Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 170501
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1201 AM CDT Fri Mar 17 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday)
Issued at 249 PM CDT Thu Mar 16 2017

At 19Z, WV and VIS satellite imagery was showing a low amplitude
baroclinic wave advecting out of the Northern Rockies region with
associated boundary at the surface over west central Nebraska
undergoing frontogenesis at the current hour. This will be the
frontal feature that impacts northeastern KS near or just after
the 12Z time frame Friday morning.

Currently, over northeastern and east central KS, gusty southerly
winds around 20mph continue this afternoon ahead of this weak system
and should stay strong enough even after sunset to still be
noticeable through the late evening hours.  This will help moisture
to continue to advect into the region at the low levels.  Dewpoints
in the 50s have currently made it to the KS/OK border.  Chances
remain small for patchy fog to develop after midnight for a period
of time, but this will require winds to calm enough so as to not
just remain stratus. Currently, the wind may be the inhibiting
factor for patchy fog, so perhaps fog may just be limited to valley
regions. Outside of that, do expect at least slight chances for
drizzle to fall out of the low stratus over mainly portions of east
central KS south of I-335 corridor as isentropic lift increases for
a few hours over that region on the 295-305K surface with small
pressure deficits in place.  This should quickly be shoved to the
east/southeast as the cold front enters the region.  Dry air will
filter in quickly behind the front, which should give way to a
pleasant day Friday. Expect mostly clear skies with temperatures
around the mid 60s with cooler H85 temps in place as well.

.LONG TERM...(Friday night through Thursday)
Issued at 249 PM CDT Thu Mar 16 2017

For Friday night through Sunday, models show upper level ridging
over the central plains while surface ridging on Saturday gives
way to return flow by Sunday. There isn`t much in the way of large
scale forcing noted in the models, so the forecast is for dry
weather to persist. Increasing southerly winds on Sunday should
bring low level moisture and warmer temps to the region. 850MB
temps are progged to warm to around 20C across north central KS.
So highs look to be in the 80s for the entire forecast area. The
one hiccup to the high temp forecast could be some low clouds
that form during the morning with the strong low level moisture
advection. Not sure how much of an impact this could have since
both the GFS and NAM scatter out the low clouds by the afternoon.

A cold front is expected to move through Sunday night and Monday
as a shortwave moves across the northern plains. GFS forecast
soundings keep a capping inversion over the boundary layer and
with much of the dynamics with the upper wave passing north of the
forecast area, am not sure there will be much precip with the
boundary. Have some slight chance POPs over northeast KS with the
frontal passage in case a storm is able to break through the cap.

The upper ridge redevelops for Tuesday and Wednesday before the
main weather maker impacts the area late in the week. The GFS and
ECMWF show some energy rounding the top of the ridge with some
weak mid level frontogenesis forming over north central KS.
Forcing for precip doesn`t look all that impressive, but models
continue to show the potential so have some chance POPs in for
Tuesday morning across the northern half of the forecast area.

For Wednesday and Thursday, an upper low is progged to move out
into the plains. The GFS is the more progressive solution with the
ECMWF and GEM still a little slower with the upper low. Timing
questions aside, models have been persistent in bringing this
system out for the last couple days so have some likely POPs for
Thursday. Instability doesn`t look all that impressive within the
warm sector of the system. Nevertheless steepening lapse rates
argue for at least a mention of thunder. There could also be some
warm air advection showers and storms Wednesday night as moisture
returns in advance of the system.

Temps Monday through Wednesday are forecast to be more on the
mild side with an easterly component to the winds. Highs are
expected to be in the 50s while lows stay in the 30s. Warm air
advection should cause temps to trend warmer Thursday, but
increasing clouds are expected to keep the warming to the 60s and
possibly 70 degrees.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1156 PM CDT Thu Mar 16 2017

MVFR cigs continue to develop southeast of TAF sites but are
struggling to spread north. Have backed off on ceiling inclusion
but maintained at least a tempo group at TOP/FOE for the most
likely hours. Also included LLWS for the next few hours as the LLJ
is increasing to around 50 kts at 2000 feet but will weaken and
shift out of the north as a cold front comes through between
10-13Z.

&&

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

$$

SHORT TERM...Drake
LONG TERM...Wolters
AVIATION...Barjenbruch



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