Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 172332
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
632 PM CDT Tue Oct 17 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Wednesday)
Issued at 354 PM CDT Tue Oct 17 2017

Weak upper jet remains in place today from the Pacific Northwest
into the Plains. Clear skies have been the rule behind the first
upper wave, with more scattered high cloud entering the area from
the northwest late today with the second wave. Southwest surface
winds continue, though a weak trough was over western and central
portions of Kansas for weaker speeds in the western CWA.

Little cloud to speak of tonight and Wednesday with the old surface
ridge still located over east Texas and west to northwest flow aloft
persisting. Another modest low-level jet develops tonight, and
should keep lows near to slightly above this morning`s levels.
Another weak trough/very modified cold front works into the area
late Wednesday afternoon driven by a wave in the northern branch
working east across south central Canada. Temperatures should still
manage to reach into the middle and upper 70s on continued southwest
winds.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 354 PM CDT Tue Oct 17 2017

The extended period consists of continued above normal temperatures
and more weekend thunderstorm chances....

Wednesday night -- Upper level trough across central Canada will
continue its progression eastward. Directly on its heels, an upper
level ridge will overspread all of the central Plains late
Wednesday night and Thursday. Sfc high pressure across the
northern Plains will push into the Great Lakes region Thursday
night, allowing a southerly fetch from the Gulf to overspread the
central Plains. As a secondary upper level trough encroaches on
the Pacific northwest, cyclonic upper level flow will once again
return to the central Plains. ECMWF/GFS/Canadian all in agreement
with a lead wave traversing the area during the daytime hours on
Friday. At this point, have a dry forecast as guidance suggests a
stout EML will be in place, inhibiting any thunderstorm
development. Gusty southerly winds are expected by Friday
afternoon as a 6 hPa pressure gradient will setup across the CWA.
Sustained winds near 20-25 knots are expected with gusts upwards
of 30-35 knots, given mechanical mixing of an H85 50 knot jet to
the surface.

Friday night -- Warm air advection will continue across much of
the central Plains as the 50+ knot LLJ remains planted across the
area. With the increased boundary layer mixing through the night,
increased overnight lights a few degrees into the low to middle
60s. Saturday -- The aforementioned upper trough and surface cold
front will approach the CWA. Surface dew points will surge into
the low 60s, ahead of the front. Thunderstorm development is
expected during the afternoon and evening. Given the strong low
level winds, damaging wind gusts would be the primary hazards. The
sfc front and upper trough will exit the region by midday Sunday.
Sfc ridge will overspread the region Sunday afternoon into Monday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 631 PM CDT Tue Oct 17 2017

VFR conditions are expected through the period. Main concern for
will be LLWS at TOP and FOE after 06Z and lasting through 13Z.
Winds will increase after 14Z from the south with gusts near
22 kts.

&&

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

$$

SHORT TERM...65
LONG TERM...Baerg
AVIATION...53


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