989
FXUS63 KGRB 151148
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
648 AM CDT Sun Sep 15 2024

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Isolated showers and a few storms will continue in central and
  north-central WI through early this afternoon. Severe weather is
  not expected.

- Dry weather and summer-like temperatures are expected this week.
  Highs will range from the upper 70s to middle 80s. The next
  chance of rain will not arrive until late this week or next
  weekend.

&&

.DISCUSSION...
Issued at 359 AM CDT Sun Sep 15 2024

Short Term...Today...Tonight...and Monday

Minor precip chances and above normal temperatures are the main
focus from this forecast period. Lingering moisture from the
remnants of Francine was producing isolated showers over portions of
central and north-central WI this morning. Meanwhile, patchy ground
fog was being reported across portions of far eastern WI, where
winds were calm and little cloud cover prevailed. This fog will burn
off soon after sunrise.

Today...Anticipate the isolated showers to continue in central and
north-central WI for the remainder of the morning, and possibly into
the early afternoon, until dry air from high pressure to the east
retrogrades into the area this afternoon. Cannot rule out a few
rumbles of thunder before the precip ends, with MLCAPE of 400-700
J/kg in the area. By the afternoon, clouds will be on the decrease
across the region due to the dry air. The prevailing warmer airmass,
in addition to the extra sunshine this afternoon, will result in
warmer temperatures over the area compared to Saturday, with highs
ranging from the low to mid 80s.

Tonight and Monday...The dry air from the high pressure system to
the east will keep dry conditions in place overnight under mostly
clear skies with lows ranging from the mid 50s to low 60s. Dry
conditions are also anticipated for Monday. The only exception may
be across far north-central WI, where some guidance is indicating
isolated diurnal, pop-up showers and storms developing during the
afternoon. Decided to add a low chance (15%) PoP during this time,
but confidence is still quite low in this occurrence due to the
amount of dry air in the area. Another day of above normal temps is
expected on Monday with highs mainly in the mid 80s.

Long Term...Monday Night Through Saturday

The main themes of the long term are seasonably warm and dry.
Pattern is amplified, yet changeable, through the week. The rex
block that has impacted our region this weekend gives way as
organizing low off the southeast coast, which could become
tropical in nature, eventually shifts across the southeast this
week while heights build again from the plains to the Great Lakes.
Meanwhile deep troughing will reload multiple times over western
North America, but will make little progress farther east.
Eventually by late this week the pattern transitions to more of a
omega block with troughing out west, sharp ridging from the
southern plains to the western Great Lakes and the remnants of
the southeast low easing across the Appalachians toward the mid
Atlantic.

All that said, the net result for sensible weather over northeast
WI is similar to what we have had for the last week, warm and
mainly dry. The next chance for some rain does not arrive until
late this week. Though looking at trends in models and ensembles,
it probably won`t reach our area until next weekend. Temps will
be seasonably warm, though not hot, as highs persist in the lower
to perhaps mid 80s (70s lakeside) while lows drop mainly into the
50s. After the more humid weather this weekend due to the plume
of moisture from the remnants of Francine, most of the coming week
will be characterized by more comfortable humidity as dewpoints
will be centered in the 50s with even some upper 40s over the
north as high pressure over the northeast extends sfc ridging
westward across the Great Lakes.

Hazardous weather looks minimal with no real chance of thunderstorms
until next weekend and light winds on the waters. Does look like
many nights will continue to feature shallow ground fog which will
lead to localized reduced visibility in the pre-dawn hours.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 648 AM CDT Sun Sep 15 2024

Middle and high clouds prevailed across the region this morning,
as light isolated showers moved northeast over the central and
north-central WI TAF sites. The exception has been a small
cluster of showers and isolated thunder that developed near the
AUW and CWA TAF sites. Anticipate the southern end of this cluster
to reach the AUW TAF site within the first hour or two of this
TAF period, while CWA should remain dry. The trajectory of the
cluster`s center looks to remain just south of the RHI TAF site
this morning, however, some of the isolated showers surrounding it
may reach RHI. Reflected this with VCSH at RHI for now, but an
amendment may be needed. Any showers or storms will come to an end
by mid-morning. VFR conditions will prevail for the remainder of
this TAF period, with southerly winds of 5 to 10 kts, gusts to 15
kts, this afternoon.

&&

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

&&

$$

DISCUSSION.....Kruk/JLA
AVIATION.......Kruk