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683
FXUS63 KDDC 181919
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
219 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...
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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.
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&&

.DISCUSSION...
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Issued at 209 AM CDT Tue Jun 18 2024

07z observations and upper air analysis shows a large longwave
trough over the western CONUS leading to southwest winds aloft
in the central plains. At the surface a 983-985 mb low is
located from northeast Colorado through north central Nebraska
leading to strong surface to 850 mb winds and with the well
mixed layer temperatures have only fallen into the upper 70s.

For today as another 700 mb shortwave moves over the Colorado
Rockies a surface low will develop and move into northwest
Kansas by early this afternoon. As the 500 mb longwave trough
moves into the northern plains the leading edge of colder air
will track into northwest Kansas by the noon hour. This cold
front and upper level wave will set the stage for thunderstorms
to develop starting in north central Kansas and then extending
south and westward along the front by sunset. With the upper
level winds oriented parallel to the front the storms will grow
upscale and become linear quickly and there is high confidence
the storms will train along the front and start dumping heavy
rain roughly along an Elkhart to Hays line. With CAPE values in
the 2000-3000 J/kg range and 0-6 km bulk shear values at 30-40
kts and CAMs showing some embedded supercells in the line...hail
up to 2 inches in diameter and 60 mph winds are possible. The
storms will be high based so tornado risk will be low...however
given that a strong surface cold front and lower level shear
will be high we can`t rule out the possibility of some brief
landspouts with the storms.

Tonight through Wednesday the risk will turn more towards the
flash flooding. With the cold front likely to become stationary
and the upper level winds out of the southwest providing more
700 mb shortwaves to provide lift...we could see a widespread
area of rain and storms with little to no movement and training
over the same areas through much of Tuesday night into
Wednesday. Short term models have some variance north or south
of where the frontal boundary will be but there is probabilities
(around 20%) of receiving 3 inches or more from the storms and
high probabilities (70-80%) of 1-2 inches of rain. The location
of the rain will be concentrated between the highway 50 and I-70
corridors. This combined with these areas receiving 3-6 inches
of rain earlier in the month and having higher soil
moisture...leads to an increased risk of localized flash
flooding and a watch is issued for these areas. Wednesday will
also be cool with clouds and periodic rain and storms all day
that highs could only be in the 70s to around 80.

Rain should end by Thursday as ensemble upper level air patterns
have a large high over the southeast US and the upper level
trough in the northern plains exiting. This southerly flow
in the boundary layer should push the stationary front north as
a warm front and take the better lift into the northern plains.
Long term ensembles are hinting at the return of hotter
temperatures and NBM forecast output is responding in kind with
highs around 100 by early next week.
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&&

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

$$

UPDATE...Finch
DISCUSSION...Turner
AVIATION...Turner