Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 251702
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1102 AM CST Sun Feb 25 2018

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 301 AM CST Sun Feb 25 2018

As of 08Z Sunday morning a surface ridge axis extended from north TX
into the NE panhandle. Two mid-level shortwave troughs were also
noted on WV. The first continues to push across the upper midwest,
this shortwave was responsible for the drizzle and rain showers
Saturday. All of its associated cloud cover has pushed into the
Mississippi and Ohio River valleys. As a result, maximum radiational
cooling will allow temperatures to reach the low to middle 20s this
morning. The second shortwave trough of note was digging into the
four corners region. Model solutions prog this shortwave to eject
across the CWA during the afternoon and evening hours today.
Although decent mid-level ascent will be associated with the
shortwave trough, a very dry boundary layer will inhibit any
rain/sprinkles to reach the surface. As a result, the only weather
phenomena of note will be increasing mid-level cloud cover through
the day. High temperatures will reach the upper 40s to low 50s this
afternoon. Otherwise, clearing skies are expected tonight as the mid-
level pushes east of the CWA. Lows look to range from the mid to
upper 20s Monday morning.

.LONG TERM...(Monday through Saturday)
Issued at 301 AM CST Sun Feb 25 2018

The next chance for precip looks to be Tuesday afternoon through
Wednesday night which is in line with the prev forecast. Although
there remains differences in the details among the various model
solutions.

Return flow is expected to develop on Monday, but the better
moisture advection looks to take place Tuesday and into Wednesday.
Forecast soundings suggest there could be some elevated
instability for thunderstorms Tuesday night. With southwest flow
aloft and the potential for a weak disturbance within the flow,
have some POPs in the forecast for Tuesday night. The higher
chances will likely be across east central KS where models show a
better moisture across the area, while moisture advection may get
shunted away from north central KS.

The better opportunity for showers and thunderstorms looks to be
Wednesday afternoon and evening. This is when an upper shortwave
trough is progged to lift out from the southern Rockies. Again
there looks to be some signal for convective instability as models
advect dewpoints in the upper 40s and lower 50s into east central
KS. This is also the period that has some differences that need to
be resolved. The biggest being the way the ECMWF handles the
energy lifting out of the Rockies. While the GFS and Canadian show
a pretty well defined shortwave lifting across the area, the ECMWF
has trended towards holding more energy back across the southwest
and only bringing a sheared upper level trough axis through the
central plains. As a result, it is not nearly as deep with a
surface low and tends to track it further south. Another
consideration would be the GFS which appears to be quite a bit
deeper and more amplified than other solutions. This brings into
question whether the warm sector may actually move into east
central KS as the GFS shows. Since the previous ECMWF was more in
line with the current GFS and Canadian, think the idea for a more
distinct shortwave is the way to go and have some likely POPs for
the afternoon and evening across eastern KS. Have included a
mention of thunderstorms as well, but until there is better
agreement on the strength of the wave, confidence in coverage or
intensity of thunderstorms is only about average. There is a
chance for precip to linger into the pre dawn hours of Thursday as
cold air moves in behind the surface low. Again the GFS seems to
be the most aggressive. However the better forcing looks to be
moving off to the east and frontogenesis on the back side of the
surface low does not appear to be all that well organized. So
there is some concern the QPF from the GFS after midnight might
be a little overdone. However I can`t discount the potential and
have a chance for rain changing over to snow late Wednesday night.

Outside of Tuesday afternoon through Wednesday night, the forecast
looks to be dry. Have trended warm with temps for Monday and
Tuesday. Forecast soundings are trying to mix the boundary layer
to 850mb with good insolation anticipated. So think highs could be
around 60 on Monday and into the middle 60s Tuesday. A cool down
is likely by Thursday with the system exiting and a modified
Pacific airmass moves in behind it. Temps are expected to trend
warmer through the end of the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1101 AM CST Sun Feb 25 2018

VFR conditions are expected through the period with winds
becoming light after 00Z.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Baerg
LONG TERM...Wolters
AVIATION...Heller


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