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Area Forecast Discussion (AFD)

Issued by Kansas City/Pleasant Hill, MO (EAX)

                            
000
FXUS63 KEAX 222057
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
357 PM CDT Sat Jun 22 2019

.Discussion...
Issued at 357 PM CDT SAT JUN 22 2019

Severe weather along with possible flash flooding will be the main
concerns heading into this evening and overnight...

Severe thunderstorm watch 426 now in effect for the western half
of our fcst area as dewpoints in the low- to mid 70s combined 
with temperatures in the middle to upper 80s, have led to rapid 
destabilizion across our area. Latest SPC Mesoanalysis shows an 
MLCAPE axis of 5000+ J/kg extending north across our region this 
afternoon, with some residual capping still noted across far 
northwest Missouri and east-central Missouri behind an outflow 
boundary from earlier MCS activity. Main limiting factor so far 
today has been a lack of synoptic-scale forcing, however regional
GOES-16 water vapor imagery continues to show a compact shortwave
trough lifting north through the southern Plains this afternoon. 
In addition, surface analysis shows main cold front slowly 
approaching our area from the northwest this afternoon, with
visible satellite clearly showing the aforementioned outflow 
boundary extending from near Liberty south through the Missouri 
Ozarks. These surface features, combined with the approaching 
upper shortwave, will be the focus for developing convection 
across western Missouri and eastern Kansas in the next hour or 
two. Fcst soundings show fat CAPE profiles through the vertical 
with high amounts of instability noted in the hail growth region 
which is most likely in response to nearly dry adiabatic lapse 
rates in the mid-levels resulting from a migrating EML plume 
which is now in-place over the central Plains and adjoining lower
Missouri Vly. This dry mid-level air will also support strong 
damaging wind gusts with storms that develop across the area later
this afternoon, which can be seen on latest SPC Mesoanalysis 
DCAPE fcsts which highlight 1000+ J/kg across portions of the 
area. While the tornado threat appears lower than the hail and 
strong wind threat, regions near residual boundaries will need to 
be watched closely as these areas often times support higher 
amounts of low-level vorticity generation.

After convection develops, its expected to slowly move from west
to east across the fcst area. Another concern heading into the
overnight period will be the possibility of heavy rain and flash
flooding as PWAT values increase to 2" across a large portion of 
the area. In fact, latest CIRA Advected Layered Precipitable 
Water satellite imagery shows a corridor of higher mid- and 
upper-level moisture heading north from the southern Plains this 
afternoon, which further supports the idea that rainfall overnight
can be very efficient with such a warm and moist airmass in-place
over the area. Combine this with wet soil conditions from heavy 
rainfall in previous days, we could be looking at an increased 
flash flood threat later tonight and early Sunday. As a result of 
these concerns, have elected to hoist another flash flood watch 
which will remain in effect through Sunday evening for the entire 
forecast area. 

Unfortunately, shower and storm activity will likely continue for
a large part of the day on Sunday as the main cold front finally
starts to move through the region. Severe wx will remain a concern
through the day thanks to abundance of instability thanks to such
a moist pre-frontal airmass. Fortunately, rain chances should
start coming to an end through the overnight hours into Monday
morning as the front starts clearing the area. 

Cooler and less humid air looks to finally move back into the 
area on Monday as region will reside in a post frontal airmass.
Some lingering shwrs and storms will be possible through the day
as instability type shwrs/storms may develop across northern
Missouri as main upper low passes to our north. Drier and less
humid air looks to then remain in-place through at least mid-week
as high pressure settles south over the area. 

&&

.Aviation...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1223 PM CDT SAT JUN 22 2019

Very challenging fcst this afternoon as forecast models continue
to show widespread, and potentially long-lasting opportunities for 
for storms later this afternoon and evening. For now, models show
isolated storm coverage beginning around the 20z time frame,
however all seem to indicate that coverage should increase around
the 23z time frame as stronger synoptic-scale forcing arrives from
the southwest. As a result, have attempted to capture the higher 
likelihood timing with a tempo group beginning at 23z, however 
trends will have to be monitored for any cells that may impact 
area terminals sooner. When the more concentrated activity begins
moving through, expect widespread categorical decreases to MVFR
and IFR with heavy rain resulting in reduced visibilities and 
lower ceilings. Activity should gradually start moving east of 
area terminals around the 04z time frame, with lingering 
stratiform rain showers possible through the predawn hours. It 
does remain possible that MVFR, and potentially IFR ceilings may 
develop during the predawn hours, but will allow later fcsts 
address those concerns once late afternoon and evening convective 
trends become better established. Winds should remain from the 
south and southeast between 8-13 kts through much of the fcst 
period. 

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...Flash Flood Watch from 7 PM CDT this evening through late Sunday 
     night for KSZ025-057-060-102>105.

MO...Flash Flood Watch from 7 PM CDT this evening through late Sunday 
     night for MOZ001>008-011>017-020>025-028>033-037>040-
     043>046-053-054.

&&

$$

Discussion...32
Aviation...32