Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 231809 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1209 PM CST Fri Feb 23 2018

.UPDATE...

Expect gusty west winds with a gradual diminishing trend to sky
cover as drier air works its way into southern WI behind a surface
trough. Clearing skies and light winds turning to the northeast should
allow for some patchy light fog overnight. Low temperatures will
be in the mid 20s.

&&

.AVIATION(18Z TAFS)...

Ceilings will gradually rise through the day and we will see a
clearing trend with the clouds from west to east this afternoon.
Gusty west winds that developed in the wake of a surface trough
this morning will diminish around sunset. Light winds tonight will
veer to the east and increase Saturday morning. There should be
some patchy light fog inland overnight under some clear skies.

There is a chance for some low lake clouds to spread inland
Saturday morning as winds become easterly, but not a lot of
confidence in this yet, so left it out of the TAFs. Look for the
main batch of air to saturate from the top down which means the
rain should be delayed until late afternoon or early evening.
There is a chance for thunderstorms Saturday evening.

&&

.PREV DISCUSSION... (Issued 952 AM CST Fri Feb 23 2018)

UPDATE...

The drizzle and fog are diminishing this morning. Winds are
increasing out of the southeast as the visibilities come up. Winds
in the drier air in the wake of the surface trough are shifting
to the west. Clouds will gradually scatter out from west to east
later this afternoon as drier high pressure works its way in.

MARINE...

The small craft advisory expired early this morning as winds and
waves diminish. We might see a few gusts above 20 knots during the
daylight hours fairly close to the shoreline, but not enough to
keep the headline going.

It`s still looking like a gale event for Saturday night into
Sunday as a strong, compact low pressure system tracks across
southern MN, central/northern WI, and Lake Superior.

PREV DISCUSSION... (Issued 506 AM CST Fri Feb 23 2018)

UPDATE...

Will extend the Winter Weather Advisory til 8 am for Marquette
and Green Lake county til 8 am due to lingering Freezing rain,
especially in Marquette county. Temperatures will continue to
slowly rise.

AVIATION(12Z TAFS)...

LIFR early this morning, gradually improving to IFR this morning
then MVFR this afternoon behind a trough. South winds will become
westerly, with visibilities improving behind the wind shift.

PREV DISCUSSION... (Issued 310 AM CST Fri Feb 23 2018)

DISCUSSION...
Today and Tonight - Confidence is Medium...

Steadier precipitation will exit the areas from the southwest this
morning. Temperatures remain at or slightly below freezing
generally north and west of a line from north of Monroe to
north of Madison to Beaver Dam and Sheboygan. A few hundreths to
a tenth of an inch of additional ice will be possible across this
area before temperatures continue to slowly rise above freezing
during the overnight hours. Further to the east and southeast,
temperatures are above freezing, and will remain there early this
morning. Will leave the Winter Weather Advisory to expire at 6 am.
South portions of the advisory likely just rain, but valley areas
still may have pockets near freezing.

Surface high pressure will build in tonight.

Saturday and Saturday night - Confidence...Medium
Fairly strong southeast flow expected ahead of developing low
pressure. Only the NAM is bringing some lead showers into the area
during the afternoon. Would think some dry influence would be
reinforced so the dry look of the GFS and ECMWF look more
believable at this point. So, will trend the blended pops down
somewhat for Saturday afternoon. A strong negative tilt shortwave
is still on track to trek across the western Great lakes Saturday
evening. Lower level cyclogenesis will be pronounced with a track
that will favor a rain event for our area. Thermal ridge punches
north ahead of the low with 40-50 knot LLJ. Expecting rain to
become widespread Saturday evening with strongest impact from the
DCVA associated with the potent 500 millibar wave. With the
presence of at least some elevated instability will retain the
thunder mention for Saturday evening.

Later Saturday night into Sunday - Confidence...Medium
After the cold front moves through the cold advection regime will
kick in. Precipitation will trend towards a changeover to a mix
and then perhaps a little snow. Looks like minimal accumulation
as best moisture looks to outrun the influx of the more favorable
thermal profiles needed for any kind of long lasting accumulating
snow event. Winds will turn gusty from the west with the cold air
advection regime in place. Still looks like a Wind Advisory may
need to be considered for later Saturday night into Sunday as
strong wind fields and downward momentum transfer will be in
place.

Monday through Tuesday night - Confidence...Medium
Quiet period expected with low level ridging shifting through and
setting up to our east by Tuesday. Lift associated with an 850
baroclinic zone will result in more A frontal boundary and low
pressure The GFS is the more aggressive model with precip, mostly
rain, though some transition to a mix or a little snow possible
Tuesday night.

Wednesday - Confidence...Medium
Brief ridging takes hold so this is looking like a dry day
between two systems.

Wednesday night and Thursday - Confidence...Medium
Both the GFS and ECMWF show another system moving through with the
track suggesting more rain than snow. However the GFS is the
colder solution of the two and suggests a bit more potential for a
mix or some snow, especially on the back side heading into
Thursday night.

AVIATION(09Z TAFS)...IFR/LIFR early this morning, gradually
improving during the afternoon to MVFR. Southeast winds overnight
will become westerly as a front passes through on Friday, with
visibilities improving behind the front.

MARINE...Southeast winds will become westerly and diminish. Waves
will subside due to the diminishing winds and off shore flow.

The next period of concern will be over the weekend, when strong
low pressure is expected to move through the Great Lakes. This
will result in a period of strong easterly winds ahead of the low,
and then strong westerlies behind it. Gales look possible at times
over the weekend and have issued a Gale Watch Saturday evening
into Sunday night.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Watch from Saturday evening through late Sunday night for
     LMZ643>646.

&&

$$

Update...Cronce
Today/Tonight and Aviation/Marine...Hentz
Saturday THROUGH Thursday...Collar



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