416
FXUS63 KDDC 060531
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
1231 AM CDT Sat Jul 6 2024

.KEY MESSAGES...

- Isolated to scattered (15% to 30%) for severe thunderstorms
  possible late Saturday and late Sunday across southwest Kansas

- Unseasonably cool temperatures Sunday through early next week.
  There is less than 50% chance for highs to be above 90
  degrees from Sunday through Thursday.

&&

.DISCUSSION...
Issued at 257 PM CDT Fri Jul 5 2024

The ensemble clusters are in good agreement with a northwest
flow establishing itself across the Rockies and Central United
States this weekend as an upper level ridge strengthens and
moves slowly east from the eastern Pacific into California and
the Pacific Northwest. Ensembles also show decent agreement on
the timing and strength of two upper level systems that will be
crossing the Central Plains late Saturday and late Sunday. This
has resulted in increased confidence for the chance of
thunderstorms ahead of each of these upper level systems
(40-60% on Saturday and +80% on Sunday), given low-level forcing
along a surface boundary in or near southwest Kansas, along
with late day instability and shear.

On Saturday, the storms are expected to develop along a surface
boundary in eastern Colorado and northwest Kansas during the
afternoon. During this time frame the potential exists for
discrete supercells due to the flow being perpendicular to the
boundary as they develop late in the day along with a 50-60%
chance for 0-6 km shear to be >40 knots and improving late day
instability. Initially, the hazards will be large hail (1-2
inches) and strong, damaging winds based on the forecast 0-6 km
shear, high cloud bases, and forecast downdraft CAPE. As these
storms move southeast during the evening, the risk for large
hail will decrease, but strong gusty winds may still be an issue
as they weaken during the overnight hours.

On Sunday, a similar setup will exist ahead of our next upper
level trough, with storms developing along a surface boundary
that will be located in or near southwest Kansas. The main
differences between Saturday and Sunday will be the timing of
the upper level trough (early evening versus overnight), the
location of the surface boundary late in the day, and cooler
500mb temperatures. Based on where storm development is most
likely to occur late Sunday, along with 0-6 km shear >40 knots
and mid-level instability ahead of the upper trough, it appears
that the risk for large hail and strong gusty winds will be more
widespread on Sunday across southwest Kansas. This contrasts
with Saturday, when storms are expected to develop across
northwest Kansas and then weaken as they move into southwest
Kansas Saturday night.

As for temperatures this weekend through next week, below
normal seasonal temperatures (highs around 80F) can be expected
on Sunday. During this time frame, both the ECMWF and NAEFS
percentiles are down in the 10th to 25th percentile range, and
the ECMWF Extreme Forecast Index ranges from -0.6 to -0.8. This
indicates high confidence (>75%) in trending towards the current
NBM forecast guidance, which is near or below the 25th
percentile for highs on Sunday afternoon. These cool
temperatures will be followed by a slight warmup early next
week. However, temperatures will stay near or below normal for
this time of year, as several more upper-level systems embedded
in the northwest flow are expected to cross the Central Plains,
each bringing a reinforcement of cooler air into southwest
Kansas. Towards the end of the work week, improving downslope
flow will develop as the upper-level ridge moves closer to the
Rockies. A gradual warming trend can be expected for southwest
Kansas, but a dramatic warmup is not anticipated. Approximately
30-40% of the ensembles predict a stronger and deeper upper-
level trough developing midweek over the Great Lakes Region/Ohio
Valley, which would limit how far east and how quickly the
downslope warming would occur. Additionally, the latest ECMWF
Extreme Forecast Index at 00z Friday ranges from -0.5 to -0.6.

Overall, temperatures next week across southwest Kansas will be
in the 80s. Temperatures will approach 90 degrees towards the
end of the work week, but the exact timing and extent of the
warmup by Friday are still uncertain.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1228 AM CDT Sat Jul 6 2024

Light south winds will increase to 15 to 20 kts in advance of an
upper level disturbance by 15-18z. By the end of the period or
just after, thunderstorms over northwest Kansas could move
southeast and affect the TAF sites, with a windshift to the
northwest, heavy rain and small hail.

&&

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

&&

$$

DISCUSSION...Burgert
AVIATION...Finch