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Area forecast discussion...updated 
National Weather Service Topeka Kansas
1138 PM CDT Friday Jul 3 2015

..update to aviation forecast discussion...

Short term...(this evening through saturday)
issued at 312 PM CDT Friday Jul 3 2015

High pressure was gradually building south into the area this
afternoon from central Nebraska while drier low level air was
advecting into northeast Kansas from the northeast. A band of low
level moisture remained in place from directly under the high in
Nebraska through north central...east central...and southeast Kansas
and was not moving anywhere particularly fast. A few rain showers
continued into the afternoon in east central Kansas in association
with this moisture but any instability capable of producing
lightning was south of the forecast area in advance of a weak short
wave trough axis aloft. Subsidence and some drying will continue to
take over the local forecast area by late afternoon through Saturday
morning and have a dry forecast going from middle evening through
Saturday. There appears to be some low end potential for fog tonight
as clearing takes place above the remnant low level moist axis and
associated band of higher dewpoints. Winds should be light to calm
to support fog as well...but with continued weak dry advection
through this evening was unsure just how much moisture would be left
by sunset. If dewpoints are still in the 62-65 range as winds go
calm just after sunset...would expect the fog potential in those
areas to increase into the early morning hours.

Independence likely to be warmer than Friday
given widespread sunshine and weak warm advection by afternoon.
Expect highs to range from the middle 80s in far northeast Kansas to
the upper 80s in north central Kansas. Late in the afternoon...a
weak short wave trough is likely move over central Kansas. Models
are consistent in depicting modest instability and strengthening
shear associated with this trough...but are also consistent in a
weak to moderate cap being in place. For the current forecast have
kept things dry through the afternoon with the expectation that the
cap will be stronger than the short wave ascent and will limit
thunderstorm development. Given the myriad of outdoor events ongoing
on Saturday afternoon/evening...will need to keep a close eye on
this period of the forecast but for now expect a benign afternoon.

Long term...(saturday night through friday)
issued at 312 PM CDT Friday Jul 3 2015

On Saturday night the middle level shortwave trough tracks over
northeast Kansas as it progresses eastward. West to northwest flow aloft
will support a deepening Lee side trough and strengthening low level
jet overnight. The end of any 4th of July festivities should remain
dry. Early evening the jet will focus over portions of western and
central Kansas before it gradually veers eastward through the morning
hours. This lift could support any existing convection from the
afternoon peak heating, and or the development of new elevated
convection in the evening. The NAM shows this isentropic lift and
instability aloft moving over portions of central and eastern Kansas
with time. Therefore there is a chance for showers and storms mainly
through Sunday morning and possibly lingering into the early
afternoon hours. The higher chances appear to be across the
southwestern counties of the forecast area where the lift will be
better focused, which then moves into southeast Kansas later in the
morning. Otherwise the afternoon should be relatively dry and clouds
diminishing to allow highs to reach the upper 80s to lower 90s.

The next shortwave will then advance eastward over the northern and
Central Plains Sunday night into Monday morning. This will send a
cold front our way from the northwest although timing will be tied
to the speed of the wave. A few of the models are developing precipitation
early Monday morning ahead of the front across western Kansas. Not sure
if this is due to isentropic lift in the warm sector, which seems
unlikely, or an mesoscale convective system that forms along the front in far northwest Kansas
only to race ahead of it overnight. Consensus is that the front will
move through northeast Kansas during the late morning into the
afternoon. A line of thunderstorms is likely to develop along this
front extending across most of the area with the better chances in
east central Kansas. Dew points are forecast to reach the upper 60s and
low 70s, but lapse rates are rather weak along with the deep layer
shear. Severe storms are not expected at this time but can not
completely rule it out given instability should be modest. The
models then begin to disagree where this front may stall out, and
the possibility of several shortwaves tracking over the the region
within the west to southwest flow aloft. This will likely be
influenced by a decent middle level low pressure over the West Coast
middle to late week.


Aviation...(for the 06z tafs through 06z Saturday night)
issued at 1134 PM CDT Friday Jul 3 2015

VFR conds should persist through 09z when there is some potential
for MVFR visible conds to develop as winds remain light or calm and
air temperatures drop toward the dewpoint. Min dewpoints in Topeka were
in the upper 50s late this afternoon so don't expect too much fog
but could see a period of MVFR visible at all sites given surface high and
clear skies. Have included amend not schedule at kfoe since power was
lost at site and have no way to monitor visible conds at that site for
the time being.


Top watches/warnings/advisories...


Short term...barjenbrach
long term...Sanders

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