Preview of NWS' New Version of Forecast
This preview is not operational and should not be used for support decisions.

Area Forecast Discussion (AFD)

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

                            
000
FXUS63 KEAX 171735
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1235 PM CDT Wed Apr 17 2019

.Discussion...
Issued at 408 AM CDT WED APR 17 2019

Message of the day: Strong to severe storms are possible this 
afternoon and evening with hail and damaging winds being the main 
concerns. However, if cloud cover and a capping inversion stick 
around late in the day we could see a decrease in severe 
potential.

An upper level shortwave trough and surface low pressure can be seen 
moving northeast through KS and NE this morning, producing 
showers and storms. As these features approach our area this 
morning, additional low-level moisture will advect into the 
region, helping develop a stratus cloud deck across much of the 
area that should hang out through at least the morning and early 
afternoon. As the larger features move by around sunrise, we could
see just enough lift for scattered drizzle or light rain to 
develop, mainly in northwest MO and northeast KS. Right now, 
multiple soundings suggest the stratus deck should stick around at
least through the early afternoon. This will likely keep 
temperatures a few degrees cooler than yesterday, despite warm air
advection. This cloud deck will also affect the severe potential 
this afternoon. The RAP/HRRR suggest the clouds should scatter out
some after 19-20Z, with the NAM and GFS hinting at this, but 
keeping a little more low-level moisture around longer. If the 
clouds hang on through the late afternoon, then the chances for 
seeing severe weather diminish significantly. If the clouds can 
break up and the cap breaks, then strong to severe storms will be 
possible. Am leaning towards the RAP and the HRRR right now, which
would mean the clouds break up enough leading to the surface 
warming up rather quickly, which will aid severe weather potential
late this afternoon and evening. Additionally, a capping 
inversion will be in place much of the day, with the same 
soundings suggesting it weakens shortly after the stratus 
scatters. By the time this happens, the cold front will already be
along a line from the KC metro up to Mercer county MO. If this 
all pans out, we have about a 1-3 hour window (starting around 5 
PM), mainly east of I-35, for isolated to scattered strong to 
severe storms. During this time, SBCAPE will be around 2000 J/kg 
with bulk shear near 40 kts. Right now, hail and damaging winds 
are the main concerns with steep mid-level lapse rates and just 
enough DCAPE (near 1000 J/kg). Also, can't completely rule out a 
brief tornado or two, but at this point, that still looks 
unlikely. As for storm type, we could see a few single cell storms
initially, but a line of storms should form quickly along the 
cold front. Not long after the sun goes down, the severe threat 
will decrease significantly. However, moderate to heavy rain is 
likely to continue along this line of storms, especially as the 
system gains upper level support from the main upper level trough 
approaching the area tonight. PWATs are forecast to be near 1-1.25
inches, which is well above normal. Right now, the axis of higher
precipitation amounts is south of the MO River with 1-1.5 inches 
of rain expected. Localized flooding will be a concern, but flash 
flood guidance suggests we should avoid widespread flooding. This 
system will gradually move out of the area during the overnight 
hours, with perhaps some lingering showers in central MO Thursday 
morning.

Colder air will filter in behind the cold front, keeping highs 
limited to the 50s to low 60s on Thursday. On Friday, ridging will 
return to the central U.S., and will clear our skies and help 
temperatures warm back into the 60s for Friday and then 70s for 
Saturday. Our next chance for showers and storms returns Sunday, as 
we transition back into the warm sector of a developing surface low 
with a shortwave trough approaching the region. The surface low will 
be slow to push through, with multiple shortwave troughs moving 
overhead, keeping precipitation chances through at least Tuesday.
The good news is temperatures should remain in the 60s and 70s.

&&

.Aviation...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1235 PM CDT WED APR 17 2019

Main concern going forward with this afternoon's forecast involves
thunderstorm potential later this evening as well-advertised
frontal boundary sags south over the region. High-res model
guidance continues to show developing shwr/storm activity after
the 23z time frame, with activity lingering through the early
overnight hours before diminishing with time. For now, the most
likely sites to see impacts include both IXD and MKC, with chances
dropping off the further north you go. Biggest uncertainty this
afternoon remains whether developing storms will impact MCI, but
given TS was already offered with the 12z forecast, along with the
fact that development may occur just south of the terminal, have
elected to maintain a tempo group for storms for all KC terminals
this evening. As with any convective episode, short duration MVFR
and even IFR conditions will be possible with any activity that 
impacts area terminals this evening. Winds will continue to veer 
to the northwest through the period with gusts as high as 20 kts 
likely following frontal passage later tonight and continuing
through the end of the forecast period.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&

$$

Discussion...Grana
Aviation...32