Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 191103
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
603 AM CDT Fri Oct 19 2018

...AVIATION UPDATE...

.SHORT TERM...(Today and tonight)
Issued at 214 AM CDT Fri Oct 19 2018

07Z water vapor imagery shows an upper trough axis stretching from
the northern plains through the four corners region. A better
defined shortwave was digging through southern Saskatchewan while
upper ridging amplified along the British Columbian coast. At the
surface, a trough of low pressure extended from the MN/ND state line
south through the central high plains. A frontal boundary was noted
a little further west of the trough axis, but surface obs did not
show a lot of cold air behind the front over eastern MT.
Interestingly profiler data suggest the 850MB front is already
through western NEB and northeast CO. Meanwhile better low level
moisture continued to stream north with dewpoints increasing into
the lower and mid 50s across south central KS and OK.

For this morning, models indicate some disorganized vorticity
advection over the central plains along with good low and mid level
moisture. Additionally there looks to be some mid level
frontogenesis with the 850 boundary which is progged to be out ahead
of the surface trough. So will continue with POPs in the 30 to 60
percent range with the better chances along and south of Interstate
35. As the 850 front moves through by late morning, mid levels are
forecast to dry out and bring an end to the rain chances around
noon. This is all in line with the prev forecast, so there is not a
lot of change from the earlier forecast. The models tend to bring
the surface front into the forecast area late in the day and
still do not show a lot of cold air with the wind shift. Through a
good portion of the afternoon, a westerly downslope wind is
expected to prevail with increasing insolation through the
afternoon. With warm air advection from the west at 925MB, have
continued with highs in the mid 70s across north central KS and
spread highs around 70 further east towards Topeka and Emporia.
Less sunshine east of the turnpike is expected to keep highs in
the upper 60s. Skies are forecast to be clear overnight with low
level dry air advection persisting. Models maintain a weak
pressure gradient over the area so winds are expected to remain
around 5 MPH through the night. This along with the dry air should
preclude any fog formation. Lows are expected to be in the lower
40s.

.LONG TERM...(Saturday through Thursday)
Issued at 214 AM CDT Fri Oct 19 2018

Saturday through Sunday night, an amplified upper level trough
across the Great Lakes States will dig southeast across the mid
Atlantic States and New England, then into the western Atlantic.
Stronger low-level CAA across the eastern Plains and upper
Midwest will build a surface ridge southward across eastern KS
and western MO Saturday night into Sunday. A drier and cooler
airmass will advect southward across eastern KS. North winds of 10
to 20 MPH with higher gusts will occur Saturday afternoon but the
winds should diminish as the center of the surface ridge builds
south-southeast across the CWA Saturday night. Highs on Saturday
will only reach the upper 50s to lower 60s. Overnight lows
Saturday night will probably drop into the lower 30s across
northeast and east central KS. The center of the surface ridge
will move southeast of the CWA on Sunday, and surface winds will
become light from the southwest. Highs on Sunday may warm a few
more degrees into the lower to mid 60s.

Monday through Tuesday, an upper level trough will move east into
the western US and then fill as it moves east into the central
Rockies. A more amplified upper level trough will dig southeast out
of central Canada into the eastern Great Lakes States and New
England Monday night and Tuesday. The low-level CAA across the
eastern plains and upper midwest will cause a weak front to push
southeast across the CWA Monday night. The central and southern
plains will be under a low amplitude upper level ridge, down
stream from the upper trough moving east across the western US.
Highs will reach the mid to upper 60s on Monday, which may be our
warmest day of the week. The weak front will shift winds to the
north on Tuesday and Highs will only reach the lower to mid 60s.

Tuesday night through Thursday, the upper level trough across the
central Rockies will move east across the plains. Southerly low-
level winds will advect modified gulf moisture northward across KS.
The increasing isentropic lift ahead of the low-level moisture
return will cause scattered showers to develop across the CWA late
Tuesday evening and into Wednesday morning. As the the upper trough
shift east into central Plains, stronger ascent ahead of the H5
trough may increase the coverage of showers through the day on
Wednesday into Wednesday night. As the H5 trough shifts east across
the CWA the showers will shift east of the CWA during the day on
Thursday. The cloud cover and rain chances will keep highs in the
mid to upper 50s across the CWA both Wednesday and Thursday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 603 AM CDT Fri Oct 19 2018

Not a lot of change to the forecast with scattered morning showers
clearing out by late morning. Satellite shows a narrow band of
MVFR CIGS moving east through north central KS. There is good
consensus for these clouds to move through after the rain showers.
These lower CIGS are not expected to last for very long into the
afternoon with VFR conditions anticipated by 18Z.

&&

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

$$

SHORT TERM...Wolters
LONG TERM...Gargan
AVIATION...Wolters



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