219 
FXUS63 KTOP 021036
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
536 AM CDT Sat May 2 2020

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 256 AM CDT Sat May 2 2020

08Z water vapor imagery and profiler data showed a shortwave 
moving across NEB with some showers remaining north of the 
forecast area. Elsewhere a shortwave was moving over southern 
Manitoba with a closed upper low off the coast of British Columbia
and the Alaskan panhandle. At the surface, high pressure was 
slowly building south into western NEB with low pressure hanging 
on over the TX panhandle. A prefrontal trough bisected the 
forecast area with a southerly wind over east central KS and a 
northeasterly wind across north central KS. 

&&

.SHORT TERM...(Today and tonight)
Issued at 256 AM CDT Sat May 2 2020

For today and tonight, the main change from prev model runs has 
been to trend further south with the frontal boundary. 
Additionally model forecast soundings show stronger inhibition to 
a surface parcel with a stronger cap near 700 MB. So the better 
chances for precip look to be overnight when the GFS and ECMWF 
show a subtle shortwave moving overhead. Differences in the models
handling of this wave lead to some uncertainty in the better 
location of the precip and the NAM seems to be quite dry compared 
with other solutions. So have left POPs in the 30 to 50 percent 
range. Highs today may be dependent on how much insolation there 
is heading into the afternoon. The NAM and GFS develop some 
stratocu within the warm sector this afternoon while increasing 
mid level clouds are progged to move along the NEB state line. 
This combined with cooler temps at 925 and 850 MB suggests highs 
will be a few degrees cooler. The bigger change is likely to be 
across the northern counties where northeast low level winds 
prevent any significant warm air advection. Lows tonight should 
remain mild with clouds hanging around through sunrise. 

.LONG TERM...(Sunday through Friday)
Issued at 256 AM CDT Sat May 2 2020

Think the upper wave along with the precip will be exiting to the
east early in the day Sunday. Another shortwave is progged to 
move across the central plains on Monday with a reinforcing cold 
front moving through Monday night. So chances for precip remain in
the forecast. The bigger uncertainty in the forecast for Monday 
is how much will the boundary layer recover ahead of the cold 
front. The GFS seems to be the only solution that brings the warm 
sector back into northeast KS with the NAM and ECMWF tend to keep 
an easterly wind across much of the forecast area. This will 
impact temps and where surface based instability sets up. Although
even the GFS forecast soundings maintain some cap over the 
boundary layer implying elevated storms. But deep layer shear 
around 55KT would be supportive of organized updrafts and some 
potential for hail should the instability works its way into east 
central KS. So this will be something to keep an eye on. 

Surface ridging is progged to move in for Tuesday and Wednesday 
keeping temps near normal and precip chances low. An upper level 
wave potentially could move across the region within northwest flow 
aloft on Thursday. Differences between the models in the strength of 
this wave make it hard to have confidence in anything but some low 
chance POPs for Thursday and Thursday night. 

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 536 AM CDT Sat May 2 2020

Main question is how widespread precip might be and when will it
begin. The 06Z GFS is quite a bit different from the 00Z run and
the CAMs seem to show some light radar returns like drizzle before
more organized showers develop with an upper level shortwave. At 
this point think I will focus a VCSH with the shortwave since 
forecast soundings don't look like a classic drizzle setup. 
Stratocu deck looks to move in by mid afternoon at around 4 KFT. 
So VFR conditions should persist through the forecast period.

&&

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

$$

SYNOPSIS...Wolters
SHORT TERM...Wolters
LONG TERM...Wolters
AVIATION...Wolters