Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 280242
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
942 PM CDT Sat May 27 2017

.UPDATE...Adjusted rain chances this evening as rain area has
gradually shrunk over south central WI. Rain is likely through
midnight just north of Madison but becoming more scattered as it
moves toward east central WI. More development with the
approaching upper trough will occur early Sun AM with most areas
seeing rain some time in the morning.


.MARINE...Some concern for fog development around sunrise Sunday
and through the morning. Showers and isolated thunderstorms are
expected during this time with an increasing humid airmass over
the relatively cool waters of Lake MI. Areas of fog are forecast
for Sun AM with a small potential for dense fog.

Otherwise a Small Craft Advisory may be needed on Memorial Day for
breezy west winds.


&&

.PREV DISCUSSION... (Issued 709 PM CDT Sat May 27 2017)

UPDATE...The MCV and associated showers and isolated tstorms
will move into south central WI this evening. Most areas will
likely receive measurable rainfall with the heavier showers south
of Madison where better instability exists. For se WI, will also
anticipate the showers moving into the region for late evening but
perhaps more scattered via less instability. Then for late
tonight through Sun AM another round of light to moderate rainfall
will develop ahead a large scale upper trough approaching from
the nrn Great Plains. Warm, moist advection will increase ahead of
the upper trough along with PVA and some elevated moisture and
CAPE for the showers and isold tstorms. The precipitation will
become more scattered and possibly isold for the afternoon via AVA
and drying although sfc based instability will develop hence the
small chances for showers or storms through late afternoon and
into the early evening.

AVIATION(00Z TAFS)...The Cigs and Vsbys for this evening should
mostly remain VFR even with the rain that is expected. The second
round of rain beginning early Sun AM and lasting through the
entire morning however will lead to Cigs of 1-3 kft and Vsbys of
2-5SM including light fog. The main area of rain will exit to the
east by afternoon with Cigs rising to sct-bkn050 along with good
Vsbys. Small chances of showers and tstorms will remain however.

PREV DISCUSSION... (Issued 311 PM CDT Sat May 27 2017)

SHORT TERM...

Tonight and Sunday...Forecast confidence is low with respect to
PoP forecast tonight.

Complicated forecast tonight into tomorrow mrng with a potential
for a PoP fcst bust. MCV currently tracking ENE thru cntrl IA
should cross CWA tonight. Big question is what will be left of it
by the time it gets here. Model guidance not much help today as
solutions range from almost completely dry to a scenario that
would suggest categorical PoPs. Much will depend on if there is
any re-intensification of the system this aftn/evng. Think either
way, that there will be at least scattered showers assoc with the
feature as it tracks across the FA. Tried to narrow best chance
for likely PoPs to the late night into Sun mrng. There will be
additional shower and storm chances drng the aftn as a cold front
approaches late in the day. Otherwise...expect seasonal temps with
highs near 70 on Sun...cooler at the lake.

LONG TERM...

Sunday evening through Tuesday...Forecast confidence is medium:

May see a few showers/storms lingering into early Sunday evening
as a surface boundary slides through. Expect dry weather then for
the rest of the evening and overnight.

Another shortwave is progged to slide through on Memorial Day,
bringing a chance for showers and a few storms. It is still not
expected to be an all day event, so hopefully there will be plenty
of opportunities to enjoy the holiday. Temps will be within a
couple degrees of normal.

Yet another wave could bring a few showers on Tuesday, with temps
cooling to a few degrees below normal.

Tuesday evening through Saturday...Forecast confidence is medium:

High pressure sliding by to the south should bring mainly dry
weather from Tuesday evening into early Thursday. More shortwaves
will then bring shower and storm chances back into the area
Thursday afternoon through Saturday.

Temps are expected to be near normal mid to late week, through
there are some model differences by late week. The GFS brings
high pressure in from the northwest late in the week, resulting in
less precip chances and cooler temps. The ECMWF has the high
sliding by to the east, keeping a milder and more active pattern
in place.

AVIATION(18Z TAFS)...

VFR conditions should hold until more rain and low clouds move
into the region after 6Z. There is a small chance for a SHRA/TSTM
across cntrl/e cntrl WI this aftn but this threat will diminish
quickly after sunset. Scattered precip should overspread the area
after midnight and continue in an on/off fashion most of the
morning. Overall VSBYs should remain VFR but CIGs will gradually
become MVFR from SW to NE between 6-12Z. Precip is expected to end
late mrng but a chance of rain will continue area wide thru the
aftn.

MARINE...

Westerly winds will be breezy Memorial Day through Wednesday, with
Small Craft Advisory conditions possible each day. The offshore
flow will keep waves on the lower end.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

Update...Gehring
Tonight/Sunday and Aviation/Marine...DDV
Sunday Night through Saturday...DDV



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