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Area Forecast Discussion (AFD)

Issued by Topeka, KS (TOP)

FXUS63 KTOP 160826

Area Forecast Discussion
National Weather Service Topeka KS
326 AM CDT Mon Sep 16 2019

.SHORT TERM...(Today and tonight)
Issued at 325 AM CDT Mon Sep 16 2019

Expansive high clouds are spreading eastward into the Central 
Plains this morning, downstream of an upper ridge centered over the 
ridge. As the ridge shifts eastward later today, aforementioned 
high clouds should have an impact on temperatures this afternoon as 
they move across the CWA. Forecast soundings are consistent in the 
boundary layer mixing to at least 850 MB by late afternoon. With the 
setup pretty similar to yesterday, opted to increase highs by a few 
degrees into the lower and middle 90s. The main deterring factor for 
highs reaching the upper 90s are the high clouds providing some 
insulation. Depth and coverage of the cloud cover are also 
somewhat uncertain.

For tonight, lee troughing off the high plains to our west induces a 
decent sfc pressure gradient as far east as north central Kansas. 
South winds here should stay up around 10 to 15 mph. In turn, 
overnight lows hold in the middle 70s. Most of the CWA however 
cools to around 70 degrees with the light winds.

.LONG TERM...(Tuesday through Sunday)
Issued at 325 AM CDT Mon Sep 16 2019

Several upper troughs are progged to deepen across the western CONUS
before lifting across the central and northern plains beginning 
late Tuesday evening. Consensus guidance focuses much of the 
thunderstorm development from eastern Nebraska through north 
central Kansas, along the nose of the inverted trough axis. 
Moisture advection is not strong enough for higher pops at this 
time so will maintain the slight and low end chances through 
Wednesday. Uncertainty in the position of the frontal boundary and
embedded weak waves aloft greatly increase from Wednesday 
evening. Believe that the GFS may be overdone and noisy with the 
qpf amounts since the better upper lift centers over Nebraska. 
Regardless, overall pattern from guidance suggests a slight 
possibility for thunderstorms through Friday, particularly during 
the overnight period with the assistance of the low level jet.

The main upper low is still on track to lift through the northern
plains Saturday and Sunday, pushing a decent cold front and 
higher thunderstorm chances into the region. GFS holds a more 
progressive boundary while the ECMWF continues precip chances 
through Sunday so will need to monitor trends. In regards to 
temps, most of the precip chances reside during the evening hours 
and should not have a huge impact on highs, especially from 
Wednesday through Friday. Little changes are anticipated with 
readings around 90 degrees before the precip and cloud cover 
relieves highs back into the 80s Saturday and Sunday. 


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1148 PM CDT Sun Sep 15 2019

South southwest winds less than 10 kts are expected through 15Z
then increasing to around 11 kts. VFR conditions are expected
through the period.