000
FXUS63 KTOP 190452
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1152 PM CDT Fri Jul 18 2014

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Saturday)
Issued at 303 PM CDT FRI JUL 18 2014

Deeper moisture continues to spread northward across central KS
behind the departing mid/upper level shortwave. A weaker shortwave
will drop down from western SD later this evening and into tonight.
It appears that any shower activity associated with the wave will
stay in western NE and KS. Dry conditions expected through tomorrow
despite minor disturbances continue to pass over the region with the
northwest flow regime. Cumulus field will dissipate this evening
with the loss of daytime heating. Tonight mostly clear skies and
light winds allow overnight lows to drop into the upper 50s and low
60s. Patchy ground fog will again be possible across the southeast
portions of the forecast area for a brief period around sunrise
especially in the low lying areas. Tomorrow remains quiet and dry
with high temperatures in the mid to upper 80s. Southerly winds will
pick up in the afternoon with the increased pressure gradient across
the area.

.LONG TERM...(Saturday Night through Friday)
Issued at 303 PM CDT FRI JUL 18 2014

Forecast challenges in the long term include precip chances
Saturday night, magnitude of heat Sunday through Tuesday, and
timing of greatest precip chances next week.

On Saturday night, a weak disturbance will cross the northern
Plains with moderate warm advection and a moderate low level jet
across central KS into Nebraska. Elevated instability will be in
place above the warm advection layer, but soundings indicate that
it will require fairly deep lift through an inhibited layer to
initiate convection. The GFS is easily the most aggressive in
precip coverage during the period, and feel more confident in a
drier forecast. At the same time, given the magnitude of warm
moist advection, there is some small potential that lift would be
sufficient to overcome elevated CINH and have thus kept slight
chance POPs after midnight.

Sunday into at least Tuesday (and probably beyond) will then be
quite hot, perhaps into heat advisory territory especially on
Monday and Tuesday. Dewpoints will increase into the lower 70s and
may even flirt with the middle 70s by Monday depending on extent
of afternoon mixing. Meanwhile, temperatures should be solidly in
the 90s with a few 100 degree readings possible in central KS. The
current forecast T/Td combinations call for a max heat index of
around 100 on Sun/Wed/Thur, and Mon/Tues will likely range from
102 to 108. Low temperatures will only fall into the 70s, and
perhaps only the upper 70s Monday night.

Monday evening should have fairly strong instability set up across
the area with around 20 kts of deep layer wind shear. This
instability looks likely to be capped off though with the
exception of an isolated storm possible by late evening as there
is some suggestion of a weak short wave trough entering the
region. By late Tuesday, a cold front will enter the forecast
area. While this front won`t be strong, there will be enhanced
convergence along the boundary and it should enter the region
around or just after peak heating. Most model guidance suggests
strong instability, a fairly weak cap, and 30 to 40 kts of 0-6 km
shear. See a fair chance for the cap to break near the front with
strong to severe storms possible if they develop. The front
lingers in Wed morning before pushing south of the area. The upper
ridge will remain overhead though and despite the weak frontal
passage, the temperatures are likely to remain quite hot and
dewpoints should remain elevated as well...hence the continued
95-105 heat indices through the remainder of the forecast.

&&

.AVIATION...(For the 06Z TAFs through 06Z Saturday Night)
Issued at 1146 PM CDT FRI JUL 18 2014

Vfr conditions will generally be the rule at all TAF sites
through the terminal forecast period. The only exception may be
occasional mvfr vsbys in fog at KTOP in the 09z-12z timeframe.
Otherwise mainly sct stratocu around 6kft and south to southeast
winds under 5kts thru 14z then around 12 kts afterwards...although
decreasing again aft 01z/20.

&&

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

$$

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