235
FXUS63 KGRB 172313
AFDGRB

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

Updated aviation portion for 00Z TAF 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 00Z TAF Issuance
Issued at 613 PM CDT Wed Jul 17 2024

A widespread VFR cumulus field, with bases of 4-6k ft, will
dissipate with the loss of daytime heating. N-NW surface winds
gusting to 15-20 knots will also diminish early this evening.
There is a low-end chance (15-20%) for showers early this
evening, mainly across far eastern Wisconsin and mainly affecting
the MTW TAF site. Lightning is not expected with this activity.

As a high pressure system sags over the region this evening
clouds will scattered out with skies becoming clear overnight and
into Thursday morning. Another cumulus field is expected to
develop Thursday afternoon, with bases of 4-6k ft, but with less
coverage at FEW-SCT.

.OSH...A broken VFR cumulus field, with a cloud base around 6kft,
will become scattered early this evening. Any showers should stay
well east of OSH this evening. Northwesterly winds with gusts
reaching 15-20 kts will diminish 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.
Another VFR cumulus cloud field is expected to develop Thursday
afternoon, with cloud bases around 5kft and scattered in coverage.

&&

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

&&

$$

DISCUSSION.....Kruk/Eckberg
AVIATION.......Kurimski