239
FXUS63 KGRB 150317
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1017 PM CDT Mon Oct 14 2024

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Thunderstorms will be possible through this evening, mainly across
  east- central Wisconsin. Small hail will be possible with any
  storm.

- Conditions hazardous to small craft will be likely tonight into
 Tuesday. Waterspouts will also be possible.

- Expect cooler temperatures through mid-week as northerly flow
  ushers in cold Canadian air. As temperatures fall into the low
  to middle 30s, a Frost Advisory or Freeze Warning may be needed
  over east-central Wisconsin on Tuesday night, where the growing
  season has not concluded. Frost will also be possible
  Wednesday night.

- Temperatures are then expected to undergo a warming trend from
  mid-week through the weekend. High temperatures are forecast to warm
  to 10 to 20 degrees above normal from Friday through Sunday.

&&

.DISCUSSION...
Issued at 250 PM CDT Mon Oct 14 2024

Short Term...Tonight and Tuesday

A sharp upper trough dropping south across the region will produce
showers and isolated thunderstorms this afternoon and evening.
Cold temperatures aloft and steep low level lapse rates may be
enough to get some small hail. The activity should diminish by
late evening, but some lake effect rain and snow showers are
possible near thE Michigan border, and some lake effect rain
showers in the lakeshore counties. Lows tonight will be a degree
or two below normal.

Lake effect showers may continue near Lake Michigan Tuesday morning.
Then clouds will diminish over much of the area in the afternoon.
Highs Tuesday afternoon will be 5 to 10 degrees below normal.

Long Term...Tuesday Night Through Monday

After a brief period of consolidation between the northern and
southern streams early this week, split flow returns for the latter
half of the week as energy digs into the desert southwest.  With an
amplifying upper air pattern, a downstream ridge will intensify over
the Great Lakes on Thursday and Friday before flattening out
somewhat this weekend. As a result of this ridge, above normal
temperatures are forecast to return while precip amounts are likely
to remain below normal.

Precipitation chances:  Wisconsin will mostly be positioned between
high pressure to the east of the region and a cold front over the
Plains.  Northern stream energy moving across Canada will give the
front a push to the east, which is forecast to move into Wisconsin
on late Friday night into Saturday.  Precipitable water values will
climb to 150-160% of normal along the front, which is favorable for
showers. But precip amounts are likely to remain light as
convergence along the boundary and upper level supp
ort are
relatively week.

This is likely to be the only chance of precip in this part of the
forecast as the upper level ridge reasserts itself late in the
weekend into early next week.

Temperatures:  High pressure will be sliding south of the region on
Tuesday night.  While boundary layer winds will not make it an ideal
radiational cooling night, forecast low temperatures are forecast to
fall into the lower to middle 30s over the Fox Valley and parts of
the lakeshore where the growing season has not technically ended.  A
Frost Advisory or Freeze Warning may be needed.

Thereafter, winds back around to the south which will lead to a
warming trend into the weekend.  Temperatures in the 50s on
Wednesday will warm into the middle 60s to near 70 by Friday and
Saturday. South winds will be breezy with gusts to 25 or 30 mph.  A
Small Craft Advisory will likely be needed at times.

Temperatures will remain 15 to 20 degrees above normal for the end
of the weekend into early next week.

Fire Weather:  Most of northern and eastern WI have received
beneficial rainfall over the past 48-72 hours.  However, warming
temperatures, gusty south or southwest winds, humidities in the 30-
40% range, and long term dry conditions could lead to elevated fire
weather conditions on Thursday and Friday.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1009 PM CDT Mon Oct 14 2024

The showers have come to an end across most of the area during
the evening. The only exception was across the far north and near
the Bay of Green Bay and Lake Michigan where the showers are
expected to continue for a few more hours. Latest model guidance
is suggesting the precipitation should remain east of KGRB, thus
will keep the TAF site dry overnight. KMTW should see on and
off shower activity until 09z until winds back to the north. The
gusty northerly winds across eastern Wisconsin are a little slower
to materialize during the evening, but should pick up early
Tuesday morning. Gusty winds are expected on Tuesday, with gusts
of 20 to 25 knots under VFR conditions. The sky will clear out
late Tuesday afternoon or early evening along with winds
diminishing.

&&

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

&&

$$

DISCUSSION.....RDM/MPC
AVIATION.......Eckberg