000
FXUS63 KTOP 231128
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
528 AM CST Fri Jan 23 2015

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 303 AM CST FRI JAN 23 2015

Upper longwave trough axis was currently rotating over western
Texas, progged to shift east later today. A shortwave trough was
observed entering the far northern plains. As this trough tracks
over the Great Lakes region this afternoon, it will surge a weak
cold front southward into northeast Kansas during the late
afternoon. Warm downsloping winds at h85 veer to the northwest as
temps increase to near 3C. Despite the strong mixing of the
boundary layer to 900 MB, the cooler temps aloft and increasing
mid level clouds result in highs in the lower 50s. In addition,
sfc southwest winds ahead of the front increase around 10 to 15
mph gusting occasionally to 20 mph in the late afternoon. Short
term guidance on sounding profilers is showing some consistency in
mixing drier air to the surface with the passing boundary. Minimum
RH values fall to the upper 20s for portions of east central
Kansas where fire danger is likely to reach high to occasionally
very high in the late afternoon.

Mid level cloud cover dissipates shortly after sunset as mostly
clear skies return this evening. Surface inversion quickly sets in
with cross sections show increasing saturation near the surface.
Believe fog will not be a concern as northwest winds stay near 10
mph throughout the evening. This will also keep lows a bit warmer in
the upper 20s.

.LONG TERM...(Saturday through Thursday)
Issued at 303 AM CST FRI JAN 23 2015

Precip chances, while slim, seem to be centered around a couple
waves that potentially move across the area. There is better
confidence in a shortwave diving south through the plains Saturday
evening and early Sunday morning. Aside from the NAM being a weak
outlier with the wave, there seems to be a consensus in this
feature clipping northeast KS. However moisture is progged to be
limited ahead of this wave and models show higher humidities
moving south only after the better forcing has passed. Have
continued with a dry forecast due to the limited moisture progged
by the models, but did consider adding a mention of sprinkles to
the forecast.

The second chance for precip is quite a bit more uncertain due to
inconsistencies between model runs. The GFS and GEM are the
stronger solutions in bringing the remnants of a closed low that
has yet to develop over Baja California, across the central plains
mid week. The GFS has been going back and forth with a shortwave
and nearly zonal flow while the ECMWF is just starting to pick up
on the idea of energy moving into the plains. The general track
takes most of the forcing north across NEB. Meanwhile the GFS
forecast soundings suggest the boundary layer and increasing
surface dewpoints should be capped by an elevated mixed layer. Due
to the overall uncertainty, have maintained a dry forecast for
Wednesday and Wednesday night and will keep an eye on future
solutions.

As for temps, above normal readings are generally expected through
the period. Did increase the forecast highs for Saturday into the
upper 50s and around 60. Think there should be good insolation
with a dry downslope surface wind. Given the models tendency to be
to cool recently, feel comfortable trending temps warmer. Another
period where highs were bumped up was on Wednesday. Models show a
thermal ridge moving out into the plains in advance of a possible
wave with south and southwesterly winds. Think with some sunshine,
highs around 60 are plausible. Between Saturday and Wednesday, the
forecast anticipates a decent gradient from east to west in temps
as a broad upper trough to the east allows cooler air to remain
over the upper Midwest while upper ridging to the west allows for
warmer temps to persist. Regardless, there does not appear to be a
strong cold front or an airmass originating from the northern
latitudes to impact the forecast area until possibly Thursday.
Because of this, began trending temps cooler for Thursday with
highs expected to range from the upper 40s to lower 50s.

&&

.AVIATION...(For the 12Z TAFs through 12Z Saturday Morning)
Issued at 520 AM CST FRI JAN 23 2015

MVFR cigs at 6SM linger through mid morning at KTOP before
surface heating increases southwest winds after 16Z. Otherwise VFR
prevails at sites as southwest winds increase near or just above
10 kts during the afternoon. Mid level clouds dissipate overnight
as light winds veer to the northwest between 09Z and 12Z with a
frontal passage.

&&

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

$$

SHORT TERM...Bowen
LONG TERM...Wolters
AVIATION...Bowen