798
FXUS63 KDDC 021500
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
1000 AM CDT Thu May 2 2024

...Updated Aviation...

.KEY MESSAGES...

- Next storm system Friday Night will carry with it a Marginal
  Risk (1 out of 5) of severe weather.

- Widespread heavier rainfall forecast than what we have seen
  with systems in the past couple months -- 75th percentile at
  around three-quarters inch for much of western Kansas.

- Major storm Monday will bring higher severe weather risk
  across eastern half of Kansas. If storm slows down any,
  portions of southwest Kansas may be in play for a fairly high-
  end severe thunderstorm risk.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 413 AM CDT Thu May 2 2024

An active weather pattern will continue through this Short Term
period ending Friday Night as yet another storm system will build in
behind the trough that was moving across the Northern Rockies
overnight tonight. A small, rather disorganized mesoscale convective
system (MCS) was moving east across northern Kansas, which was
finally clearing Ellis County as of 810Z (310 AM CDT). The north
winds behind a cold front were drawing cooler air southward
overnight with surface observations showing mid to upper 40s across
far west central and much of northwest Kansas.

For today, we will see an initial bump in north winds after boundary
layer mixing sets in, but wind speeds will gradually decrease
through the day as a surface to 850mb high expands its influence
across Kansas. Increasing subsidence will lead to an erosion of
remaining low cloud by midday/early afternoon which will help boost
afternoon temperatures to a high of around 70 north to mid 70s along
the Oklahoma border.

Tonight, easterly winds will develop with 850mb winds veering around
from northeast to southeast in response to the next jet steak
upstream entering the Northern/Central Rockies. Low level Gulf of
Mexico moisture will not be too far away given the quick return
flow, thus low level moisture advection from the southeast will
commence Friday morning. This will likely bring in some low stratus
cloud, especially across the southern counties where moisture
advection will be highest early in the morning.

Friday, surface winds will pick up in speed once again as a lee
trough develops across southeastern Colorado as the upper level jet
streak moves across the Wyoming-Colorado region. The increased low
level winds will accelerate low level moisture movement back into
western Kansas. So, the moisture will be back. Wind shear will be
adequate for organized thunderstorms -- which is climatological for
early May out here in western Kansas. Instability will be there with
cool 500-700mb temperatures (around -15C/+6C), albeit boundary layer
warming will not be all that great. The last ingredient, forcing for
lift, will be the key ingredient for Friday Night`s system...as a
strong cold front will be in play with a sharp temperature gradient
and very high (and deep) frontogenetic forcing. The 850-700mb
frontogenesis may be enhanced due to constructive coupling of the
right-entrance region of the northern jet (across Nebraska) and the
left-exit region of the southern branch jet across New Mexico into
West Texas.

All models have at least modest QPF (0.25" or more) across west
central and southwest Kansas Friday Night due to the explained
meteorological ingredients in the previous paragraph. The timing
will be later in the night for this event, thus the severe weather
risk will not be all that great. This does not look like a supercell
setup either, as much of the thunderstorm activity across western
Kansas will be confined to the strong cold front, thus the most
favored mode will be multicell clusters and quasilinear structures.
Early in the event Friday Night, some large hail will certainly be
possible, but later in the night, the event will transition more
toward a damaging wind risk and locally heavy rainfall. The latest
WPC Excessive Rainfall Outlook for Day Two does have a Marginal (5%)
risk across much of Kansas.

QPF amounts:  The May 02/01Z run of the latest NBM is showing 25-
75th percentile amounts of None to around 0.25" across far southwest
Kansas...around 0.10" to 0.80" across the mid-section of our
forecast area (Scott City to Dodge City to Coldwater)...with a
similar 25-75th percentile range up around Hays.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 413 AM CDT Thu May 2 2024

After Friday Night`s wave moves east, Saturday will be another
benign day behind the cold front with all models showing single-
digit degC 850mb temperatures in the afternoon, which would support
highs Saturday only in the 60s. Sunday will be a transition day in
between storm systems as a much larger Pacific storm will be taking
aim on the Central Plains come Monday. Ahead of this system on
Sunday, the southeast wind machine will resume with strongest Sunday
afternoon winds out west toward the Colorado line. The latest NBM
surface sustained winds of 20 knots out west might not be high
enough.

The strong southeast winds will initially be recirculating the
remnant cool airmass from Saturday, so there will likely be quite a
bit of cloud on Sunday (along with some morning elevated
thunderstorm activity...30-40% chance). Sunday Night/Monday Morning
will likely be breezy, mild, and humid as lower to mid 60s dewpoints
make a run on southwest Kansas ahead of a formidable upper low
centered over southwestern Wyoming (per ECMWF). Monday does appear
to be a rather classic looking Great Plains severe weather day ahead
of a highly impressive looking negative-tilt 500mb trough. The
global models show a cyclonic wavebreak scenario as an upstream,
cyclonically curved jet digs in behind the ejecting upper low in a
highly dynamic manner. This will almost assuredly focus surface
cyclogenesis way up into the Dakotas late Monday (00Z Grand Ensemble
50th percentile MSLP of around 988mb around Dickinson, ND). The
impressive upper level jet cutting underneath the ejecting low will
likely enhance dryline convergence all across the Central Plains
leading to numerous severe thunderstorms, including all types of
severe weather. Monday is still 5 days out, however the SPC has
issued a 15% outlook area including the eastern half of Kansas (just
barely outside of our forecast area). Timing of this system is still
a major uncertainty, and if we see any slowing down of the Monday
storm, then the severe weather risk will have to be pulled back west
in future forecast updates.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1000 AM CDT Thu May 2 2024

Infrared satellite imagery at 15z showed MVFR stratus dissolving
southeast of the airports, as subsidence clears out the sky
through midday. VFR/SKC is expected through 12z Fri, with
increasing stratus from the south after 12z Fri as moisture
increases. Strong north winds gusting to near 30 kts will
prevail through 21z Thu, then quickly diminish to light NEly
after 00z Fri. Light winds will trend SEly Friday morning.

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Turner