Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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

000
FXUS63 KMKX 261750 AAB
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1250 PM CDT Tue Sep 26 2017

.UPDATE...


&&

.AVIATION(18Z TAFS)...

Scattered showers are expected across southern WI this afternoon
and will taper off in southeast WI early this evening. There could
be a few rumbles of thunder, with the best chance for thunder in
southeast WI.

A period of MVFR ceilings are expected behind the front this
evening. There is uncertainty about how long these low clouds will
hang around since there will be some drier air working into the
area.

&&

.PREV DISCUSSION... (Issued 1145 AM CDT Tue Sep 26 2017)

UPDATE...

A cold front associated with low pressure over Lake Superior will
track east through WI today. Southern WI is still in that warm
air mass so temperatures are heating up quickly east of Madison
where clouds are thinner. There is general upward motion over our
area due to weak vorticity advection and the entrance region of an
upper jet. Frontogenesis in the 925-850mb level is probably the
stronger of the forces right now, which is helping some showers to
develop over portions of southern WI this morning. There was even
a shower that developed in western Racine County and slid
northeast through Milwaukee before dissipating.

The surface cold front will arrive in south central and southeast
WI this afternoon. That will bring a chance of showers and some
isolated thunderstorms. There will probably be some breaks in the
line, so not everyone will get rain. We are only looking at about
a tenth of an inch of rain on average.

A period of low clouds are expected behind the front tonight.

MARINE...

Steady southerly winds will become west late this evening with the
passage of a cold front. Brisk west-northwest winds are
anticipated tonight into Wednesday morning. Gusts may approach
small craft advisory levels for a time.

PREV DISCUSSION... (Issued 639 AM CDT Tue Sep 26 2017)

UPDATE...Mid/high clouds surging northeast across southern WI.
Will need to keep close eye on temperatures as clouds may retard
temperature rise, especially in the southeast. GOES-16
microphysics enhancement showing some thinning of clouds upstream
over southeast IA into northwest IL so wl not fiddle with Max
temperatures for now. Scattered showers continue to develop to the
west of CWA as moisture advection and expect some of these showers
to spread east into the area later this morning and aftn.

AVIATION(12Z TAFS)...Expect mainly VFR conditions to accompany
scattered showers and isolated t-storms today. Large area of
upstream MVFR and lower stratus over MN/IA. As low level winds
turn more WNW later today behind passing cold front, thinking some
of these low clouds may affect southern WI for a period into
tonight. However most short term guidance show upstream low clouds
thinning before reaching srn WI. Due to uncertainty at this point,
avoided low cigs in 12Z Tafs.

PREV DISCUSSION... (Issued 332 AM CDT Tue Sep 26 2017)

DISCUSSION...

TODAY AND TONIGHT - Confidence...Medium.

Initial surge of moisture advection producing scattered showers
across western CWA early this morning.  Expect this initial
surge to weaken early this morning as it encounters drier air
farther east.  However reinforcing push of moisture advection
ahead of approaching cold front should trigger more scattered
showers and a few t-storms later this morning and afternoon
across southern WI.  Prefer GFS solution with location of
frontal boundary at 12Z, however all short term guidance carry
weak low pressure over the tri-state area northeast across northern
WI this morning and into southern Canada by this evening.  This
track will carry a cold front across southern WI today, exiting the
far southeast early this evening.  Deep moisture in place along with
the passing front and enhanced synoptic lift from southern
extent of mid-level short wave should generate at least scattered
showers and a few t-storms across CWA today.  Showers may remain
more scattered or isolated over far southeast WI which will be
farther away from synoptic forcing.  Milwaukee record high is 88
today and starting out the day in the upper 60s or low 70s.  However
increasing mid-high level clouds should keep high temps just below
reaching record levels.

Showers will diminish from west to east during the afternoon and
early evening.  Increasing low level cold air advection will
likely pull in a period of low clouds from MN/IA for a time tonight
as temperatures dip into the upper 40s and 50s.

Wednesday - Confidence...High
A much cooler airmass will be in place. The cooler air brought in
by northwest winds. High pressure will be ridging into the area.
in the wake of the frontal boundary.

Thursday - Confidence...Medium to High
A brief thermal ridge works in ahead of another front that will
be dropping south into northern WI associated with low pressure
moving east of Lake Superior. 925 temps bounce back to the mid
teens celsius with more of a westerly flow ahead of the front.
Showers associated with this feature are expected to remain in
northern WI. The cold front drops in Thursday evening. Models are
not doing much with this feature its passage thus pops are mostly
on the dry side.

Friday through Sunday - Confidence...Medium to High
High pressure regains control and the influence of this feature
dominates through the weekend. The high will shift off to the east
into the eastern Lakes for Saturday and the NE US for Sunday. A
return flow sets up for Sunday but at this time the progs suggest
all precip will remain to our west in the Plains in association
with a low pressure trough there. The coldest 925 temps are
expected Friday night into Saturday morning with a gradual rebound
for the balance of the weekend.

Monday - Confidence...Low
The ECMWF and to a lesser extent the GEM show a quicker advance of
the Plains trough into the Upper Midwest with a more progressive
mid level pattern. The GFS keeps Monday dry with a slower more
amplified 500 millibar trough. Looks like we should see a bump in
the 925 temps deeper into the teens celsius.

AVIATION(09Z TAFS)...A few showers may brush the Madison area
early this morning. Otherwise, expect scattered showers and
isolated t-storms to develop later this morning and afternoon
across southern WI as a cold front sweeps through southern WI.
Ceilings may drop to MVFR due to passing showers. Increasing
northwest winds behind front may pull in a period of low stratus
across the area tonight.

MARINE...Light southwest winds will back to mostly a south
direction this morning and waver between south and southeast for the
afternoon due to inland heating.  Wind gusts may reach 15 knots.
Recent MODIS imagery shows lake temperatures have rebounded back
into the upper 60s to around 70 well offshore while pockets of
cooler lake surface temps were located from offshore of Sheboygan
county south to Wind Point.  A cold front is expected to pass across
the nearshore waters late this afternoon and evening turning winds
to the WNW.  A tightening pressure gradient and the surge of cooler
air will result in increasing winds overnight, with gusts
approaching Small Craft Advisory levels into early Wednesday.  For
now, looks like most gusts will remain below 22 knots so wl hold off
on issuing Small Craft Advisory, but mariners should be prepared for
gusty offshore winds developing tonight.

&&

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

$$

Update...Cronce
Today/Tonight and Aviation/Marine...MBK
Wednesday THROUGH Monday...Collar



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