-- Discussion containing changed information from previous version are highlighted. --
259
FXUS63 KGLD 222205
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
405 PM MDT Wed May 22 2024

.KEY MESSAGES...

- Isolated to scattered severe thunderstorms are forecast to
  develop Thursday afternoon and evening.

- Cold front moves through Thursday evening and night with more
  severe thunderstorms possible along the front across eastern
  counties and non thunderstorm wind gusts up to 50 mph across
  the western counties.

- For the holiday weekend, expecting a chance for storms both
  Saturday and Sunday, with some severe storms possible.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 110 PM MDT Wed May 22 2024

Weak mid level ridging is present across the region currently with a
surface high in the lower levels; both of which are keeping the
skies virtually clear and the weather quiet. As we head into
the afternoon and evening a weak wave will move off of the Front
Range and onto the Plains. Winds will turn to the south and
begin advecting some moisture back into the area as a surface
trough develops; if everything can phase in time then some
isolated showers and storms may become a possibility around 01Z
across eastern Colorado and into NW Kansas. Little if any
rainfall is currently forecasted; will maintain with silent pops
due to concerns about the wave and the moisture return not
phasing. As the surface trough begins to deepen some tonight,
the southerly winds will become breezy with sustained winds
around 20 knots at times. This is forecast to help keep the
atmosphere mixed keeping overnight lows in the 40s to 50s.

The trough tomorrow looks to deepens into a surface low across
SW Kansas. Ahead of the low moisture will continue to return
from the Gulf of Mexico. A stout dryline will become present
through the afternoon which serve to be the focus for initiation
for the next round of severe thunderstorm potential. Confidence
is increasing in the dryline setting up near the Highway 25
corridor from Trenton through Leoti during the early to mid
afternoon. Discrete storms are forecast to develop along the
dryline with large hail around 2 inches in diameter damaging
winds being the primary threats as the NAM shows 2500+ j/kg of
MUCAPE with 40-45 knots of effective shear, steep lapse rate in
excess of 8 c/km and straight line hodographs. These hodographs
would support splitting of storms as well. If a discrete cell
can continue through 00Z (east of Highway 83) some tornado
threat may develop as the LLJ strengthens increasing the
streamwise vorticity. This scenario is seen in the 12Z NAMNEST
with elongating hodograph signature as well. I`ve strongly used
the NAM and NAMNEST for my forecast as these models have done
extremely will with convection and location of the dryline thus
far this spring. It is also interesting to note that the HRRR
has been consistently not initiating any storms along the
dryline, so that scenario is possible but at this time thinking
it is unlikely.

Into Thursday evening and night, a cold front then surges south
through the area. A second round of potentially severe storms may
occur along the cold front as well, as long as as the area remains
in the warm/moist sector (mainly east of Highway 25). Plentiful
MUCAPE and shear remains in place as more of a line/cluster pushes
south across the area. Damaging winds and hail will be the primary
threats. If any bowing segments occurs with the line then wind
driven hail may become more of a concern. Shower and storm
development back west across the front is a little more uncertain
due to the dry air in place; NAM and GFS both suggest 8-11 mb
pressure rises over 3 hours with and behind the front. Non
thunderstorm wind gusts around 50 mph looks to occur with this.
Blowing dust is also of limited concern due to the recent heavy
rains in the main dust source region of northeast Colorado.

Some fire spread potential will need to be monitored behind the dry
line as well as RH values look to fall into the low teens and deeply
mixed inverted v soundings look to help bring down wind gusts around
30 mph. After collaboration with surrounding offices, opted to hold
off on any fire weather highlights due to the continued spring
greenup and most importantly the recent rains. A portion of
western Cheyenne county Colorado also continues to lie in the
40th percentile ERC (Energy Release Component); however nothing
notable was being seen in calculating the GFDI with mid range
"Very High" fire spread numbers being seen which does lead me to
believe that the recent rains have helped the area mitigating
the burn ready fuels.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 110 PM MDT Wed May 22 2024

Post frontal stable air will be in place behind cold front as
another surface high sets up across the area to start the extended
period. Winds will remain breezy which is forecast to keep
temperatures from completely bottoming out despite dew points
in the mid 20s to low 30s. The pattern with a slight eastward
shift of the surface high would create lighter winds which would
then support frost concerns again across the west, so upcoming
shifts will need to monitor the position of the high. A very
similar day to today is forecast for Friday as the surface high
pushes off and another weak wave moves off the Front Range; not
anticipating any precipitation at this time.

Into the weekend, moisture again surges northward across the area so
will need watch for fog/stratus into Saturday. Saturday will
need to be watched for severe weather potential as a warm front
and dry line look to be in the vicinity of the CWA as another
low pressure system develops. There remains considerable
discrepancies regarding the positioning of the these features
so confidence remains on the low end regarding specific details.
However, with this being the Memorial Day holiday weekend,
those with outdoor or travel plans will want to monitor the
forecast very closely.

Into Sunday; wraparound precipitation may move into the area along
with cooler temperatures with highs in the 60s to 70s across
the area. Ridging then looks to develop during the new work week
with warmer temperatures making their return into the region.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
-- Changed Discussion --
Issued at 405 PM MDT Wed May 22 2024

KGLD...VFR conditions are expected through the period. A
southerly wind occasionally gusting 20-25kts is anticipated
from taf issuance through much of the afternoon Thursday before
veering to the southwest at similar speeds after about 23z.

KMCK...VFR conditions are expected through the period. A
southeast wind under 10kts at taf issuance will continue through
the night. On Thursday, southerly winds increase with gusts up
to 25, maybe 30kts. There is a possibility of showers and
thunderstorms impacting the terminal after 22z along a
forecasted dry line. The placement of the dryline may change and
thus the timing and location of anticipated convection so
adjustments may be needed in later forecasts.






.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
-- End Changed Discussion --

&&

$$

SHORT TERM...Trigg
LONG TERM...Trigg
AVIATION...99