Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Kansas City/Pleasant Hill MO
347 PM CDT Sat Mar 15 2014
Short term...(this evening through Sunday night)
issued at 347 PM CDT Sat Mar 15 2014
Low level moisture is surging northward across eastern Kansas and western
MO this afternoon ahead of a deepening cyclone over the Texas Panhandle.
This is evidenced by a cumulus field rapidly spreading northward into
the area, with a few embedded showers and thunderstorms starting to
develop where the boundary layer is beginning to destabilize. This
weak instability will spread as far north as north central Missouri later
this evening, and scattered showers and a few storms could spread as
far north as St. Joseph through 03z. Wind shear is very weak so the
threat for strong storms/small hail is pretty low.
Southern stream system over the Texas Panhandle will merge with another
wave dropping out of the northern rockies tonight. The northern
system will send a strong cold front across the area this evening,
while the phasing of both systems will lead to an area of elevated
frontogenesis lagging behind the surface front across northern MO
after midnight. While the most widespread precipitation will be
focused across the Ozarks in closer proximity to the southern stream
system, the frontogenesis to the north should lead to a band of mixed
precipitation developing over far northwest MO and dropping south
across toward the I-70 corridor late tonight and early Sunday.
Static stability will be rather low so that this band could produce
an hour or two of moderate precipitation for some areas. Thermal
profiles favor rain changing to sleet and then snow as this band
passes through with temperatures plummeting into the upper 20s and
lower 30s by sunrise. Snow accumulations will be limited by the
presence of sleet and the quick north-to-south movement of the
precipitation band. Given the fairly brief window for any appreciable
snowfall rates any snow accumulations should be around an inch or
less for most of the area as this band passes through.
By Sunday morning the band of frontogenetically-enhanced precipitation
over northeast Kansas and western MO will begin to merge with another
shield of precipitation spreading northeast out of Oklahoma and
southern Missouri into central Missouri. This will shift the focus
for the heaviest precipitation into the Butler/Sedalia areas by mid-
morning, gradually shifting south of the entire forecast area by
early afternoon. Precipitation will be transitioning to all snow
across these areas by Sunday morning, with the potential for an inch
of two of snow/sleet accumulation from Butler through Clinton and
Sedalia through early afternoon. Warm surface temperatures will keep
snowfall ratios pretty low.
The other concern will be very gusty winds behind the front tonight
with a fairly intense pressure gradient developing north of the
surface low to our south. The strongest winds will be near and south of
the US 36 corridor where the pressure gradient north of the low
will be most intense. Winds could gust as high as 45 mph across these
areas late tonight and Sunday morning, and a Wind Advisory has been
issued for these areas through 1 PM tomorrow.
Skies will quickly clear from north to south Sunday afternoon giving
way to a cold night with lows in the upper teens for most areas.
Long term...(monday through saturday)
issued at 347 PM CDT Sat Mar 15 2014
The extended portion of the forecast remains very similar to the
previous forecast. The flow will mostly zonal across the Continental U.S. With
several upper shortwave troughs traversing the northern tier states.
The first wave will move through during the day Tuesday with the
second moving through Friday. In both cases, the surface low will
track to our north, so the best precipitation chances will remain
north of the forecast area. Both waves will push a weak cold front
through the area but with the mainly zonal flow there is no push of
real cold air behind either front. As a result, we'll trend above
normal through much of the extended with the Post-frontal airmass on
Tuesday and into Saturday trending near to below normal. Overall
this is a mainly dry forecast and the above normal temperatures and
lack of rain will likely worsen the drought over the next week
during a period of time when we're supposed to see greater than half
an inch of rain a week.
Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 1247 PM CDT Sat Mar 15 2014
Clouds and a few showers/storms starting to bubble up near Joplin
could reach as far north as Kansas City later this afternoon. The
odds of thunder this far north are low enough to keep thunder out of
the tafs for now, but it can't be ruled out.
Strong cold front entering Nebraska and Iowa will roll through the
area between 8 PM and 10 PM. There could be a few showers
accompanying the front, but the biggest hazard will be very gusty
northeast winds which will frequently gust as high as 30 to 35 kts
for much of the night. A band of rain and/or snow should develop
over far northwest MO late tonight and drop south toward Kansas City
after 2 am, weakening as it does so. Snow could produce minor
accumulations less than an inch.
Kansas...Wind Advisory from 10 PM this evening to 1 PM CDT Sunday for
MO...Wind Advisory from 10 PM this evening to 1 PM CDT Sunday for