000
FXUS63 KGRB 121914
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
214 PM CDT Fri Apr 12 2024

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Northwest winds will continue to gust around 30-35 mph over east
  central Wisconsin through early this evening.

- There is a chance of thunderstorms Saturday night across the
  north, main hazards are likely to be thunder and small hail.

- More widespread chance for thunderstorms and moderate to heavy
  rainfall next Tuesday and Wednesday. A few severe storms may be
  possible, mainly across central and east-central WI.

&&

.DISCUSSION...
Issued at 214 PM CDT Fri Apr 12 2024

Short Term...Tonight and Saturday

Cold air aloft combined with surface heating has led to modest
SBCAPE values of 300 to 500 J/kg along with steel 0-3km low level
lapse rates of 8 to 10 C/km south of highway 29 this afternoon.
This has caused some light showers to pop up across portions of
central and east-central Wisconsin. Some rumbles of thunder are
not out of the question from any storms that can develop a deep
enough updraft. These showers are expected to dissipate later this
afternoon into the early evening with the loss of daytime
heating.

Clearing skies and diminishing winds are expected tonight with the
loss of daytime heating as a high pressure tracks over the western
Great Lakes region. The clearing skies and light winds will allow
temperatures to fall to around 30 across the north, with lower to
middle 30s across central and east-central Wisconsin.

The high will shift to the east on Saturday, which will turn winds
to a southerly direction by the afternoon. The abundant sunshine
and warm air advection will allow for warm temperatures on
Saturday as highs soar into the 60s across the region. Some 70
degree reading will be possible across central Wisconsin.

Long Term...Saturday Night Through Friday

Couple periods of focus during the extended period. First being a
chance for scattered showers and possible thunderstorms Saturday
night. Second being a chance for widespread rain and thunderstorms
Tuesday and Wednesday next week.

Precipitation...The high-res models that are now in range for
Saturday night are in decent agreement with a band a scatted
showers and possible thunderstorms initiating along a low-level
convergences zone that is progged to set up across northern WI
and the Upper Peninsula. There is some uncertainty with how far
north these storms will initiate as recent trends have pushed the
associated warm front further north over the UP. Regardless
modest MUCAPE values of 100-400 J/kg, effect bulk shear of 20-
35 kts and mid level-lapse rates of 7-7.5 C/km would support the
possible of a few scattered elevated thunderstorms during the
early overnight hours. Main hazards with any storms that do
develop would likely be thunder and small hail. The window for
thunderstorms looks small Saturday night as a cooler dry air mass
at the mid and upper levels moves over the region Sunday morning.

With upper level ridging expected dry conditions are forecast for
most of Sunday through Monday morning. Ensemble models are coming
into broad agreement regarding a strong cyclone developing in the
lee of the Rockies Monday afternoon and then intensifying as it
propagates northeast across the Central Plains Tuesday. This
would place central and northeast WI in the warm sector of this
system Tuesday allowing for warm and moist Gulf air to filter in.
It is still too early to dive into the specifics, but with the
expected deep layer moisture and modest instability some strong
thunderstorms do look possible. However, current guidance
suggests the better chance for severe storms will remain south of
the region toward the WI/IL boarder. Aside from the severe
weather potential PWATs of 1.25+ inches across much of the region
Tuesday into Wednesday supports periods of widespread moderate to
heavy rainfall. WPC has placed part of central WI in a 5% risk
for excessive rainfall Tuesday and the entire region in a 5% risk
for Wednesday, which seems reasonable given the expected ample
moisture. With the absent snow melt this spring many area rivers
and lakes have below normal water levels which may alleviated
some of flooding potential next week, but minor flooding in flood
prone areas is certainly a possibility.

The unsettled pattern may have some staying power through much of
next week. Models are showing a disturbance following behind the
Tuesday/Wednesday system.

Temperatures...With the warm southerly flow high temperatures
Sunday and Monday are expected to reach 60s across the region
with areas in central and east-central WI possible reaching the
low 70s depending on cloud cover. As the rain arrives
temperatures are expected to cool slightly through the mid-week,
but still remain above normal for mid- April.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1231 PM CDT Fri Apr 12 2024

Stratocumulus clouds with bases ranging from MVFR across the
north, to VFR across central and east-central Wisconsin will
continue this afternoon, with bases slowly rising throughout the
afternoon. These clouds are expected to eventually dissipate later
this afternoon and into the early evening with the loss of
daytime heating and drier air advects in from the west.

Mostly clear skies are expected later this evening and into midday
Saturday as a ridge of high pressure tracks across the western
Great Lakes region.

Surface winds gusting to 20 to 30 knots from the northwest will
ease below to 10 knots by midnight and back to the west.

&&

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

&&

$$

DISCUSSION.....Kurimski/GK
AVIATION.......Kurimski