000
FXUS63 KDDC 152036
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
336 PM CDT Fri Sep 15 2017

...Updated Short Term and Long Term Sections...

.SHORT TERM...(This evening through Saturday)
Issued at 332 PM CDT Fri Sep 15 2017

A vigorous vorticity maximum that was moving into southeast
Montana early this afternoon will continue moving northeast while
another deep trough digs from eastern Oregon into western Wyoming
by 12Z Saturday. Several minor upper level troughs were evident
along a plume of mid level moisture with H7 dewpoints of +2C to
+4C from southwest Texas into eastern Kansas. High based showers
and a few thunderstorms have persisted in the plume of mid level
moisture through the early afternoon hours. A minor upper level
trough evident on satellite imagery from southeast Colorado into
the Texas Panhandle may help to initiate a few thunderstorms near
a convergence zone/weak dryline from near HLC to east of LBL. A
cumulus field in this area has been growing since around 200 PM,
although the towers still are capped. The mid levels of the
atmosphere still are quite warm, and flow aloft is weak. It will
be difficult to get any organization or longevity to any
thunderstorms that do form.

The Wyoming upper level trough will lift out into the northern
Plains on Saturday, and a cold front will advance across western
Kansas during the morning hours. The boundary should extend from
northeast Kansas into northwest Oklahoma by mid afternoon, and
scattered thunderstorms can be expected to develop in the frontal
zone by late afternoon. High level southwest flow around 50 kts
will provide some ventilation and shear, and steep mid level lapse
rates will exist over the boundary. There will be some potential
for high wind and hail with the more intense thunderstorms.

Temperatures tonight will be warm for this time of the year with
low level winds near 15 knots, although winds will diminish toward
morning in west central Kansas as the cold front approaches.
Saturday will be a few degrees cooler than today except in south
central Kansas, where temperatures will rise into the low to mid
90s before weak cold air advection begins.

.LONG TERM...(Saturday night through Friday)
Issued at 332 PM CDT Fri Sep 15 2017

A considerably more active flow regime will evolve next week as a
mean upper level trough digs into the western United States and
southwest flow aloft becomes established over the central part of
the country. Although there may not be a well defined connection
with tropical thunderstorm activity, an area of enhanced
thunderstorms is likely to persist for a few days near the
Maritime Continent as a westward propagating equatorial Rossby
wave interferes constructively with a weak Madden-Julian
Oscillation. Enhanced thunderstorms near the Maritime Continent
often are correlated with troughing in the western United States
and increased chances for rainfall in the central part of the
country. The global models exhibit considerable spread in
forecasting evolution of the coherent tropical signals, but there
is broad consensus that enhanced thunderstorms are likely to
propagate into the western Pacific by late September. This may
favor a split flow regime in the western United States with at
least some potential for upper level cyclones in the southern
branch of the westerlies to provide increased chances for rainfall
into the first part of October.

In the more immediate future, the cold front that progresses
through western Kansas Saturday will become stationary in northern
Oklahoma Saturday night and Sunday before weakening and waving
back north as a warm front Monday. A weak low level jet may
provide enough lift to support elevated thunderstorms in at least
south central Kansas Saturday night, although chances for
nocturnal convection look better Sunday night as an upper level
trough moves into Colorado and enhances the low level jet.
Thunderstorm chances will continue Monday as the upper level
trough propagates into Kansas. There will be outflow boundaries
and the remnants of a weak warm front in western Kansas on Monday
to provide areas of enhanced upward vertical motion.

Stratus probably will develop north of the cold front in western
Kansas Saturday night, and cloud cover will persist Sunday.
Temperatures will struggle to rise above the 70s in most areas
Sunday. Warmer air will return to western Kansas Monday. A warm
plume aloft will spread from the Rockies into the central Plains
Tuesday and should result in a return to summer-like weather with
highs in the 90s.

A vigorous upper level trough will ripple through the mean long
wave position and approach Kansas on Wednesday. A cold front
should move into western Kansas Tuesday night beneath a stout EML,
and there may be little weather with the front other than a wind
shift until it encounters richer moisture and better instability
in eastern Kansas Wednesday afternoon.

The numerical models differ in their handling of synoptic scale
details later in the week. The GFS, GEM and ESRL Reforecast models
maintain more troughing in the western United States than the
more progressive ECMWF and seem more reasonable. Southwest flow
aloft is likely to persist most of the week with an enhanced
chance for thunderstorms again Friday and Saturday, although
details are impossible to anticipate with skill that far in the
future.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1246 PM CDT Fri Sep 15 2017

VFR conditions will continue through Saturday. An upper level
trough extended from northeast Wyoming across western Kansas to
near the Texas/New Mexico border early this afternoon. An area of
showers and thundershowers with bases near 080 will continue
across south central Kansas in advance of the trough into the
early afternoon but will remain east of TAF locations. A dryline
will move to near a line from Wakeeney to Ashland by late
afternoon, and isolated thunderstorms with bases near 070 are
possible near HYS and east of DDC after 22Z. Any thunderstorms
that form will weaken after 02Z.

A weak cold front will enter northwest Kansas after midnight and
will move to near a line from CNK to GAG by early afternoon.
Scattered thunderstorms may form Saturday afternoon near the
front.

Low level winds will be south around 20kt with gusts to near 30kt
this afternoon, diminishing to around 15kt by sunset. Winds will
veer to the west with the approach of the cold front Saturday
morning and become north 10 to 15 mph after frontal passage.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  67  89  57  82 /  10  10  20  30
GCK  61  84  55  79 /  10   0  20  30
EHA  61  85  55  80 /   0   0  10  20
LBL  63  88  58  82 /  10  10  20  30
HYS  68  83  55  76 /  20  10  30  30
P28  73  91  63  83 /  20  30  40  30

&&

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

$$

SHORT TERM...Ruthi
LONG TERM...Ruthi
AVIATION...Ruthi