Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 251628 AAA
Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1028 AM CST Sat Feb 25 2017
Light snow showers and flurries will persist through early to mid
afternoon across southern WI. This is nin response to cold air
advection, cyclonic flow, and lingering low level moisture that is
in just the right temperature layer for snow growth. Look for drier
air and ridging to move into the area this afternoon and bring
clearing skies. Temperatures are on track to be in the mid 20s today.
Look for the snow to steadily diminish from west to east early
this aftenroon. MVFR CIGS will lift to VFR levels then gradually
scatter out from west to east this afternoon. The remainder of the
TAF period will then be VFR. Look for the strong and gusty WNW
winds to diminish toward late afternoon.
Brisk northwest winds will diminish as strong low pressure over
southeast canada moves off. A small craft advisory will continue
through 9 pm this evening. Another small craft advisory will likely
be needed on Sunday as southerly winds increase in response to a
tightening pressure gradient between high pressure to the southeast
and low pressure tracking across Lake Superior.
.PREV DISCUSSION... /Issued 302 AM CST Sat Feb 25 2017/
TODAY AND TONIGHT...Forecast confidence is high.
Surface low pressure will continue to lift northeast of the Great
Lakes today. The sharp mid level trough and circulation was
spinning over southern Wisconsin early this morning and will lift
ENE of the area by around 12z. Look for the snow to come to an end
from east to west this morning...but any snow after 12z will be
rather light. Will therefore let the advisory expire at 12z this
morning. Any additional accumulations will be less than an inch. It
will be colder than we`ve seen lately with highs only in the 20s.
Clearing progresses across the area this afternoon into this evening
as weak surface high pressure drifts through, with more clouds
arriving toward midnight as a weak mid level short wave approaches
from the west. Lows tonight should occur this evening when skies are
most likely going to be clear with light winds. Temps should begin
to rise a bit after midnight as the ridge slides to the east and we
get into a weak southerly return flow with the increasing clouds.
SUNDAY AND MONDAY...Forecast Confidence...High
A weak wave passing through Sunday could bring a few morning
snowflakes to the north. Breezy southwest winds will push milder
air back into southern Wisconsin, with above normal temps likely.
Mostly sunny skies are then expected Monday under high pressure.
Milder temps will remain in the area, with highs running about 10
degrees above normal for late February.
TUESDAY AND WEDNESDAY...Forecast Confidence...Medium
Models in decent agreement showing low pressure passing through
Tuesday into Tuesday night. Should see some precip arrive by later
Monday night ahead of the low. A blend of models suggests cold
enough temps at the surface for a period of mixed precip late in
the night into Tuesday morning as temps warm aloft. A couple
models are mild enough at the surface to suggest just rain though,
so definitely some uncertainty with precip type with this period.
Any mixed precip that does form is expected to transition to all
rain by mid-morning on Tuesday.
Models are showing a secondary surface low to move in behind the
first departing low. As temps cool behind the first system, this
second low could bring a little snow Wednesday. There is less
confidence in this setup than with the first low due to model
differences with placement and timing of the second low.
THURSDAY AND FRIDAY...Forecast Confidence...Medium
Could see a little snow Thursday as a wave moves through. The GFS
has the strongest wave and better developed surface low and thus
more precip. The Canadian and ECMWF have a much weaker wave and
very little precip. Thus kept pops on the low end for now.
Decent agreement among models for Friday, showing high pressure
and colder temps to arrive for the end of the week.
Look for the snow to steadily diminish from west to east this
morning. The snow should end at KMSN by 12z and KMKE/KUES/KENW by
13-14z. The snow will hang on a bit longer up around the Sheboygan
area. MVFR CIGS will lift to VFR levels then gradually scatter out
from west to east later this morning into the afternoon. VFR
conditions should reach KMSN by 15z and southeast Wisconsin by about
17z. The remainder of the TAF period will then be VFR. Look for
the strong and gusty WNW winds to diminish toward late afternoon.
Strong and gusty west to northwest winds will persist into this
evening as low pressure continues to push off to the northeast and
high pressure slides by to our south this afternoon. A small craft
advisory will continue through 9 pm this evening. Another small
craft advisory will likely be needed on Sunday as southerly winds
increase in response to a tightening pressure gradient between high
pressure to the southeast and low pressure tracking across Lake
LM...Small Craft Advisory until 9 PM CST this evening for LMZ643>646.
TODAY/TONIGHT AND AVIATION/MARINE...Davis
Sunday THROUGH Friday...DDV