657 
FXUS63 KTOP 280506
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1206 AM CDT Tue Aug 28 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Tuesday)
Issued at 325 PM CDT Mon Aug 27 2018

An upper level trough was positioned across the northwest with 
perturbations moving around the base of the trough. Lead wave was 
moving into the Dakotas with a second wave moving into Idaho. 
Other energy may move northeast in southwest flow aloft out of the
southern Rockies across the area overnight. CAMS suggest that 
isolated convection will once again develop within the low level 
jet overnight within the moisture plume extending from the Texas 
Panhandle into southwest Iowa. Have inserted chances after 09Z as 
in the prior forecast and models suggest that scattered activity 
should wane during the mid to late morning hours. Given the strong
winds off the surface and a mixed lower boundary layer could see 
a few strong wind gusts in the morning. During the day on Tuesday,
the upper trough will move across the northern Plains with 
trailing energy further south into the central Plains. This will 
move a cold front southward across northeast Kansas through the 
day. The front looks to be in north central Kansas toward 12Z then
move southeast and exit the CWA in the evening hours. Forecast 
soundings ahead of the boundary show upwards of 4000 J/kg of ML 
CAPE along with 30 kts of effective shear along with steepening 
mid level lapse rates. Strong to severe storms are possible from 
late afternoon through the evening hours with damaging winds and 
hail the main hazards. High precipitable water values near 2.2 
inches pool along the boundary owing for high precipitation 
efficiency as well. 

.LONG TERM...(Tuesday night through Monday)
Issued at 325 PM CDT Mon Aug 27 2018

High pressure builds into the area in the wake of the system on 
Wednesday with cooler temperatures around 80 degrees. For much of 
the rest of the week and into the weekend a zonal flow aloft will 
prevail across the central Plains with perturbations ejecting 
eastward through the period bringing periodic chances for showers 
and thunderstorms. Wednesday night looks like elevated convection 
will be possible later in the night with the passage of one of the 
minor waves and moisture return to the north. Models differ with the 
ejection of another mid level trough out into the central Plains 
early next week. Highs will be mainly in the 80s, with highs friday 
in the low to mid 90s. 

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1203 AM CDT Tue Aug 28 2018

For the 06z TAFs, gusty southerly winds will persist through the 
TAF period, with a 45-55kt LLJ resulting in LLWS concerns once 
again through Tuesday morning. This LLJ may help to support some
isolated thunderstorm development near KTOP/KFOE around sunrise,
so inserted VCTS. With a cold front tracking southward into the 
region on Tuesday, there is a better potential for scattered
thunderstorms to develop mid/late afternoon into the evening
hours. While there is fairly high confidence in this storm
development, there are still minor model discrepancies with the
time and location of this storm initiation, so just have VCTS
mentioned at this time and anticipate being able to add more
specific timing in future TAF updates. Behind this frontal
passage, winds will veer to the north, with models showing MVFR
cigs developing over the area by mid/late Tuesday evening.  


&&

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

$$

SHORT TERM...53
LONG TERM...53
AVIATION...Hennecke