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000
FXUS63 KGRB 202304
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
604 PM CDT Sat Apr 20 2024

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Elevated fire weather conditions are likely Sunday and Monday
  during the afternoon and early evening hours due to relative
  humidities ranging from 20 to 30 percent and winds of 15 to 25
  mph.

- The next chance for precipitation is Monday evening through
  Tuesday. A few thunderstorms are possible Tuesday, but severe
  weather is not expected.

&&

.DISCUSSION...
Issued at 249 PM CDT Sat Apr 20 2024

Short Term...Tonight and Sunday

Low level moisture remains locked in the region for the early
afternoon hours, keeping low clouds in for at least the middle to
late afternoon before incoming surface ridging begins to scour out
the lingering cloud cover. As a result, lowered the afternoon high
temperatures a few degrees.

Tonight, surface ridging should fairly quickly bring an end to
lingering low clouds from northwest to southeast, with clear skies
across most of the region by the overnight hours. The only
exception to this could be areas near the Upper Peninsula border,
as satellite and water vapor trends do bring in some additional
high clouds for tonight. Winds should decrease a bit from the
afternoon but could remain breezy overnight, with a few gusts to
around 10 to 15 mph at times. Overnight low temperatures remain in
the upper 20s near the Upper Peninsula border to the lower 30s
near east-central.

Sunday, skies will be largely sunny through the day, which should
allow for some warmer surface temperatures into the 50s and
possibly lower 60s. Deep mixing through ~800-700mb will also mean
another fairly breezy day in the afternoon and evening, and the
potential for fairly low relative humidity values around 20 to 30
percent in the afternoon, which will create a period of elevated
fire weather conditions.

Long Term...Sunday Night Through Saturday

The upper air pattern for next week is pretty typical for this
time of the year, with a few significant weather systems coming by
and temperatures not too far from seasonable averages.

A surface high over the Midwest will allow for clear skies Sunday
night, with temperatures falling below freezing thanks to dry air
and light winds. Winds will become southwesterly Monday as the
surface high moves east and a cold front approaches from the
Plains. Forecast soundings from the RAP and Canadian models look
best as far as mixing heights and surface dewpoints. That will
make for elevated fire weather conditions Monday afternoon and
early evening. Showers along the front will probably not arrive
until the evening hours.

A sharp upper trough will move across the area Tuesday. Cold
temperatures aloft will make for showers and thunderstorms. It
could be cold enough aloft for some graupel or snow showers in
the far north. A surface high and upper ridge will follow and
bring dry and cooler weather for Wednesday and Thursday. Milder
weather is expected Thursday as southerly flow returns ahead of
the next systems, which will bring showers and thunderstorms for
Friday.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 553 PM CDT Sat Apr 20 2024

Stratocumulus clouds with bases of 3500-5000 feet AGL will
continue to clear from NW to SE this evening. A band of mid-level
clouds will drift south into the region, but should gradually
thin out with time. SCT-BKN high-based cumulus clouds are
expected to form during the late morning and afternoon on Sunday.
W-NW winds should subside early this evening, then pick up again
by late morning Sunday.

&&

.FIRE WEATHER...
Issued at 249 PM CDT Sat Apr 20 2024

Moderating temperatures and a dry airmass will lead to elevated
fire weather conditions on Sunday and Monday. Relative humidity
will be low (20-30 percent in the sandy soil regions) both days,
but winds look to be a little stronger on Monday.

Another period of elevated fire weather conditions is possible
next Wednesday and Thursday, as a dry airmass moves into the
region. Ensembles indicate PWATs are forecast to be 20-40% of
normal. Winds will likely be below critical levels due to the
proximity of the prevailing high pressure system.

&&

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

&&

$$

DISCUSSION.....Uhlmann/RDM
AVIATION.......Kieckbusch
FIRE WEATHER...Kieckbusch