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Area Forecast Discussion (AFD)

Issued by Topeka, KS (TOP)

FXUS63 KTOP 172346

Area Forecast Discussion
National Weather Service Topeka KS
646 PM CDT Mon Jun 17 2019

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Tonight)
Issued at 338 PM CDT Mon Jun 17 2019

A generally active weather pattern continues today, as an upper trof 
lifts east northeast across Missouri, with a larger scale upper trof 
moving into southern California and smaller waves traversing through 
not only the southwesterly flow put west, but also through the 
southern fringe of the northern stream across the northern plains. 
Sensible weather impacts for our area for the rest of today and 
overnight are a short break between systems, before convection 
starts to roll off the higher terrain then into central Kansas 
toward Tuesday morning. Dewpoints remain in the 60s overnight, 
making overnight lows in the lower 60s likely feel higher.  A few 
storms may linger across the north central and southeastern counties 
into the evening hours where enough low level convergence, eroded 
inhibition, and CAPE has allowed a few storms to develop in daytime 

.LONG TERM...(Tuesday through Monday) 
Issued at 338 PM CDT Mon Jun 17 2019

Primary focus has been on convective event expected for mainly late 
Tuesday.  Tough to pinpoint just which weak cyclonic shear zone 
currently over Rockies will help lead to activity across central 
Plains tomorrow.  Nevertheless, models in good agreement that weak 
short wave will drop east-southeast in broader, low-amplitude 
trough.  This should help to initiate and sustain fairly good 
coverage of thunderstorms, primarily Tuesday evening.

Models seem to hint at a possibility that either leftover High 
Plains convection or some weak warm-air advection could be affecting 
north-central Kansas Tuesday morning, but the bulk of the activity 
looks to hold off until later in the day with storms expected to 
form along somewhat diffuse dry line positioned over western/central 
Kansas.  Additional activity may form along weak east-west-oriented 
boundary near Nebraska border.

Moderate mid-level winds and deep-layer shear values of 30 to 40 kt 
could support a few severe storms.  Storms generally look to be 
progressive in nature, although precipitable water values in the 1.5-
1.7-inch range could lead to locally heavy rainfall.  With 
relatively limited rainfall over past 7 days, most rivers in area 
can probably take the inch or so of rain expected (on average).  3-
hr flash flood guidance now in the 2-3" range, so flash flooding 
threat appears to be isolated at this point.  That said, wouldn't 
rule out a spot or two nearing that guidance value (and 
considered/discussed a watch), but would prefer to allow subsequent 
shifts to refine any potential threat area.

Short-wave ridging builds in for Thursday which should lead to 
quieter weather and more of a summer-like airmass for late in the 
week.  Caveat to the quieter weather is the potential for some 
thunderstorm activity tied to a weak frontal boundary dropping 
southward into Nebraska late Thursday.

Could also see some elevated activity Saturday night ahead of 
stronger trough which looks to lead to a more significant round of 
storms late Sunday. Stronger mid-level winds, deep-layer shear, and 
plentiful instability could make late Sunday active, if GFS timing 
pans out.  Quick look at 12Z ECMWF, though, suggests timing is still 
in question with it focusing more on Saturday as the active


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 639 PM CDT Mon Jun 17 2019

Some of the shorter range models show stratus with MVFR/IFR 
ceilings developing after 8Z and continuing until 15Z ( these same
models were accurate on last night runs with MVFR and IFR 
ceilings developing after 14Z to 16Z at KTOP and KFOE Monday 
morning). Other models show no low stratus developing. Therefore, 
I put a tempo in the TAFs with MVFR ceilings from 11Z through 15Z 
TUE. If low stratus develops it should scatter out during the mid
morning hours of TUE with scattered CU bases developing above 
4000 feet through Tuesday afternoon.




LONG TERM...Drake/Manion