Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 121753
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1253 PM CDT Sat Apr 12 2014
Issued at 423 AM CDT SAT APR 12 2014
A very mild start to the day, with a warm front positioned well to
the north. A modest increase in shallow low level moisture,
characterized by dewpoints in the low-mid 50s, was pooled across the
Missouri Ozarks through much of the evening, but appears to have
finally gained enough depth to spill northward into mid Missouri. So
far, stratus has been very sparse outside of Texas, and upper cirrus
has thinned considerably leaving mainly clear skies across the region.
After a warm and rare wind-less day Friday, stronger southerly winds
are expected for today, with a net increase in boundary layer
dewpoints that should reach the mid 50s by late morning (NAM yet
again far too aggressive on quality given Gulf buoy observations).
Although a northward surge of stratus is expected this morning, the
distance appears to great to cover before it will mix out from
daytime heating. As a result, confidence is increased that 80 degree
highs will be achieved across the board for the warmest day in 2014
Meanwhile, southwest winds aloft will spread a substantial elevated
mixed layer northward from the parched southern Plains region. Given
the warm frontal position and this substantial dry capping inversion,
feel that thunderstorm chances through the day are essentially zero.
Primary lee cyclogenesis is expected to occur across SE Colorado this
evening, but models show a secondary, weaker low over southeast
Nebraska early this evening. Echoing my thoughts from last night,
best chance for isolated to widely scattered thunderstorms toward 00Z would
be northeast of this low, along and north of the wavy warm front. Any
early activity would have trouble propagating southward into the
heavily capped environment, suggesting Iowa would see the best chance
for thunderstorms early evening. With time however, any southward
moving outflow, surface low convergence and the nocturnal low level
jet may lend to an increase in activity across SE NE/NE KS/NW MO
closer to 06Z. Other than some isolated marginal hail, am not sold on
any widespread severe threat with this activity. Also tried to trim
back POPs due to anticipated coverage as well as limiting airmass
over the southeast half of the CWA. Probably could have been more
aggressive in this capacity as a well developed MCS would likely be
needed to get any activity down to the MO river/I-70 corridor overnight.
Ongoing showers/thunderstorms and convective boundaries, especially
over nrn MO will muddy the synoptic pattern early, but feel that
airmass over the southern CWA should recover ahead of the advancing
frontal zone. These areas should reach the upper 60s to lower 70s,
limited only by anticipated widespread stratus despite the warm/humid start.
Across NW MO/NE KS, highs will be reached early with precip/cold
advection leading to steadily falling temps throughout the late
morning and afternoon.
Focus of the day will be on precipitation, the bulk of which will
fall in the immediate post-frontal region where a lead southern
stream impulse will provide the forcing for ascent amidst very strong
low level baroclinity. Expect a narrow band of moderate to heavy
rainfall to progress south and east through the CWA during the
afternoon and early evening hours. Even with a relatively narrow
window, precipitable water anomalies and strong post-frontal forcing
could generate substantial QPF with modest elevated instability still
In the warm sector, scenario far less obvious. Better focus is
certainly over eastern OK and AR, perhaps far srn MO...tied to
stronger synoptic surface low and greater instability. Locally,
strongly veered warm sector winds suggest sfc-based storms in the
afternoon will be isolated and short-lived. Will need to keep a
watchful eye over the far srn/ern CWA after 18Z for any strong-severe
storms, but threat overall looks minor.
Heavy precipitation should largely exit the region after 03Z, with
strong cold advection within deep cyclonic flow suggesting very light
rain/drizzle could persist overnight. Temperatures will fall steadily
as gusty north winds continue, with readings likely ending up in the
middle to upper 30s most areas (colder far NW MO).
Skies will remain overcast through much of the day Monday prior to
the arrival of the main 500mb longwave trough axis. At the base of
this trough, a layer of mid level frontogenesis will persist beneath a
strong mid level jet streak. Most 00Z solutions continue to take this
feature south of the region, but the crazy NAM drives that secondary
axis of lift across the CWA with a much colder environment in place.
It`s solution of a couple inches of accumulating snow is ignored for
now, but with daytime highs only around 40 degrees, any precipitation
could at least fall as a rain/snow mix or snow, melting upon impact.
Definitely something to watch as we get closer.
Strong signal of a hard freeze for Tuesday morning continues.
Headlines likely required with mid 20s all but certain given optimal
radiational cooling setup.
Modest warmup Wed-Thurs back to around seasonal normals before the
next system approaches. Ensemble and deterministic solutions all over
the map in terms of intensity, placing and timing of the upstream
Pacific energy and have VERY low confidence for Thursday night into
Friday. Solutions vary from a few passing showers to widespread
severe weather, with temperature forecasts varying significantly as
well. For now, forecast reflects a low chance for rain (mainly Thurs
night) with temperatures running near normal for Friday. Highly
subject to change.
.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1251 PM CDT SAT APR 12 2014
Challenging forecast. Immediate forecast concern are the strong and
gusty southerly winds. Should lose the gusts after sunset and diurnal
Warm elevated mixed layer has overspread eastern KS/western MO and
will effectively inhibit convective development through tonight. Best
chance for showers and thunderstorms tonight will likely lie from far
northeast KS across northern MO and areas northward. A few
convective allowing models generate isolated convection late this
afternoon and early evening from east central KS into northwest MO
but confidence is low for it to form and then also reach the
terminals. Also have low confidence in 12z NAM and GFS developing a
MCS north of the terminals this evening and propagating southward
through eastern KS/west central MO. Believe the cap will be difficult
to break until the NE/IA cold front moves through the region Sunday
afternoon. There will be a much greater chance for rain after 18z