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Area Forecast Discussion (AFD)

Issued by Topeka, KS (TOP)

FXUS63 KTOP 141806

Area Forecast Discussion
National Weather Service Topeka KS
106 PM CDT Sat Sep 14 2019

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 321 AM CDT Sat Sep 14 2019

The western edge of the sfc ridge is expected to gradually exit 
eastern Kansas into Missouri later this morning. In return, moisture 
transport is beginning to increase across central Kansas as sfc 
dewpoints are progged to reach the low 70s by late afternoon. In the 
meantime, there remains a slight chance for isolated showers and 
thunderstorms to develop aft 10Z as a very weak embedded shortwave 
trough interacts with the theta-e advection band from central Kansas 
through southeast Nebraska. These showers should gradually wane by 
late morning, translating to partly cloudy skies in the afternoon. 
Overall highs were not adjusted too much with readings from the 
middle to upper 80s. At this time, it appears that any thunderstorm 
redevelopment is unlikely, especially given the strong capping 
inversion near the sfc.

Another embedded shortwave trough axis will lift over the northern 
plains late tonight. Optimal thunderstorm chances remain 
consistently over Iowa based on several previous runs. However, the 
GFS, NAM, and a few members of the HREF are similar in scattered 
showers developing as far south as northeast Kansas between 6Z and 
12Z Sunday. Forecast soundings have some meager moisture return in 
the 700 mb level, but with the ample dry air below towards the sfc, 
probabilities for widespread precip remain low.  

.LONG TERM...(Sunday through Friday)
Issued at 321 AM CDT Sat Sep 14 2019

Upper ridging builds into the central CONUS through Tuesday as a 
series of poignant upper troughs enter the Pacific Northwest region. 
Temps through this period remain unchanged, but above normal for 
this time of year with highs near 90 degrees and overnight lows in 
the lower 70s. The 00Z GFS remains the faster solution compared to 
the ECMWF on timing of the upper trough and associated cold front 
arriving as early as Wednesday. The ECMWF brings the front through 
on Wednesday night and Thursday, lacking the amount of moisture 
present on the GFS solution. The front is anticipated to lift back 
northward by Thursday as the main upper low gradually lifts 
northeast by next weekend. Southerly moisture advection enhances the 
probability for precip chances Friday into Saturday as a series of 
lead disturbances eject into the central plains. The organized 
convection focuses along the cold front as it slides back southward 
into the CWA in the Sat-Sun time frame. 


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1254 PM CDT Sat Sep 14 2019

VFR conditions hold for much of the period with high confidence.
Breezy conditions continue this afternoon until near sunset with
afternoon cumulus especially over eastern terminals. Mid clouds
may move in from the west with lower confidence in isolated
showers or storms making their way into the terminals very late
overnight. The higher confidence aviation hazard will be that of
LLWS overnight as a strong LLJ develops across the region arond
04Z lasting through around 14Z.