Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 180823
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
323 AM CDT MON JUL 18 2016
.TODAY AND TONIGHT... Forecast confidence - Medium to High.
Weak frontal boundary has just about exited far southeast WI early
this morning. Light surface winds have become mostly west to
northwest which are ushering in slightly lower humidity and
dewpoints. Just above the surface, winds a bit more robust from the
northwest at 10 to 20 knots, lowering the humidity aloft as well.
Low level mixiness also helping to prevent significant fog
development early this morning despite Sunday rainfall. A quiet
period is expected through tonight, but passing cloudiness can be
expected time to time. Occasional passing high clouds due to cirrus
blowoff from upstream convection across northern IA/MN can be
expected into tonight. Also enough lingering low level rh will
contribute to some cumulus development later this morning and
With temperatures starting out mild, expect daytime temps to rebound
into the low to mid 80s. A developing lake breeze will cool shore
areas in the afternoon.
Expect elevated instability and baroclinic zone to remain upstream
across IA extending into central IL through tonight. Hence any
convection to remain to the west and south. Lighter boundary level
winds tonight will allow patchy late night fog to develop. Fog
should be more limited in parts of western CWA due to another bout
of cirrus blowoff affecting this area later tonight.
.TUESDAY AND WEDNESDAY...Forecast Confidence...Medium
Surface high pressure will slide southeastward Tuesday, becoming
centered over the eastern Great Lakes by evening. The surface
high will continue to depart Wednesday, while an upper ridge
builds into the region. Will probably see a wave or two ride
through the top of the mid/upper ridge. Increasing moisture and
warm advection will combine with forcing from the waves to kick
off rounds of storms within the region. Models are coming into
better agreement wave timing/placement...suggesting Tuesday night
into Wednesday may be the best chance for storms.
Temps should be a couple/few degrees above normal Tue and Wed.
.THURSDAY AND FRIDAY...Forecast Confidence...Medium
Could be another round or two of storms late in the week as
disturbances move through the northern periphery of the upper
ridge. Not great confidence in the low pops in the forecast, as it
could easily be dry Thursday and Friday due to capping under the
Higher confidence Thu/Fri remains with temps, as models are
generally in good agreement that it will turn hot and humid.
Timing of any clouds and precip with the weak waves could
certainly throw a wrench in forecast temps either day. Given that
it looks mainly dry for late week though, kept the hot temps
going. Looking increasingly likely that heat headlines may be
needed for both days, with forecast heat indices in the 100 to 105
.SATURDAY and SUNDAY...Forecast Confidence...Medium
The trough and associated cold front are expected to finally move
through on Saturday. Kept some pops going, though not very
impressed with the forcing suggested by models. Looks mainly dry
then Sunday as high pressure builds into the area.
Bumped temps up a bit Saturday with the slower progression of the
trough/front compared to model solutions 24 hours ago. Should see
temps return to near normal Sunday behind the departing front.
Weak frontal boundary exiting far southeast WI has ushered somewhat
less humid air across the area overnight. Light surface winds have
veered to the northwest most areas and surface dewpoints have
dropped a few degrees into the mid to upper 60s. Just off surface,
northwest winds increase to 10 to 20 knots. These conditions will
prevent significant fog from forming early this morning. VFR
conditions expected for the forecast period with few-sct cumulus
developing later this morning and afternoon. Patchy fog more of a
threat late tonight due to lighter boundary layer winds. May put in
some light fog in eastern TAF sites late, but expected high clouds
over western CWA should help prevent fog in this area.
Much lighter winds are expected today. West to northwest winds will
become onshore late this morning and afternoon due to a light
pressure gradient and shore temperatures warming into the 80s.
Breezy southwest winds on Sunday following morning thunderstorms
resulted in upwelling of cooler water temperatures. The Atwater
Buoy located 1.25 miles off northern Milwaukee county continues to
measure water temperatures in the 40s early this morning, which
corresponds with MODIS satellite imagery from Sun aftn. The lighter
winds expected next 48 hours will allow water temperature to recover
in the shallower near shore areas.
TODAY/TONIGHT AND AVIATION/MARINE...MBK
Tuesday THROUGH Sunday...DDV