Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 181053 CCA
AFDMKX

Area Forecast Discussion...Corrected Climate section.
National Weather Service Milwaukee/Sullivan WI
228 AM CST Sat Feb 18 2017

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

A weak cold front moves southeast through the area this morning,
with weak cold air advection behind it. However the degree of
cooling looks overdone and would prefer to lean more towards the
ECMWF/NAM thermal pattern. MOS temps suggest we are back into the
mid 50s to near 60.

This means record highs of 57 degrees at Milwaukee and Madison
are again in jeopardy, especially since any lake breeze would cool
Milwaukee late.

.SUNDAY...Forecast confidence is high.

Mid-level heights will rise locally, as ridging amplifies poleward
from the eastern Gulf of Mexico into the western Great Lakes. This
amplification will occur in response to upstream troughing digging
into the Great Plains. Rockies lee cyclogeneis will commence over
northeast Colorado, with the broad surface low tracking into the
northern High Plains. Southeasterly flow will develop during the
morning and persist into evening as a warm front attendant to the
surface low lifts northeast through southern Wisconsin. Mid to high
clouds will increase during the day in association with the warm
front. We may near or exceed record highs once again in some
locations, as highs climb into the 50s to lower 60s. The Lakeshore
areas may struggle to break 50 however, given the persistent onshore
flow.

.MONDAY AND TUESDAY...Forecast confidence is medium.

A sharpening upper trough will progress from the Great Plains into
the Great Lakes and Ohio Valley. An elongated surface low attendant
to the upper wave will lift northeast from the Dakotas into
Manitoba. The associated cold front will cross southern Wisconsin
Monday night into early Tuesday, with deep layer moisture increasing
Monday afternoon. The best rain chances are associated with
frontogenetical forcing, and model spread suggests late Monday
afternoon into early Tuesday morning as the most likely time for
precipitation. The faster GFS and Global Canadian solutions would
end the precipitation late Monday night, while the less
progressive ECMWF solution would keep rain chances into Tuesday
morning. The most recent model runs are coming in a bit wetter,
and precipitation should average 0.2 to 0.6 inches, with the
greatest amounts expected in our northwest. There is a very small
amount of elevated CAPE on area forecast soundings, and added a
collaborative slight chance for thunder in our far south and
southeast. Only expecting a rumble or two at best however.
Temperatures will remain mild, with highs well above seasonal
averages. The Lakeshore communities will once again be cooler on
Monday with southeasterly low-level flow ahead of the cold front.

.WEDNESDAY AND THURSDAY...Forecast confidence is medium.

Look for zonal flow aloft on Wednesday, with a compact shortwave
trough sliding east from northern Minnesota into southern Ontario.
This wave will escort a weak surface low as it tracks along the
International Border, but precipitation with this system should
remain north of our area. Mild temperatures are expected during the
day, with cooling overnight as a cold front swings through.

The upper flow pattern transitions to southwesterly by Thursday in
response to troughing digging aggressively from the northern High
Plains into the Four Corners region. Mid to upper moisture should
increase Thursday afternoon, with top down saturation occurring by
late evening. The surface reflection of the upper wave will be
strong cyclogenesis along the Rockies Front Range. A surface warm
front associated with the surface low should be near the
Wisconsin/Illinois border by evening, with most models holding off
on any precipitation until Thursday night. Temperatures will be a
bit cooler, but should remain well above seasonal averages.

.THURSDAY NIGHT THROUGH SATURDAY...Forecast confidence is medium.

Shortwave energy will carve out a closed cyclonic circulation over
the central Great Plains on Thursday evening, with the upper
low/vorticity maximum ejecting northeast through the western Great
Lakes into Friday and Saturday. A rather expansive surface low will
accompany the wave. Forecast models are in good agreement in rapidly
deepening the incipient cyclone to around 980 to 985 mb as it tracks
from the central Great Plains towards Wisconsin on Friday. The
consensus model track would place southern Wisconsin within the warm
sector for this system, with mild temperatures and mainly rain
expected. The rain chances appear to start Thursday night, and would
continue into Friday or perhaps early Saturday. With plentiful deep
layer shear and several hundred Joules of MUCAPE, thunder is
possible with this system. However, given model variability and the
fact that we`re still several days away, things could change. Cold
air wrapping in behind the low should bring our temperatures closer
to seasonal averages for Saturday.

&&

.AVIATION/12Z TAFS/...

Main issue will be low level wind shear early this morning, but
winds at 2 thsd ft will decrease around sunrise.  West to northwest
winds are expected today into tonight, but a lake breeze may develop
far east this afternoon as high pressure moves in decreasing the
winds.

A few areas of MVFR vsbys around sunrise, otherwise VFR conditions
are expected. Mostly clear skies are expected before some high
clouds move into the area from the northwest tonight.

&&

.MARINE...

Winds and waves are expected to remain below Small Craft Advisory
levels through this weekend. West to northwest winds may gust to
around 20 knots this morning. High pressure moves into the area this
afternoon and lingers Saturday night, increasing the lake breeze
potential.

Winds and waves may reach Small Craft Advisory levels Monday into
Monday night, as a tight pressure gradient develops with the next
low pressure system moving through the region.

&&

.CLIMATE...

Corrected Madison record high for the 21st.

Record highs for Milwaukee and Madison are as follows...

LOCATION        SAT/18TH    SUN/19TH    MON/20TH    TUE/21ST
Milwaukee       57 (1877)   59 (1981)   60 (1930)   58 (1930)
Madison         57 (1981)   60 (1981)   57 (1930)   60 (1930)

The average highs during this period are 34 at Milwaukee, and 33
at Madison.

&&

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

$$

TODAY/TONIGHT AND AVIATION/MARINE...Hentz
Sunday THROUGH Friday...SPM


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