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

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000
FXUS63 KEAX 202337
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
637 PM CDT Wed Aug 20 2014

.DISCUSSION...
Issued at 308 PM CDT WED AUG 20 2014

This Afternoon & Evening:

Temperatures are very close to the convective temperature across
mainly the southern portions of the forecast area. Also, a well
defined outflow boundary has developed some CU on it from
northwestern Missouri through central Missouri. Mesoanalysis shows
very high CAPE along and south of this boundary and decent (for the
time of year) mid to upper level winds are allowing 0-6km shear
values to be about 30kts. Will keep a mention of isolated TSRA going
for the afternoon to account for this possibility.

Thursday - Friday:

High heat is expected to return to much of the area during this
stretch with heat indices ranging from 100 to 105 for Thursday and
slightly warmer for Friday. Have issued a heat advisory for the
entire forecast area, with the exception of our far northeastern
zones, to account for the heat. While conditions may be marginal for
a typical August, this summer has been anything but normal. We`ve
actually seen one the coolest summers on record and have recently
exited out of another long stretch of cooler than normal
temperatures. It`s very likely many people are not acclimated to this
level heat, even this late in the summer, because of the cool
temperatures. Also, in coordinating with outside partners, an
increase in heat related illnesses has already occurred. With it
going to be warmer these two days than most days so far this summer,
felt it prudent to go with a heat advisory.

For our northeastern counties, there is some uncertainty about cloud
cover keeping temperatures cooler than other parts of the forecast
area. This would especially be the case for Thursday. The heat
advisory may need to be expanded to that area by Friday but for now
the uncertainty is too high.

With regards to precipitation, chances look very low for much of
Thursday. Thursday night, there is a small possibility of showers and
storms moving into the area from the northwest. But there should be a
diminishing trend with southward propagation as any system moves into
warmer air aloft. A similar scenario is possible Friday and Friday
night but models seem far too aggressive with precipitation driving
into the upper ridge. Have kept Friday dry with a small chance for
storms across northern Missouri for the Friday night period.

Saturday - Tuesday:

There is some uncertainty with how the start of the extended will
unfold. The upper ridge looks to maintain its strength but a trough
will begin to impinge on it from the west. This will lead to a broad
lee troughing with a surface boundary draped into southeastern
Nebraska. This may lead to increased cloud cover and precipitation
chances which would then result in lower temperatures for Saturday
and then especially on Sunday. So for now, have kept precipitation
chances across the northwestern portions of the forecast area with
lower heat. Across the southeastern half of the forecast area, there
may again be some heat related headlines needed. For now though, the
uncertainty is too high to take the heat headlines into Saturday.

The forecast then become very uncertain for next week. Models show
the upper high building into the lower Missouri valley but also with
troughing to a tight height gradient over the Central Plains into
northwestern Missouri. Have not gone higher than mid chance PoPs and
these are mainly confined to our northern and northwestern zones.
Temperatures will still likely be in the 90s in our southern and
southeastern zones.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 636 PM CDT WED AUG 20 2014

VFR conditions expected through the fcst cycle. Main concern
overnight will be possible LLWS conditions after 6z as a low-level
jet increases to near 50 kts directly overhead...and for now have
included LLWS mention at all sites to account for the potential.
After sunrise...winds will increase from the southwest with gusts
potentially reaching 25 kts during peak heating. Fcst models do
suggest convection developing by late morning/early afternoon however
current model trends suggest best activity will remain north of area
terminals...hence no mention with current update.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...HEAT ADVISORY from 1 PM Thursday to 8 PM CDT Friday FOR KSZ025-
     057-060-102>105.

MO...HEAT ADVISORY from 1 PM Thursday to 8 PM CDT Friday FOR
     MOZ001>006-011>015-020>023-028>033-037>040-043>046-053-054.

&&

$$

DISCUSSION...CDB
AVIATION...32







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