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000
FXUS63 KGRB 111136
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
636 AM CDT Thu Apr 11 2024

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- There is a chance of thunderstorms in central and northcentral
  Wisconsin this afternoon and evening. Severe storms are not
  expected.

- There is a chance of thunderstorms Saturday night and at times
  early next week. Severe weather looks unlikely.

&&

.DISCUSSION...
Issued at 417 AM CDT Thu Apr 11 2024

Short Term...Today...Tonight...and Friday

The potential for significant rain and very strong
winds has diminished, as any phasing between the northern and
southern stream shortwaves is forecast further east than it was
the last couple of days.

An upper trough moving into northwest Wisconsin will produce
showers over central and northcentral Wisconsin through early
evening. A few thunderstorms are possible in the afternoon and
early evening. The showers will drift into northeast and east
central Wisconsin during the late afternoon and nighttime hours.

Meanwhile, the left exit region of a strong upper jet will produce
an intensifying cyclone that will move from western Kentucky to
northwest Ohio today through this evening. This is at least 100
miles east of most model forecasts yesterday. So it will not be
close enough to bring much rain to the lakeshore and Fox Valley.
The strong gradient will be close enough to bring gusty northwest
winds late tonight and Friday.

Long Term...Friday Night Through Wednesday

The focus of the extended period now shifts over to temperatures
and precipitation chances for the weekend. Additional unsettled
weather will be possible next week as well.

The weekend...
Surface ridging will keep skies clear overnight Friday night into
Saturday morning. Increasing warm air advection through the mid-
levels during the day will bring back some scattered cloud cover
by the afternoon, as well as high temps into the 60s. Saturday
evening will be the next chance for some scattered precipitation
in the area. Models hint at a weak LLJ pointed into central to
east- central Wisconsin, followed shortly after by a round cold
air advection at 850mb. The resulting relatively broad mid-level
convergence will likely support at least a few scattered showers
in the region. Lingering weak instability and mid-level lapse
rates around 6 to 6.5 C/km will also support a rumble of thunder
or two. All that said, kept pops around 30 to 35% as any
precipitation will be fairly scattered, and largely dependent on
the convergence in the mid-levels being sufficient to trigger
convection.

High temperatures for Sunday remain in question. If precipitation
forms Saturday night and cold air advection rolls through around
850mb, high temperatures may need to be lowered again from the
middle 70s, especially as surface winds shift back towards the
northwest during the day. The cooler guidance would instead bring
highs into the 60s for most of the area. Lowered highs a degree or
two for now.

Rest of the forecast...
General ensemble guidance suggests the overall pattern developing
another large upper trough over western CONUS early next week.
The trough then traverses the Central Plains sometime in the
middle of the week, potentially bringing the next round of active
weather to the region. Timing and details remain fairly variable
at this time, but suffice to say, expect unsettled weather to
continue.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 635 AM CDT Thu Apr 11 2024

VFR conditions should continue through the afternoon hours, though
with increasing middle clouds, scattered showers and isolated
thunderstorms.

An upper level disturbance will bring more frequent showers and MVFR
ceilings to the area this evening through Friday morning. Improving
flying conditions are expected Friday afternoon through Friday night.

&&

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

&&

$$

DISCUSSION.....RDM/Uhlmann
AVIATION.......RDM