Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO

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FXUS63 KEAX 092348
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
648 PM CDT Sun Aug 9 2020

.Discussion...
Issued at 157 PM CDT SUN AUG 9 2020

Primary forecast focus is on current showers and thunder and a
second round on Monday.

A challenging forecast scenario through the the morning and present.
An early morning MCS across southeastern South Dakota and
northeastern Nebraska laid down a persistent outflow that raced
southward down the Missouri River valley. This feature combined with
a weak 500mb short wave trough and considerable isentropic ascent,
sparked widespread showers and thunder across the area through
sunrise into the afternoon. The boundary reached the Ozark plateau
through noon as it slowed, becoming an east west oriented boundary.
Along and north of this focusing mechanism, showers and
thunderstorms continue to persist and slowly work their way
eastward with the track of the upper wave. No surprise, guidance
has handled this situation with less than stellar accuracy. The
only standout was the HRRR and HRRRx, the latter of which caught
on early and has maintained a usability into the afternoon.
Expectations are for the current (1:30 PM) activity to continue to
slowly build east, with rain ending through the late afternoon,
west to east. Estimate a 5 to 7 PM end time for central Missouri,
as an remaining activity shifts to the east.

It`s suffice to say, the heat advisory in effect will likely not pan
out for a decent part of the area due to the ongoing rain and cloud
cover. However, locations in northwest Missouri and northeast Kansas
have cleared out and temperatures have started to increase. Given
dew points in the lower 70s F, it won`t take much, temperatures in
the lower 90s F, to get heat index values around 100 F, maybe higher.

Overnight, early solutions suggested some rain chances, but it`s
looking dry across the region, at least through sunrise. A weak
short wave trough riding the general flow of the base of the larger
trough centered over the northern Plains and Canadian Prairies
across SD/NE, may result in some residual precipitation across
northwest Missouri/northeastern Kansas. Into the afternoon an
elongated frontal boundary will sink southward into the afternoon. A
sizable EML spread across the warm sector will inhibit convective
initiation well into the late afternoon/early evening.
Considerable warm air advection into eastern kansas and western
Missouri will result in an extremely unstable airmass. Not to
rehash the SPC Day Two outlook, but modest deep layer shear will
be a limiting factor. However, steep lapse rates will promote
strong downdrafts and as scattered convection fires in proximity
to the boundary, the strongest storms will pose a wind gust
threat. Overnight into early Tuesday, as the low level jet
increases after sunset, a few complexes may develop moving south
and southeast across the Ozarks through daybreak. The severe
concerns will drop off through the early Tuesday morning.

The remainder of the week will be marked with continual shower and
thunderstorm chances, especially Thursday into Friday as another
short wave trough moves through the region. Temperatures will top
out in the upper 80s and low 90s each afternoon.

&&

.Aviation...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 648 PM CDT SUN AUG 9 2020

Currently VFR at all terminals with showers and thunderstorms
remaining well south of the terminals this late afternoon. VFR
conditions are expected to prevail through the period. LLWS will
be a concern again overnight tonight through sunrise Monday.
Attention then turns to the threat for showers and thunderstorms
Monday afternoon/evening as a cold front will approach the region
from the northwest. For now have introduced VCTS beginning at 21z
Monday (20z at STJ). There will be the potential for strong to
severe storms given very large instability, so strong thunderstorm
wind gusts and perhaps even some large hail could briefly impact
the terminals. The front appears likely to slow down or even stall
Monday afternoon across NW Missouri, so confidence in the precise
time of the wind shift is low at the current moment. For now have
introduced a wind shift to northerly behind the front at STJ by
20z and all other terminals by 23z Monday.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...Heat Advisory until 8 PM CDT this evening for KSZ025-057-060-
     102>105.

MO...Heat Advisory until 8 PM CDT this evening for MOZ001-002-011>013-
     020-021-028>030-037-038-043-044-053-054.

&&

$$

Discussion...Kurtz
Aviation...BMW



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