Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 182340
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
640 PM CDT Sat Mar 18 2017
.UPDATE...Based on satellite trends, it appears the stratocumulus
deck will slowly dissipate through the evening but not entirely
confident skies will clear in the east. The weak boundary layer
flow and lack of stronger subsidence may keep some clouds through
the night. Otherwise high pressure will settle over WI tonight and
Sun AM before moving east with sly winds and warm advection.
850-700 mb warm, moist advection and frontogenesis with weak PVA
aloft will then bring chances of showers Sun night. Showalter
Indices of zero to -2C will bring at least slight chances of
.AVIATION(00Z TAFS)...Cigs are generally around 3.5-4.0 kft. Skies
are gradually clearing near KMSN and wwd. The clouds will
gradually decrease with scattered cloud cover expected over ern WI
around 04z but some uncertainty with this. At least scattered
stratocumulus could remain over ern WI tonight into Sun afternoon.
Also, where clearing does occur, light fog with MVFR Vsbys will be
possible around sunrise via good radiational cooling conditions.
.PREV DISCUSSION... (Issued 241 PM CDT Sat Mar 18 2017)
TONIGHT - Confidence...Medium Expecting more erosion of the
stratus/stratocu deck as the evening wears on. Much of SC WI has
seen some break up and so this trend likely to advance east with
time. Surface high will build in to the west towards 06z and then
into the east towards 12z. Diminishing winds in the works as well
with the more slack gradient with surface ridging.
SUNDAY - Confidence...Medium to High 500 millibar ridge in place
at the outset with some flattening during the day as some energy
shifts east from the northern Plains. The surface high will shift
to our east and this will set up a return sse wind regime. The
focus for precip appears be shaping up to our west or northwest
during the day so will leave dry forecast intact. 925 millibar
thermal pattern boosts to near 3-4c in the northeast and to near
6-7c in the southwest by days end. Low level traj will keep the
eastern/lake areas cooler with a potential boost into the 50s in
the western CWA.
Sunday night and Monday...Forecast Confidence is Medium to High:
Low pressure and an associated cold front is expected to bring
rain showers to southern Wisconsin Sunday evening into early
Monday. A little thunder is also possible, especially toward the
WI/IL border. Still seeing a range in model highs on Monday due to
differences in how quick the front gets through, though models
seem to be trended toward the slower and thus milder solution.
Tuesday through Friday...Forecast Confidence is High:
High pressure will return for Tue/Wed, bringing mostly sunny to
partly cloudy skies. Temps should be cooler Tue behind the
departed cold front, though still a couple degrees above normal.
Below normal temps are likely on Wednesday.
Thursday through Saturday...Forecast Confidence is Medium to
Models are in good agreement showing strong low pressure moving
through the region late in the week. This will likely bring precip
chances back into the area Thursday through Saturday. Looks like
mainly rain for this system, though the new ECMWF is farther south
and colder, suggesting a possible changeover to snow at the tail
end of the precip on Saturday.
Near normal temps Thursday should warm back above normal Friday,
cooling again Saturday as the low heads east and colder air moves
into the state.
AVIATION(18Z TAFS)...Widespread MVFR CIGS across southern WI with
some breaks gradually overtaking SC WI. Looks like at least BKN
MVFR persists into the early evening in the east with better SCT
potential in the west. Should see increasing VFR potential tonight
with LLVL RH drying out further. As winds lighten up with approach
of ridge axis some patchy fog not out of the question. May see an
uptick in mid clouds on Sunday as return WAA regime sets up,
however precip chances expected to remain off to our west and
northwest through days end.
MARINE...High pressure shifting east of the lake on Sunday will
set up a sse wind regime although winds and waves are expected to
remain below small craft levels.
Tonight/Sunday and Aviation/Marine...Collar
Sunday Night through Saturday...DDV