Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 250837

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
337 AM CDT Sun Sep 25 2022

(Issued 340 AM CDT Sun Sep 25 2022)

Today through Monday:

Rain continues for parts of the CWA from the northwest to the
southeast. Much of this appears to be training given the pivoting
of the UL closed low over the north central Great lakes. The
forcing has primarily come from the PVA associated with the closed
low aloft. With fairly moist low to mid levels the rain aloft has
been able to fall to the surface. Perhaps some help from the LLJ
but this remains primarily to the southwest where clearer
conditions preside thus the thought is this is almost entirely
driven by PVA. The UL low looks likely to continue to linger in
the region with plenty of forcing remaining. However it appears by
around 12z that moisture could diminish in the upper levels to the
point that showers early this morning should slowly dissipate
from the northwest. This is somewhat complicated because the
dryness may not last as there looks to be some additional moisture
sliding in thereafter that could bring another brief round of
showers sliding across the northern part of the CWA but this
remains more uncertain as the moisture signal remains weak. Given
the pivoting system moisture aloft as well as strong forcing from
PVA from the UL low continues bring at least slight chances for
precip to the eastern but especially northeastern parts of the
CWA. This will be very dependent on UL moisture being available
for at least a period late this afternoon and evening and remains

Overnight into Monday we will very likely see the system finally
slide far enough east to get out of the realm of influence. While
forcing will likely persist with still PVA available, the lack of
moisture will likely keep the area dry. Through the day Monday we
should expect to remain dry though there is some evidence from a
few models suggesting moisture may sneak back west at times that
could lead to a chance for precipitation, but this remains rather
unlikely at this time. Into Monday evening there may be another
wave sliding down from the northwest with some moisture that is
associated with it and is supported with decent low to mid level
moisture. This should allow for additional rain chances though it
does remain uncertain given the potential lack of congruence
between the upper level and low levels.

Otherwise Monday we should finally clear out for a period at least
for much of the western part of the CWA with clouds potentially
lingering in the east. In addition expect cooler temperatures as
higher pressure starts to build in behind the departing low.
Breezy northwest winds are also expected today and will likely
persist through Monday as a result of the increased pressure



(Issued 340 AM CDT Sun Sep 25 2022)

Monday night through Saturday:

While the center of the upper low will gradually shift into
Quebec, the western edge of the upper trough will actually linger
through Wednesday morning. Another reinforcing upper wave is
expected to dive down through southern WI Tue morning and light
rain showers could brush southeast WI once again. With high
pressure over the Plains and low pressure lingering over the Great
Lakes, the tight pressure gradient over Lake Michigan and
southern WI will allow for gusty northwest winds to persist
through Tuesday afternoon.

Tuesday night/Wed morning looks to be the coldest night with calm
winds due to the surface high pressure overhead. The National
Blend of Models (NBM) and ensemble output are starting to agree
on cooler MinT values of 35 or less inland areas of southern WI.
Some areas toward central WI could drop to around 32 degrees. We
have areas of frost mentioned in our forecast and we may need our
first frost headlines of the season.

Temperatures will gradually warm through the remainder of the week
with a dry forecast with a period of ridging overhead.



(Issued 340 AM CDT Sun Sep 25 2022)

Expect MVFR/IFR CIGS to continue through at least the morning
today with perhaps some clearing in the far west. The the system
just pivoting it appears as though low CIGS will dominate the TAF
period through the early parts of the day today before we expect
some steady clearing from the west into later this afternoon and
especially the evening. CIGS should go VFR at some point today
even if we do not fully clear out in the east. Meanwhile early
this morning some VSBY concerns with the rain and patchy fog with
potentially bring some MVFR VSBY but should clear out as rain
pushes out/dissipates and we move into the daylight hours. Chances
for rain this morning and perhaps another brief round later this
morning but overall we should get out of this cloudy/rainy pattern
by this evening. Otherwise winds will pick up from the northwest
later today becoming fairly breezy and potentially remaining so
through Monday.



(Issued 340 AM CDT Sun Sep 25 2022)

Winds across the lake will steadily pick up from the northwest
today as the low pressure departs and high pressure starts to push
in from the west. The low level jet will also bring some breezy
winds aloft that will have the potential to mix down given the
higher low level lapse rates. Most models suggest the potential
for some gales but it does not appear to be consistent and
somewhat dependent on how high we can mix and what that mixed wind
will look like. Overall the gale concern will be from this
afternoon through much of the day Monday before higher pressure
pushes in. Small Craft Advisory remains in effect from 18z today
until 0z Tuesday but may need to be lengthened for a period on the
back end. Lake effect rain showers are expected Monday into
Tuesday as colder air moves in behind the low. Conditions may be
favorable for a few waterspouts during this time period as
well. Strong high pressure expected by Wednesday which should
bring fairly light and variable winds across the lake.



LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...1 PM Sunday
     to 7 PM Monday.



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