301 
FXUS63 KTOP 190452
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1152 PM CDT Mon May 18 2020

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Tuesday)
Issued at 345 PM CDT Mon May 18 2020

Dry and overall pleasant today but slightly cooler than normal for 
mid May.  

Not too much change in the upper flow pattern as what appears to be 
an eventual Rex Block is beginning to set up over the eastern CONUS 
which is somewhat out of the norm as these set up easier over the 
western CONUS for the most part.  The old low to the east of the 
area, now over the Mid MS Valley, appears to be showing signs of 
filling over the past 12 hours.  This is still resulting in 
northerly flow into the region as well as wrap around moisture 
which is still providing slow to mix out cloud cover over eastern 
portions of the forecast area. Meanwhile, a mid level ridge is 
shifting east into the central Plains which has also been slightly
suppressed and dampened with yet another cut-off low feature 
spinning over the west coastal region. All of this complication of
the upper pattern ultimately leads to a lower confidence long 
term forecast due to inherent uncertainties with meandering low 
pressure systems. 

This afternoon, highs have been held down with cloud coverage and 
northerly cool flow into the region.  Some of the north central 
counties in Kansas just reached 72 degrees this past hour, so low to 
upper 60s to just over 70 will likely end up being the range of high 
temperatures from east to west across the area as clouds over the 
far east have yet to exit or otherwise mix out of the area.  

Tonight, with a slight breeze still in place, have kept temps in the 
upper 40s to around 50 in spots that may still see more clouds fill 
back into the area as the Mid MS Valley upper low is very slow to 
move anywhere. 

.LONG TERM...(Tuesday night through Monday)
Issued at 345 PM CDT Mon May 18 2020

For the longer range forecast, still dry until the daytime on 
Thursday when the first chances of precipitation begin to slowly 
work back into western zones.  Instability and shear look minimal 
but isentropic ascent in the mid levels may help to enhance the 
precipitation likelihood - regardless, have not been too bullish on 
chances at this time and will keep them below 40 percent range for 
now.  

Friday may be the first signs we see with a chance for more active 
and stormy weather at least over southern portions of the area 
generally south of I-70.  As a vort max that seems to be 
consistently progged by most models traverses over the region, 
enhanced shear atop dewpoints rising back to around or just topping 
60 then there could be some potential for more active storms ahead 
of a cold front sweeping through the area.  

Several other spotty rain chances into the holiday weekend appear to 
be possible as well.  However, with the overall pattern in place, 
severe threats may be minimal as shear and overall instability 
combinations may be unfavorable overall.  Again, much of this 
uncertainty is due to the apparent Rex Block to the east and the cut-
off low over the west.  Additionally, little in the way of a 
significant LLJ appears to also be a limiting factor with the 
exception of sometime Saturday night into Sunday morning.  So, in 
addition to possibly Friday afternoon, this would be the other most 
interesting time frame for storm potential at least right now.

Overall, temperatures for the time frame appear to be pushing the 
upper 80s into the weekend with generally a southerly component to 
the flow pattern helping draw up warmer theta-e airmass.  

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1152 PM CDT Mon May 18 2020

VFR conditions are expected to continue through about 08Z at MHK 
then become mvfr as stratus moves in from the east around the mid
level low. Cigs at TOP and FOE should begin as MVFR and continue
through 17Z, then become vfr. Winds northeast generally under 
10 kts through the period.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Drake
LONG TERM...Drake
AVIATION...53