Scientific Forecaster Discussion
fxus63 kmkx 230156
Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
856 PM CDT sun Sep 22 2019
The heavier/more widespread shower activity is pushing into
western Wisconsin at this hour, and on its current track, should
mainly remain north and west of the forecast area. Lighter, more
scattered activity is moving in from the southwest, and will
impact the region over the next several hours. Rain should
gradually diminish from west to east after midnight.
A cold front will pass through the lake later tonight, bringing
breezy west to northwest winds tonight and tomorrow. Right now,
winds should remain just below small craft levels tonight and
tomorrow for the nearshore. Over the open waters, a few gusts in
the 25-30 kt range are possible at times, though speeds should
generally remain under 30.
High pressure moves through the area Monday night, with southerly
flow returning on Tuesday. Another front will pass through the
lake late Tuesday or on Wednesday, bringing another period of
gusty west winds for later Wednesday and on Thursday.
Previous discussion... (issued 624 PM CDT sun Sep 22 2019)
Warm advection showers are pushing east of the area right now,
with another area of rain approaching from southern Minnesota and
northern Iowa. This activity is associated with the core of the
upper level low, and will move through the region mid to late
Rainfall rates should be fairly low with this activity, as it will
be progressive in nature. As such, suspect that we will be able to
drop at least parts of the Flash Flood Watch early.
Ceilings will remain variable through this evening, with
prevailing MVFR ceilings occasionally reaching both VFR and IFR
levels. An area of rain showers is pushing east of the terminals
right now, with another area of rain approaching from southern
Minnesota and northern Iowa. These showers will move through the
area mid to late evening. An improvement in flight conditions is
expected behind this activity, likely after midnight.
VFR will return to the area tomorrow, with breezy west winds.
Previous discussion... (issued 232 PM CDT sun Sep 22 2019)
Late this afternoon and tonight...forecast confidence - medium to
Will continue Flash Flood Watch across southern and southeast
Wisconsin for now. Large area of light to moderate showers
associated with upstream mid-level short wave should continue to
spread across southern WI next several hours. Fortunately, focus
of low level jet is shifting to the east and south, but will clip
far southeast WI through the early evening. Unseasonably high
precipitable water values will decrease overnight as drier air
surges in from the west. Low level winds will increase from the
west to northwest behind low pressure that will continue to
strengthen and move northeast across northern Illinois this evening.
Additional rainfall of one quarter inch to one inch is expected
from this aftn through this evening, which may yet result in
localized flash or areal flooding. Flash Flood Watch will likely
be cancelled this evening as widespread showers shift off to the
Monday...forecast confidence - medium to high.
Drier air will continue to feed across southern WI on Monday as
breezy west to northwest winds are expected for much of the day.
Lingering low level moisture will likely result in some cumulus
during the day. Temperatures should rebound back into the lower
70s most areas.
Monday night and Tuesday - confidence...medium
surface high to our south will be ridging into the area and may
set up a fog scenario as overall winds will be on the lighter
side. Low levels should be decoupled enough to allow for the fog
with all the low level moisture in place. The 925 winds and the
low level waa doesn't really kick in with earnest until Tuesday.
So will have some fog mention for Monday night. South/southwest
925 winds of up to 35 knots will result in breezy and mild
conditions with highs in the 70s.
Tuesday night and Wednesday - confidence...medium
low pressure will be moving north of the area helped along by a
mid level energy with the greatest punch from that also to our
north. Low level front and at least some influence from that wave
to the north will result in a chance of showers/storms overnight
and perhaps lingering into the morning hours for a time. The GFS
is quicker than the Gem/European model (ecmwf) solutions which hang onto the
precipitation chances longer. For now will keep a chance in the
morning and then dry things out for the afternoon.
Wednesday night and Thursday - confidence...medium
high pressure will build into the area and pass to our east this
period. So dry weather is expected with a return flow evolving by
Thursday night through Friday night - confidence...medium
a return to unsettled conditions is expected as a low level waa/moist
advection ramps up. There may be some breaks in the action at times
on Friday but more storms may fire along cold front Friday
Saturday - confidence...low to medium
model consensus is build high pressure into the area from the
north though some suggestion that frontal boundary could hang up
close enough to keep some precip concern going. The GFS shows a
stronger intrusion of the high into srn WI with a much further
south push of the boundary. This would lead to a drier scenario.
Sunday - confidence...low
models differ on evolution of next low with regards to timing and
placement but a continuation to the active pattern looks likely.
Lots of time yet to sort out the details but for now going with
the blended guidance.