Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Kansas City/Pleasant Hill MO
1119 PM CDT Wed Apr 1 2015
issued at 427 PM CDT Wednesday Apr 1 2015
Tonight - thursday:
In the very near term an area of convection tied to a pesky mesoscale convective vortex over
southwestern MO is expected to track northeast and graze the far
southeast County Warning Area through early evening. Have increased pops over this
region to account for this.
Attention then turns back to the west and northwest and focuses on
two areas...the NE/South Dakota cold front and an area of accas from western
Kansas into the Texas Panhandle. Per latest rap analysis and visible
satellite imagery the airmass remains capped within the cold fronts
baroclinic zone. Low-level moisture taking its time to arrive.
Latest NAM/rap suggest cin may not be eroded till closer to 00z.
Still expect a line of convection to form this evening with the
front sliding east-southeast overnight. This activity expected to
reach far northwest MO towards midnight and then continue across
northern MO. Second area being watched is the Kansas accas and 12z NAM
defined a h7 shortwave/vorticity Max that will move out of Colorado this
evening. Last several runs of the convective allowing hrrr generates
an expanding area of elevated convection which tracks east
overnight, crossing the Kansas/MO border after midnight. 18z NAM qpf
hints at this convection but delays the arrival till after 09z. Will
side towards the hrrr for now.
While the severe threat will be greatly muted due to its arrival
time and minimal instability some generous qpf is possible over our
northern and western counties. The latter due to the southerly low
level jet veering overnight and paralleling the cold front which
could result in some Post frontal training for several hours.
Convection likely to exit the County Warning Area quickly from west to east
Thursday morning. However, model consensus indicates the front will
stall just south of the cwa, close enough that low chance afternoon
pops necessary across the far southern counties to account for
potential late afternoon redevelopment.
Thursday night - Friday night:
The aforementioned stalled front will likely remain just south of
the County Warning Area during this period. However, Post frontal stratiform or weak
elevated convective rains are likely north of the boundary Thursday
night into Friday morning. An upper level trough is progged to shift
eastward within a pseudo westerly flow with pieces of energy
ejecting ahead of it through the Central Plains. This should allow
for some isentropically induced rain to form and affect most of the
County Warning Area. The rain chances will end by Friday afternoon with the passage
of the trough axis. Temperatures will be on the cool side and hover
in the 50s all day.
Clearing skies, light winds and cool high pressure will probably
send Sat morning lows to freezing or below.....With a good chance
for a frost.
Saturday - sunday:
Should be a rather benign weekend with weak ridging aloft
translating eastward and surface pressure falls across the plains
generating a southerly breeze. Should be a very pleasant weekend
with above average temperatures.
Sunday night - wednesday:
Looks like an unsettled pattern. Southwesterly flow sets up with the
passage of the upper ridge allowing for increasing moist warm air
advection. Considerable model uncertainty on pops and timing of the
next cold front. GFS is much faster and brings a cold front through
Monday night in response to a fast moving shortwave coming out of
the Desert Southwest on Monday whereas the 12z European model (ecmwf) shows no sign
of this wave...maybe a poor reflection by 12z Tuesday. In any event,
there is the potential for a couple pieces of weak energy to be
embedded within the southwesterly flow and give US a chance for some
convection. Temperatures are likely to remain above average for the
first part of the week.
Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1118 PM CDT Wednesday Apr 1 2015
Line of storms approaching far northwest Missouri will weaken a bit
once it reaches the kc area by 09z, and it's unlikely any terminal
would experience damaging hail or winds greater than 40 kts once
storms arrive. Improving conditions expected after sunrise with
perhaps some lingering MVFR clouds, otherwise quiet flying conditions