234
FXUS63 KGRB 061110
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
610 AM CDT Sun Apr 6 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Water levels will remain elevated on area rivers and streams
  into next week due to runoff from recent rainfall. Minor
  flooding is possible at a few locations.

- Accumulating snow is expected tonight into Monday morning, along
  with the potential for hazardous travel conditions overnight and
  during the Monday morning commute.

&&

.DISCUSSION...
Issued at 251 AM CDT Sun Apr 6 2025

A ridge of high pressure will sink south across the western Great
Lakes this morning, providing dry weather to the region. A quick
moving clipper system will bring increasing clouds to the region
this afternoon along with a cold front that will track through
north-central Wisconsin late this afternoon and the rest of the
area this evening. Despite the lack of deep moisture, the system
will have favorable dynamics with a potent mid level trough and
attendant shortwaves, the left exit region of a strong 110 knot
upper level jet, and a ribbon of strong 700-850mb frontogenesis.
The strong dynamics will help squeeze out as much moisture that is
available from the system tonight into Monday morning; however,
the limited amount of moisture will limit snowfall amounts as
PWATs will only be 0.40 to 0.50. Snowfall amounts of 1 to 2 inches
still look like the most likely snowfall amounts as the
probabilities of reaching or exceeding 1 inch is 40-50% north of
Rhinelander and Oshkosh and only 10-20% of reaching or exceeding 2
inches across this same area. Snowfall amounts south of these
areas will likely stay below 1 inch. The snow may result in
hazardous driving conditions, especially during the Monday morning
commute.

Winds behind the departing system will pick up precipitously on
Monday, with blustery conditions expected across the area. Small
Craft Advisory conditions will likely be met across the Bay and
Lake Michigan late Sunday night through Monday evening, with a few
gale force gusts possible at times. Strong cold air advection on
Monday will lead to steep low level lapse rates of 8 to 10 C/km up
to around 800mb. The steep lapse rates, when combined with some
lingering moisture and a possible boost in moisture from Lakes
Superior and Michigan could cause some scattered light snow
showers or flurries, especially Monday afternoon. Additional
snowfall amounts from any of this activity would be meager, on the
order of a few tenths of an inch at most.

High pressure will then provide dry weather to the region Monday
night through Tuesday night. A low pressure system passing
through central Illinois continues to trend south Wednesday and
Thursday with at most a glancing blow across southern portions of
central and east-central Wisconsin. Confidence in this portion of
the forecast is low due to the model discrepancies in this period
of the forecast as some models are completely dry across our area.

Once this low tracks off to the east, the weather looks dry Friday
into Saturday as temperatures slowly warm to around 10 degrees
above normal for this time of year.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 610 AM CDT Sun Apr 6 2025

VFR conditions will prevail today. Surface winds will generally be
west to southwest inland, with southerly winds along the lakeshore
with gusts of 10 to 20 knots. CIGS and VSBY`s are expected to
drop into the MVFR/IFR category tonight as an accumulating
snowfall is anticipated across much of the region. The
precipitation may briefly start as rain across central and east-
central WI. The snow will start out at KRHI around 01Z, reaching
KAUW around 03Z, KGRB around 04z, KATW around 05z and KMTW around
06z. Snowfall amounts will range from one half of an inch up to 2
inches with the highest amounts across the northeast.

&&

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

&&

$$

DISCUSSION.....Kurimski
AVIATION.......Kurimski