Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 241213
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
713 AM CDT Tue Apr 24 2018

.UPDATE...Lowered pops in the far southeast as -shra continue to
dry up as they rotate northwest across southern Lake MI and
northeast IL. Otherwise, sunshine in western CWA should allow
temperatures to rapidly rise through the 40s and 50s this morning.

&&

.AVIATION(12Z TAFS)...MVFR ceilings have pushed into far southeast
WI. They will last several hours before the low level winds switch
to a more northerly direction later this morning and afternoon.

&&

.PREV DISCUSSION... (Issued 331 AM CDT Tue Apr 24 2018)

SHORT TERM...

Today And Tonight...Forecast Confidence Is Medium To High.

Weak inverted trof extending northward from slow moving low
pressure over the TN valley triggering a few light showers over
northeast IL. The showers are moving NW and may affect far
southeast WI this morning. However, latest guidance shows the
upper low slightly weaker and farther south at 18Z. Also, some
guidance shows the atmosphere remaining drier over the southeast
this morning. Never the less, clouds will hang on much of the day
in the southeast CWA. The Clouds and winds turning onshore will
keep temps a few degrees cooler in the east over yesterday. Clouds
will be thinner over inland areas and south central WI, which
will allow temperatures to warm back into the 60s. A few spots may
reach 70 in the far west.

An upstream cold front over northern MN will sweep southward
across central and southern WI this afternoon and tonight. A few
showers will develop along the front, and may affect the northern
CWA including Fond du Lac and Berlin later this afternoon and
evening. The bulk of of the synoptic lift with an amplifying mid-
level short wave remains north of the area tonight. Low level
lapse rates late in the afternoon are fairly impressive, in the 7
to 9 degree range, but the loss of insolation in the evening
should weaken the showers. Hence wl confine threat to northern CWA
for now.

Wednesday Through Thursday Night...Forecast Confidence Is High.

Models are in pretty good agreement with taking high pressure
southeastward across the region Wednesday, then to the southeast
Wednesday night into Thursday morning. This will result in a
period of dry conditions across the area. Cooler temperatures in
the 50s are expected for Wednesday, as north to northeast winds
gradually weaken. Cooler values in the upper 40s are expected
lakeside. Lows Wednesday night should be in the lower to middle
30s.

Models are then showing a cold front sliding southeast across the
area mainly Thursday night. This is accompanied by a passing 500
mb shortwave trough. NAM/GFS forecast soundings are showing a
rather deep air column Thursday night, as these features move
through the area. Thus, continued the chance PoPs for this period.
May need to raise them in later forecasts if models remain
consistent with trends.

May still see a brief mix of rain and snow later Thursday night,
as temperatures fall. No accumulations are expected. Highs
Thursday should recover into the lower to middle 60s, with some
weak warm air advection. Lows Thursday night should fall back into
the middle to upper 30s.

LONG TERM...

Friday Through Monday...Forecast Confidence Is Medium.

Models suggest northwest flow at 500 mb will linger over the
region Friday into the weekend, with a ridge axis shifting east
over the region Sunday into Monday. Weak low pressure sliding
southeast across the region Friday afternoon into Friday night
should bring a cold front through the area. At this time, it looks
rather dry, so kept the forecast dry. Cooler temperatures are
expected Friday.

High pressure then slides southeast through the region Saturday
into Saturday night, bringing dry conditions with continued cool
temperatures.

A shift to south to southeast winds on Sunday are anticipated,
which should help bring milder temperatures back into most of the
area. Lakeshore areas would remain cooler with the southeast
winds. Dry conditions are expected.

A tight pressure gradient develops Sunday night into Monday, with
southwest winds becoming gusty. This will bring steady warm air
advection into the region, with much warmer temperatures possible
by Monday. Raised highs into the middle 70s for Monday, even for
areas near the lake with the gusty southwest winds. This pattern
may linger into the middle of the week, so the warm temperatures
may continue.

AVIATION(09Z TAFS)...

Mainly VFR conditions are expected for the period. However a
period of low VFR or MVFR ceilings may affect far southeast WI
this morning, associated with weak low level convergence in
vicinity of inverted low pressure trof over Lake MI. The inverted
trof gradually weakens later this morning and aftn. A few showers
may also affect northern CWA later this afternoon and evening, as
cold front approaches from the northwest.

MARINE...

Light offshore winds will again become north to northeast this
morning, however wind speeds will remain light, generally in the 5
to 12 knot range. A cold front currently over the northern Plains
will sweep across the nearshore waters of Lake Michigan this
evening. A push of cold air behind the front will result in gusty
north to northeast winds tonight, gradually diminishing on
Wednesday. These winds will kick up waves of 4 to 7 feet by late
tonight, which will also slowly diminish on Wednesday. A Small
Craft Advisory will be posted for the period.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory from 8 PM this evening to 7 PM CDT
     Wednesday for LMZ644>646.

     Small Craft Advisory from 8 PM this evening to 1 PM CDT
     Wednesday for LMZ643.

&&

$$

Update...MBK
Today/Tonight and Aviation/Marine...MBK
Wednesday THROUGH Monday...Wood


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