Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 111737

Area Forecast Discussion
National Weather Service Topeka KS
1137 AM CST Mon Dec 11 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 305 AM CST Mon Dec 11 2017

08Z water vapor imagery shows northwest flow over the plains with a
pretty obvious shortwave digging southeast through the Dakotas. An
upper ridge remained over the intermountain west and a broad upper
trough remained over the easter third of the country. At the
surface, an area of low pressure was moving southeast into MN and
stronger winds were noted on the back side of this low across the
northern plains. A very dry airmass remained over the forecast area
with the 00Z RAOB from Topeka showing PWs less than a half of an

For today and tonight, the main story will be the winds. Models show
good forcing associated with the shortwave moving across the area
today. But there is not enough moisture for the forcing to act upon
to develop any precip. None of the models are generating any
measurable precip so will maintain a dry forecast for the period.
However winds are expected to shift to the northwest and begin
gusting to near 40 MPH by the early afternoon as the low pressure
system moves into IL and deepens. These winds are expected to
persist into the evening hours. Although they should begin to
diminish towards sunset. Considered a wind advisory for parts of
northeast KS but model progs of the pressure gradient indicate the
stronger forcing remaining mainly north and east of the forecast
area. And much of the guidance keeps winds just below criteria.
Since fire weather will be the main concern for today, decided to
hold off on a wind advisory for now. Highs today should occur early
in the day as models show low level cold air advection increasing
through the afternoon. Think highs will range from the lower 50s
near the NEB state line to near 60 over east central KS. By mid
afternoon the temps should begin cooling off as cold air advection
increases. Am not sure the boundary layer will completely decouple
overnight, so will keep lows tonight in the mid and upper 20s.

.LONG TERM...(Tuesday through Sunday)
Issued at 305 AM CST Mon Dec 11 2017

On Tuesday the shortwave responsible for the wind today reaches the
eastern US and surface high pressure settles across the southern
plains. Highs on Tuesday will be about 10 degrees cooler as the
arctic air mass clips northeast KS. The next wave is forecasted to
track over the Great Lakes region on Wednesday, which will send
another cold front our way. Ahead of the front highs reach the mid
to upper 60s while on Thursday stay in the 40s. Another tight
pressure gradient will cause the winds to be gusty out of the
northwest on Wednesday behind the front. Relative humidity is
forecasted to drop into the lower 20 percent range so would expect
very high fire danger. By this weekend the western ridge breaks down
and gets pushed off the coast. This will open the door to warmer
temperatures with highs in the 60s by Monday. The shortwave waves
look to be very active with this pattern, but the lack of any upper
level ridging over the southeast US will prevent a quality moisture
return from reaching the central plains.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1135 AM CST Mon Dec 11 2017

Northwesterly winds of 15 to 25 kts with gusts over 35 kts will
develop and persist for much of the afternoon, gradually
decreasing through the night. Low VFR stratus/stratocu will drop
south from Nebraska this afternoon, but is progged to remain
above MVFR and dissipate tonight.


Issued at 305 AM CST Mon Dec 11 2017

The strong northwest winds gusting to near 40 MPH will cause
problems for any fires that get started considering fuels have cured
and are pretty dry. The most critical timing appears to be just
ahead of a wind shift/surface trough during the late morning and
early afternoon. This is when RH values are likely to be at the
lowest for the day. Once winds shift from the west to the northwest,
cooler temperatures should allow RH values to slowly recover through
the afternoon. Of course this is when the winds will be the
strongest. With this in mind will issue a red flag warning for the
entire area from 10 am until 6 pm. Winds will likely remain breezy
after 6 pm. But by this time they should be gradually diminishing
with RH values continuing to rise with the falling temps.


Red Flag Warning until 6 PM CST this evening for KSZ008>012-



SHORT TERM...Wolters
LONG TERM...Sanders
FIRE WEATHER...Wolters is the U.S. government's official web portal to all federal, state and local government web resources and services.