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Area Forecast Discussion (AFD)

Issued by Topeka, KS (TOP)

FXUS63 KTOP 212042

Area Forecast Discussion
National Weather Service Topeka KS
342 PM CDT Sun Apr 21 2019

.SHORT TERM...(This evening through Monday)
Issued at 316 PM CDT Sun Apr 21 2019

The primary concern through the short term period continues to 
reside with the potential for severe thunderstorms...

As of 20Z Sunday afternoon broad southwesterly midlevel flow was 
present across the central and southern Plains with an embedded 
shortwave trough near the CO/KS/OK border intersection. The main 
midlevel low was positioned across southern NV. At the surface a 
low was positioned near Hill City, KS with a dry line extending 
southward into the eastern TX Panhandle. A stationary boundary 
extended northeastward and a Pacific front extended southwestward
from the low, respectively. Within the warm sector, dew points 
have increased into the low to mid 50s area-wide. Deep mixing of 
the boundary later near/exceeding 850 mb has resulted in very warm
temperatures in the low to mid 80s. A stout surface pressure 
gradient near 8 mb across the forecast area combined with 850 mb 
winds near 40 kt have yield a breezy day across the area with 
sustained winds 20-30 MPH, gusting near 40 MPH.

For the thunderstorm potential this evening into the overnight, our 
attention focuses westward towards the triple point and approaching 
midlevel perturbation. A stout EML has prevented convective 
initation to this point along the aforementioned surface boundaries. 
With continued surface heating and moisture advection combined with 
the midlevel ascent, expect convective initation late this 
afternoon/early evening across portions of west-central KS. As the 
surface trough advances eastward through the evening/overnight, 
expect isolated to scattered storms to move east as well. 
Generally 1000 to as much as 1500 J/kg of MLCAPE is expected 
across portions of north- central KS. Overall deep shear is meager
with values generally 20-30 kt. The steep low-level lapse rates 
have contributed to DCAPE values exceeding 1000 J/kg. Short term 
solutions suggest a cluster of thunderstorms should overspread 
the western areas in the 01-03Z time frame. The primary hazard is 
likely to be damaging winds given large values of DCAPE and 
overall weakly sheared environment, although the strongest updraft
could support a brief period of large hail. As convection 
progresses eastward through the night, its likely to become 
elevated. The best potential for storms overnight look to remain 
north of a line from Salina to Holton. Temperatures are expected 
to remain quite mild overnight with lows only reach the upper 50s 
and lower 60s. 

Transitioning into Monday, the aforementioned surface front will 
slowly push southeastward before ultimately stalling across portions 
of east-central KS. Shortwave ridging is progged to build across the 
Plains behind today's shortwave trough. As a result, thinking the
potential for showers/storms along the front tomorrow is low. 

.LONG TERM...(Monday night through Sunday)
Issued at 316 PM CDT Sun Apr 21 2019

Transitioning into the extended period, additional showers are 
possible Tuesday as the main midlevel low ejects into the southern
Plains. 12Z solutions have trended further south with the 
midlevel low track and the associated forcing-for-ascent, although
a few showers are possible across east-central KS. Beyond 
Tuesday, a stout midlevel ridge will overspread the central US, 
yielding dry conditions through weeks-end with highs in the 70s to
near 80. The next potential for thunderstorms looks to arrive 
next weekend as a shortwave trough ejects across the Plains. 
Considerable uncertainty exists with the timing and track of the 
shortwave, continue to check back through the week for forecast 
refinements. High temperatures next weekend are progged to reach 
the low to middle 80s. 


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1237 PM CDT Sun Apr 21 2019

Gusty south winds will continue through the afternoon and early
evening hours. As the nocturnal inversion builds in after 00Z
wind gusts should decrease, although LLWS conditions are likely
after 01Z as a 40-50 LLJ near 1.5 kft remains overhead through
09-11Z. Thunderstorms are expected to traverse portions of 
northern KS late this evening into the overnight. There is still 
uncertainty whether the terminals will be impacted. At this point
MHK looks to have the greatest potential for -TS conditions, 
especially between 05-07Z. Have not mentioned any TS at the Topeka
terminals as confidence in storms impacting these sites is too 
low at this time. In addition, MVFR stratus is possible after 11Z,
especially at the Topeka sites.