706
FXUS63 KGRB 130913
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
413 AM CDT Mon May 13 2024

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- An area of smoke or haze is expected to spread over the region
  through this afternoon. The smoke or haze may result in poor air
  quality at times.

- Areas of frost are possible over the sandy soil ares of north-
  central and far northeast Wisconsin tonight and Tuesday night.

- After a dry period on Tuesday and Wednesday, the chance of rain
  and possibly some storms will return at times from Thursday
  through Sunday.

&&

.DISCUSSION...
Issued at 413 AM CDT Mon May 13 2024

Short Term...Today...Tonight...and Tuesday

A cold front was moving through the far southern part of the
forecast area early this morning. Showers had ended, and skies
had cleared across northern WI. Patchy fog was observed across
northern WI, and other minor vsby restrictions were likely due
to smoke from Canadian wildfires. Temperatures ranged from the
upper 30s and lower 40s far north to the middle 50s to lower 60s
south.

Smoke trends and frost potential will be the primary concerns
with the short-term forecast.

The close proximity of the cold front, weak short-wave energy and
the RRQ of a weak jet streak may bring scattered showers back into
the far southern part of the forecast area this afternoon, but
skies will remain partly cloudy farther north. Deep mixing should
allow dew points to mix out, with relative humidity dropping to
25 to 30 percent in the sandy soil areas. High temperatures should
warm to the middle 60s to middle 70s, except near Lake Michigan,
where E-NE winds will keep highs in the middle 50s to lower 60s.

Canadian high pressure centered over Ontario will bring mostly
clear skies, decreasing winds and a dry air mass to the region
tonight. This may lead to patchy/areas of frost across far
northern WI. This is not a slam dunk, as there is enough of a
pressure gradient to support a steady light E-NE wind through the
night. Will let the day shift take a closer look at this, and
decide on potential frost/freeze headlines. Lows should be in the
30s north, and lower to middle 40s south.

On Tuesday, the Canadian high will settle across the Lake Superior
region, with northeast winds pushing cooler and drier air into
the forecast area. Low relative humidity in the 20 to 30 percent
range will be found in the sand areas. Highs will be in the 60s,
but gusty NE winds will keep bayshore and lakeshore areas in the
middle 50s to lower 60s.

Smoke Trends: HRRR/RAP Smoke models show similar trends, with
smoke at the surface and aloft impacting the area today. An Air
Quality Advisory (issued by the Wisconsin DNR) remains in effect
through 10 am, but may be extended through the day. Minor vsby
restrictions (mainly 3-6SM) will be possible at times. Surface-
based smoke is expected to gradually clear from the north and
east late this afternoon and evening, but smoke aloft will
likely linger through tonight and part of Tuesday.

Long Term...Tuesday Night Through Sunday

Generally quiet spring weather is expected through midweek, then
becoming the weather will become unsettled from Thursday through the
upcoming weekend. Beyond Thursday, forecast confidence in the
details drops significantly due to large spread amongst and within
various ensemble systems.

Rain and thunderstorm chances:  Weak high pressure will ensure dry
weather sticks around for Tuesday night through Wednesday.  This
changes on Wednesday night when a broad shortwave trough and
associated cold front track across the northern Mississippi Valley
and western Great Lakes regions.  Chances of light rain have
increased on Wednesday night and Thursday, but with little to no
instability, will continue to leave out a chance of thunderstorms.

Details get murky thereafter, but conceptual models and the NBM
indicate that precip chances reach their minimum after the front
departs late on Thursday night into Friday.

Another period where chances of precip seem to increase is on Sunday
when ensembles indicate height falls taking place with shortwave
energy moving into the northern Great Lakes.  Some instability may
surge into the area by this time, so will have a chance of
thunderstorms.

Temperatures:  Weak high pressure, clear skies, and light winds will
be favorable for frost development on Tuesday night.  Highest
probabilities will be across the sandy soil areas of far northern
WI.

Otherwise, 850mb temps will be rebounding after reaching their
minimums on Tuesday and Wednesday.  Clouds and precip may impact
temps somewhat, but in general, there will be a warming trend
starting Wednesday into the weekend.  Temps could be approaching 80
degrees again at some locations by Saturday and Sunday.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1103 PM CDT Sun May 12 2024

Last vestiges of showers will exit east-central Wisconsin shortly
after midnight. Patchy ground fog is possible over north-central
Wisconsin. Winds will be a little erratic into the early overnight
before shifting mainly north behind the cold front.

Smoke looks to be a bigger concern into Monday as satellite and
surface observations showed a pretty thick area of smoke in
southern Canada, Minnesota northwest Wisconsin and Lake Superior.
Mainly sites reporting 3-6SM and haze. Have maintained the haze
for RHI, AUW and CWA where RAP/HRRR have the higher concentrations.

&&

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

&&

$$

DISCUSSION.....Kieckbusch/MPC
AVIATION.......JLA