Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 192331
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
631 PM CDT Tue May 19 2015

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Wednesday)
Issued at 337 PM CDT TUE MAY 19 2015

Local area becoming increasingly influenced by northern and southern
branch energy, with another rough rotating northeast out of the
Southern Rockies and another wave coming southeast into the Dakotas.
The old front was well south of the area, from the Texas Panhandle
into eastern Oklahoma with northeast winds keeping temps in the 50s
to lower 60s. 850mb dewpoint depressions were in the 10-20c range in
Kansas, but actual dewpoints in the 10-15 range were measured from
10-15C.

Setup continues to point to increasing precipitation chances
tonight. Isentropic lift ahead of the weakening upper wave increases
in depth with PW values rising steadily in the 1-1.5" range. Models
continue to struggle with where heaviest precip will be in the
region, and specifics of where developing 850mb low will track, but
much of the southern areas should be along the area of better
moisture convergence and frontogenesis for likely more continuous
precip in the evening and overnight hours. Convective instability
remains nearly absent but forcing could be enough for a few
embedded cells. Although could see some places receive another inch
of rain, expect rates to be slow enough for little concern for
flooding. Precip should be ending quickly Wednesday morning as low
level winds veer and the upper wave passes. Low cloud looks rather
prevalent with more cold air advection to keep highs in the middle to
upper 50s.

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 337 PM CDT TUE MAY 19 2015

Wednesday night through Friday:

On Wednesday night, a weak vorticity maxima will drop southeast
across the area with surface high pressure building in as it passes.
NAM suggests a chance for showers with this vort max, but shallow
moisture and weak lift overnight suggest that it will likely be dry.
Do expect some clouds and a breeze to keep temperatures in the lower
to middle 40s with some potential to go a bit colder in north
central KS if skies clear early on. The upper flow pattern flattens
out on Thursday and becomes more southwesterly by Friday as the next
trough builds over the desert southwest and shifts east. The surface
high will only slowly shift east, bringing a cool but pleasant day
on Thursday and potential for a chilly Thursday night. Current
indications are that a southerly breeze should pick up across the
area before sunrise along with increasing high clouds...working to
moderate temperatures and keep lows in the 40s again. There is
strong model agreement in a lead short wave trough ejecting into the
Plains on Friday with moisture advection into the area along with
widespread vertical motion. Little to no instability is expected as
this trough passes, and the energy weakens as it moves into eastern
KS as well...so while rain and a few storms are likely for central
KS, have lower chances with eastward extent as the system runs into
slightly less moisture and weaker ascent.

Friday night through Tuesday:

Another closed upper-level low will transverse east over the Rockies
by Saturday afternoon.  This system will bring chances for
precipitation every day from Friday evening through Tuesday.  With
moderate shear and over 1000 J/kg CAPE Saturday and Sunday, could
see some potentially stronger storms these days.  Timing with the
exiting of this system differs between the GFS and ECMWF, but with
the best instability seen Monday afternoon, another chance for
stronger storms exists.  A warm up trend will be seen this weekend
with highs topping out in the lower 80s by Tuesday afternoon.

&&

.AVIATION...(For the 00Z TAFs through 00Z Wednesday Evening)
Issued at 625 PM CDT TUE MAY 19 2015

Scattered light to moderate rain showers will continue to impact
terminals through 12Z. Conditions are predominantly VFR before
deeper moisture with the wave lowers ceilings to MVFR aft 03Z and
likely IFR aft 06Z with the heaviest precipitation. There may be
lingering drizzle in the morning before ceilings gradually lift
above 1000 feet in the afternoon.

&&

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

$$

SHORT TERM...65
LONG TERM...Barjenbruch/Heller
AVIATION...Bowen





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