717
FXUS63 KGRB 171945
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
245 PM CDT Wed Jul 17 2024

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

 - Below normal temperatures are expected tonight, then
   temperatures return closer to normal for the weekend.

 - Mainly dry weather is expected through Saturday morning. The
   next chance of showers and storms is on Saturday afternoon,
   with a continuing chance of afternoon showers and storms into
   the middle of next week. The risk of severe weather is low over
   the weekend and uncertain next week.

&&

.DISCUSSION...
Issued at 245 PM CDT Wed Jul 17 2024

Short Term...Tonight and Thursday

Minimal impacts are expected through this forecast period, with the
main highlights being lingering isolated showers through early this
evening and below normal temperatures.

This evening and tonight...This afternoon`s water vapor imagery
highlighted a mid-level shortwave trough moving over southern
Ontario. The combination of this shortwave energy and low-level
north/northwest winds allowing moisture to flow off of Lake
Superior, resulted in lake-enhanced clouds and isolated
showers/sprinkles to develop and drop south over the area this
afternoon. An area of more scattered showers over the central U.P.
was also observed on radar this afternoon, in association with the
main shortwave energy. High pressure will gradually begin to move
into the area this evening and overnight and bring an end to all
showers and clouds. Until then, anticipate a few isolated showers to
drop south into far northeast and east-central WI through early this
evening. For the remainder of the night, the combination of the high
pressure system overhead, light winds, and clear skies, cooler
temperatures are expected with lows ranging from the low 40s to
middle 50s. These values are about 5 to 10 degrees below normal.

Thursday...The high pressure system will continue to prevail over
the area for Thursday, resulting in dry conditions under mostly
sunny skies. Anticipate afternoon cumulus clouds to develop as
forecast soundings would suggest. Warmer temperatures are expected
with highs ranging from the middle to upper 70s.

Long Term...Thursday Night Through Wednesday

500mb ridge across the western United States and downstream
troughing across the western Great Lakes will continue into the
middle of next week. Temperatures will be close to normal during
the period.

For Thursday night and Friday, high pressure south of the area
will continue to move away. Sunny skies will prevail on Friday
as high temperatures return to near normal levels. On Friday
night into Saturday morning, a cold front across southern Canada
will sink slowly southward. The front will work into northern
Wisconsin Saturday afternoon, bringing a chance of showers and
thunderstorms across the north. Bufkit soundings indicated 500 to
1,000 J/KG of CAPE with 0-6 km shear values only around 10 knots.
Some of the storms could contain gusty winds and locally heavy
rainfall, but severe weather is not expected. Did linger a chance
of showers and storms into the evening, mainly north of Highway
10.

Dry conditions will prevail late Saturday night into Sunday morning
with the next chance of showers and storms Sunday afternoon. Severe
weather is not expected. For Monday and Monday night, another weak
cold front will move into northern Wisconsin Monday afternoon,
bringing another chance of showers and storms. The models continue
to show instability showers and storms during the afternoon and
evening Tuesday and Wednesday. It is too early to determine if any
of the storms between Monday and Wednesday would become severe.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1232 PM CDT Wed Jul 17 2024

Low-end VFR to high-end MVFR cigs early this afternoon as a
widespread cumulus field has developed over the region. Expect cigs
to rise above 4kft at all TAF sites during this afternoon.
Northwesterly winds are gusting around 15-20kts early this afternoon
and will start to diminish this evening as winds back and become
more westerly. There is a low-end chance (15-20%)for a few showers
across far northeast and east-central WI this afternoon, however,
do not expect any lightning with these showers.

As a high pressure system sags over the region this evening clouds
will scattered out with skies becoming clear overnight and into
Thursday morning.

.OSH...A VFR cumulus field with a cloud base around 4kft has
developed over OSH late this morning. Broken cigs will become
scattered late this afternoon with cloud bases rising to around
6kft. There is a slight chance for a rain shower at OSH between 21-
00Z this afternoon, however, confidence is not high enough to
include in the TAF at this time. Northwesterly winds will pick up
with gusts reaching 15-20 kts during the afternoon before
diminishing this evening as winds back and become more westerly.
Skies should clear out this evening and overnight has a high pressure
system settles in over the region.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION.....Kruk/Eckberg
AVIATION.......GK