378
FXUS63 KGRB 290835
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
335 AM CDT Wed May 29 2024

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Areas of frost are possible late tonight into early Thursday
  morning across far northern WI.

- Due to recent rainfall, a few rivers are expected to remain at
  bankfull but below minor flood stage through late this week.

&&

.DISCUSSION...
Issued at 333 AM CDT Wed May 29 2024

Short Term...Today...Tonight...and Thursday

Frost potential is main concern with return to dry weather in the
offing. Last vestiges of the heavier showers and thunder that
brought heavy rain to parts of east-central Wisconsin Tuesday
afternoon and evening has shifted to south of the area early this
morning. Widespread clouds and a few sprinkles still remain in
the wake of the system that brought the showers. These clouds
extend from central Upper Michigan across northeast and east-
central Wisconsin and will gradually diminish this morning. The
only other blemish on a mostly sunny late morning and afternoon
will be scattered fair weather high based cu developing over
central Wisconsin. Gradient winds will be from north- northeast,
so it will stay cooler lakeside today with highs around 60 into
the lower 60s. Elsewhere mixing to H8 supports highs in the upper
60s to near 70 over parts of central Wisconsin.

Frost still possible for northern Wisconsin tonight. No significant
changes to continuity with lows in the lower to middle 30s which
is also agreed upon by latest MOS guidance. High pressure overhead
with light winds leads to prime cooling potential with low PWATs
helping the cause. Ensemble data not near as bullish on the
potential with NBM probabilities of min temps less than 36F along
the Michigan border barely up to 30 percent with most of the area
less than 10 percent. HREF probabilities check in at 20-30
percent for same thresholds. Given the synoptic setup and what MOS
guidance is showing (as low as 33 at LNL), thinking these
ensembles are underdone. Per coordination with DLH and MQT, will
let dayshift take final crack at location of the frost advisory
headline. Seems at the least Vilas, northern Forest and Florence
counties would be good starting point for an advisory but could
see additional counties as well. Elsewhere, readings will drop
into the upper 30s to lower 40s, warmest near Lake Michigan.

Plenty of sunshine on Thursday as high pressure slowly shifts
east. That high off to the east will result in lake breeze off
Lake Michigan extending as far west as the Fox Valley in the
afternoon. Highs will follow that gradient with readings again in
the low to mid 60s near Lake Michigan, but pushing into the 73-75F
range farther inland where deeper mixing occurs with minimal lake
cooling influence.

Long Term...Thursday Night Through Tuesday

Dry weather will be in place at the beginning of the extended
before more active weather returns again over the weekend into
early next week.

Thursday night through Friday...
Upper riding and surface high pressure will move eastwards
Thursday night, bringing back weak southerly flow by Friday
morning. The warmer air will make for a warmer night than
Wednesday night and will also add a couple degrees to the high
temps, with most of the area likely to get into the middle to
upper 70s. The influx of warmer, more moist air will also bring
some showers with them into western WI. A few of these showers
may yet clip portions of central or north- central WI late in the
day, but most of Friday should remain dry.

Rest of the forecast...As the ridge continues to slide eastwards,
the axis of warmer and more moist air will shift into our neck of
the woods, bringing in a window for scattered light showers
sometime late Friday night through Saturday afternoon. Instability
will be lacking during this period so little to no thunder is
expected, but the early rain and clouds will keep high
temperatures from reaching into the 80s. Sunday has trended drier,
but a few of the long term models still hang on to a couple
showers as a weak shortwave crosses in the afternoon, so kept the
slight pops in place for the afternoon. The drier forecast does
support the warmer temperatures getting into the upper 70s to
lower 80s however. Finally, the next period to watch will be late
Sunday night through Monday morning, which is when models bring
the next clipper like low pressure system through the region, with
the trailing cold front likely to be our next round of widespread
rainfall for early next week.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1000 PM CDT Tue May 28 2024

Isolated showers should end by the beginning of the new TAF
period, as a short-wave trough departs. Clearing has already
occurred over the western part of the forecast area, and should
spread into eastern WI later tonight into early Wednesday. Expect
VFR conditions to prevail, except in NC WI, where patchy ground
fog will drop vsbys to IFR overnight into early Wednesday. Cannot
rule out the potential for fog in east central WI, where heavy
rainfall fell earlier today, but winds should provide enough
mixing to prevent it in most areas. Winds will be from the north
tonight, then gradually veer NE-E on Wednesday.

&&

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

&&

$$

DISCUSSION.....JLA/Uhlmann
AVIATION.......Kieckbusch