628
FXUS63 KGRB 191948
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
248 PM CDT Sat Oct 19 2024

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Conditions hazardous to small craft possible later this
  afternoon through tomorrow morning along the northern nearshore
  waters of Lake Michigan due to building waves. A Small Craft
  Advisory has been issued.

- Light showers possible across the far north later this evening.

- Well above above temperatures through Tuesday. Near record temps
  Sunday and Monday, with localized readings of 80 degrees
  possible from central Wisconsin to the Fox Valley.

- Next chances for rain arrive Tuesday night into Wednesday.

&&

.DISCUSSION...
Issued at 247 PM CDT Sat Oct 19 2024

Short Term...Tonight and Sunday

A broken mid-level cloud deck began to build in from the north
and west this afternoon as weak warm air advection and narrow
corridor of moisture made their way into northern Wisconsin.
Frontal boundary remained stalled across central Minnesota to
western Lake Superior. Afternoon temperatures read mainly in the
upper 60s to low 70s as 950 mb temperatures warmed to around 15C
and mixed down to the surface. Cloud cover kept temps at bay in
the mid 60s across north-central Wisconsin.

Expect upper-level flow to remain split, with the northern
stream/westerlies along the US/Canada border and a cutoff low
sitting and spinning over the Four Corners. The closed upper low
will eject a weak shortwave into the upper Mississippi Valley
later this evening, carrying low-end chance PoPs across north-
central Wisconsin as the trough axis works over the north. Any
shower activity is expected to be light and short-lived as it
contends with dry air/high pressure to the south and east.

Tomorrow will be slightly warmer than today as we remain caught up
under south/southwesterly return flow from high pressure over the
Ohio River Valley. Highs in the mid to upper 70s remain in the
forecast, with localized 80 degrees possible in central Wisconsin
tomorrow afternoon. Record highs should be safe, although some
locations in the Fox Valley will be cutting it close. Winds will
begin to ramp up late tomorrow morning and early afternoon as the
pressure gradient tightens up along the northwest quadrant of said
high pressure. With decent mixing on tap, 900 mb winds between 35
and 40 knots should be able to make it down to the surface,
resulting in potential for gusts of 25 to 30 mph.

Long Term...Sunday Night Through Saturday

Record to near-record warmth will continue early in the week along
with dry weather as a high pressure remains across the Ohio
Valley. A cold front will bring the chance for rain and cooler
temperatures to the region Tuesday night and Wednesday. Despite
the rain showers, QPF amounts will be rather light with total QPF
during the event expected to stay well below 0.50 inches as
probabilistic ensemble guidance indicates the chance of exceeding
this amount is rather low (around 10 percent across the far
north). Therefore, the drought is expected to continue across the
region or even expand.

Behind this departing cold front, dry weather will return on
Thursday as a ridge of high pressure tracks across the western
Great Lakes. Although cooler temperatures are anticipated, they
will still be around normal for this time of year.

A weak cold front will bring another small chance (around 20
percent) for rain to the region Thursday night and Friday. This
front will be lacking strong upper level dynamics and moisture;
therefore, very little to no precipitation is anticipated with
this cold front. Temperatures will also creep up to a few degrees
above normal by the end of the week.

Another weak cold front is expected to track across the region
sometime next weekend. The timing of this front is still
uncertain, so it is difficult to pin down what part of next
weekend will be dry and what part will have rain showers. At this
time the chance for rain next Saturday is low (15 to 30 percent),
but that could change in subsequent model runs. Temperatures
should also stay above normal for the first part of next weekend.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1224 PM CDT Sat Oct 19 2024

Expect VFR conditions through the end of the TAF period as high
pressure influences us from the southeast. A broken mid-level
cloud deck began to build in from the north and west early this
afternoon, although ceilings remained around/above 10k ft. Mid
clouds will continue to increase from north to south through this
evening, impacting primarily the western TAF sites. Opted to carry
a PROB30 mention at RHI to cover any light rain potential late
this evening, although confidence in any showers reaching the TAF
site is low. Southwesterly winds then diminish overnight, setting
the stage for LLWS concerns based at around 1 to 2k ft as a 50
knot nocturnal low-level jet works its way over northern
Wisconsin. LLJ then weakens late tonight, ending LLWS from west to
east by mid-morning tomorrow.

&&

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

&&

$$

DISCUSSION.....Goodin/Kurimski
AVIATION.......Goodin