Area Forecast Discussion
Issued by NWS Dodge City, KS

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FXUS63 KDDC 141700
AFDDDC

Area Forecast Discussion
National Weather Service Dodge City KS
1100 AM CST Sat Jan 14 2017

...UPDATE TO AVIATION...

.SYNOPSIS...
Issued at 837 AM CST Sat Jan 14 2017

WV imagery indicates a strong closed off upper level low shifting
slowly eastward across Baja California, enhancing a southwest flow
aloft across the Western High Plains. Near the surface, a broad
area of high pressure is locked in across the Northern Plains and
the Upper Midwest.

&&

.SHORT TERM...(Today and tonight)
Issued at 340 AM CST Sat Jan 14 2017

A high impact ice storm will begin tonight as the deep upper
level cyclone near 30N west of Baja California propagates across
the southwestern United States and into southeastern New Mexico by
Sunday evening. The numerical models are in good agreement on the
trajectory of the upper level cyclone as it is ejected in advance
of the next upper level trough near 140W that subsequently drops
into the southwestern United States Sunday and Sunday night.
Shallow arctic air will remain entrenched in southwestern Kansas
throughout the event while very warm and moist air flows over the
cold dome. Surface dewpoints early this morning were in the 10-15
degree F range with little advection to modify the dry air. As
precipitation begins to fall into the dry air, wet bulb cooling
will keep temperatures cold. The GFS and NAM appear too quick to
modify the shallow cold air, and the ARW and ECMWF appear to have
the best handle on evolution of surface temperatures.

There probably are several minor upper level troughs in the moist
southwest flow aloft east of the upper level cyclone near Baja
California, but the extensive cirrus shield makes it difficult to
identify them in satellite imagery. One minor trough was moving
through eastern Kansas tonight, and weak lifting with the upper
level trough and divergence in the entrance region of the strong
polar jet extending from northeast Colorado to New England
supported a few light showers in northeast Kansas. There appears
to be another subtle upper level trough in eastern New Mexico that
will move into western Kansas later this morning. A few freezing
rain showers are likely to move across southwest Kansas with the
approach of the upper level trough, but model soundings remain dry
in the mid levels through the morning hours. As such, only a few
sprinkles are expected at the surface. Temperatures will rise only
slightly today with extensive cloud cover, and highs near 30 seem
reasonable.

As the upper level cyclone propagates east to near the southwest
New Mexico border tonight, increasingly diffuluent upper level
flow and increasing isentropic lifting will occur in western
Kansas. Widespread freezing rain should develop this evening and
continue Sunday. Quantitative precipitation forecasts are very
impressive. Nearly all of the GFS ensemble members dump 1 to 2.5
inches in southwest Kansas; the ECMWF accumulates 1.5 to 2 inches
across all of southwest Kansas, and the NAM has totals between
0.75 inches around Scott State Lake to more than 2.5 inches in
south central Kansas. Depending on rainfall rates, there may be
some melting and runoff of ice that accretes on exposed objects.
Even so, it is likely that there will be very heavy ice
accumulations from late tonight through Monday morning. Rainfall
may be heavy enough to cause local drainage problems at times, and
the potential for flooding will have to be monitored as the event
evolves.

.LONG TERM...(Sunday through Friday)
Issued at 340 AM CST Sat Jan 14 2017

Significant icing will continue Sunday and Sunday night in
southwest Kansas. Temperatures Sunday may rise above freezing in
Comanche, Pratt and Barber Counties but will remain below freezing
elsewhere. As the upper level cyclone moves into western Kansas
Sunday night and Monday, low level north flow will increase, and
cooler temperatures will spread south in the lee of the Rockies.
Precipitation will change to sleet or snow as the cold air spreads
east, and a few inches of snow accumulation can be expected before
the precipitation winds down Monday morning. There may be
sufficient freezing rain yet after 12Z Monday in Trego and Ellis
Counties to merit extending the ice storm warning, but confidence
in the precipitation type and intensity is not high enough to
justify doing so at this time. Increasing north winds Monday will
cause additional damage to ice coated trees and power lines.
Temperatures will remain cool Monday with highs from the lower 30s
in west central Kansas to the lower 40s in south central Kansas.

Significant warming will occur Tuesday and Wednesday as strong
west to southwest flow across the northern Rockies result in
development of an extensive warm plume in the lee of the
mountains. Another strong upper level trough will move into the
western United States Thursday and approach the Central Plains
Friday. Although low level moisture will be limited, there may be
a few showers as the trough moves across Kansas Friday and Friday
night. A blocky pattern will evolve late in the week as an upper
level anticyclone builds west of Hudson Bay and a deep upper level
cyclone closes off over the Southern Plains. Cooler air will
invade Kansas next Sunday as the surface cyclone deepens along the
Gulf Coast, but arctic air will be confined to Alaska and
northwestern Canada. Moisture flowing around the deepening cyclone
probably will result in another opportunity for rain or snow,
especially in southern Kansas, next Saturday night and Sunday.

In the longer term, a return to colder weather appears likely
from late January into February. Stratospheric warming is in
progress over Asia, and the numerical models suggest that the warm
pool will spread into Alaska and the northwest territories by the
last week of January. In addition, a coherent area of upper level
divergence will enhance thunderstorm coverage in the western
Indian Ocean by late January, and energy propagation from this
thunderstorm cluster will favor ridging Alaska and western Canada.
Details that far out are highly uncertain, but it is likely that
there will be additional invasions of cold arctic air after 26
January.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1100 AM CST Sat Jan 14 2017

MVFR cigs will persist in the vicinity of KDDC and KGCK through
late this evening as low level stratus prevails across southwest
and central Kansas during the period. MVFR cigs will develop later
tonight at KHYS. Periods of IFR cigs will then be possible later
tonight as areas of freezing rain begin to move northward out of
Oklahoma into southwest and south central Kansas. Easterly winds 5
to 10kt will develop late this afternoon then persist across
southwest and central Kansas through early Sunday morning as high
pressure shifts slowly eastward across the Upper Midwest.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  31  25  32  28 /  60  90  90  90
GCK  32  25  32  27 /  30  90  90  80
EHA  34  27  33  26 /  70 100  90  80
LBL  30  27  33  28 /  70 100  90  80
HYS  30  25  29  27 /  30  70  80  80
P28  32  27  36  33 /  70 100  90  90

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
Ice Storm Warning until 6 AM CST /5 AM MST/ Monday for KSZ030-
031-043>046-061>066-074>081-084>090.

&&

$$

SYNOPSIS...JJohnson
SHORT TERM...Ruthi
LONG TERM...Ruthi
AVIATION...JJohnson



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