597
FXUS63 KGLD 031045
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
445 AM MDT Fri May 3 2024

.KEY MESSAGES...

- Thunderstorms will develop along a cold front surging
  southeastward through the area late this afternoon and
  evening. Damaging winds and instances of large hail appear to
  be the primary hazards. Isolated supercells capable of
  producing all hazards may develop in advance of the front,
  south of Highway 40 in CO/KS, between 4-8 pm MDT.

- Fire weather concerns return Monday through Thursday for most
  of the Tri-State area, but favor along and south of I-70.

- Thunderstorms, a few of which may become strong to possibly
  severe, will be possible Monday afternoon/evening.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 345 AM MDT Fri May 3 2024

Overview: An upper level low centered invof the Saskatchewan-
Manitoba-North Dakota border this morning will slowly progress
northeastward across central Manitoba/Ontario (today-tonight)
and northward into Hudson Bay (Sat-Sat night).

Today-Tonight: Shortwave energy presently centered invof
southern Idaho will track eastward across southern Wyoming today
(rounding the base of the aforementioned upper low and broad
upper trough over the Northern Plains).. then lift northeastward
across South Dakota and Minnesota (tonight). A low-level
southerly return flow regime will be re-established in the lee
of the Colorado Front Range today.. as the MSLP-H85 height
gradient re-orients and tightens in response to the development
of a modest lee cyclone in Colorado (aided by the aforesaid
shortwave energy /DPVA/ approaching from the west).
Strengthening southerly flow will advect seasonably rich low-
level moisture (4-9C 850 mb dewpoints) beneath a pronounced
elevated mixed layer (8-9 C/km H7-H5 lapse rates) in place over
eastern Colorado and northwest Kansas.. yielding 500 J/kg
(Colorado) to 1500 J/kg (western Kansas) MLCAPE at peak
heating. Guidance indicates that an evaporatively-cooled
airmass /effective cold front/ emanating from fairly widespread
precipitation over portions of Wyoming and the Nebraska
Panhandle will surge southeastward through northeast Colorado
late this afternoon (~00Z) and northwest Kansas by ~03-04Z this
evening.

Simulated reflectivity forecasts via recent runs of the HRRR
and NAM NEST indicate that convection will [1] rapidly develop
along the effective cold front in northeast CO late this
afternoon and [2] increase in coverage along the front as it
progresses into an increasingly unstable airmass (with southern
and eastern extent) this evening.. where damaging winds and a
few instances of large hail are anticipated to be the primary
convective hazards.

However, guidance also suggests that isolated convection..
possibly discrete supercells.. will develop in advance of the
front along the Arkansas River Valley in southeast Colorado
(Bent-Prowers-Kiowa counties) ~22Z, progressing eastward into
western Kansas ~23-02Z. *If* discrete supercells develop, all
convective hazards are on the table.. mainly in the 23-02Z time
frame.. before said updrafts are consumed/cannibalized by the
southeastward advancing cold front.

Sat-Sat night: Benign weather and cooler temperatures will
follow, on Saturday.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 243 AM MDT Fri May 3 2024

For the long term period, active weather is possible Monday with
generally average temperatures and daily precipitation chances
through the week.

Sunday is forecast to have an upper low/trough push into the Western
CONUS and move towards the Four Corners region. Meanwhile, moisture
is forecast to stream in from the south near the surface as a
surface low develops along the Front Range while additional moisture
moves in over the mountains. This could lead to a fairly cloudy day
where temperatures will cap in the 60`s, though any area with sun
for a couple of hours should reach the 70`s, especially near and
west of the Colorado border. Showers and a few storms could develop
with all the moisture in the area, but the severe threat should be
near zero with instability still forecast to be fairly low with
MUCAPE generally near or less than 500 J/KG.

Sunday night through Monday is when conditions are forecast to get
more interesting as the upper low moves near and over the area along
with the surface low. One the first things to watch will be the
winds. With the speed of the upper trough and how deep it could get,
the pressure gradient and height gradients could get fairly strong
and allow winds to exceed 30 mph and gusts exceed 55 mph starting as
soon as Sunday evening. However, confidence is currently only around
40% as ensembles show a fairly high spread in 500mb tracks and
progression. This in turn also affects the surface low and it`s
progression. One of the main things that could keep the winds on the
lower side is that some of the ensembles are pulling the trough
north. This would shift the stronger gradients more towards Nebraska
and the Dakotas. Our winds would still strengthen above 20 mph with
gusts above 35 mph, but high wind criteria warnings would become
unlikely. The chances for the high winds then increase the further
south the track of the main surface low goes (farthest south looks
to be around the Southern KS border). In either scenario, low
temperatures Sunday night will likely stay in the 50`s with the
moisture, cloud cover, and increased winds over the area.

For Monday, conditions are fairly variable given the surface low has
solutions with tracks that go through the area during the day or hug
the KS/CO border along with tracks that are north of the area and
south of the area (I am referring to the deepest part of the surface
low). In scenarios where the low moves through the area and is to
the east during the day, moisture would lower across the area,
increasing critical fire weather chances and lowering storm and
severe storm potential. In solutions where the low and front stay
over or near the area, critical fire weather conditions become less
likely while storm and severe storm chances increase. Winds
approaching high wind warning criteria become more likely as well.
Would could be of particular concern is if the low is south of the
area and the warm front is draped across the area. We then begin to
face scenarios similar to recent events with a warm front and a
dryline/cold front acting as storm genesis points. High temperatures
are forecast to be in the 60`s behind the system and in the 70`s and
maybe low 80`s ahead of the system. Monday night remains just as
varied with conditions ranging from calming and dry, to stormy with
high winds. Currently, don`t have a good inclination towards any one
scenario so have gone with a more neutral forecast and am waiting
for better consensus in guidance and maybe better sampling of the
system (since it is still offshore).

Tuesday and Wednesday look to be more "average day" with near
average temperatures in the 60`s and 70`s and some small chances for
precipitation as the upper pattern is forecast to turn more to a
broad trough with the initial disturbance pushing east while the
trough as a whole spins over the Northern Plains. Will need to watch
for critical conditions south of I-70 with the drier air over the
area dropping RH into the teens.

For the end of the work week, currently forecasting near average
conditions in a broad trough pattern. Guidance is split on whether
the upper trough just pushes off to the east or if a small low
splits off and retrogrades west. In either case, there is the
possibility of another front if the trough is strong enough as it
pushes off to the east, though there may not be much moisture
available for storms to work with.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1005 PM MDT Thu May 2 2024

KGLD...VFR conditions are expected through about 01z. A
southeast wind under 10kts at taf issuance will veer to the
south at similar speeds by 12z. From 13z-00z, southerly winds
gusting up to 40kts are expected. After 01z, sub VFR cigs and
vis are anticipated as showers and thunderstorms move through,
associated with a cold front. Northerly winds gusting up to
40kts or so are expected both due to the strong 3 hour pressure
rises behind the front and from the expected convection. Gusts
could be higher.

KMCK...VFR conditions are expected through about 01z. A light
and variable wind is expected from taf issuance through 13z.
From 14z-00z, southerly winds gusting up to 35kts are expected.
After 01z, winds shift to the north, gusting up to 40kts as a
cold front and strong 3 hour pressure rises move through. Sub
VFR cigs and vis are anticipated due to showers and
thunderstorms moving through.

&&

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

&&

$$

SHORT TERM...Vincent
LONG TERM...KAK
AVIATION...99