Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 220920
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
420 AM CDT Fri Aug 22 2014
Issued at 419 AM CDT FRI AUG 22 2014
Today - Tonight:
Excessive heat and humidity continues to be the main theme today
with similar heat index values as Thursday. Have expanded the
advisory to include northeast MO as the hotter air is expected to
spread into this region. Primary caveat is how long/much of the
convective cloud debris will linger and how much of the upstream mid
level cloudiness now over central KS can migrate northeast.
An upper ridge axis extends north from a large dome of high pressure
centered over the central gulf coast. Despite the presence of this
feature convection blossomed over north central KS Thursday evening
and now an expanding MCS over southern IA and extreme northeast MO.
Moderately strong moist isentropic ascent on the 310K through 314K
surfaces appears to be the primary catalyst with quasi-stationary
front now distorted by the IA/MO convection. A look at the h7
temperatures progged through this evening reveals a relatively
uncapped environment and the potential for additional widely
scattered elevated convection this evening with another surge of
isentropic ascent on the same surfaces. Will blanket northern MO
with chance PoPs to account for this.
Slightly warmer air at h7 is expected to spread into the region,
effectively capping the airmass and rendering the region rain-free.
With h8 and 925mb temperatures unchanged or slightly warmer
Saturday`s highs should be similar to Fridays if not a degree or two
hotter. Better/deeper mixing should yield slightly lower dewpoints
but no net improvement of heat index values. Given that feel it`s
warranted to extend the advisory into early Saturday evening.
Increasing concerns that there will be no change in airmass but this
far out runs the risk of better/deeper mixing lowering dewpoints and
any debris left over from nocturnal convection can limit heating,
resulting in heat index values not reaching criteria. Later shifts
will need to re-evaluate. Extending the excessive heat for a fourth
day would require issuing an Excessive Heat Warning.
Monday - Tuesday:
Looking more and more like the excessive heat will linger into the
first part of next week. However, it also appears dewpoints will
continue to mix out more with each passing day. This would result in
heat index readings below criteria. An elevated mixed layer will
continue to cap any convection and result in a dry forecast.
Tuesday Night - Thursday:
Finally a break in the heat as a cold front is expected to dive
southeast through the CWA Tuesday night and bring a chance of storms
to the entire CWA. Cooler and somewhat drier air is expected to move
into the region with the passage of the front.
.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 1154 PM CDT THU AUG 21 2014
VFR conditions generally expected through the fcst cycle. Convection
this evening across northeastern Kansas will continue moving east
towards far northwestern MO during the early morning hrs. Potential
exists for activity to work into STJ and maybe even MCI during the
early morning hrs. Right now...STJ stands a better chance per latest
model trends and will maintain VCTS mention for now. Any lingering
activity should clear shortly after 12z with possible redevelopment
later in the afternoon across far northern MO. For now...no mention
due to distance in the fcst cycle along with continued low confidence
in overall storm placement. Winds will remain from the southwest with
speeds generally in the 10-15 kt range during the day before
weakening after 00z.
KS...HEAT ADVISORY until 8 PM CDT Saturday FOR KSZ025-057-060-102>105.
MO...HEAT ADVISORY until 8 PM CDT Saturday FOR MOZ001>008-011>017-