Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 291116
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
616 AM CDT FRI JUL 29 2016
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 259 AM CDT FRI JUL 29 2016
Early this morning the region remained under northwesterly flow
aloft as a broad mid-level trough was anchored across the eastern
U.S. Water vapor imagery showed a shortwave over western and
central Kansas that supported some scattered thunderstorm
development early this morning. While the best moisture and lift
will remain focused west of the area, have kept some slight chance
PoPs in through this morning as some short range models show the
potential for some isolated storms to skim near the southwestern
edge of the forecast area. Additionally, another shortwave was
noted in water vapor imagery across eastern Nebraska, and this weak
wave will track southeast, clipping northeast Kansas this morning.
As a result, have slight chance PoPs in northeast Kansas by sunrise
as some isolated showers and storms may skim across that area. While
much of this precipitation should diminish by late morning, have
kept some PoPs in through this afternoon, primarily across the far
southern part of the forecast area. Expect ongoing scattered showers
and storms across southeast Kansas today as a front will be stalled
out near the Kansas/Oklahoma border. This stationary boundary in
combination with additional weak embedded shortwaves may help to
spawn the development of some isolated storms late this afternoon
into this evening, however confidence is still low in this afternoon
development. There is also model uncertainty with regards to the
potential for thunderstorm development this evening and overnight.
Most models show the potential for any scattered storms being
primarily across central to east central Kansas and further south.
However, the NAM shows a shortwave developing over Nebraska and
tracking southeast into the CWA overnight into Saturday morning.
This NAM solution would result in precipitation chances extending
into northeast Kansas overnight. At this time, the NAM appears to be
an outlier solution, so have trended more toward keeping PoPs
focused across central and east central Kansas.
Expect low/mid clouds to linger across the area for much of
the day, which should limit afternoon heating and keep temperatures
a few degrees cooler than normal with highs in the low/mid 80s. This
cloud cover may scatter out some across northeast Kansas tonight,
resulting in low temperatures ranging from the mid to upper 60s from
northeast to southwest.
.LONG TERM...(Saturday through Thursday)
Issued at 259 AM CDT FRI JUL 29 2016
On Saturday, will have 30-50 kt mid/upper level northwest flow
over the region, and it appears likely that the effective surface
front will be over northern OK into southwest KS.There is some
uncertainty in frontal placement based on early morning
convection and any outflow influence on the front. Believe the
bulk of early day storms will be south of the forecast area, but
as the front makes a gradual shift north through the day will see
at least a small chance for storms to impact far southern parts of
the forecast area. Most indications are that much of the day will
feature subsidence aloft though with rather good model agreement
in timing of short wave energy. There is also fair agreement that
a short wave trough will cross the area on Saturday night. Expect
a modest low level jet to converge into east central KS with flow
riding over the surface front just to the south. Lapse rates aloft
are rather modest as well but forecast soundings and lifting
mechanisms do point to a likelihood uncapped elevated convective
parcels and scattered thunderstorms in the area looks like a good
bet. Effective shear may be sufficient for storm organization but
this currently does not look like a very good setup for severe
storms. Thunderstorms may linger into Sunday morning but as the
ridge builds and the warm front moves north through the day,
expect much of the region to become capped and the focus for
overnight storms should also shift northeast as well, leaving the
local area looking to any organized MCS activity to propagate
south into northeast KS, and this activity seems likely to stay
The upper ridge will rather firmly situated over northeast KS
Monday through Thursday. Can not completely rule out thunderstorm
development in (or movement into) the area on any given day mainly
due to the expectation for frequent MCS development to our north.
However, the period looks much more likely to be dry and even if
any organized storms from the north would try to push a cold pool
into the local area, the EML would likely do a good job of
prohibiting thunderstorm development. The silver lining with this
upper ridge is that it does not appear to be as strong/hot as the
most recent heat wave with 500 hPa heights only forecast to peak
around 5940m as opposed to the 6000m of the previous strong ridge.
Regardless...it will be hot and several days see potential for
heat indices to be in the 100-108 range.
.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 614 AM CDT FRI JUL 29 2016
For the 12z TAFs, VFR conditions are expected through the period.
While there is a slight chance for a few isolated showers and storms
today into tonight, confidence in occurrence, let alone location,
is too low to warrant a mention in the TAFs. Winds will be light,
generally out of the north.