Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 101137
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
637 AM CDT Tue Oct 10 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 308 AM CDT Tue Oct 10 2017

Mid level low pressure is currently located over southwest KS and is
forecasted to lift northeastward throughout the day. Ahead of the
low pressure system isentropic ascent over northeast KS is
supporting isolated to scattered showers. A mid level dry punch has
also spread over the area, which is providing steeper lapse rates
above the moist layer in the lower levels. Instability seems to be
on the order of a few hundred j/kg so only expecting minimal
lighting. The chance for isolated to scattered showers will continue
through the morning hours with the better coverage remaining around
the NE/KS state line. Later this morning the mid level low pressure
will lift over the forecast area. Water vapor shows that the low is
associated with an area of deeper moisture. This along with mid
level frontogenesis and positive vorticity advection should support
another round of showers later this morning through the afternoon.
The exact coverage of this precipitation is somewhat unknown at this
point given subtle model differences. Brief periods of moderate
rainfall rates could be possible during this time frame as depicted
by some of the high res guidance showing QPF upwards of half an inch
in isolated spots.

The diurnal temperature swing will be muted today given the
reinforcement of cool air north of the front, widespread cloud
cover, and scattered precipitation expected. Therefore highs will
only reach the mid to upper 40s. The surface low pressure will drift
eastward today through MO so the pressure gradient should gradually
relax, but wind gusts will generally remain around 20 to 30 mph
until this evening when they decrease. This evening the mid level
low pressure lifts over the mid MS valley allowing surface high
pressure to build into the area. This surface ridge is forecasted to
set up through central KS tonight, which will support clear skies
and calm winds. The only exception will be portions of northeast KS
where some low level moisture remains in place keeping low stratus
over those locations. If this is correct the lows may need to be
adjusted higher. Across central KS the lows tonight may drop into
the mid 30s while upper 30s elsewhere. Therefore there is a chance
for frost especially in the sheltered valleys. Will let the day
shift fine tune the low temperatures as well as the cloud cover
location and timing in order to see if a frost advisory will be
needed.

.LONG TERM...(Wednesday through Monday)
Issued at 308 AM CDT Tue Oct 10 2017

Wednesday through Friday, a broad upper level trough will develop
across the western conus with an amplified downstream ridge across
the eastern US. Expect southwesterly flow at mid levels to increase
across the central plains which will cause a lee surface trough to
amplify across the high plains. After a cool start Wednesday morning
light and variable winds will gradually become southeasterly with
highs in the mid 60s. As the southerly winds increase Thursday and
Friday expect WAA to help warm highs into the mid to upper 70s on
Thursday and lower to mid 80s by Friday.

Friday night through Saturday night, the upper trough across the
western US will move east across the plains. A surface cold front
will begin to slowly push southeast across the CWA late Friday
night and through the day on Saturday. There will be enough
residual gulf moisture return and ascent ahead of the approaching
H5 trough for periods of showers and a few thunderstorms late
Friday nigh through Saturday night. Highs on Saturday will range
from the mid 60s across north central KS, northwest of the
surface front, to the upper 70s in the warm sector across east
central KS.

Sunday through Tuesday, there may be a few post frontal showers
Sunday morning across east central KS but these should shift east of
the CWA as the upper level trough lifts northeast into the upper
midwest by Sunday afternoon. Skies Sunday afternoon should clear
with highs in the upper 60s to lower 70s. The upper level flow will
be from the west-northwest early next week with the stronger H5 jet
max located across the northern plains. At the surface a broad area
of high pressure will move southeast across the southern plains.
Expect dry conditions early next week with mostly clear skies. Highs
Monday and Tuesday will be in the lower to mid 70s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 630 AM CDT Tue Oct 10 2017

MVFR ceilings have moved into the area ahead of an mid level low
pressure. That low pressure will bring scattered showers later
this morning and afternoon. There could be a brief period of
restricted visibility although generally VFR. There may also be a
brief period of IFR ceilings before the heights begin to rise
through the late afternoon and evening. The back edge of the
stratus may need to be fine tuned, and it could linger around
TOP/FOE slightly longer than anticipated.

&&

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

$$

SHORT TERM...Sanders
LONG TERM...Gargan
AVIATION...Sanders



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