Area Forecast Discussion
Issued by NWS Dodge City, KS

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FXUS63 KDDC 241845
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
145 PM CDT Thu May 24 2018

...Updated Long Term...

.SHORT TERM...(Today and tonight)
Issued at 407 AM CDT Thu May 24 2018

A mesoscale convective system (MCS) was moving across northwestern
Oklahoma during the overnight hours -- farther south than mesoscale
models forecast, thus have keep POPs highest just along the Oklahoma
border through the early morning hours. This MCS occurred in
vicinity of the right-entrance region of a north-south oriented
upper level jet extending from the western Dakotas into eastern
Colorado. The main upper low was located over eastern Montana, but
trailing shortwave energy could be seen on water vapor loop and RAP
analysis extending from eastern Wyoming to northern Utah. The
feature across northern Utah is of most interest this morning, as
short-term models show this moving into Colorado later in the day,
resulting in low level winds veering to easterly component behind
very weak cold front (more or less a surface trough axis as the air
behind the front will be downslope modified).

What will probably happen is that initial convection will fire off
the Palmer Divide mid to late afternoon in the drier air where
mixing heights will be high. A storm (or storms) will likely move
east along or just south of I-70 toward the Kansas border by early
to mid evening, interacting with more moisture/higher CAPE. Deep
layer shear profiles look good for at least marginal supercell
structure with solid 90-degree turning from near-surface (south) to
6km AGL (from almost due west). All convective-allowing models show
strong/severe convection organizing into at least a small MCS later
in the evening as it moves deeper into Kansas. In the grids, will
have 50-60 POPs mainly along/north of Highway 96 with 20-30 POPs
down to the Highway 50 corridor. Should a MCS organize early enough,
there will likely be a tendency toward right-moving into low level
jet. The NSSL WRF-ARW model suggest this more southern solution down
toward Highway 50, although the consensus among all models is that a
MCS will track more east or east-southeast between Highway 96 and I-
70. As far as convective mode goes for the DDC CWA, the thinking is
that a MCS will at least be in the formative stages with best chance
at early supercell phase being in GLD CWA across northwest Kansas
and adjacent east-central Colorado. For that reason, will be going
with most likely largest hail size across DDC CWA in the quarter to
golf ball size range with max wind gusts 60-70 mph.

.LONG TERM...(Friday night through Thursday)
Issued at 145 PM CDT Thu May 24 2018

Long term forecast will be highlighted by persistently above
normal temperatures (both highs and lows) along with a small
chance for a late day/evening thunderstorm virtually every day.

A rather odd upper air pattern is forecast on Saturday, with
strong ridging over Kansas, sandwiched between a 568 dm closed
upper low in Nevada, and a developing tropical cyclone in the Gulf
of Mexico. Subsidence beneath the ridge axis looks very strong
Saturday, and agree with the model blend that keeps SW KS dry.
Plenty hot, with afternoon max temp grids in the 95-101 range.
Normal for late May is lower 80s. SE winds of 10-20 mph.

Synoptic pattern remains the same Sunday, but edges eastward, with
the ridge axis centering near Wichita by late afternoon. 12z ECMWF
develops tropical cyclone Alberto strongly in the central Gulf of
Mexico. Weak SW flow aloft develops aloft over SW KS, with
convergence along the attendant lee troughing focusing scattered
afternoon convection across the western zones. Despite strong SEly
winds, moisture supply will be less than ideal to support severe
convection (robbed by offshore flow west of Alberto). 12z ECMWF
only supports surface dewpoints in the lower 50s at storm
initiation time. As such, storms that form over the western
counties Sunday afternoon will be high- based and form in an
inverted-V environment, with a primary risk of strong downburst
winds. With no airmass change, temperatures will remain stagnant,
with continued lows in the 60s and highs in the 90s.

Memorial Day, tropical cyclone Alberto is progged to make landfall
in the central Gulf Coast. The ridge of high pressure separating
Kansas from Alberto will progress further eastward, centered over
SE KS. Western closed low edges eastward as well, into Utah. SW
flow aloft will be somewhat stronger, with models hinting at
embedded shortwaves to enhance late day convection. ECMWF shows a
modest increase in moisture quality, courtesy of continued
moisture advection on strong SE winds. Again, Alberto will have
something to say about this, but ECMWF still shows lower 60s
dewpoints returning to SW KS Memorial Day afternoon, along with
convective QPF initiation. Given the climatological peak of severe
weather season, will need to monitor for severe potential on
Memorial Day closely, despite the tropical cyclone`s presence. The
best wind flow/shear to support strong convection appears to be
Monday, before trough lifts into the northern plains and weakens.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1237 PM CDT Thu May 24 2018

Terminals are in VFR conditions through this afternoon, with
southerly/southeasterly wind at 15-20 knots and gusts to 25-30
through sundown. Wind becomes less than 10 knots thereafter
through the morning. Convective Allowing Models are consistent
with a thunderstorm complex developing along the Colorado/northern
Kansas border this afternoon ahead of a cold front, and moves
east through western Kansas in the evening. Highest confidence
for TSRA is in KHYS from 2-6Z. Have placed VCTS in GCK and DDC
from 2-5Z due to uncertainty in how far south the storms will
form. Periods of MVFR conditions can be expected as storms move
through. Winds shifts northerly/northeasterly in the morning as
the weak cold front moves into Southwestern Kansas, albeit wind
stays at less than 10 knots.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  92  63  92  63 /  20  30  10  10
GCK  92  61  92  61 /  10  20  10  10
EHA  92  60  93  61 /  10  10  10  10
LBL  91  63  97  63 /  20  10  10  10
HYS  91  63  91  63 /  20  50  10  10
P28  90  66  96  66 /  20  20  10  10

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

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


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