000
FXUS63 KGRB 141128
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
628 AM CDT Sun Apr 14 2024

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Elevated fire weather conditions are expected today. Mild
  temperatures, gusty northwest winds up to 20 to 25 mph along
  with relative humidity values of 15 to 30 percent are expected
  this afternoon into early this evening. Conditions will be
  conducive to grass fires.

- Elevated fire weather conditions are expected again on Monday.
  Mild temperatures along with relative humidity values of 20 to
  35 percent are expected during the afternoon and early evening
  hours. Winds will be lighter with gusts only around 15 mph.
  Conditions will be conducive to grass fires.

- Showers and a few embedded thunderstorms are expected from Tuesday
  into Wednesday. Severe thunderstorms are not expected at this
  time, but heavy rainfall will be possible.

- Strong east to southeast winds expected Tuesday into Tuesday night,
  with gusts to 30 to 45 mph. Gusts to near gale force possible
  on Lake Michigan Tuesday night.

&&

.DISCUSSION...
Issued at 434 AM CDT Sun Apr 14 2024

Short Term...Today...Tonight...and Monday

Scattered thunderstorms moved east of the area early this morning.
Some patchy fog developed across the north, especially Vilas
County where the visibility in some spots was down to a half mile
or less. An outflow boundary from the thunderstorms pushed the
front southward to near Marshfield to just north of Oshkosh to
Manitowoc at 3 am. At 3 am it was 39 degrees at Manitowish Waters
to 63 degrees at Wautoma.

The main concern for today and Monday will be the expected mild
and dry conditions that will result in elevated fire weather
conditions. Some of the latest guidance has come in slightly
warmer and this is supported by the model forecast of 925 mb
temperatures. Humidity readings are expected to drop into the
15 to 30 percent range with winds gusting to 15 to 25 mph
this afternoon. Will highlight the fire weather concerns in
the Hazardous Weather Outlook, the morning weather story, and
a Special Weather Statement. Conditions will be getting close
to critical fire weather conditions this afternoon through
early this evening across portions of central and east-central
Wisconsin. High temperatures should top out in middle to upper
60s north to the lower to middle 70s south. A few upper 70s are
possible in the corridor from Shawano through Waupaca to Wautoma.

Winds should diminish quickly early this evening. Along the
lakeshore, winds will more than likely turn onshore around sunset
once the deeper mixing diminishes. Clear skies and light winds
should allow temperatures to fall into the middle 30s to lower
40s overnight.

For Monday, elevated fire weather conditions are anticipated
again. It will be a few degrees cooler with highs in the 60s
to lower 70s. Humidity values will be fairly similar to Sunday
but the main item is the winds will not be as strong with gusts
to only around 15 mph. Skies are expected to turn partly cloudy
during the afternoon.

Long Term...Monday Night Through Saturday

The main forecast concern in the extended forecast will be the
arrival of a strong low pressure system Tuesday into Wednesday,
bringing widespread rainfall and scattered thunderstorm activity.

A stacked strong low pressure system will be on its way towards
the western Great Lakes Monday night into Tuesday. The latest
ensemble guidance has slowed this system down a little, keeping
northeast Wisconsin dry at least through daybreak Tuesday. Still,
strong low level flow will advect in ample warmth and moisture and generate
sufficient isentropic lift to support widespread rainfall by the
afternoon. Instability will be fairly limited but there should be
enough dynamic forcing to produce isolated to scattered embedded
thunder, especially in the evening along the lakeshore where low-
level speed convergence seems likely near the Lake Michigan
shoreline. With PWATs around 1-1.3 inches, rainfall could be
heavy at times Tuesday afternoon through Tuesday night especially
with any convection. Winds will alos be on the increase Tuesday
evening through Tuesday night as the surface low approaches
southeast Wisconsin, with some gusts in the area up to 30 to 45
mph, highest in central Wisconsin. Wednesday, the surface low
finally pushes across the region, accompanied by additional
scattered showers and possibly a few storms in the afternoon.
Any rainfall during this time will likely be lighter than on
Tuesday, as the best moisture will have departed the region by
then.

As the remnants of this system depart northwards it will phase
with another broader low over Canada. This will shift mean flow to
the west to northwest over our area for the end of the week and
bring a chance for some light precipitation Thursday, including
some light snow to the north. Drier conditions then follow for the
end of the week and early next weekend.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 628 AM CDT Sun Apr 14 2024

Some lingering patchy fog and low CIGS from KD25 to KRHI east to
KIMT will burn off by 14z, otherwise VFR conditions are expected
through Monday afternoon. Winds will gust to around 22 knots
from the northwest this afternoon. Winds will quickly subside
around sunset. Looking ahead, rain will arrive later in the day
Tuesday if not Tuesday night. Rain and storms are possible at
times Tuesday night and Wednesday. East to southeast winds will
be on the increase during this time frame, with gusts over 25
knots possible.

&&

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

&&

$$

DISCUSSION.....Eckberg/Uhlmann
AVIATION.......Eckberg