Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 242030
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
330 PM CDT MON OCT 24 2016
Tonight and Tuesday...Forecast confidence medium.
High pressure over Minnesota is expected to slide east across the
region tonight. Light winds and mostly clear skies are anticipated,
as the high moves across the area. These conditions should allow
lows tonight to drop into the middle 30s in most inland areas, and
upper 30s near the lake.
Patchy frost can be expected away from Lake Michigan, with areas of
frost in cool spots within low lying areas. Will hold off on a Frost
Advisory for the southeast six counties at this time, though it is
close for Walworth and parts of Waukesha Counties. Evening shift can
re-evaluate need for it.
The high moves out of the region on Tuesday, and allows for east
southeast winds to develop over the area. The NAM remains dry for
Tuesday afternoon, with a fair amount of dry air below the 700 mb
The GFS/Canadian models continue to bring some QPF into the southern
and western portions of the area on Tuesday, with more moisture in
the low levels. They also have the influence of some differential
cyclonic vorticity advection with a passing elongated 500 mb
vorticity maximum. There is some 850 mb/700 mb mid level
frontogenesis response and warm air advection pushing into those
For now, kept lower end PoPs in the western counties later Tuesday
afternoon. However, could see some showers occurring, given the
upward vertical motion fields pushing into the area. These PoPs may
need to be raised in later forecasts for Tuesday afternoon. Highs in
the mid 50s are expected in most areas.
Tuesday night through Thursday...Forecast confidence high.
Models are in good agreement with the track of a shortwave trough
and surface low for this period. The low will track along the WI
and IL border Wed evening reaching near Detroit, MI by 12z Thu.
Widespread rainfall will begin Tue nt and continue for much of Wed
as strong low to mid level warm advection and frontogenesis
progresses across the area. The sly 40 kt llj is the main
catalyst for these processes while overall lift is being aided by
increasing PVA aloft. Strong q-vector convergence is depicted in
the 925-700 mb layer during this time while PWs rise to 1 inch. A
consensus of models yields forecasted rainfall totals around 1
inch in far srn WI to 1.60 inches toward central WI. Cyclonic flow
and stratus clouds will linger on Thu although a weak high
pressure ridge and possibly some clearing may build into the area
late in the day.
.LONG TERM...Friday through Monday...Forecast confidence medium.
The extended models are in better agreement for this period. Sly
flow and strong warm advection is depicted for Fri followed by a
cold front Fri night or Sat in response to low pressure tracking
from the nrn Great Plains through the nrn Great Lakes. Temps will
warm into the 60s on Fri with chances of showers Fri-Fri night.
Nly surface flow and cold advection for Sat-Sat night will give
way to High pressure on Sun. Another round of sly flow and strong
warm advection will occur for Mon-Mon night.
VFR conditions are expected tonight into Tuesday across TAF sites.
High pressure will slide east across the region tonight, before
moving east of the region Tuesday. The high will bring mostly clear
skies into this evening, with middle to high clouds moving east into
the area later tonight into Tuesday.
North to northeast winds will continue to weaken into early this
evening, with light and variable winds tonight. Light east southeast
winds are then expected Tuesday. There is a possibility for rain
showers to affect Madison Tuesday afternoon, but will leave mention
out of TAFs for now due to some uncertainty.
Waves of 3 to 4 feet south of North Point Lighthouse should continue
to slowly diminish by early evening, with weakening winds.
Issued a Gale Watch for 12Z Wednesday to 00Z Thursday across the
nearshore waters of Lake Michigan. There is a good shot at frequent
southeast wind gusts to 35 knot gales during this time, with the
tight pressure gradient and good low level mixing with the passing
low pressure system.
A Small Craft Advisory will likely be needed for a few hours leading
up to the current Gale Watch later Tuesday night. Another may be
needed for Wednesday night, as the high waves slowly subside.
LM...GALE WATCH from Wednesday morning through Wednesday evening for
TONIGHT/Tuesday AND AVIATION/MARINE...Wood
Tuesday NIGHT THROUGH Monday...Gehring