Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Dodge City Kansas
1117 am CST Wednesday Jan 28 2015
..updated synopsis and aviation discussion...
issued at 1109 am CST Wednesday Jan 28 2015
At 12z Wednesday a 500mb trough was located from Wyoming to
eastern Utah. Further east an upper level ridge axis extended from
eastern Texas to Minnesota. Over the Central Plains and northern
plains an 850mb trough stretched from the Panhandle of Texas to an
area of low pressure located in northeast North Dakota. At 12z
Wednesday a trough of low pressure at the surface was located from
western Oklahoma to central Nebraska. A cold front appears to be
located across western Nebraska to northeast Colorado.
Short term...(today and tonight)
issued at 310 am CST Wednesday Jan 28 2015
A 500 millibar shortwave trough extended from the northern rockies
into West Texas early this morning. This wave will continue east out
over the Central High plains later this afternoon. A fairly dry
airmass in place across the central Continental U.S. Will result in only some
scattered high level cloudiness across western Kansas today and
tonight. This system will push a cold front through western Kansas
this morning. Breezy conditions will develop as northerly winds
become gusty behind the front. The initial surge of cooler air
behind the front will not be overly strong and temperatures should
still be able to rise into the upper 60s to middle 70s.
A stronger surge of colder air will move south across western Kansas
tonight. This afternoons gusty winds should diminish some around
sunset but look for winds to increase again tonight as cold air
advection strengthens. There could be some cold advection stratus
developing toward Thursday morning.
Long term...(thursday through tuesday)
issued at 349 am CST Wednesday Jan 28 2015
An upper level low will take shape over the Desert Southwest
Thursday and Friday. Isentropic lift will result in an increase in
cloudiness Friday and possibly some rain in the far southwestern
corner of Kansas late in the day. This system will shift
southward and weaken by late Saturday as a shortwave trough
approaches western Kansas from the northwest. A system arriving
from the northwest like this one would often not yield
precipitation in the winter; however, the airmass will have
previously been moistened by the aforementioned isentropic lift so
that middle level frontogenesis is expected to result in areas of
light precipitation. There is still a great deal of uncertainty
with respect to precipitation type (rain or snow) and amounts.
Given the weak Lee troughing, south winds and lack of cold
advection, this looks mainly like a rain and wet snow event with
minor accumulations. The main question is how effective
evaporational cooling will be at chilling the air in a 2000 feet
layer just above the ground, preventing the falling snow at middle
levels from melting just before reaching the ground. These details
are hard to predict 12 or 24 hours before an event, much less
72-96 hours prior. Just a very slight change in temperature can
mean the difference between rain or snow. The best chance of
accumulating snow may be Saturday night before the precipitation
ends as Arctic air arrives from the north.
Maximum temperatures will generally decrease through late week
and the weekend, with highs only in the 20s to lower 30s Sunday
behind the Arctic front. The coldest minimum temperatures ought
to be Monday morning, with mainly teens (possibly some single
digits as well). Temperatures are expected to return to seasonal
averages by Monday and Tuesday as Arctic high pressure moves off
to the east and the middle level flow becomes more zonal, along with
weak Lee troughing and southerly winds.
Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 1109 am CST Wednesday Jan 28 2015
VFR conditions can be expected today given that only high level
moisture will precede an upper level trough as it crosses western
Kansas. Gusty northwest winds are expected to be around 20 knots
this afternoon based on the mean mixed layer wind speeds from the
rap and NAM between 18z Wednesday and 00z Thursday. Sustained wind
speeds will then decrease after sunset to 10 to 15 knots.
Northwest winds will become more northerly and increase to around
20 knots towards daybreak on Thursday as a enforcement of colder
air crosses western Kansas.
Preliminary point temps/pops...
ddc 71 36 50 26 / 0 0 0 0
gck 70 34 50 28 / 0 0 0 0
eha 69 35 49 32 / 0 0 0 0
lbl 73 35 52 30 / 0 0 0 0
hys 70 35 48 25 / 0 0 0 0
p28 74 39 51 26 / 0 0 0 0