217
FXUS63 KGLD 290130
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
730 PM MDT Tue May 28 2024

.KEY MESSAGES...

- Chance for severe weather and flooding throughout the week.
  Confidence in specific hazards change each day, but a very
  active pattern is expected.

&&

.UPDATE...
Issued at 722 PM MDT Tue May 28 2024

Severe Thunderstorm Watch 347 continues to look on track through
03Z. Two continued longer lived left mover supercells continue
to trek to the northeast across Kit Carson county and southern
Yuma county. Larger area of precipitation to the south isn`t
looking as robust as early as the environment may be a bit
worked over. Will continue to watch for torrential rainfall
potential and perhaps some localized hydro issues especially in
low lying areas. Did introduce some patchy fog into the forecast
due to the continued SSE moisture advection, recently saturated
boundary layer and lighter winds around sunrise. Am targeting
locales south of the Interstate for this potential as this
appear to be where winds will be lightest at.

Severe potential continues to remain on track as a broken line
of storms looks to move off the Palmer Divide and moves east
into the area. Hail and wind threat currently look to be the
main threats similar to today.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 153 PM MDT Tue May 28 2024

Morning and early afternoon convection occurred along narrow
band of 700 mb frontogenesis which has moved southeast of the
area. Additional convection is expected later this afternoon and
into this evening as a shortwave trough moves out of the
Rockies. There is also a weakening cold front moving out of
Nebraska and possible outflow boundary from earlier convection.
CAMs show best chances for additional storms will generally be
south of a Joes, Colorado, to Scott City, Kansas, line.
Moderate surface based instability early in the evening will
quickly weak by around 03z when storms will probably become
elevated with persistent MUCAPE. Deep layer shear will also be
strongest early in the evening before weakening with time. So
all signs point to a marginal severe risk early, but storms
weakening after about 03z. Mean precipitation amounts through
06z are around a quarter of an inch, but some locally higher
amounts of a little over 1 inch will be possible according to
HREF 90th percentile QPF. A few scattered showers and isolated
thunderstorms may persist after midnight mainly in eastern areas
with additional amounts of less than a tenth of an inch. Low
temperatures will be in the 50s.

Ridge axis moves east on Wednesday with a pronounced shortwave
trough moving into the Rockies in the afternoon. Showers and
thunderstorms will initiate on the Front Range and move across
eastern Colorado in the afternoon, probably not reaching the
Kansas border until after 00z. Most if not all of the area will
be dry until then with high temperatures in the upper 70s to
around 80. Broken line of showers and thunderstorms will then
move west to east across the area Wednesday night. Initial line
may have a hail/wind threat early in the evening before
transitioning to mainly a wind threat further east later in the
evening. 6-hour mean precipitation amounts are around a quarter
of an inch through 06z, with some locally heavier amounts of 1
to 1.25 inches possible generally north of Interstate 70.
Amounts between 06-12z will be lighter, though can`t completely
rule out some local amounts in eastern areas approaching 1 inch.
Low temperature will be in the 50s to around 60.

Showers and thunderstorms may persist into Thursday morning as
the upper trough axis and accompanying surface cold front slowly
move through the area. Should see additional post frontal
development during the afternoon as another vorticity lobe
rotates around the main low in the northern plains. Not sure how
much instability can recover given the morning clouds and
precipitation, but there is some potential for severe storms
with any clusters propagating off the higher terrain to the
west, with the main hazard being wind. Deep layer shear tops out
at around 30 kts which may limit more organized convective
threat. However, as storms move further east Thursday night the
0-6 km winds diminish to 10 kts or less, suggesting slow storm
motions. Mean 6-hour QPF through 06z for areas east of Highway
25 around a half inch but higher percentiles are between 1-2
inches. There is some concern for flooding given these
parameters and antecedent rainfall the previous few days. High
temperatures will be in the 70s and lows in the 50s.

The pattern does not change much on Friday. Showers and
thunderstorms linger in the morning, mainly in eastern areas,
then redevelop in the afternoon with another wave rotating
around the main upper low now in central Canada and low level
upslope flow. Instability is weak to moderate, highest in
Colorado, but there is an increase in deep layer shear to 40-50
kts, sufficient for a severe risk with any discrete cells in
the afternoon and evening hours. However, QPF is much lower
compared to previous days which may mitigate any additional
flooding concerns. Not much change in temperatures with highs in
the 70s and lows in the 50s.

&&

.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
Issued at 153 PM MDT Tue May 28 2024

Looking ahead to the weekend, pattern does not really change for
either Saturday or Sunday. Southwest flow aloft is forecast with
embedded waves providing synoptic scale lift for precipitation.
Sufficient instability and shear for a risk of severe storms is
also indicated. On Sunday, may see a dry line and front come
into play, but difficult to pin down exact locations of either
at this time range, but better chances for precipitation may be
pushed a bit east on Sunday with the dry line. Temperatures warm
up both days, with highs in the 80s on Saturday and 80s and 90s
by Sunday. Lows will be mainly in the 50s.

For Monday and Tuesday, another system will cut off an upper
low over the northern plains with shortwave energy rotating
around it over the central plains both days, which is more or
less a repeat of the current pattern. Until there is a more
substantial pattern change, possibly mid to late week with a
building ridge, shower and thunderstorm chances will continue.
Temperatures show little variation with highs in the 80s and
lows in the 50s.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 440 PM MDT Tue May 28 2024

Storms are developing fairly quickly across eastern Colorado and
may impact the KGLD terminal near the start of the period. Mean
flow is to the SE which makes me lean towards the terminal not
being impacted but will need to watch on a either a left mover
the northeast or additional upscale growth; so an AMD may be
needed. Storm threat should end around 04Z, will then need to
watch for stratus or fog potential around sunrise due to the
newly saturated boundary layer and continued moisture advection
from the ESE. Winds will become breezy from the south Wednesday
near 30 knots at times, will then need to watch to for
additional storms just after the end of the period.

&&

.HYDROLOGY...
Issued at 256 AM MDT Tue May 28 2024

Highly efficient moisture return looks to begin late Tuesday night
and continue into the end of the workweek via the 850 mb LLJ. This
moist conveyor belt will cause PWATS to increase above 1 inch
starting Wednesday and potentially remain that way until Saturday.
The highest values will be in the eastern CWA, but the majority of
the Tri-State area will have a good chance (60%+) at seeing PWATS
above 1 inch. Throughout this active pattern, a high melting layer
is also expected, generally 11,000-15,000 feet agl.

Tuesday does have a very low concern for flooding (~5%) as clusters
of storms could produce multiple rounds of precipitation over the
same area. This precipitation is expected to remain more in the
southern CWA where conditions have been dry, so the ground will
likely soak it right up.

Wednesday and Thursday are currently the best days for storms to
create heavy rainfall that could lead to rate-driven flash flooding
and duration-driven areal flooding. Friday and Saturday are also at
risk for flooding potential due to a combination of efficient rain
producing storms and potentially multiple days of heavy rain
saturating the soil.

Current confidence in localized flooding occurring in the latter
half of the week is around 10-15%.

&&

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

&&

$$

UPDATE...Trigg
SHORT TERM...KAK
LONG TERM...CA/KAK
AVIATION...Trigg
HYDROLOGY...