Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 231907
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
207 PM CDT Mon Apr 23 2018

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Tuesday
Issued at 206 PM CDT Mon Apr 23 2018

The latest RAP analysis and satellite/radar imagery show a ridge
of high pressure extending east from New England and into the
northern Mississippi Valley early this afternoon. A cold front
remains largely inactive across eastern North Dakota, while a
larger low pressure system is spinning over the central
Mississippi Valley. The far northern edge of the cirrus associated
with this southern system continues to reach northeast WI.
However, any deeper moisture remains north and south of the
region. With a dry airmass in place, forecast concerns revolve
around clouds and temps tonight, and small precip chances on
Tuesday afternoon as the front from the north moves into the
region.

Tonight...Low pressure will continue to spin over the southern
Ohio Valley, while the surface ridge axis will weaken over
northern WI. As minor height falls occur aloft, will see mid and
high clouds push in from the south and across northeast WI. Low
levels will remain dry though, so no threat of precip. Temps will
continue their slow warming trend and will go with a range from
the low 30s over the north to the upper 30s over the southern Fox
Valley.

Tuesday...Will continue to see some high clouds along the Lake
Michigan shoreline during the morning, but those clouds should
depart by midday. Then attention turns to the west where a digging
shortwave trough will push a weak cold front across the northern
and central parts of the state during the afternoon. The shortwave
itself appears relatively robust and will bring a moderate amount
of upper support. However, moisture as well as low level
convergence are lacking, so coverage of showers appears isolated
to scattered at best. Will keep a small chance of showers from the
Fox Valley to north-central WI for the afternoon. Otherwise,
clouds will be on the increase during the afternoon with highs
ranging from the low to mid 60s in the east to the low to mid 50s
over Vilas county.

.LONG TERM...Tuesday Night Through Monday
Issued at 206 PM CDT Mon Apr 23 2018

The effects of the cold front, arriving late Tuesday afternoon,
will linger into the start of the long term for Tuesday night.
Kept slight chance pops for Tuesday night due to possible post-
frontal rain. This shortwave trough/cold front will exit the
region by early Wednesday morning. In addition, cooler air will
funnel in behind this front, causing Wednesday high temperatures
to rise slightly below normal with even cooler temperatures along
the lakeshore.

The next shortwave trough/cold front will move into the region
Thursday afternoon. Model guidance is in better agreement with
timing and the evolution of this system compared to yesterday.
However, the GFS and Canadian present more mid-level
frontogenetic forcing allowing for more lift and precipitation to
occur. The forecast timeframe for precipitation would be Thursday
evening and Thursday night. The precipitation would start as rain
then transition to a mix or all snow before ending Friday
morning.

Then quiet weather returns for next weekend. Temps return above
normal by Sunday.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1048 AM CDT Mon Apr 23 2018

Ridge of high pressure extending over the Great Lakes region will
continue to produce VFR conditions and light winds through the
period. A weak cold front will approach the area on Tuesday
afternoon. A slight chance of showers will be possible along it
after the taf period. Otherwise, clouds will generally be on the
increase tomorrow with cigs lowering.
&&

.HYDROLOGY...
Issued at 206 PM CDT Mon Apr 23 2018

River levels continue to rise from the snow melt runoff. A few
rivers have already reached minor flood stage as of this afternoon,
with many others forecast to reach or exceed bankfull this week.
There are a few chances of rain this week, Tuesday afternoon and
then again toward Thursday afternoon and Thursday night. Both
systems are not expected to generated much rainfall, so runoff
will occur from the warmer temperatures chipping away at the
snowpack. The upcoming weekend looks dry as well.

&&

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

$$

SHORT TERM.....MPC
LONG TERM......Hykin
AVIATION.......MPC
HYDROLOGY......Hykin


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