Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 251738
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1238 PM CDT Sat May 25 2013
.SHORT TERM...(Today through Sunday Afternoon)
Issued at 255 AM CDT SAT MAY 25 2013
MCS over south central Nebraska is being fed by a 50-kt LLJ, which
will begin shifting its focus eastward into western IA and northwest
MO through sunrise. This, combined with a thermal wind vector from
the north-northwest, should favor a propagation of this convective
system southeastward toward northwest MO through the morning.
However, low-level wind fields will weaken after sunrise, and the MCS
will be tracking into a region of much lower elevated instability
over northern and western Missouri. Therefore expect this complex to
weaken considerably by the time it reaches the forecast area later
this morning. While thunderstorms are likely at least across the
northwest portion of the forecast area, the threat for severe weather
or excessive rainfall is low.
This thunderstorm complex is the first in a series of convective
waves that will affect the region over the weekend as several weak
impulses interact with a recurring nocturnal low-level jet over the
Plains. Depending on clouds left behind from this morning`s complex,
the airmass should become unstable across eastern KS and western MO
later this afternoon. This may set the stage for another thunderstorm
complex developing slightly further south across northeast KS and
northwest MO this evening where the nose of the LLJ will set up. Any
thunderstorm activity will be dealing with weak shear aloft and is
unlikely to be severe.
Sunday`s thunderstorm chances are quite a bit less certain due to the
possibility of lingering clouds and convective boundaries. Should the
airmass become unstable by afternoon, scattered thunderstorms will
again be possible especially north of I-70.
.LONG TERM...(Sunday Evening through Friday)
Issued at 255 AM CDT SAT MAY 25 2013
A weak shortwave along with the nocturnal LLJ will allow for
scattered thunderstorm development Sunday night into Monday. The
good news is that this activity will shift into Iowa and eastern
Missouri quickly in the morning, leaving much of the daytime hours
of Memorial day warm and dry. Afternoon redevelopment will be
possible primarily over the extreme northern portions of the CWA
where capping is weaker and remnant outflow boundaries may exist.
Additional nocturnal thunderstorms will be possible Monday night as
the mid-level flow pattern begins to shift in response to deeper
troughing over the western CONUS.
Tuesday and Wednesday: Warm temperatures, with increasing humidity,
but generally dry conditions are to be expected. Increasing ridging over
the central United States should push low-level baroclinic zone to
the northwest of the CWA, resulting in the highest chances of precip
west and north of the CWA. Breezy southwesterly winds both Tuesday
and Wednesday may result in temperatures in the middle 80s for some.
Thursday and Friday: Medium range models continue to disagree with
the eventual evolution of upper troughing in the West. ECWMF
continues to hold onto a deeper upper trough that pivots eastward on
Thursday. Meanwhile, the GFS is not quite as deep with upper
troughing, but is starting to trend towards the deeper ECMWF
solution. Both models suggest convection increases Thursday and
Thursday night, with the potential for a lingering baroclinic zone
inducing additional activity into the weekend.
.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1232 PM CDT SAT MAY 25 2013
For this afternoon, I am expecting VFR cigs and vis along with south
to southwest winds under 10 kts with brief gusts to 15 kts. Later
tonight the possibility exists for the development of scattered SHRA
and TSRA. Forecast confidence is low as to whether the three
terminals will see any of the activity. For that reason have placed
VCTS in the TAFS beginning late tonight. The scattered SHRA/TSRA are expected
to persist through the remainder of the TAF period.