Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 140313
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1013 PM CDT Wed Mar 13 2024

.KEY MESSAGES...

-Shower and thunderstorm potential increases tonight, continues
 Thursday. Small hail possible from the strongest storms.

-Temperatures decrease into next week.

&&

.UPDATE...
Issued 1000 PM CDT Wed Mar 13 2024

Forecast details largely remain on track with some pockets of convection
forming just south of the WI/IL border. Expect a few rumbles of
thunder overnight. A few stronger cells may produce pea-sized
hail closer to daybreak tomorrow as MUCAPE increases aloft,
mainly above the freezing level.

CMiller

&&

.SHORT TERM...
Issued 315 PM CDT Wed Mar 13 2024

Tonight through Thursday night:

Developing low pressure in the central Great Plains is slowly
increasing easterly winds in southern Wisconsin, with a 500 mb
shortwave progressing eastward through a region of elevated
moisture and producing a few showers and perhaps an isolated
thunderstorm or two this afternoon into this evening. These
showers are fighting dry air in the boundary layer and may
initially produce only virga. However, falling temperatures this
evening combined with evaporation from earlier shower activity
should lead to rainfall reaching the surface later this evening.
The developing low will then begin to propagate eastward along
WAA surface frontogenesis tonight, bringing additional showers
and thunderstorms to southern Wisconsin through the overnight
hours. Elevated instability sits near the WI/IL border
throughout the overnight hours and into Thursday, leading to
continued chances for isolated thunderstorms.

Uncertainty in thunderstorm strength on Thursday remains. The
surface warm front remains just south of the WI/IL border, with
northeasterly surface winds off Lake Michigan expected to hinder
the majority of convective activity. However, warm air
overrunning the surface frontal boundary is indicated on many
CAMs in the morning hours on Thursday, which would result in
some marginally unstable conditions aloft supportive of a
marginal hail threat in far southern Wisconsin. Outside of this
region, steady rainfall is expected. Rainfall will slowly
diminish from north to south Thursday night.

Northeasterly winds increase and become gusty Thursday as low
pressure in Illinois ejects eastward. Winds will diminish
Thursday night. Northeasterly winds will bring in temperatures
near freezing Thursday night, with perhaps a few show showers
developing as the low exits. No accumulation is expected.

MH

&&

.LONG TERM...
Issued 315 PM CDT Wed Mar 13 2024

Friday through Wednesday:

Synopsis: Positioned downstream of mean ridging along the West
Coast, northwest upper level flow will prevail across the Western
Great Lakes through the majority of the long term period. Embedded
within the aforementioned northwesterly pattern, a series of
impulses will cross near or over the area from Saturday through
Monday. The first will progress from the Canadian Prairie Provinces
toward Lake Huron on Saturday, pulling an accompanying surface low
from Lake Superior toward the southern Hudson Bay in the process.
The low will concurrently pull a cold front through Southern
Wisconsin Saturday morning and afternoon, with an isolated shower
possible over far northern counties. Blustery northwest winds will
become established in the wake of the cold frontal passage, bringing
noticeably cooler conditions to the region on Sunday and Monday. The
cooler air will be advancing into the area beneath additional
disturbances aloft, which will support chances for light rain & snow
showers during the PM hours on Sunday and Monday. High temperatures
will gradually moderate Tuesday and Wednesday as surface flow
becomes more westerly in character.

Saturday: Changes from the current mild/above-normal temperature
pattern are in store as a cold front crosses the area during the
morning and afternoon hours. Anticipate a largely dry FROPA given
the passage of the best DPVA to our north, but have continued
isolated shower mentions over our northern tier of counties given
closer proximity to said forcing. Temperatures will begin to drop
during the late afternoon/early evening hours as gusty northwest
winds become established behind the front.

Sunday & Monday: Additional precip chances during primarily the
afternoon/early evening hours remain in the forecast each day with
cold air in place aloft and impulses continuing to track across the
region. Despite surface temperatures climbing into the mid-30s at
points (particularly leading up to/during the peak of diurnal
heating), dew points ranging from the upper teens to low 20s will
support wet-bulbing potential & attendant snowfall during any round
of precip. Best chances are currently favored on Sunday, when a more
organized clipper will be passing overhead. Probabilistic QPF
forecasts currently point toward any accumulations being minor, with
> 0.1" progs from the GEFS and CMC coming in at or below 20% each
day. Will nevertheless be monitoring trends over the coming forecast
cycles for any potential changes.

Quigley

&&

.AVIATION...
Issued 1012 PM CDT Wed Mar 13 2024

Ceilings will continue to decrease overnight to IFR by tomorrow
morning as moisture lifts north into the region and shower and
scattered thunderstorm activity develops. Rain should be showery
and scattered into tomorrow around dawn, before steadier
stratiform rain takes hold after dawn and before noon,
continuing into the evening hours. Winds will be breezy, with
northeast gusts to 25 knots.

CMiller

&&

.MARINE...
Issued 315 PM CDT Wed Mar 13 2024

Northeasterly winds will increase steadily through tonight as low
pressure moves from the Texas Panhandle into northern Missouri. A
few thunderstorms are possible this evening as a weak warm front
lifts into the southern half of Lake Michigan. Breezy northeast
winds are expected Thursday through Thursday night, shifting to
become northerly into Friday as the low passes by just to the south
of Lake Michigan. Dense fog will also be possible during this time,
especially over the southern third of the lake.

Another area of low pressure of 29.3 inches will cross southern
Ontario Saturday, bringing a round of breezy southwest winds ahead
of the associated cold front, and followed by northwest winds behind
the front. Gusts to 30 knots will be possible.

Nearshore: Persistent onshore, north-northeast winds will build high
waves starting early Thursday morning near Sheboygan and by late
morning near Winthrop Harbor. Gusts up to 30 kt are expected during
the afternoon hours. Northerly winds will diminish Friday morning,
but the high waves will linger through Friday afternoon and subside
north to south.

Cronce

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644...6 AM Thursday to 4 PM
     Friday.

     Small Craft Advisory...LMZ645-LMZ646...9 AM Thursday to 7 PM
     Friday.

&&

$$

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