Area forecast discussion
National Weather Service Kansas City/Pleasant Hill MO
631 PM CDT Tue Jun 18 2013
Short term...(this evening through Wednesday night)
issued at 423 PM CDT Tuesday Jun 18 2013
Concerns on multiple levels over the next 24-36 hours. Northwest
flow aloft combined with weak frontal boundaries plus outflow
boundaries from ongoing convection. And can't Forget weak isentropic
ascent later tonight and tomorrow.
For this evening: the primary focus will be along a weak frontal
boundary which extends from northeast Kansas through west central
MO...running just south of the kc Metro. Low level moisture/moderate
instability has pooled along and south of the feature. A decaying
mesoscale convective vortex over southeast NE help get the northeast Kansas convection going.
The models did a poor job handling the NE mesoscale convective vortex. However, the qpf
output closely mimics the ongoing convection. Activity will slide
southeast along this boundary through sunset with the far southwest
counties the most likely to see active convection. NAM bufr
soundings depicted a classic inverted vee sounding profile which
favors downburst type wind potential.
Other isolated and weaker elevated type convection over the south of
a stj to Macon line will likely dissipate by early evening. A
secondary backdoor cold front over southeast Iowa has isolated
convection along it but expect this convection to only glance the
northeast tip of the County Warning Area. This front will continue to push southwest
and eventually blend with the airmass currently over the County Warning Area.
Overnight thru Wednesday night: nocturnal elevated convection needs to be
considered after midnight as the northeast Kansas/west central MO
boundary likely moves little. Weak isentropic ascent of an uncapped
airmass suggests widely scattered elevated convection could reform.
GFS/ECMWF/sref qpf output provides a signal at such an occurrence
while the NAM appears to be too far east. Will throw in slight
chance pops for late tonight over the southwest 1/3 of the County Warning Area and
expand them eastward tomorrow.
Models also very similar with a shortwave embedded within the
mid/upper level ridge rolling eastward off the Front Range of the Colorado
rockies on Wednesday. This feature will move through the ridge axis
as it approaches the western County Warning Area tomorrow afternoon. With a
moderately unstable airmass, weak shear and the likelihood of a left
over frontal boundary we have the ingredients for scattered
convection to once again pop-up during peak heating. While the
current forecast carries low chance pops one could argue going
higher. However, given the possibility of missing on timing and
location will let the next shift determine this. In addition, expect
any convection to be relatively slow moving due to the shortwave
working its way through the upper ridge. That combined with
precipitable water values increasing to 1.5+ inches suggests locally
heavy rainfall will be possible with any of the stronger
storms.
Long term...(thursday through tuesday)
issued at 423 PM CDT Tuesday Jun 18 2013
Only minor changes in the medium range guidance as a more typical
Summer-like pattern develops over the Continental U.S..
Thursday: mid-level ridging will begin to build by Thursday with
ongoing convection potentially ongoing at daybreak as eml begins to
move northeast. Will be some potential for renewed afternoon
convection should a well develop mesoscale convective vortex or shortwave move into the
region.
Friday-sunday: mid-level heights will begin to rise into the
weekend and for the most part should preclude widespread
convection. However, very humid and rather warm conditions develop
across the region. While soundings indicate a capped environment
each afternoon, any minor shortwave which travels NE in the broad SW
mid-level flow could spark a few widely scattered storms each
afternoon. Of higher concern will be heat index values topping out
either side of 100 each day into early next week.
Monday-tuesday: the broad ridge will begin to flatten by early next
week, which may allow for a limited chance for precip as several
waves move through the central Continental U.S..
&&
Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 628 PM CDT Tuesday Jun 18 2013
Mini convective complex over east central Kansas/west central MO will
pass south of the terminals as the system tracks southeast along a
weak frontal boundary. This will result in a VFR forecast for all 3
terminals.
Do have some concern for late night elevated convection forming over
eastern Kansas/western MO but low confidence on occurrence and areal
coverage keeps the terminal dry until tomorrow afternoon when better
instability will be present ahead of a disturbance aloft tracking
east through Kansas.
&&
Eax watches/warnings/advisories...
Kansas...none.
MO...none.
&&
$$
Short term...mj
long term...dux
aviation...mj
