Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 181433 AAA

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
933 AM CDT WED MAY 18 2016


An area of clouds associated with a weak circulation over Lake
Michigan has pushed into the southeast forecast area this morning.
These clouds will likely dissipate by late morning. Otherwise,
expect late morning and afternoon diurnal cumulus similar to
yesterday. Northeast winds will probably keep the bulk of these
clouds away from the lake. Temperatures seem to be on track to
reach forecast highs, so no significant updates to the forecast
are expected today.



VFR ceilings in the southeast will probably slowly dissipate
through late afternoon. Diurnal cumulus at around 5 kft is then
likely late morning into the afternoon, mainly away from Lake
Michigan. Should see another round of diurnal cumulus at a similar
height on Thursday.



A weak inverted surface trough was producing a few light showers
over the southern open waters this morning. Mesoscale forecast
models are in good agreement in keeping any additional shower
development south of our area as high pressure noses in from the
north this afternoon. Light northeasterly winds this morning will
veer to easterly this afternoon as onshore flow develops. Could see
some cumulus around 6-7 kft through early afternoon before lake
influence moves inland during the day. A land breeze will develop
overnight with light westerly winds. Waves today should average 1 to
2 feet today, before decreasing to around 1 foot tonight.


.PREV DISCUSSION... /Issued 327 AM CDT WED MAY 18 2016/

TODAY...Forecast Confidence High.

Will let Frost Advisory continue though temperatures are holding up
especially in the east with 5 to 10 knot surface winds. Readings
across South Central WI are in the mid to upper 30s so looks good
for frost there. However dew points have fallen to the upper 20s to
mid 30s in the east and expect readings away from the lake to fall
enough through sunrise to produce areas of frost that will support
continuing the advisory.

Models take last vort max through state today around base of
positive-tilt 500 mb trough that finally swings east tonight. GFS
depicts a stronger vort max that contributes to overall forcing
generating light pcpn along a lake-breeze front tracking west this
afternoon across far southern WI/nrn IL. However the GFS forecast
soundings in these areas are lacking moisture and look similar to
the soundings yesterday so only expect a shallow layer of scattered
to broken diurnal cumulus this afternoon.

925 mb temperatures rise to between 11C and 10c over the western
half of the CWA yielding highs in the mid 60s with highs lowering to
the east with persistent cool east to northeast winds.

TONIGHT...Forecast Confidence High.

Another clear and relatively calm night but not as cool with the
axis of the surface high shifting far enough southeast for weak
south to southwest winds to provide some mixing. Could still see
some patchy frost in the eastern CWA where winds will be a bit
lighter and dew points a bit lower, but will be limited to low-
lying rural locations so no advisory anticipated for tonight.

Surface high pressure will keep a very quiet wx regime in place this
period. Other than diurnal cumulus clouds, temperatures will warm a
bit each day with eastern portions of the cwa being affected by a
lake component each day. This will result in a east/west gradient
in temperatures in the far eastern portion of the cwa. A weak and
slightly cyclonic 500 millibar flow pattern will dominate through
Friday. Then a 500 millibar trough axis shifts across srn WI
friday night into Saturday morning. However soundings are parched
so dry forecast remains despite the passage of this mid level
feature. A pronounced 500 millibar ridge builds in for sunday. The
surface ridge axis is proggd to be across the mid miss vly into
lwr mi.

MONDAY - Confidence...Medium to High
The northern plains starts to get more energized with mid level
negative tilt wave riding northeast. SFC low rides into canada.
More of a southerly flow evolves across WI with surface high well
to our east.

MONDAY NIGHT AND TUESDAY - Confidence...Medium
Next chance of precipitation arrives when 500 millibar flow pattern
becomes a bit more southwest. A surface trough may interact with a
warmer and more moist environment and produce at least scattered
shra/tsra. Superblend pops has a good handle on the pops spreading
in monday night and continuing into tuesday.

AVIATION/12Z TAFS/...Expect VFR conditions through the forecast.
Looking for scattered to broken diurnal cumulus development again late
this morning and afternoon but forecast soundings indicate bases around
5k feet. Light north to northeast winds will become more easterly
this afternoon as a lake breeze pushes east to west with little
resistance from a weak surface gradient with broad surface high
pressure over the western Great Lakes.

MARINE...Light north to northeast winds will shift more easterly this
afternoon with the development of an onshore wind/lake breeze, then
back to the west tonight with the land breeze. Winds turn southwest
Thursday as the axis of the broad surface high settles to the
southeast. The lingering light pressure gradient will offer little
resistance to an afternoon lake breeze with winds turning southeast
Thursday afternoon into the evening.

Weather will remain quiet as the high pressure remains across the
Great Lakes through the weekend. Expect light south winds becoming
onshore during the day, with low wave heights.


.MKX Watches/Warnings/Advisories...


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