Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 190502
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1202 AM CDT Sun Mar 19 2017

.UPDATE...


.AVIATION(06Z TAFS)...Sct-bkn040 over far ern WI for Sun AM with
mostly clear skies over south central WI. Middle to high clouds
will then increase by late afternoon or early evening. Cigs will
lower to 3-5 kft For Sun night with chances of showers. Light fog
via MVFR Vsbys will be possible late Sun night and Mon AM within a
moist frontal zone.


&&

.PREV DISCUSSION... (Issued 934 PM CDT Sat Mar 18 2017)

UPDATE...Clouds are steadily dissipating across srn WI. Ern WI
is on the wrn periphery of a large stratus deck so partly cloudy
skies may continue there through the night and into Sun, while
south central WI becomes mostly clear. 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 tstorms. The most focused area of tstorms
will likely develop over ern IA and nw IL where nose of LLJ and
greatest elevated CAPE is present.

MARINE...Nly winds tonight will veer sly for Sun afternoon
through Sun night. Swly winds on Mon will then veer nly with a
cold frontal passage. The winds and waves will remain below Small
Craft Advisory conditions during this period.

PREV DISCUSSION... (Issued 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
tstorms.

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)

SHORT TERM....

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.

LONG TERM...

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
High:

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.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

Update...Gehring
Tonight/Sunday and Aviation/Marine...Collar
Sunday Night through Saturday...DDV



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