National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KDDC 302016
AFDDDC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
216 PM CST Sat Nov 30 2013

...Updated for short term discussion...

.SHORT TERM...(This evening through Sunday)
ISSUED AT 212 PM CST SAT NOV 30 2013

Dry northwesterly flow at mid and upper levels will persist through
Sunday. The surface pressure gradient is advertised to be weak, with
only small low level thermal advections. Good radiational cooling can be
expected tonight with mainly clear skies and light winds with
dewpoints in the 20s. Temperatures should bottom out in the mid to
high 20s. Sunday will be only slightly cooler with continued light
winds and highs in the mid to high 50s, along with only a few high
level clouds in association with a strong upper level jet streak.

.LONG TERM...(Sunday through Friday)
ISSUED AT 409 AM CST SAT NOV 30 2013

The invasion of arctic air by mid week poses the greatest challenge
for the extended period. There is some uncertainty regarding the
speed of the arctic air as it plunges south from the Northwest
Territories/Yukon, but there is no doubt that it will come and that
it will persist for several days. There is support for an extended
period of cold weather in the central United States and the Midwest
through much of December with only brief periods of moderation
between surges of cold air.

Tropical thunderstorms continue to be very active from the eastern
Indian Ocean to the Maritime Continent, and the velocity potential
field has become more organized into a wave one pattern in recent
days. Most of the numerical models do suggest that eastward
propagation of a coherent cluster of thunderstorms toward the
Maritime Continent will occur by 12-13 December, but it is uncertain
how much this will affect the flow in the North American sector.
Relative atmospheric angular momentum has decreased in recent days,
and the relative angular momentum tendency still is negative.
Although the signal is not strong, the atmosphere appears to be best
represented by phase one of the Weickmann/Berry GWO phase space
diagram. Phase one correlates with anticyclonic flow aloft in the
eastern Pacific and cyclonic flow aloft in the western United
States.

Ocean temperatures in the north Pacific continue to be anomalously
warm from around 130W to the dateline with only slightly below
climatological temperatures near the west coast of North America.
There have been anomalously high heights since September in the
northern latitudes between about 130W and 170W, and ridging is
likely to continue in the eastern Pacific. Stratospheric
temperatures have been warming from Europe to east of Greenland, and
this warming may suggest evolution of a blocking anticyclone in the
north Atlantic. The ESRL reforecast model is trending toward
shifting the coldest air around the hemisphere toward eastern Canada
in early December. The persistence of ridging in the eastern Pacific
and intensification of the polar vortex in eastern Canada favors
surface anticyclogenesis in Alaska, the Yukon and the Northwest
Territories and southward progression of successive surges of arctic
air into the United States.

In the shorter term, a strong upper level trough near 170W is
pumping considerable warm air north toward western Alaska, and a
full latitude ridge is likely to evolve near 145W by early next
week. The upper level cyclone evident on satellite imagery over
eastern Alaska will dig into the Pacific Northwest by Monday night,
and frigid arctic air will begin moving into Montana and Wyoming. As
the upper level trough propagates slowly east into the Rockies
Wednesday, the arctic front air will continue to plunge south in the
lee of the Rockies. Monday will be anomalously warm with downslope flow
and temperatures rising well into the 60s in western Kansas. The
GFS carries a stronger trough across North Dakota and Minnesota
Tuesday than the GEM or ECMWF and pushes the arctic boundary into
northern Kansas Tuesday. Confidence in the GFS solution is not
high, but shallow arctic air often moves faster than the numerical
models suggest. Assuming that the ECMWF is too weak with the
trough moving across the northern plains Tuesday, the cold air may
filter into northwest Kansas by noon Tuesday. The boundary likely
will be very slow to progress south during the day Tuesday with
strong mid level flow across the Rockies and downslope flow in the
lee of the mountains. Temperatures once again should rise into the
60s in advance of the boundary. The cold air should plunge south
across all of western Kansas Tuesday night, and temperatures
Wednesday should hold steady or fall during the day. Very cold
temperatures will persist through the weekend. Minor upper level
troughs in the southwest flow over the arctic air mass will
support snow flurries or areas of light snow in the very sharp mid
level baroclinc zone Thursday and Friday, but the potential for
anything significant is low.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1159 AM CST SAT NOV 30 2013

A weak pressure gradient and the lack of low level moisture will
result in light wind and clear skies through the TAF period.


&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  26  58  31  65 /   0   0   0   0
GCK  25  59  29  64 /   0   0   0   0
EHA  26  59  33  64 /   0   0   0   0
LBL  26  59  30  64 /   0   0   0   0
HYS  26  55  30  63 /   0   0   0   0
P28  28  57  30  65 /   0   0   0   0

&&

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

$$

SYNOPSIS...Gerard
SHORT TERM...Finch
LONG TERM...Ruthi
AVIATION...Finch