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Area Forecast Discussion (AFD)

Issued by Topeka, KS (TOP)

FXUS63 KTOP 172358

Area Forecast Discussion
National Weather Service Topeka KS
658 PM CDT Wed Apr 17 2019

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Thursday)
Issued at 317 PM CDT Wed Apr 17 2019

Focus through late tonight remains on thunderstorms chances and
their impacts. 

Central Plains remains flanked by main two upper level systems to
the north and south. Surface cold front is somewhat ill-defined 
with an apparent boundary from near Marysville to Abilene, and 
another from Medicine Lodge to near Lubbock TX at 19Z. Isolated 
convection has persisted to the north and northeast along the
northern boundary early this afternoon with visible satellite 
trends also not supporting rapid destabilization despite RAP 
analysis suggesting little convective inhibition. Low clouds ahead
of the front remain rather persistent and are keeping strong 
heating and mixing in check.

Most guidance is similar in scattered to numerous convective cells
developing around 0Z along a consolidated front in southern
portions of the local area, however some rapid-updating solutions
keep some separation to the aforementioned boundaries into the 
early evening. The persistent cloud suggests inhibition remains 
considerable and expect the stronger convergence that develops 
late today will be needed for the most convection to occur, but 
will keep some small chances along the northern boundary early on.
Deep shear remains fairly strong though vectors are oriented 
along the boundary and suggest somewhat unorganized and varied 
storm motions and types and should keep concerns limited to hail 
and wind. Synoptic boundary is rather slow moving and there will 
be some potential for training though outflow from any segments 
moving off the line could push the effective front south to keep 
persistent heavy rains to the southeast. Southern upper trough 
should reach central portions of Oklahoma well before dawn and 
usher the front well southeast by late tonight. 

Deep north-northwest flow develops Thursday as a weaker wave 
rotates around the consolidating upper trough. Cool temps aloft
and meager low level moisture may allow for isolated to scattered
showers to form with diurnal mixing in much of the area Thursday 
afternoon. Pacific nature to the airmass brings highs back into 
the lower to middle 60s. 

.LONG TERM...(Thursday night through Wednesday)
Issued at 317 PM CDT Wed Apr 17 2019

Winds Thursday evening back off as skies clear but expect temps to
remain above any frost concern. Northerly flow continues into 
Friday night as the upper trough deepens to the southeast and a 
northerly low-level wind component to the winds across the 
western Gulf of Mexico through early Saturday. Multiple upper
troughs work their way east into the western and central Plains
Sunday into at least Tuesday with much to be determined on their 
placement and timing. The aforementioned Gulf wind character 
should keep instability and moisture muted but at least diurnal 
thunderstorms will be possible. There is general agreement for
upper ridging to return around Wednesday for lesser precipitation
chances. Temperatures should remain relatively close to normal in
this regime. 


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 630 PM CDT Wed Apr 17 2019

Maintained a VFR forecast for the terminals through the night.
There may still be a window of opportunity for showers or perhaps
an elevated thunderstorm over the next several hours generally
through 06Z. However, as the cold front continues to advance south
this opportunity may wane quicker. Expect winds to increase
overnight into the morning from the northwest. May need to
increase the gusts in subsequent forecasts.