075
FXUS63 KGRB 120344
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1044 PM CDT Sun Aug 11 2024

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Showers and a few scattered, non-severe thunderstorms are
  possible (15% to 25% chance) Monday and Tuesday afternoon and
  evenings, mainly in northern WI.

 - Widespread precipitation becoming likely (40 to 60% chance)
Thursday into Saturday, but low confidence on exact timing and
magnitude of precipitation at this time. Heavy Rainfall cannot be
ruled out during this period.

&&

.DISCUSSION...
Issued at 259 PM CDT Sun Aug 11 2024

Our weather pattern will be fairly  for the next few days.
Similar to yesterday (Saturday) afternoon, widespread cu/sc
establishes itself across northern/north-central WI under WNW
flow. Scattered pockets of 850 moisture flux convergence phased
with pockets of 950mb frontogenetical forcing will be a
sufficient catalyst for a few of these SC/CU clouds to grow tall
enough to produce a few scattered showers. With a few hundred
joules of CAPE available during peak daytime heating, a few
rumbles of thunder are possible. However, the severe weather
parameter space is not supportive of severe weather at this time.

Temperature-wise, highs for the next few days should be within a few
degrees of normal for this time of year, with lows around 50
degrees, and highs in the upper 70s.

Heading into the Thursday - Saturday timeperiod, a nearly vertically-
stacked low is slated to establish itself near NE Iowa/SW Minnesota.
Overall progression with this system is slated to move very slowly.
The instability and shear parameter space doesn`t reflect anything
notable for severe potential with this setup, so focus will be on
locally heavy rains, especially given the slow movement of this
system. The GFS ensemble runs have been much more bullish with this
system than the ECMWF. Overall, the GFS family does seem slightly
more plausible, so will initially lean some more towards it.

If the GFS pans out, am at least slightly concerned about the
potential for heavy rainfall. PWATs approach 2 inches, and the
forecast vertical sounding profile looks to suggest efficient
rainfall... as supported by 0-6 km mixing ratios of 8 g/kg & a wide
swath of warm cloud depths 4.0-4.5km at times.. Even the less-
bullish EC ensemble moisture parameters are anomalously high based
on mid August climatology with 925/850mb specific humidities and
precipitable water values in the upper 90th percentiles.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1043 PM CDT Sun Aug 11 2024

Patchy ground fog is possible overnight in central and
northcentral Wisconsin, especially areas that received rain
showers Sunday afternoon and evening. If it materializes, it
should dissipate by 13z Monday.

There is a slight chance of showers late Monday afternoon and
early evening in central and east central Wisconsin as a weak
disturbance moves across the region. Otherwise, VFR conditions
are expected tonight through Monday night.

&&

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

&&

$$

DISCUSSION.....Kotenberg
AVIATION.......RDM