Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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524
FXUS63 KMKX 241446 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
946 AM CDT FRI JUN 24 2016

.UPDATE...

Could see high clouds advect in from the west today and some
afternoon cumulus away from Lake Michigan. Otherwise, expect
mostly sunny skies under high pressure. Temperatures seem to be on
track for forecast afternoon highs, so no significant forecast
updates are expected for the remainder of the day.

&&

.AVIATION/18Z TAFS/...

VFR conditions will continue most places through the day
Saturday. There could be a little fog tonight, but some increasing
cloudiness from the west and an uptick in low level winds will
likely disrupt any widespread fog from developing.

Will continue to look at 12Z guidance this morning in order to
evaluate precip potential for tomorrow. At first glance, it looks
mainly dry through tomorrow afternoon, with bulk of showers/storms
holding off until evening and overnight when the trough comes
through.

&&

.MARINE...

Light northeast to east winds will veer southeast this afternoon.
South to southeast winds ahead of an approaching cold front will
approach Small Craft Advisory levels Saturday afternoon and night.

&&

.PREV DISCUSSION... /Issued 330 AM CDT FRI JUN 24 2016/

TODAY AND TONIGHT...Forecast Confidence Is High.

Mid-upper level ridging and surface high pressure to bring quiet
weather to the region through tonight. Some residual low-level
moisture and weak convergence along apex of inverted surface trough
that is still nosing into the southeast CWA has produced some
stratocumulus over the southeast early this morning but the clouds
are sinking south and dissipating with the departure of the inverted
trough.

Low-level relative humidity forecasts indicate a ribbon of higher RH
will rotate around and lift northward into the CWA around the
western periphery of the departing high. GFS MOS guidance and CU
rule forecasts alone in indicating afternoon broken cumulus through
the central CWA. But the GFS forecast soundings show very dry air
above/below the very shallow saturated layer around 4k ft so will
keep the overall sky condition as scattered, though a brief period
broken cumulus not out of the question.

00Z NAM is a bit quicker and stronger with a lead vorticity maximum
moving into the state toward Saturday morning, but slower with the
850-700mb warm advection. This leads to mid-level lapse rates
sufficient to produce elevated CAPE of 1000 J/kg being acted on by
the lift with the vort max and warm advection, bringing
showers/storms into the far west before 12Z Saturday. GFS and ECMWF
soundings show a cap between 850mb and 660 mb that prevents any
elevated instability and no lift with the slower approach of lead
vorticity maxima ahead of short wave trough over eastern Montana at
12Z Saturday, so will keep area dry through 12Z Saturday.

SATURDAY AND SATURDAY NIGHT - Confidence...Medium
588DM ridge axis across WI at the outset will shift east with a
potent mid level low shifting newd into Canada from the Dakotas. A
southerly flow will draw in a warm and moist airmass. Progs send
dewpoints back into the 60s. 925 temps will reach the low or mid 20s
celsius supportive of highs in the 80s. A strengthening 850 LLJ just
to our west combined with a weak wave riding newd may lead to some
tsra across mainly the western CWA during the afternoon. The GFS and
ECMWF are in pretty good agreement on this. The 850 jet leans over
the state Saturday night with better forcing proggd to our north
with srn WI situated more in the entrance region of the jet core.
The upper dynamics do increase with shortwave energy becoming a
source of vertical motion along with lower level frontal forcing as
surface/850 boundaries arrive. The models have been rather
consistent showing Saturday night being the best window for tsra
potential. The upper jet axis shifts newd on eastern periphery of
the progressive trough will enhance upper divergence Saturday night.
SWODY2 has cwa in marginal risk area and is reasonable given
expected instability in place evening into the overnight hours at
the time when best forcing comes into play. However highest CWASP
numbers are to our northwest and north. Will maintain the going
high pops.

SUNDAY - Confidence...Medium
Surface/850 trough exits to the east in the morning. Will keep
some POPS in the se cwa during the morning as progs suggest some
lingering frontally induced shra/tsra. Warm airmass remains in
place with 925 temps in the mid 20s celsius.  Looks like a steady
wsw wind would push that warning all the way to Lake Michigan.

MONDAY THROUGH WEDNESDAY - Confidence...High
Still looks like a warm Monday with main cool push arrives Monday
night as surface high takes hold and dominates into mid week. 925
temps are the coolest Monday night into early Tuesday with the ECMWF
showing 925 temps dropping below 10c. The GFS is a smidge warmer.
But overall this period will see 925 temps in the teens celsius. So
a quiet and cool late June pattern setting up.

THURSDAY - Confidence...Medium
The surface high is proggd to shift towards the Ohio Valley with a
weak frontal boundary bringing a better chance of precip to
northern WI. At this time it looks most of our area should see
another dry day with 925 temps still in the teens celsius.

AVIATION/12Z TAFS/...Dissipating pocket of VFR stratocumulus over
parts of the southeast should be gone by 12Z. Patchy MVFR/IFR fog
should also be gone by 13Z with morning mixing. Some indications
in the GFS model guidance of broken VFR-level cumulus developing
around 4k feet this afternoon with ribbon of low level moisture
over the central forecast area, but other models showing nothing
more than scattered diurnal cumulus. Will go with the scattered
solution. Light north to northeast winds will veer east this
morning then southeast this afternoon.

Will hold off on any showers or thunderstorms in the forecast
through 12Z Saturday, and out of KMKE through 18Z.

MARINE...Light north to northeast winds will veer east this
morning then southeast this afternoon. South to southeast winds
ahead of an approaching cold front will approach Small Craft
Advisory levels Saturday afternoon and night.

&&

.MKX Watches/Warnings/Advisories...
WI...None.
LM...None.
&&

$$

UPDATE...DDV/Hentz
TODAY/TONIGHT AND AVIATION/MARINE...REM
Saturday THROUGH Thursday...Collar



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