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000
FXUS63 KGLD 250746
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
146 AM MDT Thu Apr 25 2024

.KEY MESSAGES...

- Significant severe weather is possible Thursday for most of
  the area with the main threats being tornadoes and very large
  hail. The threat is conditional as a cap could prevent storms
  from forming.

- A Fire Weather Watch and Red Flag Warning is in effect
  Thursday south of I-70 and west of Highway 25 for low humidity
  and strong winds.

- Blowing dust is also possible Thursday afternoon for near and
  south of the I-70 corridor.

&&

.UPDATE...
Issued at 722 PM MDT Wed Apr 24 2024

Confidence is increasing in overnight convection affecting
portions of the east and northeast counties. RAP soundings
indicate an increasing environment for strong to marginally
severe hail occurring with MUCAPE around 1400 j/kg, effective
shear of 40-45 knots, EBWD shear in excess of 40 knots and lapse
rates of around 8 C/km which should bring about the potential
for hail around quarter size. PWATS are also in excess of 1 inch
which would support a very heavy rain threat as well. Would be
surprised if flooding becomes a concern due to the antecedent
dry conditions along with fast storm motion. However if
backbuilding does become an issue than may need to watch this
more closely.

Confidence also does continue to increase in the potential for a
significant severe weather event Thursday afternoon. Virtual all
CAMS are now convecting along the dry line during the afternoon
hours which is quite the change vs what was seen last night
where everything was capped. It appears that the reasoning for
this is due to the low stratus being favored a bit further north
and east. A slight concern I do have is regarding upper level
cirrus potential as RH values in the 400-200mb level do show
around 30% RH values during the afternoon hours and signals of
cirrus is also seen in RAP soundings. If this is the case this
may be one of the many factors that may limit convective
initation or sustained of any updrafts. Others are if the CAP
is to strong and any potential impact that any outflow from
overnight/morning convection may have; especially regarding the
tornado potential. Despite all the continued uncertainties that
do continue to shadow this event, the potential is there for a
few intense supercells with very large hail and perhaps a
significant tornado threat as 0-3 SRH values are around 200-225
and 0-1 SRH around 100 and does steadily increase into the later
afternoon and early evening hours.


Regarding location for tomorrow; have been noticing a slight
westward trend with where guidance wants to place the dry line.
Similar signs were seen with last week`s severe event where the
NAM was the relatively most accurate with the location of the
dry line and other guidance were playing catchup. I feel the
same thing is again applying in this scenario as well. Reasoning
for this may be due to the undoing of soil moisture across the
area; yes we have been dry lately but the area is coming off of
a wetter past year; SPORT soil moisture also does support this
theory as soil moisture has slightly improved over the past
week. Overall current expectations is that the dry line does end
up developing a bit further west perhaps around the Highway 27
corridor, creating a slightly larger warm sector.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 248 PM MDT Wed Apr 24 2024

Tonight, the 850 mb LLJ will strengthen and shove more moisture into
the CWA. At the surface, easterly winds will cause upslope flow,
leading to stratus and patchy to locally dense fog. This fog may
begin around 10Z and potentially last until 18Z. The stratus will
linger around longer than the fog and potentially cap the severe
environment tomorrow afternoon/evening.

Also tonight, a shortwave looks to fire off a few showers and storms
around 7Z. Small hail and some gusty winds are possible (5% chance),
but confidence for severe weather is less than 2%. These showers
and storms are expected to form near the eastern Colorado border and
move east. The precipitation will exit the CWA in the late morning.
If these showers and storms linger and are fairly strong, this
precipitation could deplete the environment of ingredients for the
later storms.

After 18Z, southerly winds will pick up with gusts up to 35 kts in
the southerly portions of the CWA. Depending on where the dryline
sets up, locales to the west will be much more dry. RH values to the
west of the dryline will drop into the lower teens. This will create
critical fire weather conditions for locations south of I-70 and
west of Highway 25. Most locations will only briefly see the
critical conditions, but there is high (80%) confidence that Greeley
county will see prolonged critical conditions. If the dryline stalls
out farther to the east and north, surrounding counties will have a
good shot at hitting Red Flag Warning criteria, hence why the Fire
Weather Watch has been left in place.

Blowing dust will also be possible (~20-50% chance) in locations
along and south of Highway 36. Along the Kansas Colorado border will
see the best conditions for blowing dust. Visibility reductions down
to 2-3 miles are possible in plumes of blowing dust. Brown-out
conditions cannot be ruled out.

The dryline will be the trigger for the severe weather in the
eventing. SPC has added an Enhanced risk to the southeastern CWA for
Thursday afternoon-night. This is based on a hatched/significant
hazard for 30% chance of hail and 10% chance of tornado. For this
event, the environment will be highly primed for tornado and hail
hazards, but there will likely (60%) be a hefty inversion that will
work to cap the updraft potential. If the cap does break, isolated
discrete to clusters of severe storms will form and all hazards will
be possible, with a focus on tornadoes and hail. The entire Tri-
State area will have potential to see severe weather, but chances
increase farther to the southeast.

Storms are expected to start firing around 18-21Z with the highlight
of the severe storms being 21Z-06Z. The prime location for the
severe storms will be in the southeastern CWA and the storms will
move to the northeast. After 06Z, the severe weather threat will
lower over the following 6 hours. During this time, we will begin to
get the wrap-around precipitation from the northwest. These are
expected to just be showers with a few weak thunderstorms embedded
within. Less than 0.5 inches of QPF is expected with this system
with most of that falling north of highway 36.


As the low pressure system leaves the area on Friday, strong
northwesterly winds are expected to follow. Gusts up to 40 kts are
already expected due to the pressure rises.

Temperatures overnight tonight and tomorrow night will cool to
around 50. High temperatures tomorrow will be highly dependent on
the dryline location and extent of the stratus. Under the stratus,
highs will only reach the upper 60s to lower 70s. In the southwest,
behind the dryline, low to mid 80s are forecast. Friday will be a
bit more uniform with the northwestern CWA only warming into the mid
60s and the southern CWA reaching into the mid to upper 70s.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 144 AM MDT Thu Apr 25 2024

From the latest runs of the GFS and ECMWF, several rounds of
precipitation look to impact the region in the extended period.

For the upcoming weekend, a cutoff slow-moving 500mb low works off
the central Rockies on Saturday. With an amplified ridge over the
eastern portion of the country, this system is expected to make a
N/NE trek from western Kansas then lift into southwest Nebraska for
late Saturday night into Sunday.

At the surface, low pressure moves into southwest Kansas ahead of
the upper low, with a frontal boundary extending northeastward
towards eastern KS/NE. This low does kick a bit faster eastward than
the upper support. This will allow for an easterly upslope flow to
shift northerly as the low passes.

The result of this surface low/front moving through the area,
combined with upper level support, will be chances for showers and
thunderstorms to occur. Based on the surface low track from both the
GFS/ECMWF, highest pops/QPF chances favor locales along/north of I-
70 as 80-90% chance for precip will occur, tapering to a 40-60%
chance south of the Interstate.

QPF numbers are widely ranging over this event, from 0.20-0.30" east
and south, to 0.70-1.30" in northern/western locales. These higher
numbers are aided by the upslope easterly early on. The bulk of the
QPF will occur Sat/Sat night. With PW values approaching 0.80-1.00"
especially for N/NE zones, hydro concerns could crop up. This will
be on top of what areas have already received rain from Thu-Thu
night.

Looking for the surface gradient Saturday night into Sunday to
increase/tighten with gust potential into the 30-40 mph range before
tapering late Sunday.

Going into next week, zonal flow aloft expected through midweek with
some amplification late Wednesday into Thursday. There will be a
couple weak shortwaves riding through the zonal flow that will help
to trigger a few rw/trw especially in the Wed/Thu timeframe. Surface
low/front across KS during this time will focus moisture/instability
mainly east of the CWA, but eastern zones could see 15-20% chance
for convection. ECMWF/GFS do differ on this as strong ridging aloft
does occur late for the ECMWF, so will stay close to the latest NBM
for precip potential. At most, above normal temperatures are
expected as 850 mb temps will range in +14c to +19c range but will
be highly dependent on cloud cover especially towards the midweek
timeframe.

For temps, going into the upcoming weekend, with a frontal boundary
over southern portions of the area Saturday a wide range in daytime
highs is expected with upper 50s to mid 60s west and upper 60s to
the upper 70s east. Warmest areas will be in the extreme E/SE
portions of the CWA. On Sunday, cooler with mid 50s to lower 60s
expected.

Going into next week, another warmup begins with highs on Monday
reaching into the 70s, upper 70s to mid 80s for Tuesday and
Wednesday, peaking Thursday with 80s area-wide.

Overnight lows Saturday night will range from the mid 30s west into
the mid 40s east. Sunday night, mid to upper 30s expected. Next
week, overnight lows will range mainly in the 40s Monday and Tuesday
nights, trending warmer for Wednesday and Thursday nights with a
range from the upper 40s to mid 50s.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1033 PM MDT Wed Apr 24 2024

Moisture return is ongoing across the Plains. Ceilings are
forecasted to gradually drop over the next few hours as IFR to
LIFR conditions continue to remain likely; some patchy dense fog
remains possible throughout the night but am anticipating
stratus will be the primary reduction in flight category.
Showers and storms remain forecasted at KMCK tonight as well
starting around 07Z with a low chance that will become severe
with large hail and torrential rainfall the primary hazard. LLWS
is also occurring at each terminal as the low level jet aids in
the moisture return.

Stratus looks to remain at each terminal for most if not all of
the day with the exception being KGLD where a dry line will help
erode clouds. The other story will be the severe thunderstorm
potential with the relative higher confidence at this time that
KMCK will be impacted. All hazards of severe weather will be
possible.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Fire Weather Watch from noon MDT /1 PM CDT/ today through this
     evening for KSZ013-027-028-042.
     Red Flag Warning from noon today to 8 PM MDT this evening for
     KSZ041.
CO...Fire Weather Watch from noon MDT today through this evening
     for COZ253-254.
NE...None.

&&

$$

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