Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 251133
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
533 AM CST Tue Nov 25 2014
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 311 AM CST TUE NOV 25 2014
Mostly clear skies and light winds continue through the morning
hours with low temperatures dropping into the lower 20s and upper
10s. Today a shortwave within the northwest flow will drop out of
Canada and track over the region. Low level southwest flow ahead
of the wave should allow temperatures to reach the upper 40s to
low 50s, which the direction some of the short range guidance is
trending. The latest models are also suggesting that the main
shortwave energy will pass over far SW IA. Weak isentropic lift in
the mid levels develops ahead of the wave over north central KS
after 03Z. This area of lift will advance eastward over northeast
KS between 06-09Z. The lift will be slightly stronger over far
northeast in closer proximity to the shortwave. Soundings show a
rather deep dry layer that extends from the surface up to around
800 mb. The lift appears too weak and brief to allow most areas to
see any measurable precip. If any precip is able to survive this
dry layer the wet bulb cooling would still only support rain. The
only exception will be far northeast KS where a rain snow mix
could occur with little to no accumulations expected. Although
once the temperatures in the column become more supportive of snow
the saturation and lift becomes better focused east into MO after
12Z. A trailing cold front pushes through the region around 06Z
shifting the winds back to the northwest with a gradual increase
before sunrise, and low temperatures tonight are generally in the
low to mid 30s.
.LONG TERM...(Wednesday through Monday)
Issued at 311 AM CST TUE NOV 25 2014
Wednesday through Thursday (Thanksgiving), an upper level trough
over IA and extending south-southwest across eastern KS early
Wednesday morning will dig southeast across MO into the western OH
river valley by late Wednesday afternoon. Low-level CAA across the
plains and Midwest will only allow Highs on Wednesday to reach the
upper 30s to lower 40s, despite decreasing cloud cover. Northwest
surface winds of 15 to 25 MPH with higher gusts will make it even
feel colder. The winds should diminish by late afternoon.
Travel weather across KS and points south and west will be good.
Traveling east across IA and northern MO into IL there may be some
light snow accumulations. A bigger snow storm will be moving up the
east coast with heavy snow possible from the interior portions of
the mid Atlantic states, northeast across New England. Expect travel
delays across the Mid Atlantic and northeast US.
A surface ridge of high pressure will move east across the CWA
Wednesday Night. Light winds and mostly clear skies will allow
overnight lows Wednesday night to drop into the upper teens to lower
On Thanksgiving, the surface ridge of high pressure will shift east
towards the MS river valley. Surface winds will become southeasterly
across the CWA through the day. The winds may increase to 10 to 20
MPH across the western counties of the CWA by late afternoon. After
a cold start highs will warm into the lower to mid 40s across the
western and southern counties. Highs across the extreme northeast
counties will only reach the upper 30s.
Friday through Saturday, the northwesterly flow aloft will become
zonal as a lee surface trough develops across the highs plains.
Southerly winds will help to warm Highs into the mid to upper 50s on
Friday with upper 50s and lower 60s on Saturday.
Sunday through Monday, An amplified upper level trough over western
Canada will dig southeast into the northern plains and upper
Midwest. The strong low-level CAA across the northern plains will
cause a stronger cold front to push southeast across the CWA
Saturday night into Sunday morning. The front will push through
dry across much of the CWA. Both the ECMWF and GFS show the
northwest edge of deeper moisture lifting northeast over the
shallow cold airmass across the extreme southeast counties of the CWA.
At this time most of the precip will be in the form of light rain
late Sunday afternoon into the early evening hours before 850mb
winds turn to the northwest. Therefore, I placed in a 20 percent of
showers southeast of I-35 on Saturday afternoon. Highs Sunday
will only reach the mid to upper 30s north of I-70 with lower to
mid 40s south of I-70. Highs on Monday will continue to be cool as
the surface ridge axis shifts east across KS. Highs on Monday
will only reach the mid 30s north to lower 40s south.
.AVIATION...(For the 12Z TAFs through 12Z Wednesday Morning)
Issued at 522 AM CST TUE NOV 25 2014
VFR conditions expected through the taf period. There is a slight
chance for very light rain between 06-09Z tomorrow at TOP/FOE.