Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 191402
AFDMKX

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

.MARINE...Surface ridge axis spanning north/south across Lake
Michigan will shift to the east and result in a light ese wind
this morning and then increasing from the sse this afternoon.
Highest waves will end up being in the northern cut north of Port
Washington due to longest fetch there. However, expect winds and
waves to remain below small craft levels.

PC

&&

.PREV DISCUSSION... (Issued 609 AM CDT Sun Mar 19 2017)

AVIATION(12Z TAFS)...Light low level onshore flow continues to
carry low clouds from over Lake Michigan onshore and inland to as
far west as KUES, KBUU and KETB. High clouds moving southeast
across WI helping to obscure the low clouds over eastern CWA, but
can still vaguely see that the low clouds are progressing wwd. As
low level winds continue to veer to the southeast and increase
later this morning, expect low clouds to erode and move off to the
north and northwest. Still expecting scattered showers and isold
T tonight across srn WI as surge of warm air and moisture
convergence moves across the region.

PREV DISCUSSION... (Issued 330 AM CDT Sun Mar 19 2017)

SHORT TERM...

TODAY AND TONIGHT - Confidence...Medium to High.

Light onshore flow pulling lake clouds inland in some eastern areas
early this morning.  Light surface winds remain onshore this morning
so sct-bkn low clouds will likely be affecting portions of eastern
CWA this morning, possibly lingering into the afternoon.  Better
mixing of low level drier air this afternoon should help to thin any
remaining low clouds.  Otherwise, passing mid-high level cloudiness
elsewhere today. Light boundary layer winds and clear to p/cloudy
skies should allow patchy early morning fog but no significant.
visibility restrictions. High pressure ridge wl slide off to the
east this morning. Increasing south winds in the low levels behind
the ridge wl pull warmer air into the area today. Onshore breezes
wl keep eastern areas cooler, but south central WI likely to
climb into the 50s with 925H temps rising to around 3c, and no
snow cover.

Weak low level warm air and moisture advection sweeps across
southern WI tonight along with a passing mid-level late night short
wave.  Column precipitable water increases rapidly to around 1 inch
tonight ahead of approaching northern plains cold front. Enough
increase in warmth and moisture to create elevated instability of
100-500 j/kg (discounting warmer NAM).  Better synoptic scale lift
and layer q-vector convergence remains over southern CWA during the
night as low level jet passes by to the south of WI.  Hence wl
continue small chances for T across southern and southeast CWA
during the night.  Also introduced some fog late tonight as boundary
layer winds decrease as baggy front moves through the area.

LONG TERM...

MONDAY... Forecast confidence is medium.

A baggy pressure gradient over WI with the weak surface low pressure
trough should lead to lingering fog, low clouds, light showers and
drizzle through Monday morning. The cold front is expected to reach
southern WI Monday afternoon which will help scour out the moisture.

Right now, forecast highs Monday in the 50s are dependent upon some
clearing. If it looks like the clearing won`t happen then temps will
be lower. Cooler by the lake.

TUESDAY AND WEDNESDAY... Forecast confidence is high.

High pressure with dry weather will dominate these two days. High
temperatures in the 40s to upper 30s are expected, with lows in the
20s. Colder air will arrive Tue afternoon/evening on a dry cold
front with brisk north to northeast winds. Min temps Tue night are
expected in the lower 20s as the high moves overhead.

THURSDAY THROUGH SUNDAY... Forecast confidence is low.

Southerly winds with return flow around the high will usher moisture
back into southern WI by Thu evening. A weak shortwave could bring
light precip (snow) to northern WI late Wed night, but this should
miss southern WI or just give us flurries.

Warm frontal precip is expected to arrive late Thu afternoon or
evening. Despite significant differences between the models, they
all suggest that strong warm air advection should allow for this
precip to be in the form of rain. Went with non-diurnal temp trend.

The GFS shows a fast-moving system while the ECMWF has a deeper
500mb trough and a slower-moving system impacting southern WI Thu nt
through Saturday. The Canadian model is a sort of a compromise right
now.

Nonetheless, the weather pattern favors thunderstorms over much of
the Midwest ahead of this mid level trough over the Plains. Too
early and uncertain to discuss severe potential for southern WI.

It looks like temperatures will recover by later Sunday. There`s a
chance of rain Sunday night into Monday on the leading edge of the
next system.

AVIATION(09Z TAFS)...

Cloud forecast not as optimistic as earlier thought for this morning
in far east. Low clouds continue to reform over the western side of
Lake Michigan and graze the lakeshore counties.  Very low level
onshore flow is pulling some of these clouds inland and it looks
like this could continue through mid-morning.  Patchy low clouds
could very well hang in into the afternoon until better mixing
occurs.  Still anticipating scattered showers and isold t to affect
southern WI tonight.

MARINE...

Passing high pressure is resulting in light and variable winds this
morning.  Light onshore winds will continue to veer to the southeast
and begin to increase this afternoon and evening as pressure
gradient tightens.  Weak cold front moving through the northern
Plains toward the western Great Lakes will cause the increasing
winds later today.  Pressure gradient remains fairly loose and baggy
tonight as cold front moves into western WI so winds at the surface
are not expected to further strengthen and reach advisory criteria.
Cold front will move through southern Lake Michigan later on Monday
causing winds to veer back to the north. Expect showers and a
possible rumble of thunder later tonight into Monday ahead of the
advancing cold front.  Some patchy fog may also occur as the front
passes through the near shore waters on Monday.

&&

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

$$
Today/Tonight and Aviation/Marine...MBK
Monday THROUGH Saturday...Cronce



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