Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 162326
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
626 PM CDT Wed May 16 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Thursday)
Issued at 309 PM CDT Wed May 16 2018

Short-term forecast will include a few showers and perhaps a short-
lived thunderstorm or two this afternoon and early evening.

Overall pattern, as seen from GOES-16 and upper air samplings,
suggests most significant PFJ energy remains along the northern
tier of the CONUS/Canadian border region. A weak cut-off low is in
the process of filling over the western CONUS with a weak
northwest to quasi- zonal flow over the Central Plains. Surface
boundaries remain well south and north of the area with weak
surface ridging into the region. That said, there is a weak mid
level wave working through southeastern NE into northern MO and a
remnant MCV to the south in eastern OK and western AR. The weak
wave will continue to bring a slight chance for some brief showers
and a clap of thunder or two as low level lapse rates have risen
to around 7.5 C/km over the area. Inverted V type profiles have
thus set up. So, storms that do form could exhibit brief heavy
rain and some gusty outflow winds but nothing is expected to be
severe at this time. Short lived nature of the storms may also
make it difficult for even small hail to be too big of a concern.
This activity will likely end near sunset and again primarily
impact eastern portions of the forecast area and far northeast KS.

With mixing up to the 800mb level and some insolation through high
cloud cover, temps have risen into the low 80s today, which is still
around seasonal norms.  Lows tonight dip into the 60s with dry
conditions overnight.  May be some areas see some shallow fog in the
morning, but probably in the lowest lying areas as to be expected.

Thursday have kept the forecast dry with heights rising over the
area as a mid level ridge translates over the area and a general
lack of forcing or boundaries is evident over the area. Highs
into the middle 80s should be more common.

.LONG TERM...(Thursday night through Wednesday)
Issued at 309 PM CDT Wed May 16 2018

Long term forecast into overnight Thursday and into Friday bring
returned chances for showers and storms into part of the weekend.
Weak embedded waves in the southwest flow over the Rockies will help
storms initiating in the foothills within upslope flow regime to
move out over the High Plains into the overnight period.  Some
guidance keeps these storms on track into the forecast area for
Friday morning.  These will not likely remain severe as they move
into the area and dissipate.  As a lee low undergoes cyclogenesis
Friday afternoon over southeastern CO vicinity, WAA should increase
over the area and showers and storms could develop into the
afternoon hours and early evening.  Deep layer shear does increase,
but still appears to remain marginal at this time.  Instability does
develop with the greatest theta-e air advection over western areas
into north central KS.  This would be the likely area for any strong
to severe storms to develop.

Saturday is also a period to watch for possible strong to at least a
few severe storms to develop, but question remains on position of
the warm front as model solutions have yet to have general good
agreement on warm frontal position as well as the track of the
surface low.  GFS has nudged the boundaries further north into
Nebraska and maintains slightly stronger shear and negatively tilted
low amplitude trough over the area.  NAM and ECMWF appear to be
further south with track of the low and vary on strength of deep
layer shear.  Just too much uncertainty at this point to either rule
out strong to severe storms or be too bullish on them for that
matter.

Overall, temps remain above seasonal norms with a bit of relief on
Sunday on the back side of the Saturday system.  However, a quick
rebound into the mid to upper 80s with mid 60s dewpoints will be
common.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 626 PM CDT Wed May 16 2018

Outflow boundary from early afternoon convection in NW Missouri
continues to push south and encourage further updrafts. Will go
ahead with VCTS at TOP and FOE at this point through boundary
layer should stabilize significantly in the next few hours in
light winds and 20-25F temp/dewpoint spreads. Winds could gusts
could be the main aviation impact. Additional outflow wind and
lingering high cloud further inhibits BR formation, and with
somewhat more wind forecast for the lower levels and higher
crossover temps today compared to Tuesday, will keep any
visibility restrictions out.

&&

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

$$

SHORT TERM...Drake
LONG TERM...Drake
AVIATION...65


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