000
FXUS63 KEAX 110908
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
408 AM CDT Tue Mar 11 2014

.DISCUSSION...
Issued at 408 AM CDT TUE MAR 11 2014

Today - Tonight: Have several forecast concerns covering a number of
elements. First is the abnormally warm temperatures. Second is the
the risk of a few strong thunderstorms popping up during the late
afternoon and early evening hours. Third is the return of wintry
weather with some minor snow accumulations likely.

A fairly pronounced upper trough is noted in water vapor imagery
from MT thru UT. Models have been consistent over the past few days
in handling this feature as they break off a piece of energy and
track it east through the Central Plains. Downstream height falls
will induce falling surface pressures resulting in a deepening of
the surface low currently over northwest KS. While the NAM has the
most northern track of this feature the more southern route taken by
the GFS and ECMWF has shown a gradual northward shift over the past
couple of model runs. In addition, a closer inspection of the GFS
and ECMWF surface elements notes the low pressure center being
stamped well south of where the actual circulation is generated by
the surface winds. So, am inclined to favor a more northern track of
the surface low through the CWA this afternoon and early evening.
This allows most of the CWA to reside within the warm sector. And
with the same airmass in place have raised high temperatures across
the board. The only negating parameter will be an increase in high
clouds this afternoon. If we had full sun we`d be knocking on 80
degrees.

Concerns for more than just general thunder this afternoon entails
impressive 0-6km bulk shears in the 60-80kt range, MLCAPEs between
500-700 J/kg, 30-40kt southwesterly low level jet and a
west-southwesterly 90kt speed max at 250mb nosing through the CWA
and juxtaposed over the south-southwest low-level jet. While quality
of moisture leading to marginal MLCAPE values will be a limiting
factor believe the extremely strong shear will help balance the
scale to allow for a few strong storms approaching severe levels
to form from near the surface low southward along a pseudo dry-line
and possibly near the east-west frontal boundary. High winds and
sub-severe hail are possible.

As the Central Plains shortwave continues east this evening another
upper trough will be diving south-southeast through the central
Canadian plains and into the Upper MS Valley and accelerate the cold
front through the CWA as well as pour much colder and drier air
southward. While the models are similar in evolving a post-frontal
deformation zone there are differences in timing with the GFS/ECMWF
more progressive. Inspection of the vertical thermal profile yields
a north-south phase transition from all rain this evening over the
entire CWA to a changeover to snow. The ground will lag in cooling
due to the recent very warm temperatures so then the precipitation
changes over to snow much of it will melt upon contact. Best bet for
any meaningful accumulations will be over northeast MO.

Northerly winds will ramp up with the passage of the cold front as
the pressure gradient tightens in response to a deepening shortwave.
Will hold off on issuing a wind advisory as they should remain just
below criteria.

Wednesday - Friday: Cold air advection all day Wednesday looks like
it will result in slightly cooler temperatures than the previous
forecast so have lowered them some. Have also added some flurries as
a h7 vorticity max dives south-southeast through the eastern portion
of the CWA.

Thursday and Friday look uneventful with temperatures quickly
rebounding back above normal.

Saturday - Sunday: Medium range models still advertising a
moderately strong shortwave zipping through the central U.S.
Saturday night and Sunday with another surge of cold air. This could
produce rain and snow Saturday night/early Sunday. Too early to
include any snow amounts.

Monday: Another quick recovery with temperatures bouncing back to
near normal.


&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 1156 PM CDT MON MAR 10 2014

Introduced some low level wind shear as winds just off the surface
appear to be in the 30 to 40 kt range, with nearly calm surface
winds. FROPA timing does not seem to have changed much, so kept the
same timing for FROPA, but bumped up the wind strength for the late
evening to overnight hours. Still looking at rain/snow at the
terminals late in the period, with a better chance for precip at
KSTJ. Introduced some precipitation mentions to KMCI and KMKC.
Precipitation will likely start as rain, then change to more of a mix
then snow shortly after this forecast period.


&&

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

$$

DISCUSSION...MJ
AVIATION...Leighton