Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 192056
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
356 PM CDT Fri Sep 19 2014
Issued at 932 AM CDT FRI SEP 19 2014
Day 3 of trying to get rid of this pesky stratus. Inspection of
current TOP Raob and latest BUFR soundings indicate the moisture
will remain trapped under the low-level inversion for the better part
of today. 12z NAM/RAP condensation pressure deficit progs also hold
onto this cloud cover over the western 1/2 of the CWA into at least
the early afternoon hours....and it is not unreasonable to expect it to
last until sunset like yesterday and then rapidly dissipate. With
this in mind will hold onto the cloud skies into the early afternoon
before scattering them out. Also means lowering max temperatures
across the western portion of the CWA.
Issued at 355 PM CDT FRI SEP 19 2014
Tonight through Saturday Night:
This will likely be the most active portion of the forecast as two
frontal boundaries drop through the region Saturday/Saturday night.
First we`ll address what`s been a daily challenge in handling the
stratus over eastern KS/MO. Tonight will be the last of the stratus
problem for awhile. Just enough mixing and warmer/more humid air was
finally able to at least generate some breaks in the cloud deck.
Current thinking is we`ll once again clear off shortly after sunset
but with the moisture still trapped under the low-level inversion am
expecting to see low stratus/fog reform over the western CWA.
Fortunately there should be sufficient mixing to lift and break up
the clouds by mid morning.
Good warming through h8 via southwesterly winds will give us our
warmest weather in a number of weeks. An amplifying upper trough
over the western Great Lakes will force a cold front through WI/MN
while a trailing trough gently shifts south through IA/NE,
eventually settling into northern MO Saturday morning. Any
convection along the surface trough tonight should weaken and may
not even make it into the CWA. Ample advection of moderately
unstable air...MLCAPES upwards of 3000J/kg...ahead of this feature
will enhance afternoon/evening convection along the boundary.
However, a veered wind profile does not favor organized severe
weather. 0-6km shear of 25-30kt may be just enough to support a
renegade severe storm during peak heating. Believe convection along
the boundary will be scattered vs a solid line so 40-50% PoPs seem
An upstream cold front will quickly drop south from MN and reach
northern MO after midnight. This may energize stalled convection
near the MO River and force it out of the CWA by Sunday morning.
Sunday through Monday Night:
Broad area of Canadian high pressure will surge south and send much
drier and cooler air through the CWA and remain in place through
Tuesday through Friday:
Water vapor satellite imagery depicts our next weather maker just
off the central CA coast in the form of a closed upper low. The
medium range models are in good agreement in dislodging this feature
and ejecting it northeast into the Northern/Central Plains by
Tuesday. However, this system will then be moving into an upper ridge
which the models tend to have difficulty in handling the finer
details of energy moving through a mean ridge. So, overall confidence
on how soon any associated convection reaches the CWA is modest at
best. For now the eastward extension of any convection will be held
to mainly northwest MO. Temperatures will see a slow but steady
increase during this period and remain slightly below average.
.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1245 PM CDT FRI SEP 19 2014
Extensive IFR/low end MVFR stratus deck covering eastern KS and much
of western MO will gradually thin as well as erode from the west.
It`s certainly possible that the center portion of the stratus deck
will linger over west central MO till sunset and then dissipate
shortly after sunset...just like yesterday. With the low-level
moisture remaining trapped under the inversion, any clearing over
western MO and eastern KS may last for the evening hours only. The 12z
NAM 925mb condensation pressure deficit prog indicates LIFR cigs and
MVFR visibilities will reform after midnight and which seems
reasonable. Expect these conditions to abate by mid morning as the
inversion erodes while winds veer to the southwest.
A cold front will drop south into northern MO Saturday morning. Any
associated convection will likely be dissipating as it enters
northern MO. A better chance for convection will develop Saturday
afternoon across northern MO.