Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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408
FXUS63 KMKX 142328
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
528 PM CST Tue Nov 14 2017

.UPDATE...Warm air advection and deeping moisture aiding patchy
light showers and sprinkles development over southern WI last hour
or two. Expanded chance for light rain farther east for the early
evening, but if expansion continues, will be updating again to go
with higher pops for light showers this evening.

&&

.AVIATION(00Z TAFS)...Expect lower ceilings to spread across the
remainder of the CWA during the evening with lower ceilings then
carrying over into Wednesday afternoon. Light fog may return
overnight with the best chance late tonight and Wednesday morning
as the rain diminishes before winds pick up from the west behind
the passing front.

&&

.PREV DISCUSSION... (Issued 254 PM CST Tue Nov 14 2017)

SHORT TERM...

Tonight and Wednesday - Confidence...Medium
A relatively mild and moist southerly flow will remain in place
tonight ahead of an approaching frontal boundary. Rain will
overspread the area and become most widespread a little later on
as mid level energy combines with low level forcing to result in
the greatest forcing. The mild temps will keep the precipitation
in the liquid form. The progs show the front exiting to the east
Wednesday morning so expecting a decrease in rain coverage as the
morning wears on. 925 temps will drop into the negative side of
zero celsius during the afternoon as northwest winds usher in a
period of cold air advection.

Wednesday Night and Thursday...Forecast Confidence is High.

The shortwave over the Great Lakes moves off Wednesday evening.

The southern edge of the stratocumulus should reach into at least
northern and eastern areas Wednesday night.

A mid/upper level ridge and moderate 700 mb downward motion should
then bring a brief period of quiet weather Thursday, with a
surface high moving across Wisconsin.

LONG TERM...

Friday Through Sunday...Forecast Confidence Is Medium...

A strong trough moves across the northern plains and becomes
more negatively tilted. The GFS and Canadian have now trended
toward the slower and slightly weaker trough as it moves across
Wisconsin Friday night/Saturday evening.

A surface low will intensify across the Upper Great Lakes during
this period, but to the east of Wisconsin.

Models are more in line, but the ECMWF is a still a little more
south and a little slower in the cyclogenesis just east of
Lake Huron.

Warm air advection develops Thursday night and begins to bring
more moisture into the region. The GFS has backed off on any
precipitation Thursday night with all models now dry. Rain
develops later friday.

It will be windy, but with a weaker low any wind advisories
are unlikely, but it still may be windy enough over lake michigan
for gales.

Possibility of snow accumulations in our area is low, as by the
time the cold air moves in behind the low, the precipitation is
diminishing.

By Sunday afternoon all models have a surface high across the
Upper Mississippi River region.

Monday and Tuesday...Forecast Confidence Is Medium...

A somewhat cyclonic northwest flow exists across southern
Wisconsin.

A south flow begins sunday night, with a surface low moving across
the lake Superior region Monday night. This then brings some cold
air advection into southern Wisconsin.

AVIATION(21Z TAFS)...

Moist southerly flow continues into tonight
until front passes. While some light rain potential exists early
this evening, more meaningful rain arrives a bit later in the
night as mid level wave catches up with frontal boundary. Meso
progs suggest a window of 06-14z for the most likely window of
rainfall. Plenty of IFR cigs heading this way. Already seeing MVFR
cigs into SC WI. Would expect some IFR vsbys as well as the night
wears on with the rain adding to the moist low levels with the
already higher dew points in place ahead of the front. Once front
moves through Wednesday morning, pops will diminish from west to
east along with an improvement in cigs/vsbys.

MARINE...

6 PM startup for Small Craft Advisory still looks good
at the moment. Southerly winds are evolving on back side of high.
Will continue to monitor the ramp up in speeds for a potential
earlier start time. Frontal passage Wednesday morning results in a
wind shift to the WNW. Winds will remain gusty with highest waves
towards open waters.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory until 8 AM CST Thursday for LMZ643>646.

&&

$$

Update...MBK
Tonight/Wednesday and Aviation/Marine...Collar
Wednesday Night through Tuesday...Hentz



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