Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 112038
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
338 PM CDT Fri Apr 11 2014
Issued at 337 PM CDT FRI APR 11 2014
Short Range (Tonight-Saturday):
Relatively quiet compared to the second half of the weekend. High
pressure will retreat eastward tonight and allow a warm front along
the MO/AR border to lift northward through the CWA. Past several
model runs of NAM have shown a warm advection signal for isolated
elevated convection to pop up over the CWA around midnight and
lifting newd. While NAMs elevated CAPE in excess of 1000 J/kg may be
excessive it should be enough for isolated convection. Will take a
stab and add a mention of it. Prefer taking this route vs not having
it in and adding it later in a reactive mode.
Low-level moisture will return overnight with near 60 degree
dewpoints anticipated for tomorrow. With visible satellite imagery
showing stratocu over southeast OK/northeast TX can see this cloud
cover spreading northward late tonight. Warm boundary layer
temperatures will battle the expected increasing high clouds.
Current forecast may be a bit conservative. A bit more sun than
currently forecast and temperatures could reach lower 80s.
Pronounced elevated mixed layer will overspread the warm sector
which will cover the entire CWA. Models continue previous trends of
being a bit slower advancing the IA/NE cold front southeast. This
seems reasonable given a lack of an upper wave moving through. So,
will keep PoPs confined to far northern MO and from mid afternoon
on. Should any convection pop during this period there is a risk of
isolated severe storms due to the combination of moderate
instability...MUCAPEs around 2000 J/kg and 0-6km shear from 35-40
Medium Range (Saturday Night-Sunday Night):
An upper level trough lifting northeast out of the desert southeast
and Southern Rockies will send pieces of energy embedded within a
sub-tropical plume of layered moisture. With the warm sector likely
remaining capped most of the convective activity should initially be
focused near the aforementioned cold front. Will focus highest PoPs
across northern MO Saturday night but also allow for some
backbuilding southwest towards the low level jet. Any convective
outflow could send convection southward towards the MO River as well.
Sunday will be a challenge as convective debris and any old
boundaries will play havoc with temperatures and convective
redevelopment. However, do expect the most widespread convection to
occur on Sunday as the southern stream system approaches while the
boundary layer becomes nearly saturated. Precipitable water values
are around two standard deviations above normal so heavy rains are
likely owing to the potential for training cells.
Showers and thunderstorms will become more numerous with time as the
cold front sinks southeast and through the CWA. Will likely see
areas of post-frontal stratiform rain Sunday night as the
deformation shield takes it time to move though.
Long Range (Monday-Friday):
A pronounced upper trough in the northern stream will dig southeast
Sunday night/Monday and delay clearing as well as maintain a threat
for additional post-frontal rain into Monday morning. Favor the
slower NAM/ECMWF on their timing of the upper trough axis/clearing.
Strong cold air advection in the wake of the cold front will make
for a raw day on Monday. 12z NAM is way too cold as taking it at
face value would yield highs only in the lower 30s. Will trend
towards colder temperatures on Monday using the CONSAll blend.
Tuesday morning will likely see sub freezing overnight lows and
frost/freeze headlines will likely eventually be needed. Otherwise,
Tuesday and Wednesday will be quiet with a gradual warming trend,
although still below normal.
GFS/ECMWF continue to signal some unsettled weather moving into the
region by Thursday. However, timing and strength of the upper trough
remain questionable so will use low chance PoPs for now.
.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1232 PM CDT FRI APR 11 2014
Benign weather through this evening with light winds. While terminals
will remain dry there is a risk for isolated elevated convection
east of terminals mainly after midnight.
Low level moisture will return northward over the next 24 hours.
Satellite imagery and surface observations show MVFR cigs over
southeast OK/northeast TX. Condensation pressure deficit progs
advect this moisture/cigs across eastern KS/western MO before
sunrise. Increasing winds/mixing should scatter out this cloud cover
by mid morning.