Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 181135
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
635 AM CDT Tue Apr 18 2017

.AVIATION(12Z TAFS)...

VFR conditions are expected through today. Look for southeast
winds to increase quickly this morning, reaching gusts to 25 to 30
knots by early afternoon, especially away from Lake Michigan. The
winds will gradually veer to the south during the afternoon and
diminish in speed this evening. Low pressure tracking across
northern Wisconsin this afternoon will drag a cold front into
southern Wisconsin this evening. The front should reach KMSN by
around 03-04z and KMKE about 07-09z Wed. A chance of showers will
accompany the front. CIGS will likely drop to MVFR levels in the
wake of the front.

&&

.PREV DISCUSSION... (Issued 317 AM CDT Tue Apr 18 2017)

SHORT TERM...

TODAY AND TONIGHT...Forecast confidence is high.

High pressure pushes off to the east today, while a fast moving low
pressure system takes a track across northern Wisconsin this
afternoon.  A cold front trailing southwest from the low will drop
into our western forecast area this evening, reaching the WI/IL
border by 12z Wednesday.  We should see some showers along and ahead
of the front as it moves through and there is just enough CAPE on
the soundings to support an isolated rumble of thunder.  The first
showers could be moving into our far northwest by mid afternoon, not
getting to Milwaukee until this evening.  Winds will be southeast
this morning, veering south by early afternoon and becoming quite
gusty, in the 30-35mph range.  The southeast winds will make it feel
very chilly by the lake (and farther inland) this morning, but as
winds turn more southerly, that cooling effect will be limited to
areas right along the shore this afternoon. Those southeast winds
will also bring in some pretty dry air, something the advancing
showers will have to overcome initially.

LONG TERM...

Wednesday through Thursday... Forecast confidence is medium.

Models show the surface front (northerly winds) sliding into
northern IL on Wednesday morning. The cold lake will help to
accelerate it, so expect winds to turn northeast near the lake
during the mid morning hours, then farther inland by early
afternoon. High temperatures will occur early in the day, then
fall through the afternoon as brisk, cool east winds and rain take
over.

The entrance region of the upper jet, nose of the low level jet,
and a 500mb shortwave trough will slide into northeast Iowa and
southern WI Wed afternoon along a tight 850mb baroclinic zone.
This forcing should bring a round of showers and isolated,
elevated thunderstorms to the area from late Wednesday afternoon
through Thursday morning. There is a good amount of moisture with
this slow- moving system, although the models trended a lot
farther north with the qpf axis from yesterday. Highest rainfall
amounts should be over central WI with over an inch of rain.
Southeast WI should receive the least amount with around a half
inch.

Rain chances linger in areas toward central WI through Thu due to
the slower upper trough. Clouds and brisk northwest winds will
keep temperatures very cool, with highs only in the upper 40s to
mid 50s.

Friday through Sunday... Forecast confidence is high.

Drier air will drop into southern WI in the wake of this system
on Friday. Temperatures will remain cool due to northeasterly
winds.

A large upper low tracking across the south half of the country
will bring rain chances to northern IL, so the system is now
expected to remain to our south. Easterly winds and mostly cloudy
skies will keep temperatures cool in the 50s through Saturday.
Highs on Sunday should creep into the lower 60s well inland from
the lake.

Monday and beyond... Forecast confidence is low.

The GFS and ECMWF handle an upper trough over the northern Plains
a lot differently for early next week, so precip chances and
temperatures for southern WI are uncertain.

AVIATION(06Z TAFS)...

Cirrus clouds triggered by increasing upstream warm air advection
continue to spill eastward across Minnesota into Wisconsin.
Expect these clouds to continue affecting southern WI through the
late night. VFR conditions expected for the bulk of the forecast
period, however some lower cigs may approach MVFR levels with any
showers that develop Tuesday evening. Continues to look breezy on
Tuesday, especially farther away from Lake Michigan. Inland gusts
may reach 30 to 35 knots.

MARINE...

A tight pressure gradient between exiting high pressure and low
pressure tracking across northern Wisconsin this afternoon will
bring a rather short period of elevated winds today into this
evening. The strongest winds and largest waves will be found up
toward Sheboygan. A small craft advisory has been issued for today
into this evening.

FIRE WEATHER...

Southeast winds and deep mixing will bring lower dewpoints for
this morning through about early afternoon. Winds turning
southerly thereafter will result in increasing dewpoints during
the afternoon. In general, min RH`s will be in the 30 to 40
percent range, but it wouldn`t be surprising to see a few spots
drop into the upper 20s percents before rising this afternoon.
With strong winds and mild temps expected today, this will bring
concern for increased fire danger.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory from noon today to 7 PM CDT this evening
     for LMZ645-646.

     Small Craft Advisory from 10 AM this morning to 10 PM CDT this
     evening for LMZ643-644.

&&

$$

Update...Davis
Today/Tonight and Aviation/Marine...Davis
Wednesday THROUGH Monday...Cronce



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