Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 291125 AAA
Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
625 AM CDT Wed Mar 29 2017
Was tempted to cancel the Dense Fog Advisory for a couple
northeast counties given observations and webcams, but latest
satellite is showing some fog or low cloud development in that
area. Thus figured it was worth keeping those counties in for a
couple more hours until the expiration.
Otherwise, should see the fog hang on in the south half of the
forecast area this morning...winding down around mid-morning. Fog
may keep going into late morning toward Lake Michigan.
Will see fog hang on into mid-morning, possibly into late morning
toward Lake Michigan. Daytime mixing should improve conditions for
Attention then turns to precip ahead of approaching low pressure.
Rain will move into the west by late afternoon, spreading east
across the forecast area during the evening hours. The rain will
persist through Thursday.
Still looks like there could be a mix with or changeover to snow
in the north tonight into Thursday morning, mainly north of a
line from Wisconsin Dells to Port Washington. It will be a
struggle to get much accumulation due to borderline temperatures,
though an inch or so is possible. Snow will transition to rain
everywhere by late Thursday morning.
Lower clouds and visibilities will return tonight into Thursday
with the arrival of the precipitation.
.PREV DISCUSSION... (Issued 326 AM CDT Wed Mar 29 2017)
Today and tonight...forecast confidence is medium to high:
Extended the Dense Fog Advisory farther west per latest satellite
and obs. May need to eventually include the last row of western
counties if this area of fog keeps going. Still looks like daytime
mixing should bring an end to the dense fog by mid-morning, so no
change to the expiration time of the advisory.
High clouds will continue to push in from the west this
morning...with cloud bases gradually lowering into the afternoon as
deeper moisture arrives ahead of approaching low pressure. Tricky
temps today given the current fog/stratus in the area and
approaching clouds. Stuck close to a blend of model temps due to the
Rain is expected to arrive in the west by late this afternoon,
spreading east across the forecast area this evening and continuing
overnight. The rain is still expected to mix with or changeover to
snow in the north. Models have been trending north with this system
the last 24-36 hours though, which has resulted in somewhat lighter
amounts this forecast. Temperatures will be borderline through this
event, so accumulations will struggle where it does snow.
THURSDAY AND FRIDAY... Forecast confidence is medium.
The weakening upper low and surface low will track across Illinois
through tonight. Rounds of light rain are expected across southern
WI Thu and Thu night as waves of vorticity and frontogenesis
spread through the area. Brisk east winds and precip will keep
temperatures raw, with highs Thu in the upper 30s and lows Thu
night in the lower to mid 30s.
There is a chance for some snow to be mixed into the rain early Thu
morning, but temps will warm above freezing rather quickly as the
low gets closer.
Drizzle or light rain is expected to linger all the way through
SATURDAY... Forecast confidence is high.
Drier air with high pressure building into the region on Saturday
will help to scour out the clouds a little. Highs should return to
the 50s inland from the lake.
SUNDAY THROUGH TUESDAY... Forecast confidence is medium.
Another upper low will track from the southern Plains through the
mid Mississippi River Valley over the weekend. The rain with this
system is expected to remain primarily south of the WI/IL border,
but may clip southern WI Mon into Tuesday. Precip type should be all
Fog and low clouds will continue to drift westward across southern
Wisconsin early this morning. Improving conditions are expected by
mid morning on Wednesday with VFR CIGS/VSBYS returning for a time.
Lower MVFR CIGS will stream back in by evening ahead of advancing
low pressure. Precipitation will overspread the area during the
evening. It should remain rain along the WI/IL state line, but
become mixed with or change over to snow for a time north of
Milwaukee and Madison.
Dense fog is likely to continue into mid-morning, so will leave the
advisory as is for now.
Gusty winds and higher waves are likely from this evening into
Friday night as low pressure moves through the region. Have decided
to issue a Small Craft Advisory for this period.
WI...Dense Fog Advisory until 9 AM CDT this morning for WIZ052-
LM...Dense Fog Advisory until 9 AM CDT this morning for LMZ643>646.
Small Craft Advisory from 10 PM this evening to 4 AM CDT
Saturday for LMZ645-646.
Small Craft Advisory from 2 AM Thursday to 4 AM CDT Saturday for
Today/Tonight and Aviation/Marine...DDV
Thursday THROUGH Tuesday...Cronce