000
FXUS63 KTOP 121740
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1240 PM CDT Wed Mar 12 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 330 AM CDT WED MAR 12 2014

Water vapor loop this morning depicts the main upper trough axis
across northeast Kansas. A weaker embedded wave was tracking
southward over Nebraska where some low clouds were observed. Across
northeast Kansas, should see the cloud cover continue to clear from
west to east this morning as the surface low exits the region. The
tight pressure gradient holds northerly winds in the 10 to 15 mph
range through this morning before increasing with the daytime
heating between 15 and 20 mph sustained by noon time. Strong
momentum transfer from the surface through 800 mb on the latest RAP
soundings easily suggest highs may peak in the lower to middle 50s.
A few locations may become even warmer in the upper 50s if cloud
coverage is more sparse, especially for north central areas. In
terms of fire weather concerns, northwest wind speeds peak in the early
afternoon before gradually decreasing into the late afternoon.
Decent mixing in the boundary layer by late afternoon brings minimum
relative humidity percentages down to the upper 20s in north central
Kansas. Very high fire danger is expected once again this afternoon
across north central Kansas. By early evening, winds turn towards
the west and slacken from 5 to 10 mph as surface high pressure
passes over Oklahoma. Clear skies and light winds should quickly
cool off temps to the low 30s Thursday morning.

.LONG TERM...(Thursday through Tuesday)
Issued at 330 AM CDT WED MAR 12 2014

The long term period remains fairly quiet with a west to northwest
upper flow pattern and occasional...mainly dry...short wave trough
passages. Will have a bit of a roller coaster pattern with warming
periods ahead of the short wave troughs and some post trough
cooling. Expect these short waves to impact the local forecast area
on Friday morning, Saturday night, and late Tuesday.

One of the main changes in to the forecast in the long term was
toward drier and warmer conditions on Thursday, followed by warmer
conditions Thursday night. Thursday will be one of the "warm-up"
days this week with warm advection through the day, along with sunny
skies and expected deep mixing into a dry layer above the boundary
layer. These conditions all support warmer and drier surface
conditions, and recent model performance suggests that in these
situations the forecast should be near the upper end of temperature
guidance and the lower end of dewpoint guidance. Thursday night
should see continued 8 to 15 mph southwest winds and warm
advection...also a strong signal lately to forecast near the upper
end of temperature guidance. A cold front will begin to move into
northern Kansas around Sunrise on Friday which could impact lows
near the Nebraska border depending on eventual timing. The frontal
passage on Friday is very likely to be dry as the airmass will be
quite dry in advance of the system and any stronger lift will be
focused both to the northeast and southwest of the local area.
Friday will be slightly cooler, although still likely around 60
degrees.

By Saturday, a disturbance slides well south of the local area but
may pull some extra cloud cover into east central KS...potentially
keeping low temperatures Sat morning a bit warmer. A stronger short
wave moves through on Saturday night, and while the initial wave
will probably pull a bit of moisture into the area, model agreement
is good in taking the heart of the Sat night system west and south.
The end result seems to be small chances for mainly light
precipitation. Surface high pressure nosing in from the northeast
will be another factor in potentially limiting precip chances with
low level dry advection. Cold advection from this system points to a
cooler day on Sunday, but another warm-up day is in store for
Monday...which may very well end up behaving like Thursday of this
week...with warmer temperatures and drier conditions from Monday
into Monday night.

&&

.AVIATION...(For the 18Z TAFs through 18Z Thursday Afternoon)
Issued at 1240 PM CDT WED MAR 12 2014

VFR conditions will continue through the period. Northwest winds
around 10 kts with gusts to near 18kts will still be possible
through 22Z then decrease to less than 10 kts from the west after
00Z.

&&

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

$$

SHORT TERM...Bowen
LONG TERM...Barjenbruch
AVIATION...53