000
FXUS63 KTOP 192329
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
629 PM CDT Sat Jul 19 2014

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Sunday)
Issued at 313 PM CDT SAT JUL 19 2014

The northwest flow aloft will gradually transition as an upper level
ridge builds into the central plains from the southwest US. This
will guide the weak shortwaves embedded within the flow further
north therefore avoiding the area. The current wave passing over NE
is responsible for an MCV, which at the moment is moisture starved
and dealing with insufficient lapse rates as it moves through far
northeast KS. Isentropic lift on the 315 K surface develops over
northern KS overnight although moisture and instability remains
limited. Also, low level dry air would prevent most precip from
reaching the ground. The surface ridge continues to slide eastward
into the mid MS valley allowing for a tighter pressure gradient
further into eastern KS. These slightly higher surface winds should
inhibit the development of fog later tonight with the exception of
far southeast KS and a few of the river valleys. Veered winds and
increasing 850 mb temps will help keep low temps in the mid to upper
60s. Tomorrow partial thickness increase as the ridge builds
overhead causing an 8 to 10 degree rise in temps. With the thermal
ridge axis more aligned over northwest KS into central NE north
central KS should reach the upper 90s. The skies will become partly
cloudy with wind gusts increasing to around 25 mph by the
afternoon.

.LONG TERM...(Sunday Night through Saturday)
Issued at 313 PM CDT SAT JUL 19 2014

There has not been a lot of change in the long term with the
primary forecast focus being on very hot conditions Monday and
Tuesday, and thunderstorm chances late Tuesday.

An upper ridge axis will extend from western Mexico into northeast
KS and the Great Lakes on Monday with very hot temperatures in the
low levels under the ridge. Low level moisture will also be
trapped under the ridge with dewpoints across the region expected
to be in the lower 70s for the Mon/Tues period. There are plenty
of indications that temperatures will top 100 both afternoons with
the best chance in north central KS, but this will be dependent
also upon the extent of low level mixing. Any substantial mixing
would result in warmer temperatures and lower dewpoints, which in
the end would likely equalize each other in terms of heat index.
The current forecast calls for a heat index of 102 to 109 on both
days with the lowest values in east central KS. At this time, it
would seem that any forecast uncertainty would suggest that this
forecast may have more potential to go warmer than cooler, and
barring any major changes before Monday, heat products may be
warranted. Additionally, Tuesday morning lows will probably hold
in the middle to upper 70s, offering little relief.

Precipitation appears unlikely on Monday or through the First half
of Tuesday, although not completely out of the question. While
inhibition is forecast to decrease below 100 J/kg late Monday,
there is not a strong forcing mechanism. Monday night will see a
renewed LLJ with some elevated instability, but the focused ascent
on the LLJ should be well north of the area. By late Tuesday, a
weak cold front is forecast to move into northern KS with some
glancing affect of height falls from a northern CONUS short wave
trough passage. While CINH will be rather high, expect isolated to
scattered thunderstorm development in association with the frontal
passage. The airmass will be moderately to strongly unstable, and
with such hot conditions would seem to be a favorable setup for
locally damaging winds should storms develop. Shear may be
sufficient for supercells as well, which could enhance the
localized severe potential. The main question though is whether or
not the cap will break, and severe storms are certainly not a
guarantee.

Otherwise in the long term, temperatures cool a bit but remain
quite summer-like mainly in the 90s from Wed through Saturday.
While Wed may be the coolest day of the period, it appears that
high dewpoints may pool behind the front and lead to continued
uncomfortable conditions. There are a few more small chances for
precipitation, mainly in northeast KS in association with the
passage of weak short waves to the north. There are suggestions of
a slightly stronger disturbance by late Friday/Saturday, but with
low confidence in this weather pattern.

&&

.AVIATION...(For the 00Z TAFs through 00Z Sunday Evening)
Issued at 621 PM CDT SAT JUL 19 2014

Vfr conditions will continue through the period. Expect enough
mixing overnight to preclude the mention of any fog in the
terminal fcsts. South winds will steadily increase beyond 14z
at all sites with gusts 20 to 22 kts through 00z/20.

&&

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

$$

SHORT TERM...Sanders
LONG TERM...Barjenbruch
AVIATION...63