574
FXUS63 KDDC 031501
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
1001 AM CDT Fri May 3 2024

...Updated Aviation/Key Messages...

.KEY MESSAGES...

- Much needed rainfall expected across much of southwest Kansas
  Friday night and early Saturday. Some strong to marginally
  severe thunderstorms are possible.

- North winds and cooler air Saturday.

- Severe thunderstorms are expected in Kansas Monday, with the
  risk of hail and tornadoes east of US 283 Monday afternoon and
  evening.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 400 AM CDT Fri May 3 2024

The main forecast challenge will be in the Tonight period with
respect to severe weather risk and how much/where heaviest rainfall
will occur.

Overnight water vapor loop showed the first northern branch jet
streak lifting northeast out of the Northern Plains into the Upper
Great Lakes region with the next upstream jet streak entering the
Northern Rockies. The lower troposphere was beginning to feel the
influence of the next jet approaching with low level winds
continuing to slowly veer around from the northeast to the east
overnight. Observations were showing lower to mid 50s dewpoints not
too far south of our forecast area across western Oklahoma and the
Texas Panhandle. This increasing moist upslope low level flow
pattern was manifesting as low stratus development per Nighttime
Microphysics RGB satellite loop. As low level winds continue to veer
to the southeast, moisture advection will increase into southwest
Kansas today. As this is happening, our upstream jet streak will be
rounding the base of the shortwave trough as it moves east across
Wyoming later today.

Low level cold frontogenesis will ramp up in earnest late this
afternoon and this evening across northeast Colorado and southwest
Nebraska. South of the front, a 998-1000mb surface low will be
across southeastern Colorado. Increased lee trough/dryline
convergence near this surface low will foster development of surface-
based thunderstorms across southeast Colorado ahead of the cold
front. There is a high degree of confidence in convective initiation
as just about all convection-allowing models (CAMs) show development
in the 21-24Z time frame late today. HREF mean SBCAPE in the 1000-
1300 J/kg and favorable looking hodographs with rather well-shaped
clockwise curvature in the 0-3km layer support supercell structures
with the surface low/dryline initiation across southeast Colorado.
There is a fairly solid clustering of 50+ J/kg 2-5km AGL Updraft
Helicity from Baca and Prowers County, CO into our western counties
of Hamilton-Stanton and points east toward Scott-Finney-Haskell
County by 01Z (8pm CDT) or so. Any supercells will be capable of
golf ball to perhaps 2-inch diameter hail stones as the primary
risk. As the cold front approaches west central KS later tonight,
additional storms will form with the mode being more linear in
nature with the greatest severe risk being 55 to 70 mph wind gusts.
The initial supercell(s), should they form as forecast, may wipe out
some (or most?) of the CAPE which complicates the severe weather
risk later on tonight with the main cold front. Regardless, low
level moisture will continue to advect northward toward the front
late tonight with very strong low level winds ahead of and behind
the front with intense cold frontogenesis. The magnitude of
convergence/frontogenesis is expected to result in numerous showers
and thunderstorms. Most models now have a rather large area of one-
half to one inch of rain, and given the forcing for ascent and other
aforementioned meteorological reasons, it is hard to argue with this
aggressive QPF.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 400 AM CDT Fri May 3 2024

Monday continues to be the most hazardous looking weather day in the
Long Term period as a very impressive cyclonically-curved jet streak
enters the Great Plains. The exit region of this jet will aim
squarely on Nebraska and Kansas with the mid level and surface
cyclones undergoing robust development through the day Monday. We
will likely see both severe weather and fire weather risk late
Monday. There remains high uncertainty in where exactly the dryline
and/or mid level cold front will be positioned by the time
convection initiates Monday afternoon. The ECMWF, no surprise, is
the farthest west of the three main global spectral deterministic
models with the dryline/dry intrusion front feature somewhere
near/west of Pratt by "go" time. The EC has mid 60s dewpoints
driving north into south central Kansas with a classic looking
vertical wind shear profile very  much on the supercell end of the
spectrum. Monday`s main question will be how long mode can be
supercell. The shape/orientation of the upper level jet almost
orthogonal to the orientation of the dryline/dry intrusion front is
an important pattern recognition component to consider as many
historical Great Plains tornado outbreaks have a similar type of
upper level jet pattern with a large warm/moist sector out ahead of
it.

On the other side of the dryline, the development of drought
conditions and stunted green-up so far this spring west of Highway
283 will likely yield Critical Fire Weather risk as afternoon
relative humidity is likely to fall below, if not well below 15% on
a strong southwest wind 20 to 35 mph.

Monday`s storm will be the last severe weather risk across
southwest/south central Kansas for the foreseeable future as the end
of the Long Term period and beyond will be characterized by
anomalous high surface pressure, cooler temperature, and drier air
as the North America pattern becomes one of ridge in the west and
trough in the east through at least 13 May. The latest ECMWF and
GEFS Ensemble systems are in rather remarkable agreement at Day 10
regarding this cooler/drier/essentially non-existent severe wx
pattern as we head deeper into the middle-third of May.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1001 AM CDT Fri May 3 2024

VFR is expected to continue at all airports through at least
00z Sat. Broken mid level clouds will prevail through Friday
afternoon with increasing S/SE winds, gusting to near 25 kts.
A strong cold front is scheduled to sweep through the airports
in the 06-09z Sat time range, accompanied by an abrupt, strong
northerly wind shift, gusting to near 30 kts. Numerous rain
showers and thunderstorms are expected to accompany frontal
passage. Confidence was high enough to include convective
TEMPO groups in this 18z set of TAFs for all airports, in this
06-09z range. Outflow winds from the strongest storms may
approach 50 kts. Rain showers are expected to diminish from
NW to SE through 12z Sat, with widespread MVFR stratus ceilings
through Saturday morning.

&&

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

&&

$$

SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Turner