Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 240915
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
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.

&&

.AVIATION(09Z TAFS)...

MVFR ceilings are pushing into the area this morning, and should
gradually fill in as the morning goes on. Rain and perhaps even a
few thunderstorms will move through from late afternoon into the
late night hours, along with IFR to LIFR vis and ceilings. Winds
will be from the east during this time, with a few gusts to around
25 KT.

Later tonight, precipitation will end as a front sweeps through
the region. Behind that front, westerly winds look to become quite
gusty, with the strong west winds continuing into Sunday morning.
From late Saturday night and Sunday morning, a few wind gusts to
around 35 KT will be possible.

&&

.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 9 PM CST Sunday for LMZ643>646.

&&

$$

Today/Tonight and Aviation/Marine...Boxell
Sunday through Friday...Wood



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