781
FXUS63 KGLD 261101
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
501 AM MDT Wed Jun 26 2024

.KEY MESSAGES...

- Not as hot today; thunderstorms develop across east Colorado
  late afternoon/early evening before spreading into Nebraska
  and Kansas. Severe possible along with torrential rainfall.

- Scattered severe storms again Thursday with large hail,
  damaging winds, torrential rainfall and perhaps a window of
  opportunity around sunset for a tornado.

- Near daily chances for thunderstorms Friday into next week.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 225 AM MDT Wed Jun 26 2024

A moist airmass is starting to advect into the area from the
northeast where dew points have been increasing 5-10 degrees with
the passage of the incoming boundary. Weak isentropic lift and
interaction with the moist boundary is leading to some scattered
showers across northern Kit Carson county as of 08Z; RAP suggests
that this corridor may continue to move south through sunrise so
have introduced slight chance pops (15%) to account for this.
)Surface high continues to reside across the SW CONUS, but is
forecasted to flatten out through the day today. As a result, a
reprieve from the triple digit heat looks to be in store for the
area with highs in the low to mid 90s.

Main focus for the day will be thunderstorm development across
eastern Colorado. Discrete strong to severe storms look to develop
during the late afternoon hours and into the evening as a shortwave
emanates off of the Rockies; some supercellular characteristics may
be possible as well with shear around 40 knots and 3000 j/kg of
MUCAPE. Large hail looks to be the primary hazards initially
across Yuma, Kit Carson and Cheyenne (CO); will need to watch
for flooding potential as well especially with any right moving
storms as the motion is around 5 knots and PWATS increasing up
to around 2 inches. The storms are then forecasted to grow
upscale into a cluster with perhaps a damaging wind potential
as they move across the state line especially with cold pool
driven enhancements. Some localized flooding potential may occur
as well with the high PWATS but currently think that storms
will be moving quickly enough to avoid any further hydro issues.


The difficult portion of today`s forecast will be how much the
surface high across the south breaks down. If some amplification
remains then the rainfall will shift to the north or be delayed
until the subsidence exits the area such as the ECMWF. Other
guidance such as the RAP/NAM differ on the area with the
greatest moisture  with the RAP favoring north of I70 and the
NAM to the south. All this said, continues to keep me from
increasing pops to much and does bring some cautiousness.
Overall though this does appear to be the area`s relative best
chance at meaningful precipitation that has been seen in a few
weeks.


Thursday, will see the moist air mass continue across the area. Will
need to watch for stratus and perhaps fog across the area during the
morning; fog will be dependent on how quickly the rainfall can exit
and how much occurs. Fairly decent agreement with guidance with
850mb moisture greater than 90% hanging around the eastern
portion of the area for the good part of the day in the form of
stratus. With the stratus and dewpoints in the low 70s have
lowered high temperatures for the day into the low to mid 80s
across the east. Western portions of the area will see more
breaks in sun where highs in the low to mid 90s remain
forecasted.

Another threat for severe storms exists on Thursday, but the
coverage and hazards will be highly dependent on how the Wednesday
system plays out. Large hail and damaging winds will be the primary
threat; the large hail threat may be a bit more uncertain given
meager lapse rates of 6.5 to 7.0 C. It appears that two zones for
convective initation will be in play as a warm front and a dry line
will be present across the area; will also need to watch for any
additional lingering boundaries from the potential storm
cluster from Wednesday night. A tornado threat may also develop
along the warm front and across any additional outflow
boundaries as forecast guidance is showing 0-3 SRH around 300
m2/s2 and 0-1 SRH around 150 m2/s2. NAM hodographs show decent
low level shear as well; a dewpoint depression of around 10
degrees and 3000 j/kg of SBCAPE does indicate that any storm
should be surface based. PWATS will continue to be very high as
well around 2 inches still which will lead to continued concern
for torrential rainfall and perhaps additional flooding concerns
especially where heavy rainfall may fall Wednesday night.

Friday, will see a similar pattern as another wave moves off of the
Rockies bringing shower and storm potential to the area. Storms
again look to initiate across eastern Colorado and move into
the adjacent states; moisture and PWATS at this time don`t
appear to be as high and there may be some capping concerns as
well. A warm front does look to be draped across the area again
as well but the exact location differs between models so is
difficult to pinpoint down at this time. Highs are currently
forecasted in the 90s across the area with the potential for
upper 90s across the south.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Issued at 215 AM MDT Wed Jun 26 2024

For the weekend, will be on the northern periphery of a ridge
centered over the southern plains. Perturbations rotating around
it will approach from the southwest each afternoon and then move
across the area during the night with a chance for showers and
thunderstorms. At the surface, will see post frontal upslope
winds on Saturday with temperatures closer to normal.
Surface based instability will be just hugging the southern
Kansas counties and nosing into northeast Colorado Saturday
afternoon, which would be the only locations that could see a
marginal severe risk due to deep layer shear around 45 kts.
Surface instability goes to zero fairly early Saturday evening
with only some lingering weak elevated instability through
Saturday night with scattered showers and isolated storms. Low
temperatures will be in the 60s.

On Sunday, a narrow corridor of moderate instability develops
along/just west of the Colorado and Kansas border by the
afternoon with the moist return flow at the surface. Deep layer
shear will be around 35 kts, and with the better instabilty
expect to see a higher risk for severe storms, especially in
Colorado and near the Colorado/Kansas border. Instability will
weaken as storms move northeast Sunday evening with the severe
risk declining, but if storms manage to cluster may see some
locally heavy rainfall as indicated by the GFS across areas
north of Interstate 70 and into southwest Nebraska. High
temperatures will be in the upper 80s and lows in the upper 60s.

For Monday and Tuesday, the ridge weakens as a shortwave trough
moves from the northern Rockies into the northern plains. It
will drive a front through the area sometime late on Monday.
However, the area may get dry slotted ahead of the front with
westerly winds. Moisture appears to be very limited and
instability is weak. Models still showing scattered convection
with some synoptic scale forcing on the southern fringe of the
upper wave. Confidence is on the low side for any severe threat
at this time other than gusty winds with deeply mixed inverted-v
soundings. Temperatures ahead of the front will warm back into
the lower 100s and lows Monday night ranging from the lower 60s
in Colorado to the lower 70s in north central Kansas.

Will be post frontal on Tuesday with moist low level return
flow by Tuesday afternoon resulting in modest instability in
southern areas, fairly weak elsewhere. Looking at convection
developing from the southwest in the afternoon with shortwave
rotating around the southern ridge and across the area Tuesday
night. Some suggestion of locally heavy rainfall from the GFS
across southern areas in the better instability, but confidence
at this time range is low. High temperatures on Tuesday will be
in the mid to upper 90s and lows Tuesday night in the 60s.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 457 AM MDT Wed Jun 26 2024

Watching a corridor of stratus develop across Yuma/Washington
county in Colorado; some uncertainty whether or not this will
stretch into the KGLD terminal but will monitor very closely.
Have opted to go with a tempo of sct010 to show the potential
for IFR conditions this morning. Stratus will be short lived
as it should be completely gone by 15Z. Breezy winds around 15
knots with some sporadic gusts up to 20-25 knots will be present
throughout the day. Potential for a cluster of storms to affect
each terminal overnight into Thursday morning. Do have to
overcome some dry air at KGLD so will mention the VCTS but if
signals that the dry air isn`t as pronounced then a rain
mention may be needed. Strong signal for stratus again Thursday
morning especially for KMCK; KGLD is on the fringe of it so will
again go with the SCT wording for the TAF at this time.

&&

.HYDROLOGY...
Issued at 225 AM MDT Wed Jun 26 2024

Any storms that develop across western portions of Kit Carson,
Cheyenne (CO) and Yuma counties late this afternoon and evening
will have the potential for torrential rainfall leading to some
flooding. Precipitable water values look to increase to around 2
inches during this time frame along with right moving storm
motion of 5-10 knots storms will not move very quickly and may
produce localized areas of flooding. Due to the recent hot and
dry weather and localized and conditional potential of this
threat have opted to not issue any hydro highlights. Storms look
to grow upscale after initial discrete cells but may have to
overcome some dry lower level air across NW Kansas. Once the low
levels can saturate then the continued potential for torrential
rainfall will return along some isolated flooding potential in
low lying areas.

Scattered storms are again forecasted on Thursday with continued
very high PWATS around 2 inches. There is potential for multiple
rounds of rainfall Thursday afternoon and into the overnight
hours. Those who see heavy rainfall Wednesday night will be most
at prone for additional flooding.

&&

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

&&

$$

SHORT TERM...Trigg
LONG TERM...024
AVIATION...Trigg
HYDROLOGY...