Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 210451 AAC
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1151 PM CDT Thu Apr 20 2017

.UPDATE...


&&

.AVIATION(06Z TAFS)...

A few light rain showers or drizzle may clip northern portions of
the area for the next few hours. Otherwise, ceilings should
gradually lower to around 1500 to 2000 feet above ground level by
09Z Friday, with lower ceilings moving southward into the area.
These should linger into Friday morning, before rising and mixing
out by afternoon.

Gusty west northwest winds should linger overnight, before slowly
weakening and becoming north to northeast. Some gusts to 15 knots
are possible in the afternoon.

Wood

&&

.PREV DISCUSSION... (Issued 900 PM CDT Thu Apr 20 2017)

UPDATE...

A few light showers may slide into northern portions of the area
this evening, as 500 mb shortwave trough moves through the region.
Otherwise, area of low clouds should generally continue to linger
into the overnight hours and Friday morning. There are breaks in
the low clouds in western Wisconsin, and they may slide
southeastward into western portions of the forecast area later
tonight and Friday morning.

Gusty west winds should gradually weaken overnight into Friday
morning, as they shift to the northwest. Lows may need to be
reduced a bit in areas that see some clearing later tonight.

Wood

MARINE...

Small Craft Advisory continues until 15Z Friday across the
nearshore waters of Lake Michigan. Gusty west winds will veer to
the northwest later tonight into Friday morning. Frequent gusts up
to 25 knots are expected during this time.

High pressure building into the region Friday will bring weakening
winds, which will veer to the northeast Friday afternoon. High
waves will remain over the open waters of Lake Michigan.

Wood

PREV DISCUSSION... (Issued 706 PM CDT Thu Apr 20 2017)

UPDATE...

AVIATION(00Z TAFS)...

A few light rain showers may clip northern portions of the area
early this evening. Ceilings may vary between 2500 and 3500 feet
above ground level, with gusty west northwest winds, into the
middle evening hours.

The ceilings should then become around 2500 feet later this
evening, dropping to 1500 to 2000 feet later tonight into early
Friday morning. Winds should weaken during this period, with some
gusts lingering near Lake Michigan.

Ceilings should mix out by midday Friday, with mostly clear skies
by early Friday evening. Winds will veer north to northeast
Friday, with some gusts to 15 knots in the afternoon.

PREV DISCUSSION... (Issued 326 PM CDT Thu Apr 20 2017)

SHORT TERM...

TONIGHT AND FRIDAY...Forecast confidence is high.

Low pressure will continue to push out of the region. The cold
front associated with the low pushed through the CWA this afternoon,
and we are firmly entrenched in CAA. There is an expansive area of
clouds well upstream on the backside of the low, stretching across
all of WI and into much of MN.

Models are generally doing a good job depicting the ample low level
moisture upstream. Model consensus shows clouds lingering through
the night before gradually clearing tomorrow as the low pushes
completely out of the region. Winds will veer from the west to the
north as high pressure builds in behind the low, leaving us firmly
within CAA through most of the period. The cloudy skies overnight
and clearing afternoon skies should balance out the CAA, leaving us
with near normal temperatures.

LONG TERM...

Friday night through Monday...Forecast confidence is high:

High pressure will be in place for the weekend into early next
week, bringing plenty of sunshine and mainly above normal
temperatures. It will be cooler near Lake Michigan through this
period due to onshore winds.

Monday night through Thursday...Forecast confidence is medium:

The pattern is expected to become active again Monday night
through mid week as multiple low pressure systems move through the
region. Models are in decent agreement in targeting Monday night,
Tuesday night, and Thursday/Thursday night as the best chance for
showers. There is some variability among models though, so these
rain periods are not set in stone. Could see little thunder by
midweek, depending on how far north the systems go.

A blend of model solutions suggest temperatures within a few
degrees of normal through this period, though there is the
potential for warmer temps Tue based on the ECMWF and Canadian
solutions. Also, the ECMWF and GFS suggest below normal temps Thu,
though the Canadian is milder. Needless to say, there is some
uncertainty with temperatures next week.

AVIATION(18Z TAFS)...

Low pressure will continue to push off to the east, but ample low
clouds associated with the low remain well upstream of southern WI.
Models in good agreement showing the low clouds lingering at least
through the night, though there are some differences regarding
just how quickly clouds clear out Friday morning. Most guidance
keeps cigs at all TAF sites just above 2kft through the night.
That said, IFR cigs will be just to the north. At this time, I do
not expect IFR cigs to reach as far south as the TAF sites, but
given the proximity of potential IFR cigs, will have to keep an
eye on cigs through the night.

The center of the low has moved out of the area, so winds have
picked up. While gusts will fall off overnight, the pressure
gradient will remain tight, resulting in sustained winds around 10
kts through the night.

MARINE...

Low pressure will continue to push to the east, setting up a tight
pressure gradient and strong offshore winds across southern
Wisconsin. The strong winds look to linger a bit longer than
previously anticipated, so the SCA has been extended until 15z
Friday.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory until 10 AM CDT Friday for LMZ643>646.

&&

$$

Update...Wood
Tonight/Friday and Aviation/Marine...BSH
Friday Night through Thursday...DDV



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