422
FXUS63 KGLD 180838
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
238 AM MDT Sat May 18 2024

.KEY MESSAGES...

- Active period begins this evening with showers and storms
  overnight; marginally severe hail is possible along with
  torrential rainfall.

- The relative better potential for severe weather is Sunday and
  Monday. Very large hail and damaging winds are the primary
  hazards Sunday.

- Cooler with frost concerns mid week.

- Active weather may return next weekend (Memorial Day Weekend)

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 226 AM MDT Sat May 18 2024

Weak cold front and associated wind shift is moving into
northern portions of the CWA currently. Some spotty virga or
sprinkles may be possible post frontal for an hour or two. The
cold front then looks to stall south of the area during the day
time as a surface high then develops across eastern Nebraska.
The surface high will then create a more easterly/upsloping
component to the winds along for some moisture return. A
disturbance then moves off of the Rockies during the mid to late
afternoon time fram allowing for some showers and storms to
move into the area from the Front Range and move to the
northeast. The above mentioned stationary boundary then begins
to creep ever so slowly back to the north overnight Saturday and
early Sunday morning. The lift from the Rockies wave looks to
interact with this boundary and form additional storms roughly
along a Cheyenne Wells to Norton line. Last night the NAM was
the most aggressive with showing a couple thousand joules over
elevated MUCAPE; more guidance is starting to suggest this now
as well which has increased my concern for some instances of
severe hail around quarter size starting around 06Z through
sunrise Sunday. Looking at forecasted 0-6 wind shear it appears
that the strongest shear looks to be around initiation time near
06Z and then waning through sunrise. PWATS increase to around
1.25 inches overnight as well creating the potential for
torrential rainfall. Still continue to think that any flooding
potential will be low as these storms will moving fairly
quickly but will need to keep an eye on back building and
training storms as some guidance does suggest that rainfall may
last through about 8am Sunday.

Sunday, then continues to be the day of interest for the short term.
Severe threat is looking a bit more promising than vs 24 hours ago.
Last night there were some concerns about fog/stratus lingering
across eastern portions of the area which would limit overall
instability. While this does continue to remain a possibility,
especially if morning convection does linger; most guidance has
the temperatures rebounding. I did nudge down high temperatures
across the northeast a few degrees if this scenario does pan
out; but was not as aggressive as I would have been last night
in this situation.

As anticipated last night, the severe threat has shifted more
westward as guidance has gotten on board with the western
placement of the dryline which the NAM was suggesting. Discrete
storms look to initiate along the dryline (roughly Highway 385)
during the afternoon hours. I have fairly high confidence (70%)
that these storms will remain discrete as a cap will be in
place. Any storm that does manage to develop during this time
will have the potential for very large hail, perhaps up to
tennis ball size with MUCAPE around 2500-3000 j/kg, steep lapse
rates and 0-6 shear around 40-45 knots. Once storms finally do
initiate they are anticipated to grow upscale into more of a
cluster posing more of a damaging wind and heavy threat; this
currently favors locales east of Kansas Highway 25. Dependent on
how much rainfall occurs Saturday night into Sunday morning,
there may be more of an increased threat for flooding. Locales
east of Highway 83 may be the relative more at risk as some
portions of Gove County received 1-3 inches of rain earlier in
the week. Storms look to move completely out of the area between
10p-1am CT across the east. Some additional storms may try to
develop behind this cluster but currently think these should
remain sub severe.

Some near critical to locally critical fire weather concerns look to
be present behind the dryline with RH values in the low to mid teens
and gusts up to 25 mph especially from around the 22-00Z time
when mixing should be strongest; mainly favoring Cheyenne county
Colorado. Not planning and fire weather headlines this forecast
package due to the anticipated limited spatial area and more
marginal conditions. Upcoming shifts will need to keep an eye on
this potential however.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 226 AM MDT Sat May 18 2024

Monday will see another potential for showers and perhaps severe
storms. Monday`s setup is a bit more difficult as the better forcing
is a bit further north. Continue to anticipate the potential
for two rounds of potentially severe thunderstorms with discrete
cells initially and then a potential MCS developing during the
evening hours. Moisture will for sure be in place across the
area with drier air to the south of the CWA. Watching for an
initial shortwave during the afternoon hours interacting with a
developing surface low across SW Kansas. This would be the
timeframe for initial discrete cells. All hazards may be
possible with this initial activity with MUCAPE of around 1500
j/kg, very strong 0-6km shear in excess of 55 knots and low
LCL`s supporting 1500-2000 j/kg of SBCAPE.

A potential 2nd round of severe weather may occur as a potential
MCS moves across northern portions of the CWA with an advancing
cold front. Damaging winds, torrential rainfall are the primary
hazards but may need to keep an eye on potential quick QLCS
spinup tornadoes across the leading edge of the line. Continue
to think widespread flooding with the torrential rainfall is
unlikely given very high Corfidi Vector motions but will need
to monitor for back building of rainfall behind the initial
line (post frontal). This MCS should be through the CWA between
1-3 am CT.

Another round of rainfall looks to move through the area Tuesday
with a 2nd but stronger cold front. Currently not very convinced on
overall severe threat as the environment may be worked over from
previous days storms, but wind shear would be sufficient for a
potential severe storm. The front looks to move through the
area during the mid afternoon; with best threat of rainfall
being post frontal with a wave off of the Rockies during the
late afternoon/early evening hours.

Mid-week at this time does appear to be more tranquil as the area
will be in between systems. However towards the latter portion of
the week and into Memorial Day weekend another trough with moisture
return ahead of it moves into the area.

Temperatures for the extended period look to start out cooler with
the rainfall and cold fronts. Tuesday night and Wednesday morning
continue to look to be the coldest nights with overnight lows in the
mid 30s to mid 40s. I continue to have concerns for frost
development Wednesday, especially if clouds clear out as winds
will be light and enough boundary layer moisture would be in
place especially if enough rainfall can occur. I have added in
patchy frost across portions of Kit Carson and Cheyenne counties
in Colorado. Some guidance does indicate clouds and
precipitation linger through Wednesday morning which if the
case would eliminate frost potential, but give how far into May
we are and more and more cold sensitive vegetation blooming and
being sold figured to go ahead and add in the frost into the
forecast where confidence is highest at this time.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 1053 PM MDT Fri May 17 2024

For KGLD & KMCK... VFR conditions are forecast through the
period. LLWS has been observed and will continue through the
night. Around 08-09Z, a wind shift to out of the northwest is
still expected and winds will pick up a bit. Winds will remain
elevated around 15kts with gusts around 27kts until the late
afternoon hours. The last thing of note is that some storms are
possible around the 02-06Z time frame. Currently chances are
30% or less so just have VCTS at KGLD where storms are more
possible (but could still miss the terminal to the south).

&&

.HYDROLOGY...
Issued at 226 AM MDT Sat May 18 2024

Some potential does exist for torrential rainfall and isolated
flash flooding starting Saturday night/Sunday morning into early
portions of the new work week. The majority of the area,
especially western and southern portions have seen a lack of
rainfall in recent weeks and worsening drought conditions.
Overall main concern for any hydro issues lies to the east of
Highway 83 in Kansas where portions of Gove county for example
received 1-3 inches of rainfall earlier in the week. PWATS will
rapidly increase tonight around 1.25 inches and remain above 1
inch for the duration of the weekend. Overall widespread
flooding potential is relatively low as overall systems should
be fairly quick moving with fast Corfidi Vectors. The overall
main concern for any hydro related issues lies in multiple
rounds of heavy rainfall and any potential training locales.

&&

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

&&

$$

SHORT TERM...Trigg
LONG TERM...Trigg
AVIATION...KAK
HYDROLOGY...Trigg