Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 190349
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1049 PM CDT Thu Apr 18 2019

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Friday
Issued at 203 PM CDT Thu Apr 18 2019

The latest analysis and satellite/radar imagery show low pressure
exiting the region north of Lake Huron, while upper troughing is
moving overhead. Within the sharp cyclonic flow, widespread low
clouds are resulting in overcast conditions and some drizzle,
particularly over the northwoods, where 850-700 mb dewpoint
depressions are the lowest. Looking upstream, cloudy skies are
prevailing to the arrowhead of Minnesota, but clearing is
occurring with a much drier airmass over eastern North Dakota and
northwest Minnesota. Forecast concerns generally revolve around
spotty shower and drizzle chances into the evening, before
attention turns to temps and low humidities for Friday.

Tonight...The sharp upper troughing and ribbon of deeper moisture
thins out this evening as a surface ridge axis builds towards the
area from the northwest. Patchy drizzle and spotty showers will be
possible until mid to late evening as this occurs, with the
highest chances over far northern WI. Then clearing is expected
to move from northwest to southeast from late evening through the
overnight. The pressure gradient will remain rather tight tonight,
so winds are expected to hold up temps somewhat. So lows are only
expected to fall to near 30 degrees over the north to the upper
30s over east-central WI.

Friday...Any lingering low clouds are expected to depart east-
central WI early in the morning. Then high pressure will bring
mostly clear skies for the rest of the day. The pressure gradient
will gradually slacken through the day so think winds will
diminish somewhat in the afternoon after a gusty start to the
day. Remained close to the previous forecast for high temps,
though there is some potential for temps to over-perform given the
model projected 925 mb temps. Highs mainly in the upper 50s to
the low 60s away from the lake.

.LONG TERM...Friday Night Through Thursday
Issued at 203 PM CDT Thu Apr 18 2019

Dry weather is expected for the first part of the weekend as a
ridge of high pressure tracks through the western Great Lakes
region with temperatures warming into the 60s away from the lakes.
The forecast becomes a bit more uncertain later in the weekend and
into early next week as a low pressure system tracks through the
region. There are significant differences in the models regarding
this system regarding amounts and placement of the rainfall,
therefore will not deviate much from the SuperBlend output for
this run.

After a brief dry period Monday night into Tuesday, the weather
looks to become unsettled again Wednesday and Thursday as another
low pressure system takes aim for the area. Out this far the
models are even worse as the GFS develops a significant low over
the western Great Lakes with abundant rainfall while the ECMWF is
completely dry with a high pressure overhead. The Canadian model
is somewhere in between, developing a low but not as far north
and with less QPF than the GFS model. Again given the model
differences will not deviate much from the Blend.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1048 PM CDT Thu Apr 18 2019

Low clouds will clear from the northwest. That process has begun,
but strengthening flow off Lake Superior will delay it in the
east. Anticipate VFR conditions across the area by morning,
continuing into Friday.
&&

.HYDROLOGY...
Issued at 203 PM CDT Thu Apr 18 2019

Many area rivers and streams will be on the rise and
cresting over the next 24 to 48 hours, as a result of the heavy
rain yesterday, and ongoing snow melt over the northwoods. Several
rivers in the Wisconsin, Menominee, and Wolf river basins are
forecast to remain above flood stage through the weekend, with
some remaining in flood stage next week. The Wisconsin River will
see some of the most dramatic rises, with the river near
Rothschild forecast to reach major flood stage later today or
tonight. Boaters and fishermen should exercise caution, as the
high water levels may create fast flows on some rivers into the
weekend. The next chance of rain will arrive on Sunday. However
there remains quite a bit of uncertainly on timing and amounts.
Any additional rain will aggravate the flooding situation.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....MPC
LONG TERM......Kurimski
AVIATION.......Skowronski
HYDROLOGY......MPC


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