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000
FXUS63 KGLD 251102
AFDGLD

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

.KEY MESSAGES...

- Significant severe weather remains forecast for today
  (Thursday) with very large hail (1" - 3"+) and tornadoes
  (including the possibility of long-lived or significant
  tornadoes) as the main threats. The severe weather is forecast
  to impact the area during the afternoon and evening hours.
  There is a 20% chance that a cap or a different environmental
  factor will prevent severe weather.

- A Red Flag Warning is in effect Thursday for Kit Carson,
  Cheyenne [CO], Wallace, and Greeley counties during the
  afternoon and early evening hours.

- Blowing dust chances have lowered, but could still see hazy
  skies and some degraded air quality this afternoon.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 346 AM MDT Thu Apr 25 2024

Active and potentially dangerous weather remains forecast for today.
As an upper trough swings into the Four Corners region, a low
pressure system remains forecast to move into the Western portion of
the Tri-State area by the early evening hours. Accompanying the
system will be a dryline that will have multiple impacts on the
conditions for the day. First the dryline is forecast to move in
from East Central Colorado and the low stratus clouds as it
advances. Areas that clear by the early afternoon hours would be
able to warm into the 80`s with 850mb temperatures generally around
25C. With the warm temperatures and dry air, relative humidity is
forecast to lower into the low teens (single digits could also be
possible). With winds increasing with the system, critical fire
weather conditions are forecast to develop as the dryline advances.
The consensus is that Cheyenne and Kit Carson counties would dry out
potentially around noon and remain dry through the early evening (if
the dryline goes as forecast). This would provide multiple hours of
critical conditions and have issued a Red Flag Warning for these
counties. Have also added Wallace county and kept Greeley county in
the Red Flag Warning as the dryline is forecast to impact them
during the early afternoon and hours and linger for a few hours. As
long as storms don`t form until later in the afternoon, critical
conditions should be met for 3 hours before the environment is
modified.

The biggest impact and threat from this system is the severe weather
potential. Storms are forecast to form around the mid afternoon
hours along the dryline and warm front across the area and move to
the northeast. The severe window is from 2pm MT / 3pm CT until 12am
MT / 1am CT with the 2pm-9pm window being the prime window for the
severe storms. The initation point will depend on where the dryline
and warm front are in the early afternoon, but the current consensus
is along Highway 27 and Highway 36. One of the biggest changes is
that cloud cover is forecast to clear earlier which will erode the
cap according to most guidance. This could cause any initial storms
to be lower end severe storms with all instability quickly utilized
and lower shear with winds generally uni-direction from the south.
However, as these storms move off to the northeast, they are
forecast to move into a more moist environment, with a weakened cap
in place, and much higher shear as near surface winds would be more
from the southeast. When storms move into this environment, the risk
for significant hail and tornadoes will increase and currently
favors counties along Highway 25 and Highway 83. Counties further
east will also have a good chance for the significant severe weather
unless the cap strengthens through the day and is too strong. With
the hail, hail is still forecast to exceed 2 inches with 3 to 4
inches possible if a strong supercell develops. Multiple tornadoes
will be possible with 0-1km shear around 30-40 kts and SRH around
200-500 m^2/s^2. Given that these parameters extend across most of
the eastern half of the area, long lived tornadoes could be possible
depending on how the CIN and any prior outflows modify storms.

There are some considerations for the severe weather. As alluded to
already, there is the possibility of a cap setting up and inhibiting
storms. However, chances have lowered with the faster cloud cover
clearing, allowing the cap to mix out. If outflows from earlier
storms move through the area, there is a chance they could try to
initiate storms earlier which would increase cloud cover and use
some instability. The chance for any modification preventing storms
is currently around 20%. Some surface conditions during the early
afternoon that would help indicate a higher chance for severe
weather would be dewpoints above 50 (better chance of breaking any
cap) and winds from the east/southeast (higher shear and storm
relative helicity).

In regards to blowing dust for today, chances have decreased for
significant reductions in visibility in the latest guidance as winds
speeds are a bit below what local research suggests is the threshold
and lapse rates would allow mixing out of any dust, likely leading
to more of a hazy sky and some poorer air quality.

Tonight, the severe storms are forecast to push off to the east with
some clearing in the area initially. However, as the low pushes off
tot the northeast, wrap around precipitation could move in, favoring
Eastern Colorado and Southwestern Nebraska. Any storms would have a
low chance of producing severe hail as elevated instability is
forecast with MUCAPE around 1500, but lower shear around 30 kts may
prevent storms from sustaining themselves. Lows tonight are forecast
to drop into the mid 40`s and mid 50`s.

Tomorrow, precipitation could still be ongoing at the start of the
morning with the wrap around potential. With that, mostly cloudy
skies forecast which would help keep temperatures in the 60`s and
70`s. Winds are forecast to strengthen in the wake of the low with
sustained speeds around 20 to 30 mph with gusts up to 55 mph during
the morning and early afternoon hours. Winds would then lower later
in the afternoon as the low moves farther away and the pressure
gradient weakens. We still may not be done with storms later in the
day as another upper trough/low is forecast to begin nosing into the
Four Corners region. This could allow some storms to fire up over
Eastern Colorado and move east. Thankfully, shear and CAPE are
forecast to be lower which would keep storms sub-severe.

Friday night would then see skies clear for most of the area and
lows drop into the 40`s. There could be some lingering
showers/storms in Eastern Colorado.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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 453 AM MDT Thu Apr 25 2024

For KGLD... IFR ceilings are forecast for the first few hours
this morning until cloud cover begins to clear. VFR conditions
are then forecast for the remainder of the period, though
thunderstorms are forecast to impact the terminal this
afternoon. While timing could change by a few hours still,
currently forecasting thunderstorms to form near and potentially
over the terminal between 21-23Z with storms possibly nearby
for a few hours after that. It would be good to look for updates
and watch from 18Z-03Z when storms are more likely. Otherwise,
near surface winds will strengthen during the day before
weakening as the sun sets and storms pass.

For KMCK... MVFR ceilings are forecast to lower to IFR within
the first few hours as moisture continues to move into the area.
These lower ceilings should persist through the day (30% chance
they lift during the afternoon hours) with near surface winds
strengthening from the southeast through the day. Thunderstorms
are then forecast to impact the terminal between 22-00Z with
chances for additional thunderstorms after that, but lower
confidence at this time. Thunderstorms will be possible between
20-08Z so keep an eye out on conditions and for forecast
updates.

&&

.HYDROLOGY...
Issued at 252 AM MDT Thu Apr 25 2024

Portions of the Tri State region could see some potentially
impactful precipitation from showers and thunderstorms over an 84-
hour period starting today and going late into the upcoming weekend.
These chances will come in two rounds, one Thursday/Thursday night
and the other this weekend. Precipitation amounts will be highly
dependent on track and movement and overall coverage.

Rainfall totals that are currently forecasted during this time have
around a half inch or less south and east of a line from Hill City
to Colby, Kansas and southwest to the Tribune area. North and west
of this line, up to 0.80" to a localized 1.60" is possible. The
highest totals are currently focused west of a line from Burlington
Colorado to McCook Nebraska.

Area soils are pretty dry at this time and should be able to handle
around 1 to 2 inch rainfall, but will have to be monitored for
potential for any training of storms in localized areas, especially
for areas that may have seen a lot of rain today/tonight and may see
more storms over the weekend.

There are currently no Flood Watches in effect.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Red Flag Warning from noon today to 8 PM MDT this evening for
     KSZ027-041.
CO...Red Flag Warning from noon today to 8 PM MDT this evening for
     COZ253-254.
NE...None.

&&

$$

SHORT TERM...KAK
LONG TERM...JN
AVIATION...KAK
HYDROLOGY...JN