418
FXUS63 KGLD 031944
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
144 PM MDT Fri May 3 2024

.KEY MESSAGES...

- Thunderstorms will develop along a cold front surging
  southeastward through the area late this afternoon and
  evening. Damaging winds and instances of large hail appear to
  be the primary hazards. Isolated supercells capable of
  producing all hazards may develop in advance of the front,
  south of Highway 40 in CO/KS, between 4-8 pm MDT.

- Fire weather concerns return Monday through Thursday for most
  of the Tri-State area, but favor along and south of I-70.

- Thunderstorms, a few of which may become strong to possibly
  severe, will be possible Monday afternoon/evening.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 130 PM MDT Fri May 3 2024

Not much has changed from previous thinking with two areas of
concern for the remainder of the afternoon and this evening.
Convective initiation has occurred in eastern Colorado near Las
Animas. HRRR shows this activity expanding into northeast
Colorado south of I-70 and northwest Kansas over the next few
hours. Latest analysis and forecast of SBCAPE shows 1500-2000
j/kg available along with effective bulk shear values of 40-50
kts. Those parameters should be sufficient for a few severe
thunderstorms capable of producing large hail, damaging winds
and perhaps a tornado with any discrete supercell. Further
north, initiation has also occurred along the cold front in the
Nebraska panhandle. As the cold front surges south this evening,
convection will increase rapidly into a line capable of
producing damaging wind gusts. Given the same parameters above,
a few embedded cells in the line will also be capable of
producing large hail and a brief tornado. The front will exit
the area by around 06z ending the severe threat, though a few
showers and storms may linger past 06z in southern and eastern
areas. Mean precipitation amounts for the event range from
around a tenth to a quarter of an inch in Colorado, a quarter to
a half inch west of Highway 83, and around a half inch east of
Highway 83. The higher percentiles show locally up to 1 inch
possible in just about the entire area, with up to about 1.5
inches in northeast corner (McCook, Oberlin, Norton) and
southern areas (Tribune, Leoti). Winds will gradually diminish
overnight with low temperatures ranging from the lower 30s in
Colorado to the lower 40s in north central Kansas.

Saturday will be mostly sunny and breezy with just a hint of
shortwave ridging aloft ahead of weak shortwave in southeast
Colorado. High temperatures will be in the lower 60s. Saturday
night now looks dry with the shortwave staying south of the
area. There will be some increase in clouds with low
temperatures in the lower 40s. Models do hint at fog developing
in western portions of the area late Saturday night into Sunday
morning (along the Kansas and Colorado border area and
westward).

Southwest flow aloft continues on Sunday with embedded weak
waves which may result in a few isolated showers and
thunderstorms by Sunday afternoon. There is a very narrow
corridor of weak instability forecast along the Kansas and
Colorado border area with a 100-200 j/kg currently indicated.
So, not expecting any severe storms should any develop. High
temperatures will be in the upper 60s to lower 70s. Shower and
thunderstorm chances increase going into Sunday night with
height falls ahead of the approaching trough and nocturnal low
level jet. MUCAPE increases overnight to 1500-2000 j/kg with
shear values of 40-50kts. So may see elevated thunderstorms late
with a risk for hail, but confidence is low at this time range.
Low temperatures will be in the 50s.

Main trough axis ejects out of the Rockies and across the plains
with a negative tilt on Monday. Surface low will deepen in the
Nebraska panhandle with the dry line trailing south into the
forecast area. The dry line will be the focus for convective
initiation in the afternoon and the models indicating the dry
line will likely be in eastern areas at least for a few hours
before moving east. Timing of initiation will be critical, but
if it happens before the dry line moves out may see a short
window for severe storms along/east of Highway 83. Instability
and shear will be more than adequate for a risk of large hail,
damaging winds and tornadoes. West of the dry line may see few
wraparound high based showers, but no severe threat. However,
afternoon relative humidity values will be dropping to near
critical or critical values and wind speeds also appear to meet
critical thresholds for fire weather concerns. Precipitation
should be east of the area Monday night. High temperatures will
range from the upper 60s in Colorado to the upper 70s in north
central Kansas and lows Monday night in the upper 30s to lower
40s.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
Issued at 243 AM MDT Fri May 3 2024

For the long term period, active weather is possible Monday
with generally average temperatures and daily precipitation
chances through the week.

Sunday is forecast to have an upper low/trough push into the
Western CONUS and move towards the Four Corners region.
Meanwhile, moisture is forecast to stream in from the south near
the surface as a surface low develops along the Front Range
while additional moisture moves in over the mountains. This
could lead to a fairly cloudy day where temperatures will cap in
the 60`s, though any area with sun for a couple of hours should
reach the 70`s, especially near and west of the Colorado
border. Showers and a few storms could develop with all the
moisture in the area, but the severe threat should be near zero
with instability still forecast to be fairly low with MUCAPE
generally near or less than 500 J/KG.

Sunday night through Monday is when conditions are forecast to
get more interesting as the upper low moves near and over the
area along with the surface low. One the first things to watch
will be the winds. With the speed of the upper trough and how
deep it could get, the pressure gradient and height gradients
could get fairly strong and allow winds to exceed 30 mph and
gusts exceed 55 mph starting as soon as Sunday evening. However,
confidence is currently only around 40% as ensembles show a
fairly high spread in 500mb tracks and progression. This in turn
also affects the surface low and it`s progression. One of the
main things that could keep the winds on the lower side is that
some of the ensembles are pulling the trough north. This would
shift the stronger gradients more towards Nebraska and the
Dakotas. Our winds would still strengthen above 20 mph with
gusts above 35 mph, but high wind criteria warnings would become
unlikely. The chances for the high winds then increase the
further south the track of the main surface low goes (farthest
south looks to be around the Southern KS border). In either
scenario, low temperatures Sunday night will likely stay in the
50`s with the moisture, cloud cover, and increased winds over
the area.

For Monday, conditions are fairly variable given the surface
low has solutions with tracks that go through the area during
the day or hug the KS/CO border along with tracks that are north
of the area and south of the area (I am referring to the
deepest part of the surface low). In scenarios where the low
moves through the area and is to the east during the day,
moisture would lower across the area, increasing critical fire
weather chances and lowering storm and severe storm potential.
In solutions where the low and front stay over or near the area,
critical fire weather conditions become less likely while storm
and severe storm chances increase. Winds approaching high wind
warning criteria become more likely as well. Would could be of
particular concern is if the low is south of the area and the
warm front is draped across the area. We then begin to face
scenarios similar to recent events with a warm front and a
dryline/cold front acting as storm genesis points. High
temperatures are forecast to be in the 60`s behind the system
and in the 70`s and maybe low 80`s ahead of the system. Monday
night remains just as varied with conditions ranging from
calming and dry, to stormy with high winds. Currently, don`t
have a good inclination towards any one scenario so have gone
with a more neutral forecast and am waiting for better consensus
in guidance and maybe better sampling of the system (since it
is still offshore).

Tuesday and Wednesday look to be more "average day" with near
average temperatures in the 60`s and 70`s and some small chances
for precipitation as the upper pattern is forecast to turn more
to a broad trough with the initial disturbance pushing east
while the trough as a whole spins over the Northern Plains. Will
need to watch for critical conditions south of I-70 with the
drier air over the area dropping RH into the teens.

For the end of the work week, currently forecasting near
average conditions in a broad trough pattern. Guidance is split
on whether the upper trough just pushes off to the east or if a
small low splits off and retrogrades west. In either case, there
is the possibility of another front if the trough is strong
enough as it pushes off to the east, though there may not be
much moisture available for storms to work with.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1118 AM MDT Fri May 3 2024

VFR expected to prevail at both KGLD and KMCK through this
afternoon. Isolated storms may develop in northwest Kansas late
this afternoon, but probability of directly impacting the
terminal is low. Tonight, a strong cold front will move through
both terminals between 02-04z. The front will be accompanied by
thunderstorms and strong surface winds shifting to the north.
Some visibility restrictions due to blowing dust will be
possible along and immediately behind the front. Storms will
continue south during the late evening with surface winds
gradually diminishing through the overnight.

&&

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

&&

$$

SHORT TERM...024
LONG TERM...KAK
AVIATION...024