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Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
1113 PM CST Mon Nov 11 2019

Update...

No changes to the forecast. Cold and windy conditions will
continue through the overnight hours.

&&

Aviation(06z tafs)...

Mostly clear skies are expected through Tuesday afternoon. Winds
overnight will remain gusty from the northwest, though the gusts
should start to settle down toward morning. Breezy northwest winds
will gradually weaken and become more westerly with time on
Tuesday, before becoming light by early Tuesday evening. Winds
will eventually turn to the south and southwest late Tuesday
night, increasing as we head into Wednesday morning.

&&

Previous discussion... (issued 911 PM CST Mon Nov 11 2019)

Marine...

Gusty northwest winds will continue across Lake Michigan tonight
into tomorrow morning. The Gale Warning for the south half of the
open waters is now in effect through 9 am. A Small Craft Advisory
continues for the nearshore.

High pressure will move through the Ohio Valley tomorrow, with
winds gradually decreasing tomorrow afternoon and night. However,
they will quick switch around to southerly by early Wednesday
morning, becoming quite gusty through the day. A few gale force
gusts aren't out of the question during this time.

A trough will pass through the western Great Lakes Wednesday
night, diminishing and veering winds to the west northwest by
Thursday morning.

Previous discussion... (issued 307 PM CST Mon Nov 11 2019)

Short term...

Tonight and Tuesday...forecast confidence is high.

A strong, cold Canadian high pressure system will slide through
the Central Plains tonight, then east across the southern Great
Lakes and Ohio Valley later Tuesday into Tuesday night. The main
story with this massive ridge is the cold airmass. The diurnal cumulus
that developed this afternoon, in the sunshine behind the cloud
shield from today's system, will dissipate this evening. Winds
will decouple and temps will radiate out under clear skies with
very low dew point air. The forecast lows tonight would break
record lows for November 12th. Highs in the teens on Tuesday may
break a few low maximum temperature records. Bundle up.

Tuesday night through Wednesday night...forecast confidence is
high.

Warm air advection develops Tuesday night, as the core of the
Arctic airmass begins to move out of the area. Lows should occur
by later Tuesday evening, then slowly rise with the warm air
advection intensifying and clouds moving into the area later
Tuesday night. Model certainty still shows high confidence in
single digit lows, close to but may not be cold enough to record
lows.

Another round of accumulating snow looks to occur for mainly
Wednesday afternoon and evening across the area. Models are
generally showing the warm air advection and low level jet nose
transporting deep moisture into the area Wednesday morning, with a
round of low to mid level frontogenesis response moving through
the area during the afternoon. There is some upper divergence from
broad jet coupling.

The main 500 mb shortwave trough slides just south of the area
later Wednesday afternoon and evening, though there will be some
differential cva to help with upward vertical motion. All snow is
expected once again, within the cold airmass lingering over the
region.

The deterministic models have trended higher with quantitative precipitation forecast amounts with
this system, with the ensembles a little lower. Used the ensemble
model output of around 0.10 inches south to around 0.18 inches
north as a baseline for quantitative precipitation forecast for this event. This was somewhat
close to the wpc/consall blend for quantitative precipitation forecast and around the 50th
percentile per model certainty. Slrs should be relatively high,
in the 14/17 to 1 range.

Snowfall totals of 1 to 2 inches south, to 2 to 3 inches north
are forecast, which was also around the 50th percentile. Given the
trend with the model quantitative precipitation forecast with the past couple of snow events,
these amounts may trend upward in later forecasts. This would
impact the evening commute on Wednesday, so will have to watch
this in later forecasts for possible headlines. Temperatures will
modify slightly, but continue to be well below seasonal normals.

Long term...

Thursday through Saturday...forecast confidence is moderate.

Things should dry out Thursday into Thursday night, with high
pressure passing by to the southwest of the region. Temperatures
will slowly modify, but remain well below seasonal normals.

A cold front tries to push southwest into the area Friday into
Friday night, as high pressure moves southeast across Lake
Superior and north of Lake Huron. It looks fairly dry during this
period, with winds shifting onshore. The influence of the high to
the east of the region Friday night into Saturday should keep the
area dry, with winds gradually veering southeast. Temperatures
will continue to slowly modify, perhaps reaching above freezing
for highs by Friday and Saturday. This is still well below normal.

Saturday night through Monday...forecast confidence is moderate.

Models suggest that an amplified 500 mb shortwave trough moving
eastward through the region Sunday night, with another in its wake
for Monday. Very gradual warm air advection Saturday night into
Monday may occur, with perhaps enough column moisture for some
rain/snow chances at times. Temperatures will slowly modify but
remain below normal.

Climate...

This period of cold air will bring the potential for near record
to record cold to the region. Here is a run down of record lows
and record low Max temperatures. Current forecasts are in
parentheses.

Milwaukee:

Date record lowrecord low Max

11/11 15 (14) 26 (24)
11/129 (10) 23 (20)
11/13 5 (9)

Madison:

Date record low record low Max
11/11 9 (10) 23 (23)
11/12 7 (5) 16 (19)
11/13 2 (7)

&&

Mkx watches/warnings/advisories...
WI...none.
Lm...Gale Warning until 9 am CST Tuesday for lmz080-669-671-673-675-
777-779-870-872-874-876-878.

Small Craft Advisory until noon CST Tuesday for lmz643>646.

&&

$$

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