Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 252259
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
559 PM CDT Sat Mar 25 2017

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Sunday
Issued at 225 PM CDT Sat Mar 25 2017

The latest RAP analysis and satellite/radar imagery show an area of
low pressure spinning along the Kansas/Missouri border, and an
associated warm front extending eastward across central Illinois to
northern Pennsylvania early this afternoon.  Band of light rain
north of this boundary has been creeping northward across southern
Wisconsin, and should reach the southern Fox Valley later this
afternoon. Meanwhile, a potent Canadian high pressure system has
been feeding dry air into northern WI, which has kept temperatures
in the 30s. Though partial clearing has pushed its way into northern
Lake Michigan, widespread overcast conditions continue.  As the low
pressure drifts northeast over the next 24 hours, precip trends and
potential for freezing rain across northern WI are the main forecast
concerns.

Tonight...Occluded low pressure will slowly chug its way northeast
across the central Mississippi Valley while a strong Canadian high
will exit over Quebec.  The waning influence of the high will allow
for increasing moisture transport from north to south across the
state during the evening, highest over eastern WI within the warm
conveyor belt.  Ample dry air in the mid-levels will keep the precip
at bay across the north until late in the evening or early
overnight, but the most persistent precip will occur over eastern
WI.  Despite the late arrival of the precip, the threat of freezing
rain remains over north-central WI.  Dewpoints didnt fall off much
this afternoon, so temps should not fall much due to evaporative
cooling.  However, even with min temps in the 30-32 degree range,
not comfortable going without a freezing rain advisory tonight
across the north with precip amounts upwards of a tenth of an inch.
With coordination from MQT will hoist an advisory from late this
evening until 9 am Sunday morning.

Sunday...The low pressure system will continue to drift closer to
the region into the southern Great Lakes.  Though the main slug of
moisture shifts towards the lower peninsula of Michigan during the
day, progged soundings continue to look saturated at most locations
during the morning, which should be good for occasional light rain
and drizzle.  The chance of precip should diminish some during the
afternoon from west to east as the deepest saturation exits to the
east.  With the widespread clouds, rain, and northeast to north
winds, temps should only rise into the upper 30s to middle 40s.

.LONG TERM...Sunday Night Through Saturday
Issued at 225 PM CDT Sat Mar 25 2017

As the current low pressure system delivering precipitation to
Northeast Wisconsin moves northeast through the Great Lakes and
out of the region, another low will sweep by to our south. This
second low will move east into the Ohio Valley during the first
half of the work week and is not expected to deliver much, if any,
precipitation to Northeast Wisconsin. Some cloudiness is possible,
but skies should become mostly clear for the latter half of
Tuesday and most of the day Wednesday.

The next low pressure system to impact Northeast Wisconsin will
develop over the Southwest U.S. on Wednesday and move into the
Midwest by Friday. This system has potential to deliver heavy rain
to our area at times into next weekend as it phases north. The low
will not be particularly effective at tapping cold Canadian air,
so precipitation should remain liquid for the most part. Any
freezing rain should be limited to Northern counties during
nighttime hours when coldest temperatures occur, producing
scattered slippery spots.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 559 PM CDT Sat Mar 25 2017

Ceilings and visibilities will continue to lower as rain shifts
back north over the area. Some surface icing possible over far
northern WI, including RHI, late tonight. IFR conditions will
continue through the afternoon Sunday.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 11 PM this evening to 9 AM CDT
Sunday for WIZ005-010>012.
&&

$$

SHORT TERM.....MPC
LONG TERM......ML
AVIATION.......JKL


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