Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 221648 AAA
Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1148 AM CDT SAT OCT 22 2016
Area of clouds will continue to gradually move east of the area
into early this afternoon. Mostly sunny skies are then expected
for the rest of the day. Southwest winds with warm air advection
should bring highs into the upper 50s in the eastern counties, to
the lower 60s in the western counties.
A few clouds may move through the area overnight tonight, with
light winds. Milder lows are expected, with upper 30s to lower
40s in most areas.
Low pressure will then slide east southeast across the region on
Sunday, bringing a cold front southward into the area during the
afternoon. The airmass is expected to remain relatively dry during
this time. There should be some low clouds that slide southeast
into the area behind the front during the afternoon. Leaning
toward keeping the area dry during this period.
VFR category clouds are expected to slide east of the area by
early this afternoon. Mostly sunny skies are then expected for the
rest of the day. Light southwest winds are expected into this
afternoon. A few gusts to 15 knots are possible.
A few clouds may move through the area tonight. Light winds may
allow for light fog in low lying areas, but TAF sites should have
visibilities in VFR category.
Low pressure will slide east southeast across the area Sunday,
with a cold front sliding south into the area during the
afternoon. Light southwest winds in the morning will veer
northwest to north by later in the afternoon. Some gusts to
around 20 knots are possible as well.
A tightening pressure gradient behind a passing cold front later
Sunday afternoon into Sunday night may allow for northwest to
north gusts up to 22 knots. Waves will build to 2 to 4 feet Sunday
night and linger into Monday morning, highest south of North Point
Lighthouse. A Small Craft Advisory may be needed for late Sunday
afternoon into Monday morning.
.PREV DISCUSSION... /Issued 330 AM CDT SAT OCT 22 2016/
TODAY AND TONIGHT...Forecast Confidence Is High.
Added some sprinkles to the northern counties between 09Z and 12Z as
a few drops may survive to the surface per low condensation pressure
deficits coincident with isentropic adiabatic omega noted on
isentropic surface forecasts associated with 850-700mb warm
advection. Once the mid-level warm advection clouds clear the area,
expect mostly sunny skies. Winds come around to the southwest as
surface ridge axis shifts east, with 925 mb temperatures rising
about 4c-5C through the day, so highs should reach the low 60s in
the west, with mid-upper 50s in the east where clouds do not clear
until early afternoon.
Weak surface pressure gradient and clear skies allow surface winds
to decouple but some mixing as near-surface inversion will be
shallow. Enough surface moisture advection ahead of Plains
cyclogenesis as ridge shifts to the eastern Great lakes will help
hold low temperatures close to the upper 30 to low 40 dew points.
SUNDAY - Confidence...Medium
500 millibar shortwave will be racing southeast from nrn MN to lwr
MI. Surface low and attendant cold front proggd to shift through srn
WI from late morning into the afternoon hours. Winds shift north and
925 thermal profile cools a bit though better dropoff holds off
until Sunday night. So for the most part we are seeing 925 temps in
the 8-10c range with a little more cooling noted on the GFS prior
to 00z. So will keep the mild 60s in place. Model qpf stays to our
north closer to forcing associated with 500 vort so will keep the
dry forecast intact.
MONDAY - Confidence...Medium
A large surface high will dominate. The 500 millibar flow will be
northwest with an anticyclonic curvature. A cooler airmass will be
in place with highs back into the 50s.
TUESDAY THROUGH WEDNESDAY NIGHT - Confidence...Medium to High
Models have been pretty consistent with the evolution of a wet and
unsettled period. Surface high shifts east on tuesday though
lingering anticyclonic influence/dry feed may hold off precip
advancement for a time, however models do show the development of a
warm advection wing that may shift into portions of the southern and
western cwa during the afternoon. Potent shortwave enhances
cyclogenesis Tuesday night into Wednesday across Iowa. Moisture feed
will be enhanced by a strengthening 850 LLJ. Some variations on
track of 850/surface low though models all show and have
consistently showed a wet day for Wednesday and continuing into
Wednesday evening as 500 millibar wave and associated lower level
forcing lingers. So high POPS are in place with potential for
locally heavy rainfall as well. Found little evidence for thunder on
THURSDAY - Confidence...Low to Medium
Significant differences on mid level flow. The GFS cuts off 500
millibar low in mid miss vly with the ECMWF showing a more
progressive trough across the western Great Lakes. Meanwhile the
GEM shows broad ridging. Despite these differences there is still
evidence to support at least some morning shra across the ern cwa
during the morning. So will keep the Superblend pops in place to
account for this lingering potential.
FRIDAY - Confidence...Medium
Still quite a bit of variation in the mid level flow pattern with
the ECMWF showing a northwest anticyclonic flow and the GFS showing
a southwest flow with broad ridging with 582DM heights. Much more
of a bump in temps following the GFS with 925 temps back over 10c
while the ECMWF more like 5-6c. Superblend pops are dry and looks
good since either model scenario would yield that solution
despite the differences.
AVIATION/12Z TAFS/...VFR conditions expected through he forecast.
Broken to overcast mid level clouds should move east of the area
by early this afternoon. Light winds will turn southwesterly at 10
to 15 knots this afternoon, then lower this evening and overnight.
MARINE...Little to no issue with winds and waves until Sunday
afternoon when winds swing around to the north and increase to
near Small Craft Advisory levels. The persistent northerly fetch
will likely build high waves by Sunday evening into Monday morning
before winds ease with broad high pressure building into the
TODAY/TONIGHT AND AVIATION/MARINE...REM
Sunday THROUGH Friday...Collar