149
FXUS63 KDDC 181926
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
226 PM CDT Tue Jun 18 2024

.KEY MESSAGES...

- Rain and thunderstorms are expected Tuesday afternoon through
  Wednesday. Some storms will produce severe wind and hail, and
  some locally very heavy rainfall is expected. Some flooding
  issues are possible through Wednesday morning, with a Flash
  Flood Watch in effect.

- Much cooler behind a cold front on Wednesday, with
  temperatures in the 60s and 70s through the day.

&&

.UPDATE...
Issued at 153 PM CDT Tue Jun 18 2024

MESOSCALE DISCUSSION...

A cold front was beginning to stall across southwest Kansas.
Convection was already developing along the boundary early this
afternoon. 0-6 km bulk shear values were marginally supportive
of supercell structures. However, shear will be stronger on the
cool side of the boundary and dewpoints/CAPE values will be
high. There may be a brief window through 6 pm or so when
tornadoes and very large hail are possible with any isolated
supercell that is located on the cool side of the boundary.
Additionally, landspout tornadoes are possible for storms
anchored along the front given the steepening low to mid level
lapse rates. During the evening hours, expect convection to form
into a line, with marginally severe hail and damaging wind the
main concern. Given the high moisture content and possibility of
training storms, flash flooding is possible for areas that
experience multiple storms.

&&

.DISCUSSION...
Issued at 200 PM CDT Tue Jun 18 2024

Midday surface observations depicted an unusually strong cold
front for mid June standards, slowing its forward progress from
the northwest zones into NW KS. Ahead of the cold front, strong
south winds continued, gusting 40-45 mph. Strong moisture
convergence along the advancing boundary is expected to result
in explosive thunderstorm development along a roughly Hays-
Dodge City-Liberal line starting around 4 pm. Strong instability
and moderate wind shear, combined with the strong surface
boundary providing a source of low level vorticity, will result
in some supercell structures for the first few hours of the
event, roughly 4-7 pm. Large hail and tornadic/landspout
potential is expected from this activity, especially where 1)
storms can remain discrete longer, and 2) surface winds retain a
backed easterly component. Hatched probability for significant
hail > 2 inches and significant wind gusts > 75 mph was
maintained on the 1630z outlook, and with an increase in tornado
probability along that preferred HYS-DDC-LBL line 4-7 pm.
Moisture content is high, with dewpoints near or above 70,
resulting in low LCLs and very efficient heavy rainfall
production. Very rare to have such a glaring flash flood
potential/risk this far west in SW KS.

During the course of the evening, and through tonight and
sunrise Wednesday, a mesoscale convective complex (MCS) will
evolve over SW KS, along and north of the slowly moving frontal
boundary. Threat during the evening will rapidly transition
from hail/wind/tornadoes, to widespread heavy rainfall toward
midnight. In fact, areas of heavy rainfall are expected through
the night, and the inherited flash flood watch is warranted and
well placed. Expanded the flash flood watch southward to
include Haskell, Meade and Clark counties. QPF of 1-2 inches is
expected to be common, especially along and south of US 50, with
2-4 inches typical where training becomes established. Some CAM
solutions are printing out some crazy rainfall totals through
tonight; one should not place much emphasis on these exact
forecast amounts and locations. Rather, the message is clear:
locally intense, flooding rainfall is expected tonight through
Wednesday morning, with hydrologic concerns. Needless to say,
heavy rain wording was included in the grids and forecast
products. Residents are reminded to avoid driving through water
of unknown depth, especially tonight after sunset.

Additional rain and thunderstorms will regenerate through at
least the first half of Wednesday, as forcing for ascent
continues above the slowly advancing cold front. All models also
generate widespread low stratus, with east/northeast winds
establishing in the saturated boundary layer. Between
unseasonably strong cold advection, and the stratus, Wednesday
will be much cooler; the question is how much cooler. For
example, 12z MET/NAM guidance keeps GCK and the northwest zones
in the 50s all day Wednesday. GFS solutions show a more modest
cooling, with a reduction of about 5C at 850 mb. Reduced
afternoon temperatures to the lower to mid 70s for many zones,
but suspect many will hold in the 60s.

A warming trend is expected Thursday through Saturday, as
temperatures quickly rebound in the strongest sunshine of the
year. Standing water and saturated topsoils from tonight`s rain
will slow this process down significantly. Still, mid 90s are
expected to be common by Saturday afternoon. 12z GEFS ensemble
members show a 30% probability of temperatures > 100 across the
favored Red Hills southeast of DDC Saturday afternoon. It
stands to reason that rain chances will also dwindle away during
this time window.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1123 AM CDT Tue Jun 18 2024

VFR will continue through the next several hours, with strong
south winds persisting, gusting to near 40 kts. Midday surface
observations showed a strong cold front draped across NW KS, and
this boundary will make progress further into SW KS this
afternoon. 12z ARW shows thunderstorms developing along this
cold front along a HYS-DDC-LBL line 21z-00z, and used this
timing as a guide in this set of TAFs. With the frontal boundary
becoming stationary for the remainder of the TAF period, periods
of rain, showers or thunderstorms will prevail through 18z Wed,
with reduced flight categories in locally heavy rainfall likely.
TAFs already include convective TEMPO groups for at least
initial development, but additional TEMPOs/amendments are likely
through the TAF period. Model consensus is for IFR stratus to
fill in behind the cold front/MCS through Wednesday morning,
with high confidence of degraded flight conditions through this
period.

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 7 PM CDT this evening through Wednesday
evening for KSZ030-031-043>046-063>066-076>080-087-088.

&&

$$

MESOSCALE DISCUSSION...Finch
DISCUSSION...Turner
AVIATION...Turner