Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 291232
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
632 AM CST Thu Jan 29 2015

.UPDATE...
Issued at 632 AM CST THU JAN 29 2015

The stronger wind gusts seems to be more isolated than earlier,
and overall obs show winds speeds below 30 MPH. With the RAP and
NAM showing the pressure gradient remaining at its current
magnitude or gradually weakening, will allow the wind advisory to
expire at 7 am. Nevertheless northwest winds of 15 to 25 MPH will
persist through much of the day.

&&

.SHORT TERM...(Today and Tonight)
Issued at 424 AM CST THU JAN 29 2015

A shortwave could be seen on the 08Z water vapor imagery passing
overhead into MO with a second shortwave moving southeast through SD
and WY. an upper level low pressure system was seen spinning well
off the Baja California coast and shortwaves within faster flow near
40N and 145W were moving towards the British Columbia coast. At the
surface, high pressure was building south through the central plains
causing gusty northwest winds from a tight pressure gradient. In
fact the gradient has been strong enough for sustained winds of
30 MPH and an occasional gust up to 45 MPH. Because of this, have
issued a wind advisory until 7 am. By then the pressure gradient
is expected to begin relaxing.

For today and tonight, the weather should remain relatively quiet
due to increasing dry air as the surface high pressure system
continues to move south. Because of this the shortwave over SD and
WY is not expected to do much in terms of sensible weather. However
subsidence behind this wave should help to erode away the low
stratus that has moved in, and think skies should clear out by the
late afternoon. Since there is not a lot of cold air behind this
front and models show the boundary layer mixing to almost 850MB,
think highs in the middle 40s looks reasonable. Lows tonight should
be a bit colder as the ridge axis moves in creating light winds with
clear skies. Expecting good radiational conditions, have adjusted
min temps down to around 20. Models show pretty high RH values
developing Friday morning suggestive of fog. Am not real confident
in fog formation since we have not had any meaningful precip lately
and soils remain very dry. Because of this think dewpoints are
likely to remain a couple degrees cooler than the air temp.

.LONG TERM...(Friday through Wednesday)
Issued at 424 AM CST THU JAN 29 2015

Gradual warm advection will take place through the day Friday
following a cold start and the arrival of the thicker high clouds
now appears will be delayed...therefore highs should recover back into
the low to middle 40s for highs.

Friday night...low and mid level warm air and moisture advection
will increase across the county warning area and persist into
Saturday. Although the atmosphere will initially be very dry
across the CWA...saturation will slowly occur west to east across
the CWA as warm air and moisture advection increases. Will maintain
a slight chance for precip over the north central in the
evening...with a increasing chances all areas overnight. Forecast
soundings Friday night continue to trend slightly warmer and
dewpoints increasing slightly as well. With still a fairly shallow
depth of warm air in place in the low levels...precip could fall as
rain or snow...although if surface temps fall to or below
freezing...precip would likely be snow. Will continue to carry a
rain/snow chance most areas Friday night...then mainly north of I 70
through Saturday. Areas south of I 70 should mainly be rain by
Saturday afternoon as freeze levels slowly increase in the
afternoon.

By late afternoon the GFS is the most aggressive with the arrival of
the colder air/front across the northern CWA with a possible
changeover to all snow which would slowly spread southward through
Saturday night. The EC and GEM are a little slower but still brings
the colder air southward through the night. Snow chances linger
through Sunday morning most areas...but should also decrease with
time as the main upper trough pushes through. At this
point...snowfall amounts look to be in the 1 to 2 inch range most
areas...but could be locally higher across the northern CWA if the
cold air moves in quicker.

After highs Saturday around 40...colder and blustery conditions will
be the rule Sunday with highs in the upper 20s to around 30 degrees.
Although wind speeds will decrease Sunday night...low temps in the 7
to 12 degree range will produce wind chills near zero.

Return flow to the south Monday should allow temps to recover back
into the upper 20s/lower 30s...then the lower 40s Tuesday before
another shortwave trough moving through the northern Plains pushes a
front through the area that night with slightly cooler highs in the
30s and low 40s on Wednesday. For now appears any snow chance will
remain north of the area.

&&

.AVIATION...(For the 12Z TAFs through 12Z Friday Morning)
Issued at 450 AM CST THU JAN 29 2015

Stratus continues to fill in from the north, and think it will
remain over the terminals for much of the day, until subsidence
from a second shortwave overspreads the area. For the most part
CIGS should remain above 2 KFT. Did lean on the optimistic side by
mixing CIGS above 3 KFT by noon based on the RAP forecast
soundings. But given how expansive the stratus is upstream, there
is some uncertainty in whether CIGS will lift and when they will
mix out. Gusty northwest and north winds will persist through the
day until the pressure gradient relaxes towards sunset.


&&

.TOP WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY until 7 AM CST this morning FOR KSZ009>012-023-024-
026.

&&

$$

UPDATE...Wolters
SHORT TERM...Wolters
LONG TERM...63
AVIATION...Wolters






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