Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 270804
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
304 AM CDT Mon Mar 27 2017
TODAY and TONIGHT...Forecast confidence is medium.
With light winds and ample low level moisture, expect areas of fog
early this morning. Do not think dense fog is high enough of a
possibility for a dense fog advisory. The baggy surface pressure
gradient will remain over southern Wisconsin through afternoon as
another surface low approaches and winds become northeast. Best
chance for rain will be in southeast WI during the afternoon and
early evening as upper level divergence increases ahead of the upper
shortwave that moves across Illinois later this afternoon.
Forecast soundings show moisture trapped beneath a low level
inversion, so the low clouds will continue.
TUESDAY AND WEDNESDAY...Forecast confidence is medium.
Zonal flow aloft will gradually turn northwest as a ridge builds
into the region. The ridge axis will be over southern Wisconsin by
Wedensday morning, and there is some evidence that a weak shortwave
will move through just behind the ridge axis.
Closer to the surface, strong high pressure will build into southern
Canada, placing southern Wisconsin solidly within anticyclonic flow.
RH fields in the lower levels dry out from north to south on
Tuesday, and should stay dry until moisture begins to build into
the SW on Wednesday afternoon ahead of a developing low pressure
system over the Great Plains. Tuesday afternoon should end up
pretty sunny, but unfortunately an area of high RH in the upper
levels of the atmosphere is progged to move over southern WI on
Wednesday, so it looks like we will have increasing cloudiness on
GFS/NAM are both hinting at a secondary surge of cold air pushing
south through the state on Tuesday. The signature is pretty messy,
but there is some coherent fgen bands and locally strong CAA
present in both models. Will leave this out of the forecast for
now, but if this does happen, temperatures will obviously need to
be adjusted downward. Additionally,with easterly winds through
the period, lakeside locations will remain cooler than spots
WEDNESDAY NIGHT THROUGH FRIDAY...Forecast confidence is medium.
Differences in model solutions remain, but overall guidance does
seem like it`s beginning to zero in on a consensus. Cutoff low
aloft/low pressure at the surface over the southern plains on
Wednesday will move to the northeast, reaching the eastern Great
Lakes by Friday evening. The GFS forecast, which was previously
tracking the low south of the Ohio river is now much farther north,
more in line with the Euro/Canadian. If anything, the Euro now
appears to be somewhat of an outlier, pushing the system through
the area a bit faster than the GFS/Canadian.
Regardless, precip is likely on Thursday as the warm front extending
from the low moves into the region. Precip could end as early as
midnight on Friday if the Euro is to be believed, and as late as
Friday night as shown by the Canadian. Temperatures will start out
right around freezing on Thursday morning, so those will have to be
watched closely. Given the warm air aloft associated with the warm
front, we may see a wintry mix situation play out on Thursday
morning before switching to rain in the afternoon. If rain does
linger into Friday, another round of wintry precipitation would be
possible in the morning.
SATURDAY THROUGH MONDAY...Forecast confidence is low.
The models bring another northern stream shortwave through the area
on Saturday as another cutoff low develops in the desert southwest.
Surface low pressure will likely develop somewhere in southern
Canada over the weekend, but there is not enough of a consensus to
get a good idea of where that will be, where it will track, and when
it will happen.
Widespread rain is winding down now in the northeast forecast area
with just a little drizzle to linger into early tonight. Could see
a little light rain brush the southeast tomorrow afternoon, but
otherwise it will be drier tonight into Monday.
Low clouds will persist into Monday. Could see some low
visibilities again tonight into Monday morning given the recent
rainfall and light to calm winds at the surface. Seeing a few
lower observations developing in the southern forecast area, but
nothing widespread thus far. Will continue to keep an eye on the
potential for dense fog into Monday morning.
With low level moisture and light winds in place, will leave the
end time of the Dense Fog Advisory, although weak northwest winds
will likely keep the thicker fog towards open waters.
Gusty north winds with high pressure centered north of lake
Superior, will likely bring Small Craft Advisory conditions back
into the area late tonight and especially Tuesday and Tuesday
LM...Dense Fog Advisory until 10 AM CDT this morning for LMZ643>646.
Today/Tonight and Aviation/Marine...Hentz
Tuesday through Sunday...BSH