS/ECMWF/GEM 850mb temperatures support high temperatures in the
upper 70s to middle 80s. Low temperatures are forecast to be in the
55 to 60 degree range.

Saturday...currently, we have a 20% chance for overnight
thunderstorms. High temperatures are currently forecast to be in the
85 to 90 degree range with low temperatures in the middle 50s to
middle 60s.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 945 PM MDT Sat Jun 29 2024

GLD: VFR conditions will prevail this evening/overnight. MVFR
ceilings are anticipated to rapidly develop around or shortly
after sunrise (~12-14Z). Deterioration to IFR is expected
thereafter, during the mid-late morning. While some improvement
to MVFR is expected during the afternoon, ceilings will likely
deteriorate to IFR-LIFR around or shortly after sunset Sunday
evening, near the end of the TAF period. Easterly winds at
7-13 knots (this evening) will gradually veer to the SE
(overnight) and SSE (Sunday morning).. increasing to 15-25 knots
during the day.

MCK: VFR conditions will prevail this evening/overnight.. and
through much (or all) of Sunday morning. Borderline VFR-MVFR
ceilings (~2500-3500 ft AGL) are anticipated to develop by early
afternoon (~16-19Z) and persist throughout the day. Ceilings
will likely deteriorate to low-end MVFR or IFR a few hours
after sunset Sunday evening, near the end of the TAF period.
Easterly winds at 6-12 knots (this evening) will gradually veer
to the SE (overnight) and SSE (Sunday afternoon).. increasing
to 15-20 knots by mid-late afternoon.

&&

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

&&

$$

SHORT TERM...Trigg
LONG TERM...99
AVIATION...BV