NWS-Milwaukee/Sullivan Forecast Discussion

 

						FXUS63 KMKX 180606 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1206 AM CST Mon Feb 18 2019

.UPDATE...

The heavier lake effect snow band split into multiple bands just
after 9 pm. These multiple bands are expected to organize into a
single band by around 2 or 3 am just south of Port Washington and
then slide south to Kenosha through 6 am. Snowfall rates are
moderate with these lake effect snow showers tonight. Inland areas
still have light snow falling, but expect the snow to diminish
from northwest to southeast overnight.

&&

.AVIATION(06Z TAFS)...

Moderate snowfall rates of around a half inch per hour are
occurring north of Milwaukee with scattered lake effect snow
showers. We will see a more confined single band develop near Port
Washington and West Bend that will make its way south through
Milwaukee, Racine and Kenosha between 9z/3am and 12z/6am overnight
as winds turn to the north.

Ceilings are trending upward as the snow diminishes from northwest
to southeast tonight. We should be VFR for the daytime hours
Monday. Lingering moisture in the low levels will give us the
potential for MVFR ceilings to return at any time through tonight.

&&

.PREV DISCUSSION... (Issued 831 PM CST Sun Feb 17 2019)

UPDATE...
Synoptic lift has shifted out of the area with light showers
lingering (away from the lake) with the weakening upper low.
Lake effect bands are apparent on radar into Sheboygan and northern
Milwaukee/Ozaukee counties. Thinking these areas, or others in
any heavier, stationary bands could see one half inch per hour rates
for several hours for totals of 3 to 5 inches. Other areas along
the lakeshore impacted by the weaker and less organized bands
could see a another 1 to 2 inches.

Delta T values are 15 and should increase another couple of degrees
early Monday. As 850mb temps cool to -15C, low level lapse rates
steepen and there is saturation in a deep dendrite growth zone
extending from 900 to 650mb, which favors a few inches of lake
effect snow in the more dominate bands. So several inches are
possible since the winds won't change much until around 4 AM.
After this time winds over the lake shift to the north which will
push any remaining showers offshore.

Thinking the advisory is ok for now to handle this.

MARINE...
Gusty northeast winds will become north early Monday. Wind gusts
will diminish Monday afternoon. Waves will reach 4 to 6 feet in
ice free areas. The small craft advisory remains in effect through
mid morning Monday.

High pressure will build into the area Monday and Monday night,
remaining over the region on Tuesday. Winds will increase from the
east once again on Wednesday as the next storm system approaches.
A Small Craft Advisory may be needed during this time.

PREV DISCUSSION... (Issued 629 PM CST Sun Feb 17 2019)

UPDATE...
No changes to the forecast.

AVIATION(00Z TAFS)...
Expect ceilings of 1500-2000 tonight, occasionally lower in the more
moderate to heavier snow bands in eastern Wisconsin. Mainly light
snow will dominate in Madison, winding down after midnight. Lake
effect snow will likely impact the lakeshore areas and
possibly UES through about 12Z. Winds will shift to the north Monday
morning which will push the lake effect offshore.

Cloud bases will likely become broken around 3000ft later Monday.

PREV DISCUSSION... (Issued 228 PM CST Sun Feb 17 2019)

SHORT TERM...

Rest of this Afternoon and Tonight...Forecast Confidence is
High...

Generally light to moderate snow continues across the area this
afternoon. There have been a few bands of heavier snow, which have
reduced visibilities to a half mile or less at times.

Large scale lift will begin to wane late this afternoon into this
evening, as the 850 MB and 700 MB lows rotate through the area.
Light snow showers will likely persist until after midnight, but
the intensity should decrease with time. The exception will be
near the lakeshore, where increasingly favorable winds and falling
850 MB temps will result in lake effect snow taking shape. We will
likely see multiple bands of lake effect snow showers develop this
evening, which should then organize into a single band tonight as
convergence improves. That band will then skirt the shoreline
through the night as winds become increasingly northerly with
time.

We look to be on track for a storm total of 3-6 inches of snow
across the Advisory area, with local maxima of 5-6 inches west of
Madison and along the lake, and 3-5 in between.

No changes are planned to the area or timing of the Winter Weather
Advisory. For the lakeshore counties, the vast majority of the
snow should be done by 6 AM, though a few light snow showers may
linger into the mid morning hours on Monday. Given that any
appreciable accumulation should be over by 6 AM, that still looks
like a good end time for the Winter Weather Advisory for this area.
Will continue with a 3 AM expiration for the counties to the
west, though at least a few tiers may be able to be expired early.

Monday and Monday Night...Forecast Confidence High...

High pressure will build into the area Monday into Monday night.
No precipitation is expected, with highs on Monday ranging from
the mid 20s south to around 20 north, and lows Monday night in the
low single digits above zero.

LONG TERM...

Tuesday...Forecast confidence is high:

High pressure will build overhead on Tuesday, with plenty of
sunshine expected. Temperatures will remain a few degrees below
normal.

Tuesday night and Wednesday...Forecast confidence is medium to
high:

Low pressure passing through the region will bring another shot of
accumulating snow to southern Wisconsin Tuesday night and
Wednesday. There are still moderate differences among models with
the track and strength of the low as well as how much drier air
aloft will move in from the south. Models overall have mainly
snow...though there has been an increasing trend in a loss of ice
aloft across roughly the southeast half of the forecast area on
Wednesday. Thus kept a mention of a mix with freezing rain going.
A blend of model solutions is still giving roughly 3-5 inches of
snow for this period (higher nw and lower se)...though still
plenty of time for the finer details to change.

Thursday through Sunday...Forecast confidence is medium to low:

High pressure is expected to bring dry weather and near normal
temperatures for Thursday and Friday.

Another low will take aim at the region next weekend. Models are
still not in very good agreement with this system, with a full
range of solutions still in play. There overall picture points to
a decent shot at snow across at least the nw half of the forecast
area, with maybe some rain mixing in southeast. A lot of time for
the details of this one to change. Hopefully the picture will
clear up a bit over the next day or two.

AVIATION(21Z TAF Update)...

IFR will continue today across the area, with occasional drops to
LIFR in heavier snow bands. Snow will slowly diminish in intensity
at Madison by evening, but will continue further east as a lake
effect band forms. This lake effect will likely impact Milwaukee
and Kenosha, and may just skirt the Waukesha area. Widespread IFR
is expected, with occasional drops to LIFR.

Winds will be easterly this afternoon, becoming more northeasterly
with time. Winds then become northerly toward Monday morning.

MARINE...

Gusty east winds will become northeasterly this evening, and then
transition to northerly late tonight. Waves will reach 4-6 feet in
the ice free portions of the nearshore, and a Small Craft Advisory
continues though mid morning on Monday.

High pressure will build into the area Monday and Monday night,
remaining over the region on Tuesday. Winds will increase from the
east once again on Wednesday as the next storm system approaches.
A Small Craft Advisory may be needed during this time.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 6 AM CST Monday for WIZ052-059-060-
     065-066-071-072.

     Winter Weather Advisory until 3 AM CST Monday for WIZ056-062>064-
     067>070.

LM...Small Craft Advisory until 9 AM CST Monday for LMZ643>646.

&&

$$

Update...Cronce
Tonight/Monday and Aviation/Marine...Marquardt/Gehring
Monday Night through Sunday...DDV