Area Forecast Discussion
Issued by NWS Dodge City, KS

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951
FXUS63 KDDC 171837
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
137 PM CDT Thu May 17 2018

...Updated Long Term...

.SHORT TERM...(This afternoon through Friday)
Issued at 1213 PM CDT Thu May 17 2018

Gearing up for severe weather operations later today and again on
Friday/Friday night.

Surprise convection that developed earlier this morning is
weakening rapidly. We are expecting it to be quiet for several
hours now, through about 4 pm, as SE winds increase markedly and
instability mounts. CAPE in excess of 3000 J/kg is expected across
along and west of US 83 by peak heating. Thunderstorms are
expected to initiate along the KS/CO border around 5 pm, and
subsequently spread eastward across SW KS this evening, reaching
Highway 283 by 9 pm. Many CAMs, HRRR and 12z NAM all show
convection remaining largely discrete/supercellular, which will
greatly enhance very large hail potential (up to 3" in diameter).
SPC has expanded severe probability and upgraded risk for large
hail, and we concur. Regarding tornado potential, low level shear
and moisture quality are less than optimal, keeping the risk low.
This said, we are talking about discrete supercells in SW KS in
May, during the early evening when SE 850 mb winds increase to
30-40 kts. A tornado can`t be ruled out, but clearly hail is the
primary threat through this evening. Maintained a severe hail/wind
mention in the forecast mainly west of US 283 through this
evening. Increased pops into the likely category for several hours
this evening. Weakening storms will progress through the eastern
zones later tonight. There is uncertainty regarding the rate of
decay, as moisture quality will only be improving with eastward
extent and time. Regardless, expect most/all activity to clear SW
KS by sunrise Friday morning. Radiational cooling will be very
poor tonight, with moist SE flow persisting, holding most
locations in the lower 60s.

Another active severe weather day is expected on Friday. Details
are still emerging. Of note, a trend toward a slower solution
continues, with 12z NAM now trending its surface low SW toward
Clayton, New Mexico by 7 pm. This is close to the ECMWF`s
continuity, placing its surface cyclone near Elkhart 7 pm Friday.
This slightly slower solution will give moisture quality some
additional time to improve, with initiation not expected until the
7 pm time frame along the US 83 corridor. Moisture quality will be
less than pristine (less than what we can normally get from the
Gulf of Mexico in May). Moisture depth in the boundary layer will
be less than optimal as seen from forecast soundings. Still, ECMWF
continues to spread low to mid 60 dewpoints into the eastern CWA,
and lower 60s can be expected along the dryline/triple point at
initiation time Friday evening. CAPE of 2-3k J/kg will be common,
with convergence and shear assisting in triggering and organizing
convection. The threat for tornadic supercells remains, with the
threat area trending SW with time. Excellent lapse rates will
continue to support huge hail from any discrete activity.
Otherwise, strong SE winds will continue moisture advection
through the daylight hours Friday, with highs again in the 80s.

.LONG TERM...(Friday night through Thursday)
Issued at 137 PM CDT Thu May 17 2018

Very little time spent on the long term, given severe weather
threatening today and Friday. Model blend from forecast builder
was largely accepted, with small chances of showers and
thunderstorms virtually every day except Sunday.

Closed low over northern Utah Friday PM ejects rather quickly into
Nebraska on Saturday. Vast majority of associated shower and
thunderstorm activity will be north of SW KS by Saturday, with
gusty W/NW winds and modestly cooler temperatures. Some wraparound
rain showers will likely clip the I-70 corridor.

Broad shortwave ridging on Sunday, delivering a beautiful spring
day and dry weather. Pleasant highs in the 70s with light winds.

Monday into next week, 12z ECMWF displays a rather odd pattern for
May, with a large scale but relatively weak closed low enveloping
the SW US. 568 dm low near Los Angeles Monday afternoon
essentially sits and spins to Las Vegas Tuesday, before weakening
and lifting north through the Rockies. Broad SWly flow aloft will
prevail over the plains as a result, with numerous embedded
shortwaves triggering virtually constant small chances of daily
convection. Given it`s May, some severe weather potential will
have to be evaluated day-to-day, as shortwaves/jet maxima interact
with the dryline and moisture supply. Temperatures will show
little diurnal change, with highs in 80s and lows in the 50s and
60s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1055 AM CDT Thu May 17 2018

VFR will prevail through this TAF cycle, outside of convective
influences. Scattered thunderstorms are expected to develop
along/west of US 83 around 21-22z, and then progress eastward
through the SW KS terminals through 06z Fri. The threat of severe
hail/wind is highest near GCK/LBL this evening, with weakening
storms expected to reach DDC around 01-02z Fri, and HYS 03-04z.
Outside of convection, strong SE winds are expected to develop
at DDC/GCK/LBL this afternoon/evening, with gusts in the 30-32 kt
range. SE winds will remain gusty overnight, followed by more
strong SE winds after 15z Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  87  62  86  61 /  20  60  30  30
GCK  87  61  88  57 /  20  60  50  30
EHA  90  60  90  56 /  40  40  10  10
LBL  89  64  91  60 /  60  60  50  10
HYS  86  63  84  61 /  10  30  30  40
P28  87  65  88  66 /  20  20  20  30

&&

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

$$

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



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