Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
371
FXUS63 KMKX 201751 AAB
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1251 PM CDT Sun May 20 2018

.UPDATE...

The rain is moving out of southeast WI early this afternoon and
clouds are beginning to thin. Look for temperatures to warm into
the upper 50s inland and around 50 near the lakeshore. The weather
will be quiet this afternoon and for most of tonight.

The next round of rain will arrive early Monday morning as a
decaying MCS (Mesoscale Convective System) slides through
northern Illinois and southern WI. Scattered rain showers are
possible all day Monday, along with a small chance for thunder.
Expect a steady easterly breeze and clouds to keep temperatures
cool once again.

&&

.AVIATION(18Z TAFS)...

The IFR cloud bases are gradually diminishing and expect ceilings
to rise to VFR during the afternoon. Clouds will remain intact
over much of southern WI this afternoon and evening.

Another round of showers and perhaps a few thunderstorms will
slide northward into southern Wisconsin early Monday morning.
These will bring IFR/MVFR ceilings and reduced visibility in
rain once again. The easterly component off the lake and moist
conditions could lead to lake fog pushing inland during the Monday
afternoon hours.

&&

.PREV DISCUSSION... (Issued 935 AM CDT Sun May 20 2018)

UPDATE...

Rain is moving through southern Wisconsin this morning. This is
associated with weak low level warm air advection, frontogenesis,
and upper divergence. This forcing is weakening and so are the
showers. Once that forcing dissipates/moves out, showers will
taper off. Expect drier conditions this afternoon, but can`t rule
out sprinkles here and there.

Temperatures will remain cool all day with a brisk east-northeast
wind and extensive cloud cover.

MARINE...

Brisk NE winds with gusts up to 25 mph will persist through late
morning before easing somewhat this afternoon. High waves up to 5
feet will gradually diminish through the evening. A Small Craft
Advisory is in effect.

PREV DISCUSSION... (Issued 616 AM CDT Sun May 20 2018)

UPDATE...

Showers and isolated thunderstorms are developing in association
with low-level warm advection and frontogenesis within an inverted
trough axis nosing into southern Wisconsin. These showers will
continue through mid morning until the better support pushes off
to the east. Any thunderstorms should remain on the weak side
given the lack of any appreciable low-level jet or effective bulk
shear for them to work with. Expect a lull in precipitation for
this afternoon and evening, before shower chances return tonight.

AVIATION(12Z TAFS)...

A mix of MVFR and IFR ceilings and visibilities are expected
through this morning with scattered rain showers and isolated
thunderstorms. A gradual improvement in flight conditions to VFR
is then expected through the afternoon. Brisk NE winds will gust
up to 25 knots this morning by the Lake (affecting MKE and ENW in
particular), before decreasing this afternoon. Ceilings may begin
to lower into the MVFR range (possibly lower) later tonight with
scattered showers possible.

PREV DISCUSSION... (Issued 312 AM CDT Sun May 20 2018)

SHORT TERM...
Today and Tonight...Forecast Confidence is High.

A mid-level shortwave/vorticity maxima will progress from the mid
Missouri valley this morning into the upper Mississippi valley by
tonight. Rain showers are expected this morning, with lift
provided by coupled cyclonic vorticity advection and jet-level
divergence atop the low-level baroclinic zone. A rumble of
thunder is possible, given MUCAPE present via RAP analysis and
present on area forecast soundings. Look for a break in the
precipitation during the late morning and into the afternoon, as
low-level moisture wanes and the upper support departs. Modest
low-level warm and moist advection returns tonight as some weak
perturbations ripple through the mid-level flow. While forcing for
ascent is rather weak, rain showers are possible overnight, with
the greatest chances towards the Illinois border. Rain amounts
should generally be a quarter of an inch or less. With the surface
front remaining to our south, look for cool northeasterly flow
and high temperatures struggling to reach 60 west of Madison.
Areas near the Lake may have a tough time cracking the 50 degree
mark.

LONG TERM...
Forecast Confidence is Medium.

A split flow upper level pattern will persist across the CONUS
much of the week. As a result, the flow aloft will be a bit
sluggish, with bouts of unsettled weather bookending a period of
quiet conditions.

A weak disturbance will slowly move through the region on Monday
bringing a chance of showers that will persist into Monday night.
Temperatures will be cooler than average under a mainly cloudy
sky.

A brief period of upper level ridging builds over the area on
Tuesday. Southerly winds will initiate a warming trend that looks
to persist through the remainder of the week. An upper low that
will slowly eject out of the southwest CONUS, should weaken a bit
as it approaches from the west as it encounters confluent flow.
There will be a few pieces of energy to break off from this low
and provide intermittent (nebulous) rain chances from Wednesday
onward. Overall the PoP forecast is a bit pessimistic, but timing
individual waves at this juncture is a futile exercise.

Bottom line for Tuesday onward is at/above average temperatures
(remaining cooler near the lake), and chances for rain beginning
Wednesday and continuing in an off again/on again fashion as we
head into the first part of next weekend.

AVIATION(09Z TAFS)...
A mix of MVFR and IFR ceilings and visibilities are expected
through this morning with scattered rain showers. A gradual
improvement in flight conditions to VFR is then expected through
the afternoon. Brisk NE winds will gust up to 25 knots this
morning, before decreasing this afternoon. Ceilings may begin to
lower into the MVFR range once again later tonight with scattered
showers possible.

MARINE...
Brisk NE winds will gust up to 25 mph this morning before easing
somewhat this afternoon. This will allow high waves up to 5 feet
to build early this morning and persist until early Sunday
evening. A Small Craft Advisory is in effect during this time.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory until 8 PM CDT this evening for LMZ645-646.

     Small Craft Advisory until 4 PM CDT this afternoon for LMZ643-
     644.

&&

$$

Update...Cronce
Today/Tonight and Aviation/Marine...SPM
Monday THROUGH Saturday...Gagan



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.