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Area forecast discussion 
National Weather Service Topeka Kansas
1247 PM CDT Tue Apr 21 2015

..update to aviation forecast discussion...

Short term...(today and tonight)
issued at 300 am CDT Tuesday Apr 21 2015

Deep upper low over the Great Lakes was making slow eastward
progress early this morning with likely a few small scale waves
rotating around it through the northern and Central Plains. Periodic
mid cloud was present over the local area via isentropic upglide
from rather brisk and backed mid level winds. At least minor amounts
of epv along the moist layer allowing some showers to form aloft,
with weak returns on radar showing some very light precip reaching
to the lower troposphere. Hrrr and rap runs quite similar to some
4km WRF runs with light precip forming over central Kansas in the
next few hours, with latest infrared imagery indicating recent cloud
development there. All nearby 0z soundings measured 850mb dewpoint
depressions around 12c, making measurable amounts hard to imagine in
this activity. A somewhat more unstable airmass develops over the
southeast quarter of Kansas this afternoon with weak surface
convergence. Will maintain small storm chances with still minor
isentropic lift and weak wave potential in place. The stronger wind
fields aloft could lead to some storm organization along with cape
around 500 j/kg and dry adiabatic low level lapse rates to produce a
very small threat for severe wind and hail in the mid afternoon to
early evening. Areas outside of storms could also see a few rather
strong wind gusts with mixing depths reaching 7000-10000ft above ground level
though some veering remains through the column. The still dry
airmass and gusty winds lead to elevated fire danger in western
locations this afternoon.

Cold front via a stronger wave rotating around the low arrives this
evening and makes quick south progress through the state tonight.
Moisture, though modest, will continue to pool ahead of this front
for some storm chances through much of the night in the southern
zones, with typical diurnal trends allowing severe concerns to
diminish. Models are allowing the boundary layer to decouple fairly
quickly behind the front, but am somewhat skeptical of this given
the baroclinic zone they advertise. If winds can fall quicker than
expected, fairly clear skies could present a frost concern, but even
if they do the window of cold and calm conditions for formation
should be rather limited. Will mention patchy frost in far north
where concern is highest.

Long term...(wednesday through monday)
issued at 300 am CDT Tuesday Apr 21 2015

Eastern Kansas remains on the southwest side of an upper surface
high for Wednesday, keeping high temperatures around 60 for most
of the area. Have kept rain chances out of the southern areas with
better chances south. Dry conditions continue Wednesday night into
Thursday, with lows in the upper 30s to near 40 and highs climbing
toward the middle 60s Thursday.

Upper pattern starts to shift Thursday night as shortwave ridge
noses out of the Southern Plains into our area, ahead of an upper
trof lifting northeast out of The Four Corners region. Initial
sensible weather impacts should be warmer lows in the 40s near 50
Thursday night with some showers possible after midnight as low
level jet makes a return over the area. Latest ec appears to be
trending toward the GFS solution for this shortwave as it moves
into the plains, taking a faster track and developing the warm
front from the surface low out into eastern or southeast Kansas.
GFS keeps the boundary south of the area and would make for cloudy
cool and rainy conditions area wide for Friday and Saturday night,
and with ec solutions also trending this way, have gone with
forecast as such.

Southern branch of the upper jet takes the shortwave trof east of
the area rather quickly on Saturday, with rain ending sometime
during the morning hours. Cooler high pressure once again noses
into the area behind the departing low and holds temperatures in
the low 60s, followed by overnight lows in the 40s. Highs on
Sunday rise a bit more into the middle 60s, and have kept rain
chances relegated to north and west while surface high continues
over the east. Another front progged to move across the area
Sunday night with northwest flow aloft returning on Monday.
Current forecast is for highs near 70, but this will depend on how
strong the front and wave are as to how much cooler air it does,
or does not, bring southward.

&&

Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1245 PM CDT Tuesday Apr 21 2015

VFR conditions are expected the entire period with gusty winds
throughout the afternoon. Mid-level clouds will move south over the
area tonight as a frontal passage veers east winds north/NE after 04z.

&&

Top watches/warnings/advisories...
none.
&&

$$

Short term...65
long term...67
aviation...heller

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