Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

Home | Current Version | Previous Version | Graphics & Text | 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
000
FXUS63 KMKX 241707 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1107 AM CST Sat Feb 24 2018

.UPDATE...

The light returns on radar are associated with 700 mb warm air
advection. Initially, there`s too much dry air for any of that
upper level precip to overcome and make it to the ground. Over
time, the air will saturate from the top down and some flurries or
light rain will have a chance later this morning southwest of
Madison.

Deeper moisture will spread into southern WI this afternoon. The
temperature profile supports a chance of snow or wintry mix, but
mainly rain as temps rise into the upper 30s and temps aloft warm
as well.

The strongest forcing will cross southern WI this evening so look
for rain to overspread the whole area by midnight. A strong cold
front will track through from west to east from late evening
through around 3 am. Showers and thunderstorms are expected ahead
of and along the front due to weak upper level instability and
strong mid level vorticity advection. There is a chance of rain
and snow behind the front, but we will dry out quickly as colder
air rushes in on blustery west winds.

&&

.MARINE...

Easterly winds will increase today and this evening across the
nearshore, with gusts between 25 and 30 kt at times. A Small Craft
Advisory will be in effect starting at 6 PM, with waves building
overnight to as much as 10 ft, particularly north of Port
Washington.

Winds will then quickly become westerly with the passage of a
cold front, increasing to gale force by dawn. Expect at least a
few gale gusts to continue into Sunday afternoon.

&&

.AVIATION(18Z TAFS)...

Ceilings are bouncing between BKN020 and SCT020 as a layer of low
clouds move in and out of southeast WI. Deeper moisture is working
into south central WI and this could bring a wintry mix initially
before becoming all rain as temperatures continue to rise through
the afternoon.

By late afternoon, expect IFR or lower ceilings with the rain,
along with areas of fog with 1 to 3 miles visibility. There is a
chance of thunderstorms from late afternoon through early evening
until the passage of a cold front. Then expect blustery west winds
early Sunday morning through the afternoon. There is a chance for
some snow right behind the front, but precip will exit quickly so
no accumulation expected.

&&

.PREV DISCUSSION... (Issued 651 AM CST Sat Feb 24 2018)

UPDATE...

Added a chance for a light wintry mix across the forecast area
this morning, especially across southern Wisconsin. Precipitation
moving north from the Quad Cities area seems to be overcoming the
dry air a little faster than initially thought, and some widely
scattered precipitation seems increasingly possible this morning.
Precip type remains questionable, with light freezing rain
reported across Iowa and Illinois. However, as the precipitation
continues north, cooler temperatures aloft, along with evaporative
cooling, should cool the column enough to result in a changeover
to some combination of snow or sleet. Either way, anything that
falls this morning should be very, very light, and is not expected
to cause any issues.

PREV DISCUSSION... (Issued 528 AM CST Sat Feb 24 2018)

UPDATE...

Made a few minor adjustments to hourly temps for this morning
based on obs and influence of cloud cover, but no major changes.

AVIATION(12Z TAFS)...

Patchy areas of MVFR ceilings will remain an issue for the next
couple of hours, before cigs lift to VFR for a short time.
Easterly winds will increase through the day, likely becoming
somewhat gusty by afternoon. IFR and perhaps LIFR ceilings and
rain, along with a few thunderstorms, will push into the area late
this afternoon or early this evening, along with some fog.

Winds will increase this evening and tonight, and veer around
from east to southeast, and then eventually to south, before
quickly becoming westerly toward morning as a front passes. Expect
to see speeds and gusts increase toward daybreak Sunday, with
gusts around 35 kt at times.

PREV DISCUSSION... (Issued 315 AM CST Sat Feb 24 2018)

SHORT TERM...

Today And Tonight...Forecast Confidence Is Medium.

Main focus for the next 24 hours will be with an approaching
shortwave and deepening surface low. Precipitation will develop
over Iowa late this morning and afternoon, pushing into southern
Wisconsin during the afternoon and evening timeframe. There will
be a very small window for a brief mix of precipitation along the
very leading edge of the precipitation, but no impacts are
expected, and any mix should quickly transition to all rain.

Forecast models are showing some elevated instability across the
area this afternoon and especially this evening, and have included
a chance for thunderstorms.

Rain should be most widespread during the evening hours, as the
surface low and main mid level wave push through. Winds ahead of
the surface low will be gusty from the east, and with temperatures
hanging out in the mid to upper 30s, it looks like a very raw
evening and night across the region. Given the easterly flow and
plenty of moisture, we will also need to watch for fog potential
tonight.

Rain will end during the latter half of the overnight as a cold
front sweeps through. Westerly winds will become quite gusty after
3-4 AM, with a few gusts approaching 40 MPH by Sunday morning.

Sunday Through Monday Night...Forecast Confidence Is Medium.

Main issue Sunday will be the strong winds. Strong cold air
advection develops in the wake of the cold front Sunday morning.
Plenty of downward mixing is expected, with a tight pressure
gradient and rather steep low level lapse rates.

Area forecast soundings from the NAM and GFS are showing
potential for southwesterly to westerly 35 to 40 knot average wind
speeds in the boundary layer Sunday morning, highest toward the
Sheboygan area. Thus, some gusts may reach Wind Advisory levels
Sunday morning. Will let the next shift take another look at these
potential wind gusts, before deciding on any headlines. Rather
mild temperatures in the upper 30s to lower 40s are anticipated
Sunday.

Winds will weaken Sunday afternoon and night, as the pressure
gradient relaxes. Winds should gradually shift to the south
southwest Monday into Monday night. This should allow for gradual
warm air advection during the Monday into Monday night period.
Thus, the mild temperatures are expected to continue. Monday highs
may reach into the lower 50s, which is a bit warmer than currently
forecast.

LONG TERM...

Tuesday Through Friday...Forecast Confidence Is Medium.

Another mild day looks to occur Tuesday, before a cold front or
weak inverted trough pushes east through the region Tuesday
afternoon or night. There is some uncertainty in this, with the
GFS showing a cold front and the ECMWF and Canadian more of an
inverted trough. GFS forecast soundings are not showing a lot of
moisture with this system. Kept lower end PoPs for now. It would
be a rain to snow transition Tuesday night, as temperatures drop.

GFS/Canadian models then show some cyclogenesis Wednesday into
Wednesday night, as a compact low shifts northeast toward and
across northern Illinois. This low lingers Thursday, before
shifting to the east Thursday night and Friday. The ECMWF
continues to show a much weaker low during this time. This may be
due to the ECMWF not phasing the northern and southern stream 500
mb shortwave troughs, which the GFS and Canadian models phase.

The GFS/Canadian bring a fair amount of QPF into the area late
Wednesday night into Thursday, much less on the ECMWF. Will
continue higher end PoPs for Wednesday night into Thursday evening
across the area. Right now, it looks to be a snow to rain change
on Thursday morning, then a change back to light snow Thursday
evening.

Will need to watch this system`s track, as a further southward
push would bring more snow than currently forecast, and colder
temperatures. Overall, temperatures look to remain above seasonal
normals through most of the week.

MARINE...

Easterly winds will increase today and this evening across the
nearshore, with gusts between 25 and 30 kt at times. A Small Craft
Advisory will be in effect starting at 6 PM, with waves building
overnight to as much as 10 ft, particularly north of Port
Washington.

Winds will then quickly become westerly with the passage of a
cold front, increasing to gale force by dawn. Expect at least a
few gale gusts to continue into Sunday afternoon.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory from 6 PM this evening to 6 AM CST Sunday
     for LMZ643>646.

     Gale Warning from 6 AM to 6 PM CST Sunday for LMZ643>646.

&&

$$

Update...Cronce
Today/Tonight and Aviation/Marine...Boxell
Sunday THROUGH Friday...Wood



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