Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 281757
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1257 PM CDT Sun Sep 28 2014
Issued at 629 AM CDT SUN SEP 28 2014
Added some isolated showers and thunderstorms across north central
Kansas through mid morning in area of isentropic ascent and within
the low level jet moisture transport.
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 330 AM CDT SUN SEP 28 2014
Early this morning an upper level low continued to be centered over
Iowa while a weak surface high extended from Illinois into eastern
Kansas. Light to calm winds have lead to patchy fog forming in the
river valleys and low lying areas and expect it to burn off about an
hour or so after sunrise.
The upper low over Iowa is expected to sag southeast with time today
keeping the cold core over Iowa and northeast Missouri. Limited
moisture and lift forecast by soundings across northeast Kansas
today. EML around 650-600mb level remains in place across most of
the CWA today except for the far northeast near the Missouri border.
Scattered mid level clouds have developed across central Kansas into
Nebraska in weak isentropic lift on the 305K surface. Not expected
any convection with mid level EML above the isentropic lift and will
go with a dry forecast. Should mix down from 825mb today with highs
in the mid 80s.
Tonight with clear skies and light to calm winds will see some
patchy fog in low lying areas in the eastern CWA as well as the
river valleys. Lows tonight are expected to fall into the upper 50s
to lower 60s.
.LONG TERM...(Monday through Saturday)
Issued at 330 AM CDT SUN SEP 28 2014
Upper ridge axis remains overhead Monday, but fairly percent height
falls take place from late in the day through early Thursday thanks
to multiple larger scale systems traversing the Plains, leading to
several periods of precipitation potential.
Initially the upper low over the Great Basin today lifts northeast
across western Nebraska Monday night, with increasing mid/low level
moisture and edge of decent forcing aloft leading to a band of
showers and perhaps a few thunderstorms pushing northeast into north
central Kansas late Monday night and further east into the local
area early Tuesday. Pacific cold front still looks to slide east
into north central Kansas late in the day, and if some clearing can
occur behind the earlier band, there will be some potential for
severe weather as mid level winds increase to around 40kt and some
veering occurs through the column with wind and hail seeming to be
the more likely concerns in week and somewhat unidirectional low
level flow. Increasing moisture transport ahead of this slow-moving
front should lead to expanding convection on east through much of
the area Tuesday night into early Wednesday, with the next upper
wave, now as a closed low in the Bering Sea, makes its way southeast
into the Central Plains late Wednesday into Thursday for another
round of precip expectations. At this point, the degree of severe
weather potential is uncertain with lack of strong forcing
mechanisms for Wednesday afternoon and evening as well as questions
on persistence of early day precip, and timing of the wave and cold
front perhaps too fast for much destabilization to occur for
Thursday. Trough axis should be exiting the area by early Friday for
rapidly drying conditions for that day with most operational and
ensemble runs lacking any tertiary waves aloft and have gone dry for
Friday into Saturday.
Monday brings another day of highs in the lower 80s, with at least
minor potential for ground fog in the east Monday night ahead of
clouds and precip. Highs Tuesday into Thursday of course depend on
insolation areas between rounds of convection, but at this point
expect enough early-day dry time in the east for lower 80s again,
with lesser confidence in the west. Temps for Friday and Saturday
drop back into the 60s in modified Canadian air.
.AVIATION...(For the 18Z TAFs through 18Z Monday Afternoon)
Issued at 1249 PM CDT SUN SEP 28 2014
All terminals will likely remain VFR for the balance of the afternoon
and evening. During the early morning hours on 29/10Z time frame
the likelihood of patchy fog developing in low lying areas will
again appear. Didn`t take vis down to VLIFR but it could be a
likely case at KTOP for a short time frame. KMHK could see some
very isolated areas of shallow fog, but confidence in that is low
at this time due to winds and cloud cover timing.