Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 200843

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
243 AM CST Tue Feb 20 2018


Today and Tonight...Forecast Confidence is Medium...

The biggest challenge continues to be in the expected surface
temps in the region hovering near or just below freezing northwest
of Milwaukee and Madison. Then the total precipitation amounts
across the area.

Decided on using the Adjusted MET temps from the NAM MOS. This
looks better than the blend, which appears to be too warm.

The focus for the heaviest rainfall remains across the far
southeast, south into Illinois. Additional We`re still looking at
totals in the 1/2 to 3/4 inch range over the far southeast tip.

Additionally, a few thunderstorms may early Morning far southeast.

Dense fog will be a problem for southern WI mainly early morning,
and have expanded the dense fog advisory north one more tier of
counties due to light winds, very moist conditions and an
existing snowpack.

There will likely be one more surge of rainfall today, due to
upward motion from the entrance region of the strong upper jet.
How far north this precipitation gets will dictate whether we see
another round of freezing drizzle and freezing rain in the winter
weather advisory area. This along with slowly rising daytime
temperatures continues the dance of any significant impacts.

We finally see a diminishing trend from west to east this evening
with most areas drying out during the evening on Tuesday, except
far southeast.

Any lingering precipitation is expected to wind down Tonight
from northwest to southeast across the area. There is some
potential for light freezing rain or drizzle to occur during this
time, as drier air mixes out ice crystals. However, upward
vertical motion will be weakening, so not sure if this will even
materialize. Cold air advection is expected across the area


Wednesday through Friday... Forecast confidence is Medium.

After a quiet and cool day with diminishing northwest winds and
clearing skies, southern WI will get set up for our next round of
mixed precip. 850mb warm air advection, vorticity advection, and
upper divergence with the right entrance region of the upper jet
will contribute to precip arriving by Thursday evening. Precip
type will be our challenge once again. Freezing rain is very
possible given warm 850mb temps and our surface temps below
freezing, although differences between models suggest that there
may be enough saturation into the snow growth region to keep the
snow in the forecast as well. Precip will taper off Friday while
temperatures warm above freezing. Ice accumulation could be
around a tenth of an inch.

Saturday through Tuesday... Forecast confidence is Medium.

Yet another system is expected to bring a mixed bag of precip to
southern WI Saturday into Sunday morning. At this time it seems
like a lower chance for freezing rain and a lot of our area should
see rain rather than snow.

Monday could bring another chance for light rain or snow.
Temperatures will remain quite mild through this period.



Conditions should generally be IFR or LIFR early this morning, as
additional rain moves into the region. Low ceilings and fog will
also continue at the terminals. Some brief breaks from the fog
will be possible at Kenosha, but this is not expected to last, as
additional moisture lifts north.

Marginal improvements are expected Tuesday, though IFR will likely
persist for most of the day. Conditions should improve from the
west this evening, as a cold front sweeps across the area.

While no freezing or frozen precipitation is currently forecast
for the TAF sites, light freezing rain and/or freezing drizzle is
expected this morning north of a line from north of Lone Rock to
Fond du Lac to Sheboygan.



Small Craft Advisory remains in effect for north of Port
Washington until 6 AM. Further south, fog will reduce visibility
to less than 1 mile at times, and a marine Dense Fog Advisory is
in effect, until noon.


WI...Flood Watch through this afternoon for WIZ064>066-068>072.

     Dense Fog Advisory until 8 AM CST this morning for WIZ056>060-

     Winter Weather Advisory until 3 PM CST this afternoon for WIZ046-

LM...Dense Fog Advisory until 8 AM CST this morning for LMZ644>646.

     Small Craft Advisory until 6 AM CST early this morning for



Today/Tonight and Aviation/Marine...Hentz
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