NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 200916
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
416 AM CDT Sat Apr 20 2024

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Elevated fire weather conditions are possible on Sunday and
  Monday afternoons due to low relative humidities ranging from 20
  to 30 percent and winds of 15 to 25 mph.

- The next chance for precipitation returns late Monday through
  late Tuesday. Rain will be the main precipitation type, but some
  snow may mix in across the far north on Tuesday. A few
  thunderstorms are also possible on Tuesday, but severe weather
  is not expected.

&&

.DISCUSSION...
Issued at 415 AM CDT Sat Apr 20 2024

Short Term...Today...Tonight...and Sunday

A mid level PV anomaly, currently visible on water vapor imagery
across northwest Wisconsin, will swing through northern Wisconsin
early this morning. This shortwave will bring scattered light snow
showers or flurries as it tracks through the area, with subsidence
behind it possibly clearing skies for a bit across northeast and
east-central Wisconsin with aid from some downsloping.

Recent mesoscale models have backed off a bit on the precipitation
for the rest of today as moisture is not quite as deep as previous
runs. Although a sprinkle can't be ruled out, especially across
central and east-central Wisconsin, the weather should mainly be
dry for today with continued breezy west to west-northwest winds.
Any clearing that occurs will cloud back over later this morning
and into the afternoon as upstream IR satellite data indicates
abundant cloud cover that will move in across the region. Highs
today will be below normal, generally from 45 to 50 degrees.

Surface ridging will build across the southern Great Lakes region
tonight, which should clear out the clouds across northeast
Wisconsin this evening. Surface winds will continue to be gusty at
10 to 15 mph, which will limit how far temperatures fall tonight.
Lows tonight are generally expected to range from the upper 20s
across north-central, to the lower 30s across east-central
Wisconsin.

High pressure will continue to build south on Sunday, keeping the
weather dry across the western Great Lakes. However, a deep mixed
boundary layer up to 700 mb will cause breezy conditions Sunday
afternoon along with very dry air and warmer temperatures. This
could cause some fire weather concerns as fuels continue to dry
out along with gusty winds and warmer afternoon temperatures.
Highs on Sunday are expected to be around normal; ranging from
the lower to middle 50s across the north, with around 60 across
the Fox Valley and portions of central and northeast Wisconsin.

Long Term...Sunday Night Through Friday

Precipitation...Dry conditions will prevail from Sunday night
through much of Monday, ahead of an approaching shortwave/trough and
associated surface low pressure system expected to bring the next
chance for precip. Although some uncertainty remains with the exact
timing and track of the shortwave and surface low, model guidance
has come into better agreement regarding the overall evolution of
this system. There is clear agreement with the precip occurring in
two rounds, first from the surface cold front sliding west to east
across the area Monday evening/night, and the second Tuesday
afternoon/evening from the trailing shortwave/trough energy dropping
southeast across the area.

The first round of precip will be supported by an impressive 40-50kt
low-level jet, but a lack in instability and the timing of the
frontal passage will lead to a little to no chance of thunderstorms.
For the second round, mid-level lapse rates around 7.5 C/km and
MUCAPE around 300-700 J/kg will support the potential for a few
thunderstorms as the precip moves across the area. Probabilities for
snow to mix in on the back side of the system remains low (less than
20%). If snow were to occur, impacts would not be expected given the
system will be exiting.

Dry conditions return for Wednesday and Thursday with high pressure
and ridging overhead. The next chance for precip arrives Friday with
a southern stream system.

Temperatures...Monday will be the warmest day next week, with high
temps about 5 to 10 degrees above normal ranging from the low to mid
60s. Temperatures will then fluctuate around normal for the
remainder of the week.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1006 PM CDT Fri Apr 19 2024

Another round of scattered snow showers is expected to impact NC
WI overnight, with possible MVFR/IFR vsbys at the RHI TAF site
during the early part of the TAF period. A few snow showers or
flurries may linger into Saturday morning before ending. Ceilings
should prevail in the 4000-6000 ft AGL range for much of the TAF
period, though MVFR ceilings may accompany any snow showers, and
may also move into NC WI late tonight into Saturday morning.
Gusty WNW winds will decrease slightly overnight, increase again
late Saturday morning, then diminish Saturday evening. Clearing
skies are anticipated by sunset.

&&

.FIRE WEATHER...
Issued at 415 AM CDT Sat Apr 20 2024

Moderating temperatures and a dry airmass will lead to elevated fire
weather days on Sunday and Monday. Winds will be a little stronger
on Sunday compared to Monday with sustained values of 15-20 mph and
gusts up to 25 mph (sustained winds 10-15 mph with gusts to 25
mph on Monday). In addition, minimum relative humidities will fall
to 20 to 30 percent on Sunday, with 25 to 35 percent on Monday.
While elevated fire weather conditions will be present each day,
concern is a little higher on Sunday due to slightly stronger
winds and lower RH values.

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.....Kurimski/Kruk
AVIATION.......Kieckbusch
FIRE WEATHER...Kurimski/Kruk