000
FXUS63 KTOP 291704
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1204 PM CDT Tue Jul 29 2014

...AVIATION UPDATE...

.SHORT TERM...(Today and Tonight)
Issued at 309 AM CDT TUE JUL 29 2014

Scattered showers and a few embedded lightning strikes have
developed from central Nebraska into north central Kansas as of 3
AM. This precipitation is in response to a band of frontogenesis
providing a fairly narrow zone of ascent within a moist and slightly
unstable elevated layer. Since yesterday, the high resolution model
guidance (NMM, ARW, RAP, HRRR) has far out-performed other guidance
in predicting this activity...and the forecast through tonight has
relied heavily on the high-res suite of guidance. The ascent should
persist or strengthen through around 15Z while it gradually shifts
southeast along line roughly from Belleville to Manhattan to
Burlington. Then expect a weakening trend after 15Z with conditions
becoming nearly dry between 21Z and 03Z when the lift is at its
weakest. While the precipitation will be persistent on a broad
scale, the showers will be more or less scattered within the main
axis of ascent and do not expect rainfall totals to be much at
all...perhaps a few areas could see more than 0.25 inch.
Temperatures will be muted by cloud cover today, with the warmest
conditions both northeast and southwest of the previously mentioned
precip axis. Highs should top out in the upper 70s to middle 80s.

The band of frontogenesis is likely to intensify once again after
03Z along roughly the same axis. This zone of ascent should
gradually pivot and shift more toward a Concordia to Manhattan to
Ottawa line after midnight. By late in the night, additional
moisture influx into the region is expected in advance of a fairly
strong short wave trough that will move from southwest Utah this
morning into southwest Kansas tonight. Again, heavy rain is not
expected but a few areas could possibly approach 0.5 inch or more
tonight where the showers are more persistent. Low temperatures
should stay a bit warmer with persistent cloud cover, generally
ranging from the upper 50s in far northeast Kansas to the middle 60s
in east central Kansas.

.LONG TERM...(Wednesday through Monday)
Issued at 309 AM CDT TUE JUL 29 2014

The aforementioned upper trough impacts portions of the CWA by
Wednesday morning. Cross sections reveal decent low to mid level
frontogenesis aiding the mid level vorticity maxima centered over
southwest Kansas. These areas expect the bulk of the precipitation
while over northeast Kansas, areas south of Interstate 70 see
optimal chances for rain showers. Precipitable water values are
fairly low given the quick invading mid level subsidence which will
help to clear out cloud cover north to south during the late afternoon.
Following consistent runs with the 4 KM WRF and the overall guidance
trends of the precip bands spreading a touch further north and east,
decided to increase pops south and add slight chances north of
Interstate 70. Mid level instability is minimal with perhaps an
isolated lightning strike. Highs Wednesday were also lowered a few
degrees based on the slightly thicker and longer duration of cloud
cover. Skies clear out Wednesday evening with surface high pressure
pushing into the region. Strong radiational cooling and calm
winds look probable for patchy fog in areas that receive rainfall.

Mostly dry north to northwest flow continues through the forecast
period with no poignant upper waves to hold high confidence on. On
Friday into Saturday, a weak front may provide additional support,
however the weak nature of the boundary combined with lacking
moisture seen on sounding profiles suggest low confidence in
initiation. With the inconsistent timing and placement, decided to
leave out mention of precipitation on Friday and Saturday to see if
any congruency in the next few runs materializes. For the latter
part of the weekend into next Monday, another upper trough dips
south over the northern plains as southerly flow increases
temperatures. After a mild week with highs in the 80s and lows in
the 60s, a warming trend commences with 90s possible for highs
Sunday and Monday.

&&

.AVIATION...(For the 18Z TAFs through 18Z Wednesday Afternoon)
Issued at 1204 PM CDT TUE JUL 29 2014

The frontogenetical band of light showers appears to be falling
apart and should remain south of the terminals this afternoon.
Models show the deeper moisture and forcing overnight and into Wed
morning favoring precip across southern and western KS. A few
solutions still try to bring some light SHRA into MHK overnight.
Again with mid level lapse rates only around 5 C/km, impact to the
terminals would be minimal. With 12Z model guidance trending
southwest with their QPF, have removed the mention of VCSH from
TOP and FOE and left the mention in for MHK. Overall VFR
conditions should prevail even if -RA moves in due to no real low
level moisture advection anticipated.

&&

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

&&

$$

SHORT TERM...Barjenbruch
LONG TERM...Bowen
AVIATION...Wolters