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

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000
FXUS63 KEAX 211717
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1217 PM CDT Thu Aug 21 2014

.DISCUSSION...
Issued at 411 AM CDT THU AUG 21 2014

Main focus for the early morning forecast is on the heat and
humidity for the next couple of days.

Satellite imagery this morning shows a shortwave ridge axis having
shifted into western Missouri today. Synoptic scale trough across the
western CONUS will continue to try and force the ridge east through
the coming days with mixed success, but the upshot in the short term
is that the induced pressure gradient across the Plains States and
upper level flow both have helped bring hot and humid air to the
Lower Missouri River Valley, and this trend isn`t changing till maybe
next week.

Today and Friday...conditions will be fairly similar, hot and humid.
The persistent southwest flow aloft with the southerly winds at the
surface have brought another bout of summer dog-days to Kansas and
Missouri. 850MB temperatures today ranged into the low 20s
centigrade, but the continuing deepening of the western CONUS trough
will help the southwest flow steer mid-20 centigrade temperatures
into eastern Kansas and Missouri today. This should result in
slightly warmer temperatures today, putting absolute temperatures in
the upper 90s within range this afternoon. When combined with the 70
degree dewpoints the southerly surface winds are bringing up from
the gulf and heat index values around 105 degrees continue to look
reasonable for both today an Friday. Hence, will continue the heat
advisory for today and Friday as is. Otherwise...have high chance to
likely POPs in for the far northwest corner of Missouri tonight as
the nocturnal jet will likely ramp up again tonight inducing more
storm development in the resulting warm air advection.

For the weekend...temperatures will likely continue to  range
through the lower to upper 90s, but the ridge axis is expected to
shift to our east as a significant trough lifts through the northern
Plains. This will have two dominate effects on our forecast. One,
dewpoints should dry out a little as surface wind trajectories
source a little more continental air than gulf air. Two, the
southwest flow aloft will likely be a bit active, resulting in
storms complexes which may or may not effect our forecast area
directly, but will definitely have secondary effects through the
cloud cover and outflow boundaries that the storms will generate.
The lower dewpoints for the weekend look sufficient to pull back
expected heat index values; generally speaking dropping them from
around 105 to around 100.

Next work week...may bring us some relief from the heat. Medium
range models continue to advertise the ridge axis moving well to our
east by next week as the west CONUS trough slowly shifts east, but
the models then quickly divergent on what the ridge will do. GFS is for
pushing out into the Atlantic, while the ECMWF is for pinching off
the trough into a closed low over the desert southwest and allowing
the ridge to quickly retrograde back into the Plains States. While
these are divergent solutions, the sensible effect on the forecast
for next week is that temperatures will back off a little from the
recent oppressive levels. Otherwise, the GFS is a much wetter
solution then the ECMWF. Have kept some POPS for the middle of next
week, but did trim them down a little as confidence in the GFS wet
solution is a bit low as the ECMWF handling of the ridge is
preferred.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1214 PM CDT THU AUG 21 2014

VFR conditions expected through the period. Current gusty southerly
winds will decrease in speed by sunset. Some chance of convection
nearing STJ overnight, with lesser chances as far south as MCI/MKC.
Otherwise, outside of a few diurnally-driven cumulus, a few periods
of mid-level cloud cover is expected.

&&

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

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

&&

$$

DISCUSSION...Cutter
AVIATION...Blair





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