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000
FXUS63 KEAX 131751
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1251 PM CDT Mon May 13 2013

.SHORT TERM...(Today through Wednesday)
Issued at 408 AM CDT MON MAY 13 2013

Today-Tuesday...

From a record cold Sunday morning to possible record high
temperatures on Tuesday, what happened to Spring? Much warmer
temperatures will begin arriving today as a high amplitude upper
ridge over the Rockies flattens as it shifts into the Plains. The
large area of high pressure which was over us yesterday will be
shoved out of the way as pressure falls from ND to TX allows surface
troughing to expand eastward. This will result in increasing
southerly flow and warmer air pressing east. There should be a
modest west to east thermal gradient with above average temperatures
over the western CWA where temperatures will approach 80 degrees.
Increasing high level clouds spilling southward on the front side of
the flattening upper ridge will likely keep temperatures from
reaching their full potential over the eastern counties.

Tuesday will yield even hotter temperatures as westerly trajectories
at h8 come straight off the plateau areas of the Central and
Southern High Plains. This favored downslope component will push H8
temperatures of 22C-25C and 925mb temperatures around 28C, which are
more commonly seen in the summer months, into the CWA. Good mixing
will likely send temperatures well above 90F over the northern and
west central counties. The record high for the date at St. Joseph
(93F) and Kansas City (91F) are within reach. There is even a chance
for mid 90s at both locations should we be able to mix out the
entire boundary layer. Believe models over selling the surface
dewpoints on Tuesday as mid/upper 60s they forecast show no link
from the Gulf of Mexico and do not fully appreciate the good mixing
of the boundary layer air that is expected plus westerly h8 winds
and southwesterly surface winds are not favorable for this high of
dewpoints. Through collaboration have significantly undercut model
guidance dewpoints. These lower humidities will also favor warmer
temperatures and supports going above guidance max temperatures.

Wednesday/Wednesday night...

Rain chances are expected to ramp up Wednesday afternoon and night
as a cold front drops southward from NE and IA. There is some
disagreement on how fast and far south the front will drop. The NAM
is the most aggressive and sends the frontal boundary into central MO
or the far southern CWA while the ECMWF and GFS stall the front over
northern MO Wednesday night. Favor the latter two models as there is
a feature that all the models eject northeastward out of northern
Mexico. Believe this feature could slow down the southward progress
of the front. So, have raised PoPs over northern MO with scattered
convection expected by Wednesday night.

.LONG TERM...(Thursday through Sunday)
Issued at 408 AM CDT MON MAY 13 2013

Warm and wet conditions will prevail in the longer-range forecast,
as a series of shortwave troughs and eventually the main longwave
trough move through the region. On Thursday, a lingering frontal
boundary will provide focus for showers and thunderstorms across
northern Missouri, before southerly return flow pushes the weak
boundary into the Great Lakes region by early Friday. Subtle ridging
will develop over the central CONUS for Friday; however, both the EC
and GFS bring a shortwave trough through the area during this
period, keeping a lower chance of thunderstorms extending through
Friday night.

A deeper, longwave trough will move onshore by early Friday, and
will gradually push east through the end of the week. Broad ascent
ahead of the trough and another weak wave make support warm-sector
precipitation late Friday night into Saturday; however, the better
chance of precipitation will come Saturday night or Sunday as a
deep surface low pushes through the northern Plains and drags a cold
front through the forecast area. Model agreement on the timing of
this feature has decreased with the 00z EC waiting until midday
Sunday to bring the front into northwest Missouri, which is in
opposition to the Saturday night frontal passage in the 00z GFS; so
as a result, have adjusted consensus PoPs down for the end of the
forecast period.

Temperatures throughout the period still look a bit above normal,
with south to southwest flow persisting almost every day and with
the upper jet residing north of the region. With warm temperatures
aloft but the potential for clouds/precipitation in nearly every
period, highs should hover around 80, and lows will be well above
normal in the mid 60`s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 1248 PM CDT MON MAY 13 2013

VFR conditions will continue through the period with just a few wisps
of high cirrus.

Otherwise, south-southeast winds around 10 knots will trends
southerly this evening, and eventually southwest by Tuesday morning
with speeds generally 10 knots or less. Strong warm air advection
above a weak surface inversion overnight may bring conditional low
level wind shear conditions across STJ overnight, and have continued
mention of LLWS for the 18Z TAF period.

&&

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

$$

SHORT TERM...MJ
LONG TERM...Laflin
AVIATION...Bookbinder