Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 170503
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1203 AM CDT Wed Sep 17 2014
...Update to aviation forecast discussion...
.SHORT TERM...(This Evening through Wednesday)
Issued at 317 PM CDT TUE SEP 16 2014
Mostly clear skies across the eastern counties have brought high
temperatures into the lower 70s while far west has been a few
degrees cooler as clouds move in. Dewpoints in the 40s this morning
have risen to the lower 50s for much of eastern Kansas.
For tonight, isentropic lift develops over the eastern half of the
area near the 305K surface. Appears at this time to maximize over
eastern or east Central counties after 06z. Will start with
slights everywhere but think parcels will need to lift northeast
before isolated storms can form. Soundings near Emporia and the
Flint Hills refuge carry more CAPE and less mid level capping than
northward locales, reaching around 2000j/kg for a time. Shear
remains low, however a quickly developing updraft into steep lapse
rates aloft could produce some hail as they develop. Will focus
some low end chance pops over the east, overnight lows in the 50s.
For Wednesday, surface low over western Kansas slowly develops and
extends surface warm front eastward into the forecast area, and
coupled with the mid level front could provide a focus for another
round of isolated storms. Lifting mechanism is not strong, however,
and may have several hours of subsidence behind morning convection
before chances increase. Again kept more focus eastward and
generally 35 percent or less all areas.
.LONG TERM...(Wednesday Night through Tuesday)
Issued at 317 PM CDT TUE SEP 16 2014
At least some mention of precipitation is in order into Thursday
with warm front in area and veered wind profiles. Could see
convection from Wednesday reinforce the front for more local
development Wednesday evening, but appears better synoptic isentropic
lift and moisture convergence will be in western and central
Nebraska, with upper flow bringing this southeast into a supportive
environment. Shear amounts and elevated lapse rates still not very
strong, but enough moisture for at moderate CAPE and near-severe hail
possibilities. This convection could easily spill over into Thursday
morning, and along with low level moisture pooled northeast of the
warm front (still expected to be to the southwest), temperatures
could be stubborn to rise. Continue to have low confidence in highs
given aforementioned issues, but have most areas a bit cooler than
Wednesday given more low cloud potential. At this point, boundary
layer winds look too strong for any fog concerns but can`t rule out
some around sunrise drizzle for mainly northeastern locations. By
late Thursday, should see storm focus shift northeast ahead of next
upper wave with upper heights rising locally and will keep Thursday
night dry. Friday still looking like the most likely dry period
through the late week with highs well into the 80s, though still
some potential problems with morning stratus possibilities.
A wet period from Friday night into Saturday evening still quite
possible as the next cold front makes eastward progress through the
Plains. Surface moisture should be high enough for at least
scattered activity, but main wrench continues to be where the
remnants of Odile will be. Latest GFS and ECMWF keep this to the
south, and could potentially be enough subsidence to its north to
keep widespread precip in check here. At this point kept mid-range
PoPs going as just how Odile and the northern states` upper trough
interact is far from certain. Cooler and drier airmass settles in
for early next week under upper ridging.
.AVIATION...(For the 06Z TAFs through 06Z Wednesday Night)
Issued at 1158 PM CDT TUE SEP 16 2014
Will see periods of MVFR cigs between 06Z-09Z with more widespread
MVFR cigs after 09Z. An area of TS is still likely to develop
between 08Z-11Z, and more likely to impact TOP/FOE than MHK.
Ceilings will continue to lower through 14Z, with a period of
likely IFR cigs (and possibly IFR vis) focused between 12Z-16Z.
Should then see a slow increase in ceiling heights followed by
scattering out of the ceiling between 16Z-19Z. Some small
potential for TS by late afternoon, but most indications point to
isolated TS or none at all through 06Z.