Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 160854
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
354 AM CDT Thu May 16 2013
.SHORT TERM...(Today through Saturday)
Issued at 354 AM CDT THU MAY 16 2013
Scattered thunderstorms focused along the 850 mb front in southern
Iowa will continue to shift very slowly to the southeast this
morning, possibly affecting the far northeast corner of the forecast
area. The surface front has also meandered northward over the last
several hours; thus, even if some additional development occurs
along the surface boundary today, the majority of the precipitation
should be mainly north of the region.
An upper low will continue to lift slowly east northeastward today
over eastern Oklahoma and southwestern Missouri, possibly fueling
scattered showers and thunderstorms today across our southern tier
or two of counties. Cloud cover associated with this feature will
spread across the CWA and hold high temperatures in the upper 70`s
to low 80`s today, and while a few stray showers or isolated
thunderstorms are not completely out of the question in the moist
and slightly unstable environment between the two aforementioned
features, widespread convective initiation is not expected.
A weak shortwave trough currently heading eastward through the
central Rockies may brush the Iowa/Missouri border late tonight and
into early Friday, then is expected to phase with the slower-moving
wave lifting out of southern Missouri on Friday afternoon. This
could result in the development of a few showers and thunderstorms
across our east on Friday, but most precipitation will likely stay
further east, and out of the CWA. Afterward, ridging will build over
the eastern Plains and keep precipitation out of the region for
Friday night and Saturday. A few isolated thunderstorms are possible
late Saturday night in eastern Kansas and possibly into far western
Missouri ahead of the next approaching system, but the majority of
any warm-sector precipitation that develops will be focused mainly
west of our forecast area.
Temperatures Friday and especially Saturday will be above normal in
the lower to mid 80`s as zonal flow gradually turns southwest over
the Plains and warm temperatures continue to stream in aloft.
Saturday is likely to be the warmest day during this forecast
period, and may even be a touch warmer than currently advertised if
cloud cover stays west of the CWA throughout the daytime hours. Lows
will also be several degrees above normal in the mid to upper 60`s.
.LONG TERM...(Sunday through Wednesday)
Issued at 354 AM CDT THU MAY 16 2013
Sunday through Monday night: This period should be rather active
with several periods of scattered showers and thunderstorms. The
framework of the medium range models are in general agreement early
on as a rather broad upper trough shifts east from the Rockies on
Sunday. However, confidence in that an upper low, and a broad one at
that, will close off over the Northern and Central Plains on Monday.
There is quite a bit of spread between individual GFS ensemble
members and it is only the operational GFS which allows the low to
close off. In addition, by Monday the ECMWF hangs back a secondary
piece of energy and upper jet segment over the Southern Rockies.
This is supported by the 00Z GEM. Should this latter scenario prove
to be accurate it would result in a further delay of the arrival of
the associated cold front and likely prolong the convective risk
into Tuesday. For now will use a model blend but with an overall low
confidence on if/how an upper low will close off.
A moderately strong southerly low level jet is expected to form from
OK through eastern KS/western MO on Sunday with the likelihood of
tapping into the moisture from the Gulf of Mexico. Expect at least
moderate instability to be present on Sunday with modest 0-6km shear
of 40kts offering the potential for strong to severe storms.
Temperatures will likely remain above average on Sunday and Monday.
Tuesday and Wednesday: Given the uncertainty of just where or if a
closed low will form it is best to use model consensus for Tuesday
and Wednesday. Going this route results in tracking the cold front
east and through the CWA and allow a Pacific airmass to spread over
the region. This slightly cooler air will result in seasonal
temperatures. While the current forecast uses only slight chance
PoPs there is the potential for warp around showers to linger on
Tuesday if the operational GFS/ECMWF prove true and form an upper
low over the Central Plains/Mid MO valley. Upper lows this far out
are always tricky and even more so as we get later into Spring.
.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1147 PM CDT WED MAY 15 2013
VFR conditions should prevail through the TAF period. However, 00Z
model runs do continue to introduce MVFR cigs between 10Z-12Z at all
3 TAF sites. Still believe models are too aggressive with boundary
layer moisture however so have maintained bkn mid level clouds
through the morning hours. Around 18Z, soundings support a scattered
to broken cumulus deck around 4kft developing at the terminals. There
is the potential for scatter thunderstorms in the vc of the terminals
during the afternoon however the best chances for precipitation appear
to be well north of the terminals along a weak surface front and well
south of the terminals near the better upper level support for
storms. Winds will be out of the south through the overnight backing
to the southeast this morning and remaining between 5-10kts.