076
FXUS63 KGRB 292307
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
607 PM CDT Wed May 29 2024

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Frost is likely across northern Wisconsin late tonight. A Frost
  Advisory has been issued for locations generally north of a
  Merrill to Antigo to Wausaukee line.

- Due to recent rainfall, a few rivers are expected to remain at
  bankfull but below minor flood stage through late this week.

- A more unsettled pattern is forecast to return this weekend
  through at least the middle of next week. Currently, Sunday
  night through Monday has the best chance for thunderstorms and
  heavier rainfall.

&&

.DISCUSSION...
Issued at 224 PM CDT Wed May 29 2024

Short Term...Tonight and Thursday

Fair weather cumulus developed this morning and continued this
afternoon across central and portions of north-central Wisconsin.
Temperatures warmed into the 60s to around 70 away from the bay
and Lake Michigan, where readings were in the 50s.

For tonight, the fair weather cumulus will erode fairly quickly
around sunset across central and portions of north-central
Wisconsin. After midnight, frost is likely across the northwoods
as low temperatures should fall into the 33 to 37 range. A Frost
Advisory has been posted for locations generally north of a
Merrill to Antigo to Wausaukee line. Low temperatures elsewhere
will be in the upper 30s and lower 40s.

Mostly sunny skies will prevail on Thursday with some fair weather
cumulus clouds developing in the late morning and afternoon. High
temperatures will climb into the lower to middle 70s away from the
bay and Lake Michigan. Afternoon relative humidity values will
drop into the 25 to 40 percent range.

Long Term...Thursday Night Through Wednesday

Dry start to the extended period Thursday night
through much of Friday as a ridge of high pressure moves over the
region. A return to a more unsettled pattern is expected
beginning Friday night as a series of disturbances are forecast
to impact the area.

Thursday night through Friday...Light southeasterly flow driven
by the passing upper ridge and surface high should keep low
temperatures Thursday night warmer compared to Wednesday night,
especially across northern WI. This will also help boost Friday`s
temperatures a few degrees with most locations expected to reach
the 70s, except along the immediate lakeshore. While most of the
region will stay dry Friday, a cold front stalling out over
western WI along with an eastward push of increasing moisture
(PWATS approaching 1") could produce a few scattered showers in
central and north-central WI beginning Friday afternoon.

Friday night through Sunday...As the ridge starts to depart the
region Friday night the eastward push of warm moist air will
continue, increasing the chance for scattered showers across the
region Friday night through Saturday afternoon. A confluent upper-
 level pattern will provide additional support for these showers.
Instability currently looks weak during the period limiting the
potential for any thunderstorms to form, but can`t rule out a few
rumbles of thunder, mainly Saturday morning. A brief period of
ridging Saturday night through most of Sunday will return dry
conditions to the region. The weak ridge also supports
temperatures nearing or surpassing 80 degrees Sunday afternoon
for locations away from the lakeshore.

Sunday night through the rest of the extended period...A more
widespread chance for showers and storms is forecast to arrive
Sunday night into Monday morning with a surge of warm moist air
out ahead of a mid-level shortwave. PWATs look more impressive
during this period with values of 1.5-1.7" which is 1.25 to
1.5 standard deviations above normal. The severe weather
potential during this period is still unclear, but with
increasing instability during the day Monday and the increase in
available moisture this period at least bears monitoring,
especially for those with outdoor plans Monday. Looking ahead
models are showing broad signs of another disturbance tracking
across the western Great Lakes toward the middle of next week.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 602 PM CDT Wed May 29 2024

SCT high-based cumulus clouds will quickly dissipate over central
WI, leaving clears skies for the overnight period. Considered the
possibility of patchy fog late tonight, but given the dryness of
the air mass, opted to leave it out for now. Will take another
look for the 06z TAFs. A few high-based cumulus clouds may reform
across the western part of the forecast area Thursday afternoon.
Light and variable winds are anticipated tonight, with a gradual
increase in SE-S winds by late morning Thursday.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 1 AM to 9 AM CDT Thursday for WIZ005-010>013-
018-019-021.
&&

$$

DISCUSSION.....Eckberg/GK
AVIATION.......Kieckbusch