990
FXUS63 KGLD 221605
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1005 AM MDT Tue Apr 22 2025

.KEY MESSAGES...

- Shower/thunderstorm chances increase across the area increase
  Tuesday night through next Monday.

- Strong to severe storms are possible this afternoon and
  evening mainly along and west of Highway 25; additional strong
  to severe storms are possible Tuesday night into Wednesday
  morning.

- Potential for more storms Wednesday along with heavy rainfall
  potential as well. There are quite a few failure modes for
  severe Wednesday which lowers confidence some.

&&

.UPDATE...
Issued at 1227 AM MDT Tue Apr 22 2025

Weak 500 mb shortwaves continue to traverse off of the Rockies this
evening and do think this will continue overnight with mainly virga
and perhaps some sprinkles as we continue to deal with dry low
levels. A wind shift boundary has stalled out across the area draped
from SW Norton county and arc back into SE Cheyenne (CO). This
boundary is forecast to slowly continue to move southeast of the
area by the mid morning hours Tuesday which will be a focus for
convection to the south and east of the CWA. There is however still
around a 5% chance that this boundary will remain stationary or
retrograde back north which will lead to afternoon storms across the
southeast portion of the area.

Onto Tuesday, a surface low is forecast to develop during the
afternoon hours across SE Colorado/SW Kansas which is forecast to
help bring moisture into eastern portions of the forecast area. As
this low develops a surface convergence boundary looks to be a
resultant feature of it across NC Colorado where some high
based showers/storms/virga would be favored to form and move
towards the northwest portion of the area around the 22z-02Z
time frame. Confidence is increasing in this occurring with
mainly strong to potentially damaging winds up to 60 mph with
inverted v soundings and 50 knot Corfidi downshear vectors
around 45-50 knots. After 03Z another shortwave is forecast to
move across the area and interact with a developing 700mb jet
and 850mb jet. 700-500mb moisture is forecast to increase as
well with the most aggressive being the NAM. I`m trending the
forecast towards the NAM as most other guidance other than the
typical drier bias RAP and HRRR are showing increasing dew
points into at least the low 50s into eastern Colorado. As all
of this interacts shower and storm chances are forecast to
increase. With the moisture advection MUCAPE is forecast to
increase along with increasing wind shear as well. Some isolated
severe storms are possible Tuesday night into the morning hours
on Wednesday with MUCAPE ranging from 1500-2000 j/kg and wind
shear around 40 knots. With EBWD forecast around around 40-45
knots, steep lapse rates of 7.5-8.5C/km think any strong to
severe threat may extend as far west as the Kansas Highway 25
area with higher chances the further east you go based on the
orientation of the 700mb and 850mb jet. Based on the forecast
soundings parameters think hail around ping pong ball size would
be the primary hazard followed by wind gusts around 60 mph. At
this time confidence in severe weather is around 5-10 percent.

Another potentially active day may be in store for Wednesday.
Guidance is all over the place with the coverage and duration of the
Wednesday morning convection which will end up playing a role in the
amount of instability in place across the area and if any outflow
boundaries would interfere or even enhance the potential
environment across the area. The area of precipitation if it
persists long enough may create a pseudo warm front with warmer
temperatures to the south and rain cooled air to the north. The
RAP is the most aggressive with instability as low to mid 60
dewpoints move into the area leading to 3000-4000 j/kg of
MUCAPE, if this is the case then hail would be the main threat.
The RAP also supports an increasing low level jet across SW
Kansas with the CWA being on the leading nose of this feature
with continued lift ongoing along a potentially stalled out
boundary. This and increasing PWATS to over an inch and slower
storm motions around 10-20 knots would lead to some concern for
backbuilding and training of storms potentially leading to some
hydro concerns. At this time, thinking that nuisance flooding
confined to typical flood prone areas and city streets is most
likely, but if the training does come to fruition then some more
impactful flooding may be realized. Confidence in nuisance
flooding is around 40-50% and more impactful flooding is around
5-10%. This stalled out boundary as well also does lead to some
concern for a tornado threat as well (if all of this does come
together) as all guidance favors 250-350 0-3 SRH which could be
come maximized if a storm could latch onto the boundary. There
is also a scenario where outflow from the early day storms
could undercut and stabilize the atmosphere and potentially
eliminate any severe threat. The potential is there for more
impactful severe weather day but confidence in severe weather
occurring at this time is 10-15% but may increase as the
mesoscale features get worked out. In summary, the next couple
of days do appear to be rather mesoscale heavy scenarios that
more than likely will change so continue to stay up to date with
the latest forecast.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 150 PM MDT Mon Apr 21 2025

Tonight...there will be a 20%-30% chance of showers and possible
thunderstorms through about midnight for locations along and north
of a line from Kit Carson to Goodland and McCook as enough moisture
in the 700-500mb layer and some weak instability move across the
area on the tail end of a weather system to our north. The primary
hazard is wind gusts up to 55 mph given favorable DCAPE. Low
temperatures are forecast to be in the middle 30s to middle 40s.

Tuesday-Tuesday night...another weather system moves into Yuma
county to Flagler by late afternoon, supporting a 20%-30% chance for
showers and thunderstorms. As this system continues across the
remainder of the area overnight, precipitation chances increase a
bit into the 40% range. High temperatures are forecast to be in the
70s with low temperatures in the upper 30s to upper 40s.

Wednesday-Wednesday night...the forecast is currently calling for a
40%-80% chance of showers and thunderstorms during the day. Similar
to yesterday, I`m thinking the pops are a bit on the high side,
especially during the day. Current thinking is that Tuesday nights
system should exit the area in the morning, leaving us in a lull
until the afternoon when moisture below 700mb moves in from the
south and 700-500mb moisture arrives from the southwest, associated
with another weather system. High temperatures are currently
forecast to be in the lower to middle 70s. If clearing develops
earlier and lasts longer, high temperatures will be a few degrees
higher. If the clouds and precip last longer, temperatures will be a
bit cooler.

Overnight, shower and thunderstorm chances increase into the 70%-90%
range as low level moisture lifts northward while the above
mentioned weather system moves across from the southwest.
Precipitable water values range from 0.70 to 1.10 inches (highest
east of Highway 83) with 0-5km wind speeds around 15 to 20 mph.

Thursday-Thursday night...it appears that based on the NAM/GFS
models, a mid level dry slot is over the area during the day while
below 700mb, there is quite a bit of moisture. I dont think it
supports the 50%-80% chances for showers and thunderstorms currently
in the forecast, not to mention the relatively low qpf forecast
numbers. High temperatures are forecast to be in the lower 60s to
lower 70s. Overnight, there is plenty of moisture below 700mb while
a dry slot persists in the 700-500mb layer. Shower and thunderstorm
chances are at 60%-80%, possibly on the high side given somewhat
unfavorable deep moisture and slightly less precipitable water. Low
temperatures are forecast to be in the middle 30s to middle 40s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Issued at 137 PM MDT Mon Apr 21 2025

For the main weather concerns in the extended period, the latest
runs of the GFS/ECMWF continue to show chances for showers/
thunderstorms, especially going into the upcoming weekend.

Friday/Friday night...both 12z guidance runs show an amplified 500mb
ridge traversing the central Plains through the day. High pressure
at the surface works in tandem allowing for a transition of
northerly flow to start the day, to southeast by 00z Saturday. As
the winds shift more easterly through the day, the CWA will see
increased, upslope moisture and a 20-30% chance for showers. From
00z-12z Saturday, approaching shortwave trough/lee-side low will
funnel increased moisture into the region on S/SE flow. There will
be an increase in instability allowing for a 30-60% chance in precip
overnight. Highest chances along/west of Highway 27 for both showers
and storms.

Saturday/Saturday night...the shortwave/lee-side trough will make a
slow push east off the Front Range over the 24-hour period. Guidance
is mixed as to the extent eastward of this due to the blocking Sfc-
500mb ridge east of the area. This will result in a persistent S/SE
flow over the area through the day, providing ample low level
moisture into the region, with PW values ranging 0.80-1.00" mainly
east of the Colorado border. There is a weak shortwave working into
the upper ridge late in the day, which will help to enhance precip
chances going into the evening hours. A general 40-50% chance during
the day gives way to a 40-70% chance from west to east in the
evening, best chances east of Highway 25. These chances include
showers and thunderstorms, some of which may produce locally heavy
rainfall.

Sunday/Sunday night...the surface trough/front now lingers/extends
over the region for this 24 hour period. Both the GFS/ECMWF low QPF
potential during this time, but with the system lingering over the
region, the NBM does carry at least a 30-40% chance for rw/trw for the
afternoon/evening along the front to the east. This looks more
reasonable compared the the GFS/ECMWF where the front is
positioned. The only caveat will be drier air working in from the SW
that may help to cut back on moisture chances.

Monday/Monday night...a low forms along the aforementioned boundary
and retrogrades a bit west during the day in advance of a 500mb
shortwave that guidance brings across the north central Plains late
in the day into the evening hours. The GFS shows more increased
moisture potential compared the the ECMWF, which wraps in drier air
ahead of the upper system. While the GFS swings through the region
as an open wave, the ECMWF is a slower closed upper low that has
more potential for wrap around moisture towards 12z Tuesday.

For temps, looking for highs on Friday to range from the mid 50s
west into the lower to mid 60s mainly east of the Colorado border.
Going into the upcoming weekend, mid 60s east to around 70F in the
west for Saturday will give way to mid 70s through the lower 80s
Sunday w/ warmest areas south of the Interstate. And for next
Monday, 70s are expected w/ warmest spots along/east of a line from
McCook, NE southwest to Sharon Springs, Kansas.

Overnight lows will range in the lower to mid 40s Friday night, mid
40s to lower 50s Saturday night. By Sunday night, trending colder
from west to east w/ lows Sunday night in the lower to mid 40s
along/west of Highway 27. East of there, upper 40s to mid 50s. And
for next Monday night, upper 30s to low 40s in Colorado. East of the
Colorado border, mainly 40s expected w/ some locales east of Highway
83 around 50F.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1005 AM MDT Tue Apr 22 2025

KGLD...VFR conditions are currently anticipated through the taf
period. An east to northeast wind up to 11kts is expected
through the taf period. Will be watching for the potential of
sub VFR cigs (if the NAM model is correct) after about 12z.
There is a possibility of a shower or thunderstorm in the area
from early this evening through about 09z but given the overall
lack of coverage and confidence there wont be a mention in the
taf forecast.

KMCK...VFR conditions are currently anticipated through the taf
period. Winds through the period will be from the northeast to
east at speeds up to 11kts. Similar to KGLD, will be watching
for the potential of sub VFR cigs (per NAM model) after about
15z. There is a possibility of a shower or thunderstorm in the
area from around 03z-09z then again after 15z. Given low
confidence and overall lack of coverage, there will not be a
mention in the taf forecast at this time.

&&

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

&&

$$

UPDATE...Trigg
SHORT TERM...99
LONG TERM...JN
AVIATION...99