599
FXUS63 KGRB 150337
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1037 PM CDT Sat Sep 14 2024

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- There is 20% chance of showers or thunderstorms in central and
  north-central WI Sunday. Severe weather is not expected.

- Summer-like temperatures are expected through next week with
  highs ranging from the upper 70s to middle 80s.

&&

.DISCUSSION...
Issued at 302 PM CDT Sat Sep 14 2024

Short Term...Tonight and Sunday

Focus in the short-term is on small precip chances and
temperatures. Radar imagery at 1930Z showed a broken light of very
weak returns stretching from southwest into north-central WI.
Some light rain may be reaching the ground in spots, but suspect
this is isolated due to the high cloud bases and lack of any rain
at ob sites.

This precip is being generated by a weak piece of energy which
broke off from the remnants of Francine and tracked north, along
with a very weak upper jet and RRQ placement. As this energy
continues to track north this evening kept low end (15-20%) PoPs
in central and north-central Wisconsin through the afternoon and
overnight. Cannot rule out isolated thunder within any shower due
to MUCAPE ~200-600 J/kg in this region, but confidence in any
thunder is decreasing as there has yet to be any detected.

Precip changes on Sunday are even lower, but with MUCAPE as high
as 1000 J/kg across northern WI, kept low-end precip and thunder
chances here through Sunday afternoon. Otherwise, cloud cover will
be widespread to start the day, with some thinning throughout the
afternoon.

Temperatures at 1930Z were in the upper 70s and low 80s, a degree
or two cooler than forecast in some spots, but overall guidance
had a low mean error. Given there will not be a significant
airmass change, will stick close to the best performing guidance
for temperatures going forward, which yields lows tonight around
60 degrees, and highs Sunday in the low to mid-80s, a few degrees
cooler near Lake Michigan.

Long Term...Sunday Night Through Saturday

Generally dry weather and well above normal temperatures are
expected across the western Great Lakes region through the
upcoming week. An upper level ridge across the Great Lakes will
keep low pressure systems approaching from the west mainly stalled
across the upper Mississippi Valley during the early part of the
week and keep our area dry. Meanwhile, an interesting upper level
pattern appears to be developing across the region during the
middle to late part of the week. A trough of low pressure was
already in place well to the west; however, a developing low
pressure system off the Carolinas will retrograde westward and
deepen as it settles in across the middle Atlantic states. This
will set up an Omega pattern across the CONUS with the western
Great Lakes firmly in the ridging portion of this pattern to end
the week. There are signs this pattern could push off to the east
next weekend, which would allow the trough to the west to approach
the western Great Lakes and bring rain to the area. That being
said, this far out it is difficult to determine when Omega
patterns break down or slide off to the east so precipitation next
weekend isn`t a given by any means. Regardless of what happens
with the pattern it looks like the region is in for continued well
above normal temperatures into next weekend.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1036 PM CDT Sat Sep 14 2024

Middle and high clouds will cover most of the area west of a IMT
to STE line overnight. There could be a few light rain showers
west of MDZ to EGV. Skies will be mostly clear across eastern
Wisconsin, which may permit the formation of ground fog just
inland from the bay and Lake Michigan. MTW, SUE, OCQ and MNM are
airports that could see the fog. It will probably not reach GRB
but not certain. Any fog should dissipate by 13z Sunday.

VFR conditions are expected Sunday, with middle and high clouds
across central and north central Wisconsin and mostly clear skies
across the east. Isolated showers or thunderstorms are possible
west of a IMT to ISW line.

&&

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

&&

$$

DISCUSSION.....KLJ/Kurimski
AVIATION.......RDM