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Area Forecast Discussion (AFD)

Issued by Topeka, KS (TOP)

FXUS63 KTOP 230850

Area Forecast Discussion
National Weather Service Topeka KS
350 AM CDT Tue Apr 23 2019

.SHORT TERM...(Today and tonight)
Issued at 345 AM CDT Tue Apr 23 2019

Ample clouds linger through today and tonight with some light 
rain showers along and south of the I-70 corridor.

A cutoff low currently positioned over southern Arizona/northern 
Sonora meanders east/southeast in a split flow pattern into 
Wednesday, keeping a relatively broad H850-500 trough in place 
over the forecast area. One perturbation ejected from the low 
overnight and led to the development of showers and storms in the 
TX/OK high country. This shortwave and attendant
precipitation/clouds is progged to spread northeastward today and
indeed precipitation echoes have developed on KICT/KTWX over the 
last couple of hours. Based on the orientation and gradient along
the backside of the H850 moisture axis, expect that any showers 
should stay along and south of the I- 70 corridor. Owing to the 
lack of any strong forcing for ascent and a dry sub-cloud layer, 
precipition amounts should be light. 

The chances for precipitation dwindle by Wednesday morning as the
upper low migrates into western Texas and the better H850 
moisture shifts southeastward. High temperatures today hinge on 
the areal extent of cloud cover from both a stratus deck shifting 
southward and a mid to high level cloud deck spreading 
northeastward from the Southern Plains convection. Per the 
synoptic setup and forecast soundings, the cloud shield should be 
thickest across central and east-central Kansas today, with 
raw/MOS guidance solutions ranging anywhere from the low 50s to 
upper 60s for highs. For now have trended towards the blended 
solutions with the understanding that this forecast is of lower 
confidence than normal.

.LONG TERM...(Wednesday through Monday)
Issued at 345 AM CDT Tue Apr 23 2019

Seasonal temperatures are on tap into this weekend with the next 
chance of rain coming late Friday into Saturday.

With the upper low pushing eastward Thursday and Friday, gradual 
H500 height rises on the backside of the system will promote 
clearing skies. A northern stream wave digging southward over the 
Northern Plains ushers a surface boundary southward Wednesday
night, but the lack of any strong synoptic lift will lead to the 
boundary quickly decaying as it reaches Kansas with little 
sensible weather impacts. Broad longwave ridging dominates the 
pattern for the end of the week with multiple shortwaves embedded 
in the polar jet stream translating along the U.S./Canadian 
border. The first of these waves digs into the Northern Plains 
late Friday into Saturday. Lee cyclogenesis is anticipated ahead 
of the wave along the Front Range, but confidence in the timing 
and track of this cyclone is modest at best given the progressive 
nature of the complex--which is reflected in the spread amongst 
the medium range guidance. 

The best forcing for ascent will likely be north of the forecast 
area with this event, but some warm sector thunderstorms are not 
out of the realm of possibilities within the LLJ corridor. High 
temperatures for the latter half of the week will remain in the 
70s amidst little change in the synoptic airmass, with confidence 
in the temperature forecast waning by late in the weekend as model
solution diversity increases ahead of the next shortwave on 


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1141 PM CDT Mon Apr 22 2019

VFR conditions are expected through 09Z with MVFR cigs developing
by 11Z, then rising to VFR around 16Z. WInds remain north 10 kts
or less, then veering to northeast after 19Z, Confidence is SHRA
not high enough to add to TOP and FOE terminals with this