490
FXUS63 KDDC 011522
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
1022 AM CDT Wed May 1 2024

...Updated Aviation/Key Messages...

.KEY MESSAGES...

- Scattered severe thunderstorms expected eastern half of
  southwest Kansas Wednesday afternoon and evening. Very large
  hail and tornadoes are possible.

- Slightly cooler with strong north winds Thursday.

- Widespread accumulating rainfall most likely Friday night and
  Saturday morning.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 306 AM CDT Wed May 1 2024

A 500mb upper low located over Montana and Idaho earlier this
Wednesday morning will move into the Northern Rockies on
Thursday and then out into the northern Plains on Friday.
Ensembles remain in good agreement with previous runs in moving
two more upper-level troughs around this slow moving upper low
over the next 48 to 60 hours. Each system will take a similar
track, moving from the Pacific Northwest to around the Four
Corners region and then out into the plains.

Our next in the series of upper level systems was exiting the
Pacific Northwest and approaching the Four Corners region. As
this system approaches today, the east to southeast wind will
continue to draw more humid air in the lower levels back into
southwest Kansas as surface pressures begin to fall along the
lee of the Rockies. As this occurs, the surface boundary located
just south of the Oklahoma border will begin to slowly lift
northward back into southwest Kansas during the day. How far
north this boundary will move today will be key to when and
where the chance for severe weather will occur later today
across southwest and south central Kansas. As of 2 am this
Wednesday morning, confidence is high (>80%) that this front
will not move as far north as what the models indicated last
night, but confidence is low (<30%) on exactly how far it will
move into southwest Kansas today. The main reason for the low
confidence is is the uncertainty of how deep our layer of
low level moisture will be north of this boundary between 12z
and 18z today and what the impact of the overnight convection
across northern Oklahoma might have. In addition, it still looks
like there will be a chance for some elevated convection later
this morning, given the 850mb-700mb moisture and warm air
advection developing near the northern edge of the mid level
warm layer that will be moving northward towards the Nebraska
border. Given the latest CAMS the best chance for this elevated
morning convection will be near and north of the I-70 corridor
and east of a Hays to Coldwater line. Should we get some
convection early this morning, then the potential exists that a
few of these storms may be capable of producing hail up to
around one inch.

As elevated convection ends around noon, the next round of
severe weather potential will be focused along and east of a
dryline and near a warm front. The dry line will extend south
of a warm front, across southwest Kansas and into northwest
Oklahoma. At this time given the low confidence on where these
boundaries will be late day have decided to use the majority of
the CAMS as a guide. Based on this the dryline will be the to
be east of Highway 283 and the warm front will be located
somewhere between Kinsley and Hays. Also, given the morning
clouds limiting the warmup today and the forecast 700 mb
temperatures of around 9C, it appears that if we do get some
convection to develop then these may be more isolated to widely
scattered then what the current CAMS suggest. Forecast shear
today suggests discrete supercells possible, if storms develop,
along the dryline with more linear mode being possible along
the warm front today. Given this even if it turns out that we
only get a few isolated storms today...any storm that does
develop will be in a favorable environment to produce very large
hail (>2) and strong gusty winds. An isolated tornado or two
also cannot be ruled out near our dryline/warm front given the
enhanced low level shear late day/early evening.

Low confidence of where the warm front will be this afternoon
be will not only impact the late day storm chances but it will
also impact temperatures. Areas north of the warm front will see
afternoon temperatures in the 60s to lower 70s. South of this
front, it will be another warm afternoon with highs in the 80s.
Also south of this warm front the afternoon humidity values will
fall back into the 15 to 25 percent range during the afternoon
west Meade. These low humidity values and developing gusty
southwest wind late day will create elevated to near critical
fire weather conditions.

As these storms move into central Kansas overnight, a cold
front will cross southwest Kansas between midnight and 7 am as
the upper-level trough exits the Central Rockies and moves out
into the West Central High Plains. This will result in scattered
convection lingering through Thursday afternoon. This area of
possible convection during the day is not expected to be severe,
but strong thunderstorms, some capable of producing penny-sized
hail and wind gusts up to 55 mph, will be possible. Even with
this said, I am not totally able to rule out an isolated
quarter sized hail or 60 mph wind gust east of Highway 183.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 306 AM CDT Wed May 1 2024

Thursday night and Friday, the upper level trough will lift
north into the Northern Plains, and this will be quickly
followed by our next upper level system. The latest short range
models currently have this upper trough located over the
Central Rockies by 18z Friday. As this next system follows a
similar track as the previous upper wave, there will be another
opportunity for precipitation for all of southwest Kansas as
convection is forecast to develop late day across northeast
Colorado and then spread east into western Kansas along a mid
level baroclinic zone/area of 0-1km thetae advection. This
Friday night system may be of interest measurable precipitation
given that the latest ensemble means were showing a 30-50%
chance of 24-hour precipitation of >0.25 ending at 1 pm
Saturday and a 20-30% chance of 24-hour precipitation of >0.5.
Granted, this chance is not very high, but it is better than
what we have seen over the past 3-4 weeks. Along with this
chance for widespread precipitation the a few of the stronger
storms early Friday night will be capable of producing gusty
winds and hail up to the size of quarters.

Once this Friday night system lifts northeast, some weak
ridging aloft crosses western Kansas as the upper low over the
Northern Plains moves into Canada. This will allow for a brief
break in the precipitation chances, but the chance for
thunderstorms will return Saturday night and then continue through
Monday as our next, more significant, upper level low/trough
exits the eastern Pacific and begins to move across the western
United States towards the Central Plains.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1022 AM CDT Wed May 1 2024

Widespread MVFR stratus at 15z is expected to improve to VFR
over the next few hours, as a warm front makes progress to near
US Highway 50 by 21z. Elevated winds will gust to near 25 kts
through this time with an easterly component. After 21z,
isolated thunderstorms are expected to develop, most likely in
the vicinity of DDC, between 21-00z. With low confidence of
impacts directly at the airport, only carried VCTS/CB for now.
Probability of convection at the other airports is too low to
warrant a mention in the TAFs. A cold front is expected to bring
a north wind shift 06-09z Thu, with strong north winds gusting
to near 30 kts. Consensus of short term models shows post
frontal MVFR stratus behind the cold frontal passage through
12z Thu. IFR stratus is most likely at HYS; in fact, IFR to MVFR
stratus is expected to hold at HYS through most if not all of
this TAF period.

&&

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

&&

$$

SHORT TERM...Burgert
LONG TERM...Burgert
AVIATION...Turner