Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

000 
FXUS63 KMKX 181746 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1246 PM CDT Fri Oct 18 2019

.UPDATE...

The forecast is on track for today. The front that will bring a
round of rain showers tomorrow keeps slowing down. The showers
should arrive after noon in Madison now and not until early
evening in Milwaukee as the line gradually dissipates. 

&&

.AVIATION(18Z TAFS)...

Thin cirrus is streaming across southern WI this afternoon and
this will persist into the evening. Look for the steady southerly
winds to diminish this evening. 

Strong winds just above the ground due to the low level jet will
develop later this evening for inland areas and diminish Saturday
morning. Thus, LLWS is included in the MSN TAF but left out of the
other TAFs.

A weakening front will track from west to east through southern
Wisconsin Saturday afternoon. The timing of the showers associated
with this front is later than previous forecasts. Showers will be
dissipating as they reach Lake Michigan.

&&

.PREV DISCUSSION... (Issued 853 AM CDT Fri Oct 18 2019) 

UPDATE...

Cold start this morning across southern WI with more widespread
frost than previous nights. Satellite is showing a thin veil of
high clouds spreading into the area but this should have a minimal
impact on temps. With more sun than clouds today and increasing
WAA, temps should not have a problem warming into the upper 50s 
to lower 60s. Ended up nudging highs up a degree or two from
previous values. Otherwise the forecast is on track. 

MARINE...

Winds increase out of the south today as a system moves into the
plains. A Small Craft Advisory is in effect for the northern
nearshore waters as waves build to 4 to 6 feet tonight. The
forecast is on track and no updates are needed at this time. 

PREV DISCUSSION... (Issued 321 AM CDT Fri Oct 18 2019) 

DISCUSSION...

Today and Tonight...Forecast Confidence is High...

A mostly quiet day is expected with dry conditions continuing as
high pressure pushes east allowing lower pressure to move into the
region. This will increase our pressure gradient across the 
region allowing winds to pick up through the day. Particularly, 
winds will be strongest further west especially with a fairly
strong LLJ to our west. With increased mixing down of this air 
increased winds and temperatures are expected further west.

Into the overnight period an upper level shortwave will begin to
push east toward the region. This will be co-located with plenty 
of low/mid level moisture. Thus, showers will likely be present to
the west but will not likely reach the area during the overnight
period.

Saturday and Saturday night...Forecast confidence is high. 

Timing for the line of showers along and ahead of a cold front 
has slowed from the previous forecasts. It looks like they may 
just be reaching Madison around mid day and Milwaukee toward late 
afternoon, possibly even early evening. The line of showers will 
be weakening as the parent low continues to lift northeast into 
Canada and the front gradually washes out. Given the slower
timing, will linger some small pops across the southeast into the
evening. Things look fairly stable, so no thunder will be
mentioned. We dry out for the remainder of Saturday night. 

Sunday...Forecast confidence is high. 

It still looks like a nice fall day with dry conditions and mild
temps in the lower 60s. 

Sunday night through Tuesday...Forecast confidence is high. 

A strong October storm system will track from Nebraska to western
Lake Superior from Sunday afternoon through late Monday night.
There are some track differences between the GFS and the ECMWF,
but not significant for southern Wisconsin. Our wettest period
with this system will be associated with an occluding frontal
boundary pushing across the area on Monday. There is some 
elevated instability, so will continue the small mention of 
thunder. The ECMWF is a bit slower than the GFS, resulting in 
some minor timing differences. The various model QPF is running
in a rather tight range...about 0.30-0.50". Plenty of clouds and
some lingering light rain or drizzle could persist through Tuesday
as this very wound up system lifts slowly northeast into Canada. 

Wednesday and Thursday...Forecast confidence is medium. 

We should dry out for Wednesday as the large storm exits and high
pressure briefly moves through the area. There is decent cold air
advection across the region, so highs will only be in the low to
mid 50s. Thursday into Friday of next week is a toss up with
little confidence at this point. The GFS and the ECMWF aren't in
good agreement. The EC has a sfc low lifting across southern
Wisconsin later Thursday into Thursday night, while the GFS has a
weak trough well south of Wisconsin. The EC looks wet, while the
GFS is generally dry.  More later. 

AVIATION(09Z TAFS)...

High clouds move in this morning and may linger during the day, 
with a few diurnal cumulus clouds possible. Light and variable 
winds will strengthen from the south, becoming gusty in the 
afternoon. The highest gusts around 25 knots will be west of 
Madison. Winds should become southeast by early this evening, 
with some gusts to around 15 knots lingering. Low level wind shear
conditions should develop tonight, with southwesterly 2000 foot 
level winds in the 40 to 45 knot range.

MARINE...

Some breezy southeasterly winds will develop across the lake 
today with strongest winds in the west/northwest parts of the 
lake. As winds shift to the south the strongest winds will mainly
be in the northern half of the lake through Saturday. This will 
increase waves to 5-7 feet through the day Saturday. This will
bring the northern nearshore area to 4-6 feet waves from 21z today
through 21z Saturday and addition to some stronger winds earlier 
in this period. Thus a Small Craft Advisory has been issued for
Port Washington to Sheboygan for this period. 

Generally, conditions will quiet down into Sunday with waves and
winds settling. However, another system will begin to push in 
overnight Sunday into Monday initially bringing breezy
southeasterly winds that could approach Gale force. The front with
this system will push through overnight Monday however winds will
remain breezy from the west with continuing potential for gale
force gusts through Tuesday. Winds will settle some by Wednesday
morning but will remain somewhat breezy. This period will see
wave heights from 6-10 feet across parts of the lake.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory from 4 PM this afternoon to 4 PM CDT 
     Saturday for LMZ643.

&&

National Weather Service Glossary of Abbreviations