Scientific Forecaster Discussion
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Area forecast discussion...updated
National Weather Service Milwaukee/Sullivan WI
754 am CST Tue Jan 23 2018
Flurries are filling in across southern WI right behind the main
area of snow that is finally moving off shore. Just a dusting is
expected through late morning. Rock County did not have the over-
achieving snowfall amounts that southeast WI had overnight, so the
driving conditions are not quite as bad per the Wisconsin 511
webpage. Therefore, I cancelled the Winter Weather Advisory for
Rock County. I left the other counties in there until 10 am to
handle the hazardous driving conditions during the morning
Previous discussion... (issued 549 am CST Tue Jan 23 2018)
Snow is winding down over southeast WI this morning. Expect the
steadier snow to end from west to east through 8 am, with light
snow/flurries lingering a little longer. The snow over-performed
over southeast WI last night. Reports in the Burlington area are
in the 6 to 8 inch range.
Look for winds to increase out of the north through late morning.
Temperatures should remain steady in the upper 20s and lower 30s
today before falling into the teens tonight.
Snow is tapering off from west to east, although expect flurries
through late morning. Northwest winds just off the surface are
around 25 knots. These should start to mix down to the surface as
the snow ends today. Winds will taper off this evening.
Look for clouds to hang around all day. Ceilings are around 1500
feet this morning and should improve to 3500 feet by early
Previous discussion... (issued 310 am CST Tue Jan 23 2018)
Today...forecast confidence is medium.
Snow overspread all of southern WI just after midnight. The
southeast corner near Kenosha was the last hold-out. Heavy, wet
snow is coming down quickly and this area will pick up a total of
2 to 3 inches, locally more possible. The Winter Weather Advisory
in effect until 10 am still looks reasonable. One could argue that
we should have put Jefferson County into it, but the worst is over
there now. It will be a treacherous commute in southeast WI this
morning, as snow is falling on top of puddles that developed from
all the rain yesterday.
The snow is winding down from Juneau to Janesville and west.
There is some concern about a loss of ice crystals in that area,
but so far no observations of freezing drizzle or reduced
visibility or anything. That area will start to saturate back up
to deeper levels as the deformation zone approaches, so the mixed
precip threat is diminishing quickly. Light snow with that
deformation band is expected to diminish as it tracks east, so
only kept a chance for snow through late morning. Confidence on
the end time is low.
Winds are increasing out of the north now, especially where the
snow is diminishing. Cold and drier air will gradually spread
into southern WI today. Temperatures are expected to hold fairly
steady, right around 30.
Tonight... forecast confidence is high.
Low level moisture and clouds will finally scour out overnight,
but a mid level trough will bring more clouds into WI. Despite the
clouds, temperatures will drop into the upper teens to around 20
Wednesday through Friday - confidence...medium to high
quiet period expected with a warming trend. Mid level flow becomes
increasingly anticyclonic into Thursday night with the 500
millibar ridge axis shifting to our east on Friday. Low level flow
turns southerly Thursday night into Friday. This is in response to
the surface high shifting east and a return flow setting up ahead
of low pressure in the northern plains. Should see the highest
temps on Friday with the more amplified thermal ridge ahead of the
approaching cold front.
Friday night through Saturday night - confidence...low to medium
while the GFS shows a more progressive trough and cold front there
is some suggestion by the European model (ecmwf) and Gem to have some energy ride
northeast along a more slowly progressing front to our east. This
would brush the area with some light rain or light snow. The European model (ecmwf)
solution is most pronounced with this scenario and the blended
pops account for this.
Sunday and Monday - confidence...low
the European model (ecmwf) and Gem show a pronounced low level thermal trough in
place with potential for some snow showers or flurries on Sunday
within a lingering mid level cyclonic flow regime. Then they dry
our for Monday. Meanwhile the more progressive GFS has a strip of
light snow arriving into northern/central WI late Sunday into
Monday morning that could clip our far north. Given the varying
solutions will ride with the blended numbers for now.
Aviation(06z tafs)...moderate, wet snow is falling over southeast WI
with 2 to 3, locally higher, snowfall accumulation. This area of snow
will pull off to the east through mid morning, which is slightly
slower than expected.
IFR ceilings expected through early afternoon, with gradual
improvement to VFR late. Clouds will hang around through the
Look for gusty north winds to diminish this evening.
Marine...gusty north winds and high waves will persist into the evening
hours. A few gale force gusts are possible late this morning north
of Port Washington. No change to the timing of the Small Craft
WI...Winter Weather Advisory until 10 am CST this morning for wiz065-
Lm...Small Craft Advisory until midnight CST tonight for lmz643>646.