Area forecast discussion 
National Weather Service Kansas City/Pleasant Hill MO 
955 am CDT Wed Apr 1 2015 


Update... 
issued at 950 am CDT Wednesday Apr 1 2015 


Have made some significant adjustments to the short term forecast. 
First, have added chance pops for this afternoon and early evening to 
the far southeastern counties in response to mesoscale convective vortex (mesoscale 
convective vortex) lifting northeast out of northeastern OK. Hrrr 
has picked up on this for a number of runs and radar composites shows 
scattered showers moving into southwest MO while satellite imagery 
depicts accas clouds further west over southeast Kansas. The OK vorticity 
is expected to lift to just south of the southern County Warning Area border by mid 
afternoon with scattered convection increasing with time. Have also 
lowered temperatures a bit where pops added. 


Second idea is to slow down the arrival of convection tied to the 
approaching northern plains cold front. With the passing of each new 
model run the trend has been to slow down the arrival of convection. 
Considering the moisture, Aka instability, will take time to arrive 
in sufficient quantity to support robust convection plus the low- 
level jet veers this evening which limits the eastward extent of 
downstream convection have no problem pairing back the evening pops. 
Will hold off on adjusting pops after midnight until the rest of the 
models arrive. 


&& 


Discussion... 
issued at 335 am CDT Wednesday Apr 1 2015 


Quite a lot to get to this morning so we might as well jump right to 
it. Water vapor imagery showing a split flow regime across the Continental U.S. 
This morning with a southern stream shortwave fueling nocturnal mesoscale convective system 
activity over central Oklahoma. Looking further to our 
northwest...northern branch wave now working through the northern 
rockies with trailing cold front extending southwest through the 
intermountain west. Meanwhile to our south...latest sfc analysis 
places stalled frontal boundary extending from southwest Missouri 
east through the Tennessee Vly. As northern stream energy drops into 
the plains later this morning...strengthening southerly flow will 
quickly lift this feature north through our region by early 
afternoon. Following its passage...strong moisture advection to get 
underway with fcst models showing mid-upper 50 dewpoints working as 
far north as southern Iowa later this afternoon. With daytime temps 
expected to warm well into the upper 70s and lower 80s...expect 
plenty of boundary layer mixing as low-level lapse rates steepen with 
time. For now...would not be surprised to see gusts in the mid 30 mph 
range during peak heating later today. Despite strong moisture 
advection from the South...Strong winds combined with dry sfc fuels 
will create elevated fire weather conditions later today...and will 
address these concerns in the severe weather potential statement and a fire weather Special Weather 
Statement. 


Of more concern however will be developing convection off to our 
northwest later this afternoon. As discussed in recent 
days...increasing wind fields combined with moisture convergence 
along the approaching front will support surface based convection 
upstream across eastern Nebraska...north-central Kansas...and 
western Iowa this afternoon. After developing...activity will quickly 
congeal into a squall line before slowly tracking southeast towards 
northwest Missouri after sunset. Overall thoughts for organized 
severe across our area continue to lower this morning as models 
remain consistent in advertising incoming convection should quickly 
becoming elevated as it enters our region due to boundary layer 
stabilization. Cannot rule out some sfc based activity working into 
far northeast Missouri early tonight...but isolated severe threat 
across these areas should decrease as convection continues to track 
southeast overnight. With further southeastward 
progression...concerns will quickly changeover to heavy rain as low- 
level wind vectors become parallel to the incoming frontal boundary. 
With pwats running anywhere between 2-4 Standard deviations above 
normal...highly efficient rainfall will be possible...especially 
across far northwest Missouri where over 1 to 1.50" of new precip 
will be possible by daybreak. Lower precip amounts are expected 
further downstream as convection weakens and becomes more stratiform 
in nature during the early morning hrs. 


Front to still linger across our region through the day on Thursday. 
Some concerns for renewed severe potential across our far southern 
zones by afternoon as daytime heating leads to modest destabilization 
south of the front. Wind fields aloft will be more than supportive 
for severe and frontal boundary position will be critical for 
possible severe activity. This morning/S models now advertising a 
further northward position than in recent days...so have increased 
daytime highs for Thursday afternoon. 


Next wave to start tracking east along the stalled front Thursday 
night/early Friday. With moisture advection continuing from the 
Gulf...potential for heavy rainfall exists mainly south of the County Warning Area 
before activity clears later in the day. This should set the stage 
for a dry but noticeably cooler weekend as high pressure settles 
south across our region. Precip chances look to increase once again 
by Monday and Tuesday as another frontal boundary begins slowly 
working through the area. Out ahead of this feature though...temps 
look to rebound nicely heading into early next week. 


&& 


Aviation...(for the 12z tafs through 12z Thursday morning) 
issued at 628 am CDT Wednesday Apr 1 2015 


Main concerns today will be increasing wind speeds ahead of an 
approaching storm system. Sustained south winds of at least 15 kts 
with gusts as high as 35 kts will be possible this afternoon during 
peak heating. Winds will remain elevated through the early overnight 
with storm chances increasing after midnight. For now...have 
advertised a prevailing thunder at all sites with low-end MVFR 
restrictions. IFR conditions will be possible under the heaviest 
activity with areal coverage of storms becoming more widespread 
during the early morning hours. 




&& 


Eax watches/warnings/advisories... 
Kansas...none. 
MO...none. 
&& 


$$ 


Update...mj 
discussion...32 
aviation...32 














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