908
FXUS63 KGRB 020904
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
404 AM CDT Tue Jul 2 2024

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

 - Periods of rain may be heavy at times through late tonight. In general,
   0.5 to 1.5 inches of rain is expected across the entire area,
   highest in central Wisconsin, which could lead to minor river
   and stream flooding, along with urban flooding.

 - Conditions will be hazardous to mariners and beachgoers on the
   bay and Lake Michigan through tonight due to gusty winds and high
   waves.

 - The next round of widespread rain arrives late on the 4th of
   July and will last through Friday.

&&

.DISCUSSION...
Issued at 358 AM CDT Tue Jul 2 2024

Rounds of showers and some thunderstorms expected through tonight.
Moderate to heavy rainfall is likely, especially over central WI.
It then turns mainly dry Wednesday and Wednesday night, before more
showers return later on the 4th, continuing through Friday. First
full weekend of July will be unsettled with chances for showers
and thunder both days.

Today...Showers with moderate to heavy rain ahead of a shortwave
trough and well to the north of main warm front are shifting
across the state early this morning. Decaying area of lightning
strikes is present over southwest cwa on edge of MUCAPE of 1-2k/kg
well to the west and southwest over IA. As shortwave and low-
level jet translate east this morning, expect widespread showers
early to be followed by additional showers through midday. Maybe a
brief lull after that over parts of the area, but there will
already be another sharp H7 shortwave (generating showers and
storms over west central IA at current) and resurgent low-level
jet taking aim into central WI as early as early to mid afternoon.
This should keep at least scattered showers going. As has been
highlighted, PWATS nearing 2 inches are well above the 90th
percentile and closer to max values for early July. Thus the
threat for heavy rain will be across the region all day. With
multiple rounds of showers at the worst and patchy drizzle and
cloud cover at the best, went lower for high temps today. 70 will
be a stretch for any spot in the cwa today and northwoods will
have tough time reaching mid 60s.

Tonight into Wednesday...Another round of moderate to heavy rain
likely as primary shortwave trough edges closer and stronger
shortwave within the trough rotates through. Right entrance jet
forcing will only enhance lift as warm front approaches.
Sfc based instability (and associated severe threat) will be
maximized along and south of the warm front and approaching low
pressure wave, but sufficient MUCAPE just upstream of our area
along with PWATs still around 2 inches suggest moderate to heavy
rain showers especially during the evening into the early
overnight hours scntral to east-central WI along increasing low-
level jet. To the west of the LLJ axis, appears showers shut down
quickly after midnight especially after weak cold front/drier air
moves through. All areas should be in the process of drying out
by daybreak as the boundary shifts east of WI. Most areas will be
dry rest of Wednesday, but a few isolated showers out of some high
based stratocu may fall across northern WI. Rebound day for temps
with readings pushing into the 80s. Soundings and MOS guidance
point to it turning breezy from the west (gusts 25-30 mph) midday
into the afternoon.

4th of July and Friday...Signals in models and ensemble guidance
remain persistent that as shortwave trough digs across the
northern Plains and sfc low spins up over the upper mississippi
river valley by Friday morning, showers will spread west to east
across WI late Thursday afternoon into Thursday night. Heavier
rain likely holds off til late Thursday night into Friday, but
sufficient forcing ahead of the trough and some elevated MUCAPE
justify pops increasing to likely for central WI Thursday evening
while there is still a bit of uncertainty on whether the more
widespread showers reach the Fox Valley and lakeshore areas by
late evening or more so overnight. Looking like widespread showers
are in store for Friday (possible heavy rain again) and with sfc
low tracking across or south of our area, it likely will be another
cooler early July day with highs probably ending up below normal.

Sat-Mon...Pattern remains active with multiple shortwave troughs
and frontal boundaries dropping across the region. There will be a
lot of dry time, but the forecast carries chances of showers
throughout. At this time, Sunday looks like the day with better
chance of more widespread showers. Temps will be at or slightly
below normal.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1024 PM CDT Mon Jul 1 2024

Rain is expected to arrive at the western TAF sites around
07z-08z/Tue and eastern TAF sites 10z-11z/Tue. The steadier/heavier
rain is expected to taper off from west to east during the late
morning and early afternoon on Tuesday, but patchy drizzle or
light showers may continue during the afternoon. Another round of
more significant rain is expected to arrive during the late
afternoon and evening hours as a short-wave trough and resurgent
low-level jet impact the region. There may be a small chance of
thunderstorms during the late afternoon and evening, but
confidence is not high enough to mention any storms in the TAFs.

Flight conditions will deteriorate to MVFR/IFR at RHI/AUW/CWA
late tonight into early Tuesday, and to MVFR at GRB/ATW/MTW in the
late morning and afternoon.

Have continued the mention of LLWS at RHI/AUW/CWA late tonight
into Tuesday morning, but current models suggest the threat will
remain northwest of GRB/ATW/MTW. SE-S surface winds will prevail
through the TAF period, with winds becoming quite gusty during the
day on Tuesday.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Beach Hazards Statement from 7 AM CDT this morning through
Wednesday morning for WIZ022-040-050.
&&

$$

DISCUSSION.....JLA
AVIATION.......Kieckbusch