Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 310451
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1151 PM CDT Mon Mar 30 2015
...Update to aviation forecast discussion...
.SHORT TERM...(This Evening through Tuesday)
Issued at 330 PM CDT MON MAR 30 2015
20Z water vapor shows northwest flow from the northern plains into
the southeastern U.S. There may be some weak perturbations within
the flow, but the more obvious shortwave energy is off the Baja and
over the desert southwest. An amplifying upper trough over the
northern Pacific has several shortwaves rotating towards the British
Columbia coast. At the surface, a weak trough of low pressure was
noted in the surface obs from southeast CO into eastern NEB.
The weather for tonight and Tuesday will remain nice as limited
moisture and no organized forcing will make it unlikely for precip.
Slightly more mixing and some higher humidity is expected to keep
lows a little warmer tonight. However there should be decent
radiational cooling with clear skies once again, so have gone closer
to the cooler MOS guidance. Models mix the boundary layer to 850MB
or 825MB. Good insolation and adiabatic mixing would warm afternoon
temps into the mid 70s or near 80.
.LONG TERM...(Tuesday Night through Monday)
Issued at 330 PM CDT MON MAR 30 2015
Main focus in the middle and later portions remains to be
thunderstorm chances Wednesday afternoon into Thursday. Not much
change in going expectations, with northern branch wave entering the
Northern Plains Wednesday, dragging a cold front into central
portions of Kansas and Nebraska late Wednesday afternoon. Timing of
this continues to back off a bit, with only considerable chances for
impacts coming late in the afternoon with storms likely to fire just
to the north and west of the local area. Very light QPF from a few
models Wednesday looks to be from drizzle (likely bogus) in trapped,
shallow low level moisture, and have some concern for this stratus
to keep highs from breaching the 80F mark, but haven`t changed
values much for now. Southern branch energy remains of interest, as
it now begins to swing slightly north of east late Wednesday into
Wednesday night, but still staying southeast of the local area. At
this point could see some minor subsidence occur in the late day and
early evening behind this wave, but this will likely not be enough
to prevent upstream convection to become more widespread with time.
Still somewhat shallow nature to moisture could allow for severe
concerns to diminish by late evening as low level jet veers to near
parallel with the front, but lapse rates above remain high. Upper
jet speeds also rather weak for less storm organization. Still
appears a good setup for good precip coverage for at least northern
and central areas. Front passes by midday Thursday for cold air
advection to keep highs in the middle to upper 60s. Good agreement
in the trailing upper trof`s characteristics remains lacking, but
mid-level baroclinic zone nearby with the wave moving through keeps
chance POPs in place Thursday night into early Friday. Continued
cold air advection brings Friday`s highs back into the lower to
middle 50s with frost potential Friday night.
Warming temps remain on track for the weekend as west to southwest
flow develops aloft and south to southwest low level winds return.
The specifics of the upper pattern also become diffuse by the late
weekend with some potential for convection by Sunday night if the
more progressive runs pan out. Will go ahead with slight POPs for
eastern areas at this point.
.AVIATION...(For the 06Z TAFs through 06Z Tuesday Night)
Issued at 1144 PM CDT MON MAR 30 2015
Smoke from the fires today is getting trapped in the nocturnal low
level inversion and causing lowered visibilities at some of the
taf sites. The winds are currently out of the south southwest, but
are forecast to veer through out the night. There are less fires
upwind of a westerly and northerly wind direction therefore have
did not mention MVFR visibilities within the taf. Although this can
not be completely ruled out.