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Area Forecast Discussion (AFD)

Issued by Topeka, KS (TOP)

FXUS63 KTOP 191739

Area Forecast Discussion
National Weather Service Topeka KS
1239 PM CDT Fri Apr 19 2019

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 349 AM CDT Fri Apr 19 2019

Today through Tonight, an upper level trough axis extended from the 
southern Hudson Bay region of Canada, south-southwest across the mid 
MS River Valley and into far western LA early this morning. The 
southern section of the upper trough axis will amplify into a closed 
upper low across northern MS this afternoon and lift northeast 
across eastern TN late Tonight. An upper level ridge across the 
western US will move east into the central and southern high Plains 
late Tonight. 

The isolated showers and sprinkles across the southeast counties of 
the CWA will shift southeast of the CWA after 3 AM. Isentropic 
downglide on the west edge of the amplifying upper trough across the 
lower MS river valley will clear skies across the eastern counties 
of the CWA by 12Z. A surface ridge of high pressure across the 
central and southern high plains will build southeast across the 
central and southern plains Today and the center of the surface 
ridge axis will move east across the CWA Tonight. Insolation along 
with PBL mixing as deep as 820-850mb with dry adiabatic lapse rates 
to the surface should allow highs to reach the mid 60s across much 
of the CWA. The far southwestern counties may be a few degrees 
warmer. Northwest winds will increase to 15 to 20 MPH, with some 
gusts of 25 to 30 MPH during the late morning hours and through the 
mid afternoon hours. The winds will slowly diminish during the late 
afternoon hours.

Tonight, clear skies and light winds will allow overnight lows to 
drop into the upper 30s to lower 40s. Some low-lying area may dip 
into the mid 30s.

.LONG TERM...(Saturday through Thursday)
Issued at 349 AM CDT Fri Apr 19 2019

In the long-term portion of the forecast period, temperatures will 
warm up nicely this weekend before rain chances return early next 

An upper level ridge will move over the region on Saturday, while 
winds turn to a southerly direction at the surface. WAA will occur 
at the surface and in the lower levels of the atmosphere in response 
to breezy return flow ahead of a developing low in the lee of the 
Rockies. Afternoon temperatures are expected to reach the mid 70s in 
east-central KS to near 80 degrees in north-central KS tomorrow. The 
aforementioned surface low will move into central KS on Sunday with 
the area remaining in a warm return flow pattern. Conditions should 
remain dry through daytime hours Sunday with rain and storm chances 
returning late Sunday and early Monday when the low and associated 
cold front move into northeastern KS. The best chance for 
thunderstorms appears to be Sunday evening and night, especially 
near and north of I-70 where lifting near the low will interact 
with moisture. CAPE values are likely to exceed 1000 J/kg into the
evening and nighttime hours with GFS BUFKIT data showing around 
30- 40kts of 0-6km bulk shear. A cap could remain in place over 
the area but forcing near the low should be enough to overcome 
inhibition. Given these parameters, will have to monitor for the 
possibility of strong storms capable of producing some hail and 
strong winds. Some showers and storms could linger into the day 
Monday but coverage is likely to be limited and chances remain 
fairly low beyond 12Z Monday as the cold front slides south of the

Long range model guidance begins to differ more as we head into the 
middle part of the week. Both GFS and the EC show a surface ridge 
moving over the area behind Monday's front with an upper trough 
digging into the southwestern CONUS. The EC wants to hold onto the 
precip chances ahead of the upper system through midweek while the 
GFS remains drier, keeping precip well south of the area. Current 
thought it to hold off on rain chances until confidence increases 
for the middle of the week. Will have to watch the track of the 
upper system, along with moisture return and forcing for ascent as 
we get closer in order to hone in on more details of possible precip 
chances on Wednesday and Thursday.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1236 PM CDT Fri Apr 19 2019

VFR prevails through forecast period with scattered cumulus deck
developing during the afternoon. Northerly winds sustain between
10 and 15 kts with gusts around 20 kts through 01Z. 




LONG TERM...Teefey