952
FXUS63 KDDC 251633
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
1133 AM CDT Tue Jun 25 2024

.KEY MESSAGES...

- Heat Advisory remains in effect for this afternoon for
  forecast heat index values of 103 to 107 degrees. An isolated
  location or two, particularly across Red Hills region, may
  approach 110F heat index for a brief time.

- Another round of scattered thunderstorms tonight, but the main
  activity will likely be southeast of much of our forecast
  area.

- A cold front late tonight will mark the beginning of an active
  stretch of nightly thunderstorms rolling east across western
  Kansas, mainly at night. Signals continue to be quite strong
  for widespread 1 to 2 inches of total rainfall between
  Wednesday Night and Sunday.

&&

.DISCUSSION...
Issued at 415 AM CDT Tue Jun 25 2024

The overnight water vapor imagery and RAP analysis showed a
continued split jet pattern in the upper troposphere with the main
branch at its typical summer latitude near the Canada border. The
secondary, weaker, yet still important jet farther south extended
from northern Nevada east across the Colorado Rockies. RAP analysis
had an enhanced jetlet centered across central Colorado with left
exit region across west central Kansas. This is likely the main
forcing mechanism for ascent to promote the continued generation of
scattered showers and thunderstorms through the night between
Highway 50 and I-70. The 00Z HREF had a fairly good handle on this
overnight activity as it maintained 10km neighborhood probability of
30-40% for 25+ dBZ composite reflectivity. The 00Z HREF does show
these probabilities lowering quite a bit toward sunrise, and the POP
grids will reflect this forecast weakening of overnight convection.

As we head in to the afternoon Tuesday, all the models show this
southern branch of the jet shifting northward into Wyoming, yet
keeping west central and northwest Kansas in a favorable exit region
for upward vertical motion to support another round of
thunderstorms. The increasing low level thicknesses due to rising
overall heights across the Southern Rockies will support another hot
afternoon. In fact, 850mb temperatures will be slightly warmer, thus
a larger area will likely see highs in the 101 to 104F range. Models
are also showing a relative minimum signal in afternoon highs
east/northeast of Dodge City, and the HREF does show this signal,
but even if temperatures do not reach 100 degrees in portions of the
eastern CWA, dewpoints are likely to hold in the 64 to 67F range to
keep resulting heat indices in the 104 to 107F range. No changes are
going to be made to the counties that are currently in the Heat
Advisory for this afternoon.

Using HREF 10km neighborhood probabilities as a proxy for where/when
best thunderstorm activity will be later this afternoon, signals are
strongest across northern/northwestern Oklahoma where probabilities
of 25+ dBZ composite reflectivity exceed 35% across much of the
northern half of Oklahoma. A secondary signal is shown later in the
afternoon/early evening across our northern/northwestern counties in
vicinity of a weak surface vorticity center, but the convective
signal is not nearly as strong as farther southeast, so the
uncertainty is greater.

Going forward, all the models still show a fairly strong cold front
by summer standards later on tonight into Wednesday. This will put a
temporary break on excessive heat indices (except for one more day
of very hot heat indices possible across the Red Hills). This front
will actually mark the beginning of a rather prolonged wet pattern
for western/central Kansas (and much of the Central Plains for that
matter). Post frontal moist upslope will develop by Wednesday Night,
focusing thunderstorm development across eastern Colorado. The first
of several nights of formidable mesoscale convective systems (MCS)
will likely move out across western Kansas Wednesday Night. An
ensemble approach is still the best forecast method for best run-to-
run continuity. The 00Z run of the 100-member Grand Ensemble
continues to show around 0.8" 50th percentile for Dodge City (and
much of the rest of our southwest Kansas region, for that matter).
90th percentile QPF through the end of the month are nearly 2
inches. Given multiple chances for much of the area to see heavy
rainfall over a roughly 4-night period, it is very reasonable to
think that upper end potential (1-in-10 chance) of 2-3" of rainfall
is certainly not out of the question. As it stands of this forecast,
there is really not one night out of the 4 (Wednesday Night through
Saturday Night) that is favored over any other at this point, and
there is going to be a feedback from previous night MCS that will
have ramifications on the next day`s forecast that simply cannot be
predicted on a sub-synoptic scale. Regardless, the synoptic pattern
characterized by a summer ridge that is flattened out and south of
our area will continue to favor MCS activity in vicinity of the
Southwest Kansas region through the end of the month.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1131 AM CDT Tue Jun 25 2024

Decaying thunderstorms over the south central Kansas counties
late this morning will not impact any local terminals. Through
mid afternoon expect clear conditions and VFR at all sites. By
about 23z the potential increases significantly for isolated
thunderstorms development (under 10% areal coverage) associated
with a surface cold front that should be near GCK oriented north
east to southwest. Models have favored northern areas of the
forecast area along this boundary for isolated convection,
(between 23z and 3z), meaning very low confidence exists in even
having a storm in the vicinity of any given terminal. Any storm
that does develop will be in a deeply mixed layer with good
potential for locally severe thunderstorm wind downbursts. The
front pushing though later in the evening will turn surface
winds out of the north.

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT this evening for KSZ030-031-045-
046-064>066-077>081-086>090.

&&

$$

DISCUSSION...Umscheid
AVIATION...Russell