Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 101143
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
643 AM CDT Thu Jul 10 2014
Issued at 356 AM CDT THU JUL 10 2014
Complicated sfc pattern across the central U.S. this morning as two
synoptic scale frontal zones extend from the high Plains of Colorado
and Wyoming southeast into the middle and lower Miss Rvr Vly. These
features combined with a compact shortwave seen on water vapor
imagery have led to early morning convection across central and
western Kansas. Activity has attempted to build east this morning
but with a very dry airmass over eastern Kansas and western Missouri
stemming from high pressure across the Mid Miss Rvr Vly...little if
any impacts expected across the fcst area this morning. As such...have
trimmed pops while maintaining a slgt chc mention along and west of
I-49...and this is even a stretch.
Heading into today...aforementioned high pressure is forecast to
track east into the Ohio Vly as leeside low pressure extends east
into western Kansas. As this occurs...aforementioned frontal zones
will consolidate and begin shifting northward with warm air advection
getting underway with fcst models suggesting 850-mb temps rebounding
to near 20c across the far west by 00z tonight. With mostly sunny
skies expected...high temps should easily warm into the middle to
upper 80s across the far west...with mid 80s likely east of Route 65.
In terms of sensible wx impacts...northward lifting frontal zone
should have little impact today with all fcst models suggesting any
precip across the central Plains will stem from a lingering MCV which
should remain well west of the fcst area. As a result...will offer a
dry fcst after 15z for all areas.
Fcst becomes a bit more interesting as consolidated frontal zone
continues lifting north tonight and a low-level jet strengthens to
near 50 kts overnight. As this occurs...core of strongest low-level
jet winds forecast to veer towards eastern Nebraska and western Iowa
as northern stream shortwave energy translates east through the
northern Plains. The end result will lead to best moisture
advection/convergence further north and east than this morning/s
activity with fcst models continuing to advertise nocturnal
convection mainly along and north of the I-70 corridor. With a main
synoptic scale frontal zone in play along with a fairly healthy low-
level jet...will continue to advertise likely pops for these areas
with chc and slgt chc pops further south.
Frontal boundary to continue lifting north through the area on
Friday as high Plains low continues to extend further east as a
strong front drops into the northern Plains. Lingering early morning
convection will likely track east through the morning with improving
conditions expected by afternoon as warm sector becomes established
over the area. With 850 temps expected to warm to near 24C across the
far west by afternoon...expect afternoon high temps to warm into the
lower 90s out west...with upper 80s further east where cloud cover
and lingering precip should keep things a tad cooler.
Warm and dry conditions Friday night will be followed by increasing
chances for shwrs/storms on Saturday as main frontal boundary across
southern Iowa begins heading south as high pressure builds into the
northern Plains. This will ultimately force the high Plains low to
advance east along the front Saturday night/early Sunday. Some
concerns for developing severe convection Saturday afternoon as deep
layer shear increases in a moderately unstable airmass. From this
vantage point...strong winds and hail look to be the main threats and
SPC has placed a slgt risk over northern portions of the fcst area.
Following sfc low passage Sunday...region will temporarily lie
between two frontal zones as main northern Plains front continues to
sag southward as high pressure builds south from Canada. As a
result...shwr/storm chances will continue well into Monday.
Good model agreement that main front will finally swing south across
the region late Monday evening/early Tuesday as 1025-mb high pressure
builds south from the Canadian Prairie provinces. Can`t rule out
severe wx potential with fropa as GFS and ECMWF deep layered shear
is forecast to reach the 50 kt range. Main factor potentially going
against strong convection will be that best mid-level shortwave
energy associated with upper Miss Rvr Vly closed low still fcst to
remain well north of our area. Beyond this...high pressure to take up
residence across the central plains and lwr Missouri Rvr Vly with
much cooler than normal conditions expected as 850-mb temps dip into
the 10-12c range on Tuesday. If this verifies...high temps may
struggle to reach out of the 70s both Tue and Wed. Both EURO extended
and GFS MEX guidance already forecasting highs in the mid
70s...which will be some 10-15 degrees below normal for this time of
year. With strong high pressure fcst to arrive...will continue with a
dry fcst through the conclusion of the period.
.AVIATION...(For the 12Z TAFS through 12Z Friday Morning)
Issued at 640 AM CDT THU JUL 10 2014
VFR conditions expected through the majority of the fcst cycle.
Mid/upper cloudiness should gradually erode through the day as
convection across central Kansas continues to dive southward.
Showers/storms will increase tonight as a warm front lifts north
towards the area. For now...have decided to advertise convective
possibilities with a VCTS mention at fcst sites after 6z. Winds
through the period will remain from the southeast between 10-15 kts.