Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 202116
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
316 PM CST Mon Feb 20 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 315 PM CST Mon Feb 20 2017

Upper level trough axis is currently located over central KS, and is
forecasted to progress eastward tonight. Just ahead of the trough is
a surface cold front, which will pass through the area this evening.
The trough axis also signifies the back edge of the cloud cover
across the region. So expect winds to shift to the northwest and
skies to gradually clear out this evening. Behind the front an
inverted surface trough will quickly move into eastern KS. Winds
will be relatively light within the trough, which could promote
radiational cooling. Most of the model guidance is not suggesting
any fog tonight expect for in far southeastern KS. Although given
some of the recent rain at some locations perhaps some low lying
valleys could support ground fog. The dry air filtering in from the
northwest may ultimately be the inhibiting factor though. Tomorrow
downsloping winds will keep the temperatures well above normal with
highs in the mid 70s. Sunny skies and lower dew points will
certainly cause minimum RH values to drop into the 10 to 20 percent
range during the afternoon. Also, on the north side of the inverted
surface trough the pressure gradient will support wind gusts 15 to
25 mph. This means the fire danger will be very high and extreme.
Therefore we will keep the fire weather watch in effect, and allow
the later shifts to figure out the exact locations of the dry and
windy conditions to upgrade to a warning.

.LONG TERM...(Tuesday night through Monday)
Issued at 315 PM CST Mon Feb 20 2017

Broad southwesterly flow will dominate the upper level pattern
across the Central Plains on Wednesday and will allow temperatures
to climb to some of their warmest readings of the season, likely
hitting record values (see climate section below). A dry
downslope H850 airmass originating from the lee of the Front Range
will slide eastward ahead of an H850 trough during the day with
temps aloft pushing +16 to +18 C. Nudged high temps upward a
couple of degrees into the mid to upper 70s, in line with MOS
guidance and 2-4 degrees warmer than then blended/deterministic
solutions. Would not be surprised to see multiple spots top 80
degrees. Also pushed Td values down 3-5 degrees in line with MOS
guidance to better account for the wedge of dry air just off the
surface (per recent event verification stats).

A surface boundary will advance southeastward through the CWA late
Wednesday and transition into a stationary boundary along the KS/OK
border early Thursday. A 992 mb low will develop over the OK
panhandle Thursday morning along this baroclinic zone and eject
northeastward Friday morning. Model spread increases with the
position of the low as it progresses through the CWA, which will
impact precip and weather type amounts. Leaned towards a GFS/EC
compromise that takes the low over or slightly SE of the CWA
Friday morning. Removed thunder mention for Thursday/Thursday
evening given the stout warm nose and lack of any elevated
instability. However, a 700-500 EML over a nearly saturated warm
nose could yield 150-300 J/kg of MUCAPE in the warm sector ahead
of the advancing low and have thus continued thunder mention in
the east during the early morning hours on Friday. As the low
pulls off to the NE, the deformation zone may clip NE Kansas on
Friday morning/early afternoon. The best chance for any
accumulating snow will be Friday morning in the NW CWA, but with
the forecast area near the edge of the def zone, amounts will
hinge on the exact track of the low. GFS bufr soundings show a
rather deep surface to H850 mixed layer/MAUL attendant to the
increasing CAA behind the low with winds at the top of the layer
pushing 40 kts. Near surface temps will be hovering right near the
freezing mark and given this uncertainty have left blowing snow
out of the grids until the track of the low becomes better
resolved.

The system pulls out of the region for Saturday with high
temperatures falling to near "average" for this time of year.
Confidence in the placement and timing to subsequent systems for
Sunday and early next week falls off quickly given the nearly zonal
flow pattern over the central CONUS.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1126 AM CST Mon Feb 20 2017

VFR conditions are expected throughout the period. Southerly
winds will remain at 10-15 knots through the afternoon hours,
before shifting to the northwest and decreasing to 5-10 knots this
evening.


&&

.FIRE WEATHER...
Issued at 315 PM CST Mon Feb 20 2017

TUESDAY
Tuesday will bring back the very warm and dry conditions of late
last week. Have trended all pertinent forecast elements toward the
more extreme guidance values based on verification from recent
events, resulting in elevated conditions. Tomorrow afternoon the
minimum RH values drop into the 10 to 20 percent range. Wind gusts
in north central KS are expected to gust up to 25 mph. Therefore
the fire danger will likely be very high and possibly extreme at
some locations.

WEDNESDAY
RH values will fall to between 15 and 25 percent during the
afternoon on Wednesday with mixing depths around 1 km in depth.
Southwesterly winds of around 10 kts will lessen through the
afternoon as a boundary approaches from the NW, switching to the NW
late in the day on Wednesday. RFD index values do touch the Extreme
category at times in a few areas during the day on Wednesday, but
given the lack of strong winds have held off on issuing a Fire
Weather Watch.

&&

.CLIMATE...
Issued at 327 AM CST Mon Feb 20 2017

Record Highest Minimum Temperatures:

...for February 20...

Topeka......52, set in 1930
Concordia...51, set in 1930

Record Highest Maximum Temperatures:

...for February 20...

Topeka......76, set in 2016
Concordia...73, set in 1981

...for February 21...

Topeka......76, set in 1977
Concordia...75, set in 1977

...for February 22...

Topeka......74, set in 1995
Concordia...76, set in 1982

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch Tuesday afternoon for KSZ008-009-020-021-034.

&&

$$

SHORT TERM...Sanders
LONG TERM...Skow
AVIATION...Baerg
FIRE WEATHER...Sanders/Skow
CLIMATE...65



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