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000
FXUS63 KGRB 211950
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
250 PM CDT Sun Apr 21 2024

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Elevated fire weather conditions continue through this evening
  and are possible again Monday afternoon due to relative
  humidities ranging from 20 to 30 percent and winds of 15 to 25
  mph. Slightly stronger gusts up to 30 mph are possible Monday.

- Precipitation chances return Monday evening through Tuesday. A
  few thunderstorms are possible Tuesday afternoon, but severe
  weather is not expected.

&&

.DISCUSSION...
Issued at 249 PM CDT Sun Apr 21 2024

Short Term...Tonight and Monday

Sunny skies allowed temperatures to warm steadily through the
morning hours, allowing us to hit our convective temperatures in
the 50s for much of the region. The resulting fair weather cumulus
field will likely stick around in the region through the early
evening, before steadily dissipating for the overnight. Similarly,
the deep mixing in the region will keep wind gusts around 20 to 25
mph and low relative humidity in the region for around the same
timeframe.

Tonight, winds will begin to slacken and skies should largely be
clear. This will provide another ideal night for steady
radiational cooling. Kept temperatures fairly cool for the
overnight period, especially in the typical cool spots near the
Upper Peninsula border and in portions of the northwoods where
Monday morning low temperatures may be in the lower to middle 20s.
Areas closer to the Fox Valley and lakeshore will likely remain in
the lower 30s overnight.

Monday, winds will switch over to the southwest as a low pressure
system approaches southern Manitoba. The tightening pressure
gradient will help give winds a boost as a result, with some gusts
up to 25 to 30 mph in the afternoon. The strong southwest flow
will also bring in some warmer temperatures, with most of the area
expected to get into the 60s tomorrow afternoon. That said, little
additional moisture will advect into the region, so relative
humidity readings in the afternoon will again be fairly low, so
elevated fire weather conditions are expected again for Monday
afternoon. Finally, a cold front will approached the region as the
aforementioned low pressure system passes by to our north. This
could bring some scattered showers into central Wisconsin by
Monday evening. Given the relatively scarce moisture however,
would expect any showers to be fairly light.

Long Term...Monday Night Through Sunday

A cold front will bring showers as it moves across the region
Monday night. An upper level disturbance and reinforcing push of
colder air will produce showers and isolated thunderstorms
Tuesday. The rain showers could mix with or change to snow across
the far north Tuesday afternoon, but no accumulation is expected.

A 1030 mb surface high will drop south from James Bay Tuesday night
and Wednesday and bring drier and colder air into the area. The
air will be very dry Wednesday afternoon, with precipitable water
values of .15 inches. This will make for relative humidities of 20
to 30 percent, but cool temperatures and light winds should lessen
fire threats to some degree.

Temperatures will warm Thursday and Friday as the surface high moves
off to New England and winds become southerly. SHowers and thunderstorms
are likely Friday afternoon and night if the medium range models are
correct. They have a surface low moving across the Plains, with a
decent supply of moisture advecting north.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1251 PM CDT Sun Apr 21 2024

Generally, good flying conditions are expected for the TAF period.
Fair weather cumulus are expected across the area this afternoon,
forming a scattered and occasionally broken high cloud deck that
will dissipate again in the evening. Winds will remain fairly
gusty through the afternoon from the WNW, with occasional gusts up
to 20 knots through the afternoon. Tonight clear skies and light
winds are expected. Winds then increase again during the late
morning to early afternoon period on Monday.

&&

.FIRE WEATHER...
Issued at 249 PM CDT Sun Apr 21 2024

Warming surface temperatures and a dry airmass have brought
relative humidity values to around 20 to 30 percent early this
afternoon, with wind gusts to around 220 to 25 mph. These
elevated fire weather conditions will likely continue until the
evening, when winds will begin to slacken and temperatures cool.

Monday may be of higher concern, fire weather-wise. Winds will
be slightly stronger in the afternoon, sustained around 15 to 25
mph with gusts up to 30 mph; while minimum relative humidity
readings will be similar to today, around 20 to 30 percent.

Another period of elevated fire weather conditions is possible
Wednesday and Thursday, as a dry airmass moves into the region.
However, winds will be below critical levels due to the proximity
of a prevailing high pressure system.

&&

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

&&

$$

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