Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 241953
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
253 PM CDT Fri Jun 24 2022

Forecast discussion for routine afternoon forecast issuance

.SYNOPSIS...
Issued at 252 PM CDT Fri Jun 24 2022

Showers and thunderstorms tomorrow, then breezy, cooler, and less
humid on Sunday. The seasonable temperatures and comfortable
humidity levels will continue through the middle of next week.

A seasonably strong, progressive band of westerlies will remain
across Canada and about the northern third of the CONUS
throughout the period, north of the subtropical ridge stretched
out across the southern United States. A rather strong upper
trough embedded in the westerlies will cross the region during the
weekend, with another slightly weaker trough expected to move
across the region early next week.

A very warm and rather humid air mass will remain in place across
the area through tomorrow, though temperatures tomorrow will
likely be held back by clouds and showers. Cooler and much drier
air of Canadian origin will push into the area Sunday, with
seasonable temperatures and comfortable humidity levels likely
through the middle of next week before some slightly warmer and
more humid conditions return late in the week. The precipitation
forecast is rather uncertain. High PWATs will be in place for the
FROPA tomorrow, but right now the timing/smaller scale features
modulating convection do not appear to favor widespread heavy
rainfall. There are a couple additional chances for rain next
week. The result of the 3 rain events should be totals at least
somewhat close to normal for most of the area, though as
typically the case with convection in the summertime some
locations will get considerably more rain while others might
receive little rainfall during the next week.
&&

.SHORT TERM...Tonight and Saturday
Issued at 252 PM CDT Fri Jun 24 2022

High-based showers and storms have formed within the higher
moisture axis and weak moisture convergence stretching from
central WI into far northeast WI with SB/MU CAPE around 1800-2000
J/kg, no cap, and decent lapse rates in place. But meager bulk
shear under 20 kts keeping things in check for the most part.
Additional activity is expected into the late afternoon as
conditions will not change much. Weak boundary will sag toward the
WI/MI border, which could touch off activity farther north as
well. A few stronger storms are expected, with small hail, brief
gusty winds and heavy downpours. A pulse severe storm is possible
during peak heating. All this activity will slowly wane through
the evening hours as we lose instability and moisture convergence
weakens. This will leave dry conditions for the overnight hours.
It will be a warm night with lows in the 60s to near 70.

Attention then turns to a large area of showers and storms which
will develop across southern Minnesota and Iowa overnight as a LLJ
cranks up. This area is forecast to reach our area around sunrise
across central and north central WI then spread east/northeast
across much of the area. Some disagreement on if/when this first
wave of activity will die off before reaching eastern WI. Cold
front and upper trough will also be approaching from the west
during the day, providing for additional shower and possible
storm activity. This will keep POPs going through the entire day.
It won`t be a wash-out or all day rain event, but at least two
waves of activity will be possible. Instability will be hard to
come by as extensive cloud cover looks to hold MUCAPE values under
1000 J/kg. Bulk shear will also be weak as well. So while a
strong storm or two is possible, severe weather is not expected.
Temps will also be held in check due to the clouds/rain, with
mainly 70s to lower 80s expected.

.LONG TERM...Saturday Night Through Friday
Issued at 252 PM CDT Fri Jun 24 2022

Redevelopment of convection along the cold front crossing the area
Saturday evening will depend heavily on how much recovery can
occur after mid-day showers. At this point, expect just scattered
coverage and perhaps a few strong storms.

Rain chances Tuesday into Tuesday evening will be tied to the
passage of the another mid-level trough and attendant cold front.
The return of moisture prior to the arrival of the front won`t be
great. But QG forcing with the trough and with the LFQ of an upper
speed max should result in considerable lift for mid-summer. And
the timing looks favorable (FROPA during the evening) for
maximizing precipitation.

The rain chance Thursday/Thursday night will be tied to the
return of warmer air aloft as an EML advances toward the area. The
main question is whether convection developing at the nose of a
LLJ affects the area or remains to the north/northwest.

Pretty much stayed with the NBM for temperatures as it has been
verifying well lately.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1248 PM CDT Fri Jun 24 2022

VFR conditions prevailed during the morning hours, with some mid
and high clouds pushing across parts of the area. A few sprinkles
and showers were starting to pop up across central and far
northeast WI. Expect VFR conditions to continue into tonight.
Only exception will the possibility of brief reductions in
visibility / lower ceilings if/where any thunderstorm develops
over northern WI this afternoon as a weak boundary sags into the
area. This activity will diminish in the late afternoon and
evening.

Quiet conditions are expected tonight, then ceilings will drop
from west to east Saturday morning as an area of showers and
isolated storms push into the area, reaching GRB/ATW/MTW in the
late morning or early afternoon. Winds will remain out of the
south/southwest into early Saturday afternoon. Gusts to around 20
kts will be possible this afternoon and again on Saturday.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS.......Skowronski
SHORT TERM.....Bersch
LONG TERM......Skowronski
AVIATION.......Bersch


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