Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 241129
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
629 AM CDT Mon Apr 24 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 300 AM CDT Mon Apr 24 2017

Early this morning, the mid-level ridge was shifting east of the
area with surface low pressure advancing further east into western
and central KS.  This advancing low pressure was resulting in an
increased pressure gradient setting up over central KS early this
morning, and this tight pressure gradient will continue to expand
eastward across the CWA through the day. Short-range models actually
show the strongest winds occurring mid to late morning as the 45-
55kt 850mb low-level jet shifts eastward across central KS. Expect
some of the stronger winds aloft to mix down to the surface during
the mid/late morning hours, resulting in winds quickly becoming
breezy this morning with gusts of 35 to 45 mph.  As the low-level
jet diminishes during the afternoon hours, expect the wind gusts to
diminish some as well, but still expect gusts of 30 to 40 mph. As a
result, have issued a Wind Advisory for today for locations
generally along and west of a line from Marysville to Manhattan to
Council Grove.  With these strong southerly winds in place, have
continued to trend on the warm side of guidance for temperatures
today, with highs likely reaching into the mid/upper 70s.

Tonight the surface low pressure will progress eastward across
western and central KS, with an associated cold front extending into
north central KS by Tuesday morning. As a result, expect increasing
low/mid-level cloud cover overnight.  This increasing cloud cover
along with persistent southerly winds will support low temperatures
only dropping into the mid 50s.  As the cold front advances into
north central KS overnight, there is the potential for some
scattered showers and isolated thunderstorms to develop early
Tuesday morning across north central to far northeast KS.

.LONG TERM...(Tuesday through Sunday)
Issued at 300 AM CDT Mon Apr 24 2017

Much of the area will see one more day in the 70s before the next
front moves into eastern Kansas through Tuesday afternoon and
evening. May have some morning showers in the north as a lead wave
rides over the front before it pushes southward. Dewpoints in the
eastern counties rise into the upper 50s before the front gets
there, and is capped off ahead of the boundary. This erodes
somewhere in the 21-0z timeframe and may be enough to get a few
strong to possibly severe storms along and south of the I-35
corridor, with wind and hail the primary threats. Kept some low
end thunder chances farther west, but this may be generous given
available instability as you go westward.

With decent concensus in models and ensembles taking a secondary
piece of energy southward into the Texas panhandle and into the
Red River valley through the day on Wednesday, this keeps the
forecast area in rain for much of the morning and into the early
afternoon before moving eastward. This also brings the colder air
behind the system farther southward, and shuts off the return flow
from the Gulf as it passes to our south and east. As we dry up and
clear out Wednesday night, after daytime highs only reaching into
the lower 50s, overnight lows fall into the middle/upper 30s and
will need to be watched for possible frost potential.

Highs Thursday near 60 as the next wave moves eastward into the
state, bringing rain chances as it does so. Despite the shortwave
trof axis and upper left exit region of the upper jet moving over
the front into our area Thursday night, the lack of instability
keeps forecast as showers. May be able to advect enough
instability back northward by afternoon into the eastern counties
and will bring thunder back into the forecast. Through sunrise on
Saturday, EC and GFS agree so far in lifting the frontal boundary
back over the area and along with it periods of rain.

EC ejects the upper low more quickly and farther north than the
GFS, although worth noting that the 0z run is a slight southern
shift from the previous. This evolution could keep better
instability to the east and south of the forecast area, although
current solution could impact our eastern counties with strong
storms Saturday afternoon. The slower, more southerly track in
the latest GFS would keep us on the north side of the warm front
and of the surface low track through the weekend, so there is
still much uncertainty as to how the weekend will evolve.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 622 AM CDT Mon Apr 24 2017

For the 12z TAFs, LLWS concerns will persist through mid-morning
before the surface winds quickly increase, with southerly winds
gusting upwards of 25-35kts mid-morning through the afternoon.
Winds will gradually diminish during the afternoon and by tonight,
with LLWS concerns returning once again overnight.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 3 PM CDT this afternoon for KSZ008>010-
020>022-034>037.

&&

$$

SHORT TERM...Hennecke
LONG TERM...67
AVIATION...Hennecke



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