Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 201442 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
942 AM CDT Wed Jun 20 2018

.UPDATE...

Showers continue to move in from the west, so have bumped up rain
chances accordingly. This wave of precip should move through by
early afternoon, with mainly dry weather expected mid afternoon
into early evening. There are a few pockets of clearing in the
general area, so not out the question that the sun pops out later
today in some locations. Did bump highs down a bit given the
current extensive cloud cover...but held back on a big adjustment
given the potential for some sunshine.

&&

.MARINE...

Fog has diminished per webcams, so will be letting the Dense Fog
Advisory expire.

Could see waves approach 4 feet Thursday night into Friday
morning, particularly from Milwaukee southward. Otherwise, winds
and waves will stay on the low side into the weekend.

&&

.PREV DISCUSSION... (Issued 628 AM CDT Wed Jun 20 2018)

UPDATE...

Upstream precipitation, forced by the front that has been across
the region for the last few days and perhaps some subtle
differential divergence, has pushed further east than anticipated.
This precip may continue to push into southern Wisconsin as the
aforementioned upstream forcing is also in place across the CWA.
However, HRRR continues to indicate a diminishing trend in this
precip moves to the east, so my confidence in the precip impacting
the CWA is not particularly high. Nonetheless, I will be adjusting
PoPs in our west upward to account for the approaching
precipitation.

AVIATION(12Z TAFS)...

Cigs have generally dropped to LIFR across much of southeastern
Wisconsin, and high res guidance is indicating that the LIFR cigs
will persist for the next few hours. Beyond that, there is a
strong signal that cigs will gradually improve through the
morning, eventually reaching VFR by mid afternoon.

Otherwise, the focus of the forecast is on precipitation
potential. High res guidance has persistently indicated precip
across NE IA/SE MN will fall apart before reaching southern WI.
However, the precip has already reached farther east than
previously indicated, so confidence in the high res solution is
not high. Therefore, precip chances may need to be adjusted
upward, especially in the west.

PREV DISCUSSION... (Issued 338 AM CDT Wed Jun 20 2018)

SHORT TERM...

Today and Tonight...Forecast Confidence is medium...

The stalled front that brought the dreary weather yesterday
remains in place has resulted in blossoming light showers across
much of southern Wisconsin. These showers, which appear to have
little support other than the front, are not being handled well
by the high res guidance. Given that the front is not going
anywhere this forecast period, I have a hard time buying the dry
forecast advertised by most of the meso models. Therefore, I have
included slight chance pops through 18z. After 18z, the low
levels should begin to dry out somewhat and my confidence in
precip decreases to the point where a dry forecast seemed
appropriate. Otherwise, mostly cloudy skies and continue easterly
flow should again result in cool temperatures.

LONG TERM...

Thursday through Friday... Forecast confidence is medium.

A closed upper low will track through Iowa on Thursday, northern
Missouri Thursday night, and central Illinois on Friday. Southern
WI will be on the northern fringe of the showers and thunderstorms
associated with this system. There is minimal instability in this
moist atmosphere, so expect periods of rain and isolated thunder.
We are not expecting heavy rain due to our distance from the main
forcing of the low pressure system.

Expect clouds and cool temperatures to stick around through the
end of the week. Persistent easterly winds will keep lakeshore
areas cooler than inland, although clouds will cause the whole
area to have below normal temperatures.

Saturday through Sunday... Forecast confidence is medium.

The upper low will weaken as it slides through the Ohio River
Valley over the weekend. Southern WI will transition from cyclonic
flow to general high pressure with very weak flow and weak
instability. We will still be in a moist air mass, so there is
still a small chance for random showers and maybe a rumble of
thunder. Intermittent sunshine will warm us up into the upper
70s.

Monday and Beyond... Forecast confidence is medium.

The next low pressure system will approach WI from the northern
Plains early next week and bring showers and thunderstorms back
into southern WI by Tuesday morning. The ECMWF and GFS agree that
it will slide across WI and bring thunderstorm chances through Wed
night.

AVIATION(09Z TAFS)...

We`ll remain socked in beneath stratus all morning and into the
afternoon, with cigs gradually increasing though the day. High res
forecast guidance is in good agreement, showing cigs in the LIFR
to IFR range through the early morning hours. The past few hours
of observations show cigs across the area in IFR more often than
LIFR, so have kept cigs at all TAF sites above 500 ft. However, I
do expect cigs to continue to sporadically jump between LIFR and
MVFR. By mid morning, all sites should begin to improve, reaching
VFR by the late afternoon. Otherwise, isolated light showers will
likely continue though at least mid morning.

MARINE...

Showers, drizzle, and fog will continue through much of the
morning. Visibilites will likely remain below 1 mile through at
least mid morning, so the marine dense fog advisory will remain
in effect through 15z.

The stagnant weather pattern will keep winds and waves below SCA
criteria through the weekend, though there is a period of time on
Friday morning where east winds may gust to 20 knots, pushing wave
heights just below 4ft.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Dense Fog Advisory until 10 AM CDT this morning for LMZ645-646.

&&

$$

Update...DDV
Today/Tonight and Aviation/Marine...BSH
Thursday THROUGH Tuesday...Cronce



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