Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 110903
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
403 AM CDT Fri Apr 11 2014
Issued at 403 AM CDT FRI APR 11 2014
High pressure was centered over northern Missouri early this morning,
leading to a large spread in temperatures over the region. Mid 30s
were present beneath the ridge where calm winds and clear skies
persisted, while readings were in the low 50s along the periphery of
the surface ridge where light winds were staving off the radiational cooling.
Early this morning, a weak mid level trough was quickly migrating
through SE Nebraska and Kansas. IR satellite imagery depicted a well-
define swath of mid cloud cover, but regional radar loops showed only
very light returns...most of which are presumed to be virga given the
very dry low level airmass.
Could be a spectacular sunrise depending on how the alto-
cumulus/remaining virga sets up, with a gradual clearing trend
thereafter. Even with the locally chilly start, temperatures will
climb steadily throughout the day with a late afternoon boost expected
to get readings into the 70-73 range as weak return flow begins.
Southerly onshore winds will steadily increase overnight and into the
day Saturday with surface dewpoints making a rapid climb from the
current 20s toward the 60 degree mark. A substantial capping version
will keep the warm sector quiet with afternoon highs likely topping
out close to 80 degrees!
Much uncertainty exists with respect to where convection will
initiate late Saturday and the scope of coverage. A weak surface low
(~1002mb) will likely exist over western IA Saturday afternoon along
the intersection of a warm front extending eastward, and a stationary
front arcing back through Kansas. I have serious doubts that forcing
will be sufficient for thunderstorms across srn IA prior to 00Z given
the state of capping, and have trimmed back POPs accordingly.
Assuming one or two cells can go during the early evening hours,
activity should be maintained or strengthen as the low level jet
works in concert with a strengthening surface wave over the southern
High Plains, yielding deeper convergence in the NE KS/SE NE/NW MO/SW
IA quad-state region. If enough convection can generate, there is the
potential for activity to grow upscale into a strong/severe MCS with
a net southward propagation. A lot of postulating going on here, but
such a system would rapidly decay as it entered the heavily capped
warm sector. Highest POPs remain across nrn MO overnight accordingly,
with an unseasonably mild and humid night expected, with warm sector
readings only falling into the lower 60s.
Remnant convective boundaries will potentially yield a messy warm
sector early in the day, but it is expected that continued warm
advection and some sunshine should remix the warm sector back to
homogeneity. This should allow temperatures to respond back to the
upper 60s/near 70 across much of the CWA -- noting a considerably
slower upstream trough that should delay the strong frontal passage
until late morning NW MO and during the early-mid afternoon
elsewhere. Once the front passes, temperatures will fall sharply.
Synoptic setup does not strongly favor showers/thunderstorms along
and ahead of the elongated frontal zone, owing to strongly veered
warm sector flow that would tend to limit convergence and forcing.
For this reason, have drawn back POPs ahead of the expected boundary
placement through 00Z, but have retained categorical POPs behind it.
To that end, a lead southern stream impulse is expected to arrive
across surface frontal zone prior to 00Z, just ahead of a stronger
and larger amplitude northern stream trough. This lead feature is
progged to produce a narrow axis of intense low level frontogenesis
immediately behind the surface cold front, supportive of a band of
heavy rain and thunderstorms. Nearly all numerical simulations have
keyed on this scenario, and see no reason to discount it. The
eastward acceleration of this band into the evening hours will tend
to limit point-based QPF despite the strong forcing and deep layer
moisture, with substantial precipitation quickly exiting the area
after 06Z. Am optimistic that most areas can pick up 0.50 to 0.75" of
rainfall in the short window before much drier air arrives aloft.
Strong low level cold advection and blustery north winds will replace
the warm/humid conditions with sharply colder readings for Monday.
Clouds will likely be plentiful with the 500mb trough axis not
expected to clear prior to 18Z. Coupled with brisk winds, highs will
struggle to reach the mid-upper 40s Monday, nearly 20 degrees below
Skies will quickly clear by evening, with a sprawling surface ridge
overspreading the area Monday night. Although we`ve had an extremely
late start to the 2014 agricultural season, the recent warmer weather
has driven many local growers and retailers to be rather aggressive over
the past week in putting Spring stock out to market. Thus,
frost/freeze headlines may be needed for Tuesday morning as
temperatures will likely plummet into the mid-upper 20s under optimal
radiational cooling conditions. Sensitive vegetation could be
severely damaged or killed and action should be taken to avoid
No precipitation in sight through early Friday with a steady warmup
expected, slowed only by the cooler continental return fetch
circulated around the strong eastern CONUS surface ridge.
.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 1043 PM CDT THU APR 10 2014
VFR conditions are expected at the terminals over the next 24 hours.
Calm winds late tonight will turn to the south Friday morning as the
center of the surface high slides off to the east. Southerly winds
should prevail through the day with mid-level --VFR-- clouds
beginning to advect in late Friday night.