581
FXUS63 KGLD 040841
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
241 AM MDT Sat May 4 2024

.KEY MESSAGES...

- 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.

&&

.UPDATE...
Issued at 1012 PM MDT Fri May 3 2024

The entire CWA has been cleared from earlier Severe Thunderstorm
Watches. Most of the area is not seeing any precip at this time,
and the remaining eastern zones seeing activity is seeing sub
severe returns on radar. Still could see gusts 40-50 mph in the
remnants as they exit, but severe wx is done for this night.
Have added in Fog for all areas, along with patchy frost in the
NW.

&&

.SHORT TERM /THROUGH SUNDAY 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 /MONDAY THROUGH FRIDAY/...
Issued at 238 AM MDT Sat May 4 2024

For Monday, there are still a lot of potential hazards that are
unclear if they`ll happen as there is still a sizable spread in
500mb low track and surface low setups. Compared to prior forecasts,
there is more consensus on the upper trough swinging more into the
Northern Rockies and Plains. In this scenario, the deeper part of
the low pressure would be well north into the Dakotas, Montana, or
even Southern Canada. With it, the rest of the lower pressure and
potential front would swing through the area during the day Monday
and bring dry air across most of the area. With this, the severe
weather threat would be limited to Highway 83 and east or maybe even
completely out of the area. The main hazard would be the potential
for high winds (namely gusts to 60mph+) as long as the upper low
swings near the area. Blowing dust across the area and critical fire
weather conditions south of I-70 would also be possible with the
strong winds and dry conditions (though the dust could be hampered
by recent moisture).

There are still some scenarios that keep the low closer to the area
with dryline closer to the Colorado border (instead of Central
KS/NE). While scenarios like this now have a 25% chance, it is worth
mentioning that this scenario would bring the same threat for high
winds, but the severe threat would be much greater with all hazards
possible. Critical fire weather would be more limited to parts of
Eastern Colorado and the dust threat would likely decrease as we
would have stratus which would weaken low level lapse rates.

Tuesday, the upper trough is forecasted to spin over the Northern
Rockies and Plains which will keep the area in roughly westerly flow
aloft and relatively low pressure at the surface. The main thing to
watch will be for a potential smaller wave to move around the larger
low and generate lower pressure near the area. That could strengthen
the winds a bit and maybe wrap some more precipitation into the
area, though severe weather looks to be unlikely at this time. A
small disturbance could also weaken/disrupt the height gradients
which would lower the chance for strong/high winds. Temperatures
would likely be similar to Monday in the 70`s. Critical fire
weather conditions would be possible again along and south of
I-70 depending on how dry the air gets during the afternoon.

The rest of the week looks to have troughing or laminar flow above
the area as a cut-off low is forecast to try and split off from the
main flow and shift off to the west coast. This would likely give us
average temperatures in the 60`s and 70`s with daily chances for
precipitation if smaller disturbances move through the flow and
across the area. Hazardous weather looks to be unlikely for this
time period except for the possibility of lows dropping into the mid
to low 30`s if enough cold air advects into the area and little to
no moisture returns.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1045 PM MDT Fri May 3 2024

Both terminals will see MVFR fog/ceilings that are expected to
impact the terminals through at least through 14z-16z, before
going VFR. Winds northerly around 20-30kts, diminishing to
around 10-15kts by 10z, then eventually veering southeast from
21z onward.

&&

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

&&

$$

UPDATE...JN
SHORT TERM...024
LONG TERM...KAK
AVIATION...JN