Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Kansas City/Pleasant Hill MO
645 am CDT Monday Aug 3 2015
issued at 440 am CDT Monday Aug 3 2015
Today - tonight:
Scattered convection continues to bubble within a narrow corridor
lying northwest-southeast over northwest MO. While a cold
front has nosed into northern MO it appears isentropic
ascent on the 305k and 310k surfaces is the primary
driver, the same mechanism which aided convection over the past 2
days. Due to several outflow boundaries put out by Sunday nights
convection its difficult to locate the cold front his morning.
The short range models weaken the isentropic ascent this morning so
the current convection should dissipate. Going forward think the
cold front will stall over the County Warning Area today with model consensus
dividing the County Warning Area in half. Isolated/widely scattered convection
possible along/north of the boundary during peak afternoon heating.
Pulse type convection with potential for microbursts due to extreme
instability, 0-6km shear of 4000j/kg near the front, and 25-
30kt of 0-6km shear.
Conditions for more organized/widespread convection expected
overnight due to a modest increase in the southwesterly low-level
jet. These winds should transport the higher Theta-E air northeast
and over the slowly retreating front. Highest pops painted across
the northern 1/3 of the County Warning Area.
Tuesday - wednesday:
This looks like the most favorable period for more widespread
convection with heavy rain potential as precipitable water values
exceed 2 inches or around 150% of average or 99th percentile. Models
have been clear for the past 3 days that a well defined shortwave
trough will migrate eastward across the central rockies and Central
Plains. While there remains some timing and location differences
between the models they all agree that a couple rounds of convection
are likely over the County Warning Area. High temperatures will be a bit problematic
as convective debris and any prolonged bouts of convection will
greatly limit heating. For now will shoot for the high end on the
Assumption there will be sufficient heating to achieve seasonal
Thursday - sunday:
Operational models gradually build the dome of high pressure back
into the central U.S. With surface riding from the Great Lakes
into the mid MO valley. This isn't much different than previous
runs. What is different is the models now modify this airmass
over time resulting in slightly below average to average
Thursday night and Saturday night currently carry the highest
chances for rain which is typical for this time of year. Both
the GFS and European model (ecmwf) bring a couple shortwave troughs over the top of
the broad upper high and through IA/MO.
Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 642 am CDT Monday Aug 3 2015
Small area of convection continues to pulse up and down over
northwest MO and believe this will continue through mid morning.
By mid/late afternoon widely scattered convection will be possible
generally along/north of the MO river. During the overnight period
showers and thunderstorms are expected to increase in coverage across
As for the terminals expect VFR conditions with only a small risk of
thunderstorms in the terminals. Kstj has a slightly better chance of
seeing convection tonight.