454
FXUS63 KGLD 290413
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1013 PM MDT Fri Jun 28 2024

.KEY MESSAGES...

- Scattered thunderstorms will persist across portions of the
  area this evening and overnight. Brief, localized wind gusts
  up to 65 mph cannot be ruled out in association with any storm.

- Cooler this weekend with scattered storms possible during the
  afternoon and evening hours.

- Heat returns Monday with low triple temperatures currently
  forecasted.

&&

.UPDATE...
Issued at 600 PM MDT Fri Jun 28 2024

The Tri-State area remains situated on the northern periphery of
a ridge, in modest W (500 mb) to SW (300 mb) flow aloft. While
the upper level pattern is analogous to yesterday.. the
thermodynamic environment and low-level pattern/flow regime
today is less favorable than yesterday.

23Z SPC mesoanalysis data indicates marginal instability
(~250-500 J/kg mlcape) over northeast CO and northwest KS. A
west-east instability gradient exists over central KS/NE.. with
increasing instability with eastern extent from Highway 283
(roughly along/east of a line from McCook to Hill City).. where
low-level moisture is richer (65-73F surface dewpoints). With
little in the way of synoptic/upper level forcing and very weak
low-level flow, convective development will likely be confined
to topographically/geographically favored areas (e.g. Palmer
Divide, Cheyenne Ridge). While said activity will gradually
progress eastward into northwest KS and southwest NE late this
aft-eve, environmental conditions do not appear particularly
conducive for upscale growth/organization into lines or
clusters.. nor downward momentum transport (weak surface to 700
mb flow). Strong to extreme DCAPE (1500-2000 J/kg) will
certainly support a potential for brief/localized severe
downbursts in association with any convection.

With the above in mind, severe weather potential this aft-eve
appears to be marginal/isolated in nature.. and brief/localized
severe downbursts appear to be the primary hazard.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 243 PM MDT Fri Jun 28 2024

Across the region this afternoon, the area is currently seeing
mainly sunny skies with some scattered diurnal clouds north and
southwest. With the passage of a frontal boundary, there is
currently a northerly flow with gusts up to 20 mph at times. as
of 200 PM MDT, temperatures are ranging in the 90s.

The main wx concerns in the short term will occur with
afternoon/ evening thunderstorms chances, some of which may be
strong to severe.

With a strong elongated 500mb ridge over the southern portion
country, as seen from the latest RAP40 guidance, zonal flow is
in place over the central Plains. There is a weak shortwave
currently over the central Rockies that will shift east through
this evening. This system will ride along the aforementioned
front at the surface, with the potential for triggering
convection. The latest set of CAMs(HRRR, RAP, NamNest) are
showing scattered storms approaching the western CWA by 23z-00z.
Regional radar is showing some initiation occurring over
central Colorado into the Nebraska panhandle.

While some storms could initially be severe, the elevated
nature of the expected clouds bases combined with the hot and
dry conditions at the surface ahead of approaching rw/trw, could
allow for only a wind threat. Soundings are showing this with
decent inverted-v profiles and high dcape 1400-1600j/kg as a
result. Guidance does show this dropping sharply as the evening
progresses with an eastward push of any storms. The latest SPC
outlook does have the much of the CWA still under a Slight Risk
w/ wind as the main threat. While large hail could be possible,
the drier lower levels could melt any hail before it hits the
ground. We are looking for up to 65 mph gusts with these storms.

For Saturday, high pressure pushing into the region from the
north will provide the CWA with a dry and slightly cooler day
initially. The front that was the focus for convection today
moves south of the area near the KS/OK border. Another shortwave
will pass through the upper ridge interacting with the front by
the late afternoon into the evening. The focus for any decent
storm coverage will occur along and north of the front to impact
our area, basically south of Highway 40. SPC has a Marginal
threat for severe in this region, with some guidance showing a
bit further push northward through the day, depending on where
the actual shortwave sets up. Looking for chance north of I-70
at 15-30% should enough instability push north. The main focus
will be south, peaking in the 40-50% range over Greeley/Wichita
counties. CAMs continue scattered precip into the 12z Sunday
timeframe before ending east.

Going into Sunday, the front to the south will lift north as a
warm front into the western CWA. This combined with another
shortwave, will trigger another round of convection, initially
in the west near the front(20-30%), overspreading the area
during the evening(20-40%) and eventually moving east by 12z
Monday. The western CWA is under a Marginal Risk for severe
storms by the afternoon in/near the warm front. With this front,
a return to a southeasterly moist flow will ensue, with PW
values reaching into the 1.4-1.8" range, especially in KS/NE.
Model sounding show decent rainfall potential with very moist
soundings, suggesting a decent rain threat as the activity moves
east in the evening, but hail/wind threats possible in isolated
cells.

For temps, daytime highs this weekend will range in the 80s.
Overnight lows tonight will range widely from the upper 50s west
into the upper 60s east. Weekend lows will range in the upper
50s to lower 60s Saturday night, with mid to upper 60s expected
for Sunday night.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 145 PM MDT Fri Jun 28 2024

Both the latest runs of the GFS and ECMWF continue to upper
level ridging at 500mb stretched across the southern portion of
the country, amplifying some by the end of next week. This will
allow for W/NW flow aloft giving way to SW flow aloft late in
the period. The passage of several shortwaves along the northern
periphery of the ridge will interact with a surface low and
associated front that will meander through the CWA and
eventually settling south of the CWA. Both sets of guidance are
showing a bit different set of areal coverage for rw/trw, but
the overall consensus will be the chance(20- 40%) for late
afternoon precipitation, as the evening hours will promote
higher chances(40-60%) for storms.

As with the past several days, the above normal temps as fueled
dry conditions during the daytime hours, allowing for
sunset/evening convection chances. Can`t rule out some strong to
severe cells to impacts areas, along with some localized heavy
rainfall with PW values 1-1.5" early in the week, with a 1-1.2"
range for the latter portion.

For temps, highs on Monday will range in the upper 90s over
northeast Colorado into the low 100s for locales east of the
Colorado border. For next Tuesday onward, mainly 90s expected
each day, with areas along/west of Highway 27 seeing some mid
and upper 80s mix in, especially for northeast Colorado.

With Monday having much of the region seeing at least 100
degrees, some high heat indices are possible. With the area
being dry for most of the daytime hours, low RH will be present.
Areas along/east of Highway 83, especially Graham and Norton
counties could have enough moisture present to give some
readings in the 100-103 range. West of this, readings will be
at/below forecasted highs. Conditions will be monitored for a
potential Heat Advisory issuance if warranted.

Overnight lows will mainly range in the 60s for most of the
periods, but Monday night could have 70s present for areas
along/east of Highway 83.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1010 PM MDT Fri Jun 28 2024

Aside from a potential for sub-VFR conditions associated with
thunderstorms at both terminals late this evening into tonight
(~06-09Z).. VFR conditions will otherwise prevail through the
TAF period. Aside from gusty/erratic winds invof any
thunderstorms.. winds will remain light/variable this evening
and overnight. Around or shortly after sunrise, winds are
expected to abruptly shift to the N-NNE and increase to 15-25
knots (GLD) or ~12-18 knots (MCK). Northerly winds will veer
toward the northeast and decrease to 7-12 knots by early
afternoon.. remaining light and further veering to the east by
the end of the TAF period.

&&

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

&&

$$

UPDATE...Vincent
SHORT TERM...JN
LONG TERM...JN
AVIATION...Vincent