Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 260404

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1104 PM CDT SUN SEP 25 2016

.UPDATE...A narrow band of light rain in se WI will end by 06z.
Otherwise cold and dry air advection will continue on gusty wly
winds. The first shortwave trough within the larger scale upper
trough will pass Mon am with another expected for the afternoon.
Scattered to broken stratocumulus will occur with better chances
for mostly cloudy skies and isolated showers toward central WI.


.AVIATION/06Z TAFS/...Gusty wly winds are expected Mon and Mon
night as strong low pressure tracks from Canada into the northern
Great Lakes. Mid level clouds and light rain will exit se WI early
Mon am with sct-bkn050 for the daytime hours on Mon into Mon nt.


.MARINE...A Small Craft Advisory is in effect tonight through Tue
for brisk and gusty wly winds in the wake of a strong cold front.
The associated area of low pressure will track from western
Ontario Canada to the northern Great Lakes which will help support
the brisk wly winds over Lake MI.


.PREV DISCUSSION... /Issued 344 PM CDT SUN SEP 25 2016/

TONIGHT AND MONDAY...Forecast Confidence - Medium.

Sfc cold front will make its way through S WI this afternoon and
evening. Enhanced 1000-850 mb frontogenetical forcing associated
with the front, along with a mid-level shortwave behind the front,
will support chances of showers and thunderstorms through the
evening hours. Mainly shower activity is expected this evening, but
a rumble of thunder can`t be ruled out due to lingering instability
in the form of 100-500 J/kg of MLCAPE, with the highest values in
the southeast. Tightening sfc pressure gradient will bring gusty
westerly winds overnight post-fropa.

The mid-level shortwave, with associated positive vorticity
advection, will pivot over Wisconsin Monday, which should support
chances of showers in northern Wisconsin. Instability looks very
low, so thunderstorms don`t look likely at this point. Did bring
some pops into our northern counties Monday morning and afternoon,
but only slight chances expected. Wind gusts will continue through
the day Monday as the low level jet caught in the cyclonic flow of
the mid-level shortwave will mix down to the sfc. Gusts Monday could
reach to 25-30 kts inland.

MONDAY NIGHT AND TUESDAY...Forecast Confidence Medium.

Region remains under cyclonic flow around deep, closed mid-upper
level low, with a strong short wave rotating around the closed low
swinging southeast of the forecast area by early Monday evening.
Weaker vorticity maxima spin around over WI during the day Tuesday,
which combined with instability from 850 mb cold pool moving over
brings small chances for light showers over the northeast half of
the CWA. Early sun in the far south and southwest will help high
temps reach the mid 60s with upper 50s to lower 60s elsewhere.

TUESDAY NIGHT AND WEDNESDAY...Forecast Confidence Medium.

A stronger short wave drops north to south across the state Tuesday
night, exiting to the south early Wednesday morning bringing a
better chance for light showers over southeast WI, and lesser
chances to eastern South Central. The chance for showers exits
midday Wednesday with some breaks in the clouds. Low to mid 60s for
highs after lows in the mid 40s.


Closed low finally shifts east Wednesday night with ridging building
over the forecast area through Thursday night. Both the 12Z GFS and
00Z ECMWF are showing the closed low cutting off over the mid-
Atlantic states/southern Appalachians Thursday and either lifting
north/GFS/ or retrograding back to the northwest/ECMWF/. The more
westward drift of the ECMWF brings shower chances into the far
southeast Friday, while the more eastern GFS holds the ridge over
the western Great Lakes, deflecting and dampening a short trough
approaching from the Plains, keeping the area dry through the
extended. Will follow blended PoPs that acknowledges the potential
for the ECMWF solution by brushing the far east Saturday with slight
chances for showers. Looking for at, or slightly above normal
temperatures for the extended.


Mainly VFR overnight after a cold front passes through S WI. There
could be some lingering showers and storms late in the afternoon
into the evening. MVFR cigs are possible with some of the showers
and storms as the front moves through. Expect a wind shift with the
cold front, shifting winds from the south to a more westerly
direction. Winds could stay gusty (up to 20 kts) with a tightening
pressure gradient on the backside of the cold front. Even stronger
winds are expected for Monday, with gusts between 25-30 kts.


Small Craft Advisory for the northern nearshore zone (Sheboygan to
Port Washington) will continue through 7 PM tonight. Winds will
weaken for a period before strengthening again overnight. Winds look
likely to reach Small Craft Advisory strength overnight through the
day Monday, and even into Tuesday. Waves will be between 1 and 3
feet through Monday, with the potential to reach up to 4 feet. Winds
will stay westerly through the day Monday.


.MKX Watches/Warnings/Advisories...
LM...SMALL CRAFT ADVISORY until 7 PM CDT Tuesday for LMZ643>646.



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