Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 252007

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
307 PM CDT THU AUG 25 2016

.Thursday night an Friday...Confidence is medium

Scattered to broken high clouds that were blown off of some dying
thunderstorms across southern IA have overtaken much of the CWA.
The back edge of these clouds should reach the area around 00z,
about the same time 500-300mb RH progs really dry out.

A combination of NW flow at the jet level and dry, zonal flow in
the mid and low levels should result in mostly clear skies through
much of the night, though some high clouds may linger across the
far south. On Friday, ridging aloft and high pressure should make
for a pretty nice day. We will see some moisture moving into the
area tomorrow afternoon as we get into SW flow on the upstream
side of the mid level ridging. This moisture will help those
broken mid level clouds gradually push back into the area.
Additionally, some afternoon cu seems likely across much of the

.FRIDAY NIGHT AND SATURDAY...Confidence is medium.

A stout mid-level anticyclone will remain anchored over the South
Atlantic states, with shortwave energy riding atop the eastern
CONUS ridge. A lead impulse emanating from broad troughing along
the International Border will approach Friday night, with a surge
of warm, moist advection arriving from the south. Moisture
transport is initially maximized from 6 to 12z Saturday, with
another push coming later Saturday evening. Column integrated
precipitable water values during this time climb to over 1.8
inches, as the warm cloud depth increases to around 4 kft Saturday
morning. While these moisture parameters point towards efficient
warm rain processes, corfidi vectors of 15 to 20 knots suggest
good storm motion. Will keep the thunder mention going Friday
night considering the strengthening low-level jet and few hundred
joules of available mixed layer CAPE.

After the initial round of morning showers and storms, some mid-
level drying is evident by early afternoon. This suggests a
possible break before additional showers and thunderstorms develop
ahead of surface low pressure during the late afternoon and
evening. Once again, moisture parameters point towards good
precipitation efficiency Saturday evening, with corfidi vectors
decreasing to 5 to 10 knots. This suggests slower storm motions
along with the potential for locally heavy rainfall Saturday
night. Mixed layer CAPE climbs above 1000 J/kg Saturday afternoon
into evening, with deep layer shear reaching 35-40 kt north of
Milwaukee and Madison around 18z, before pulling away to the north
by late evening. The Craven-Wiedenfeld Aggregate Severe Parameter
(CWASP) climbs into the upper 60s to near 70 during the best
CAPE/shear overlap Saturday afternoon, so this may be a period to
watch for a few stronger storms. Temperatures will be seasonal,
with lows in the 60s Friday night and highs on Saturday in the
upper 70s to perhaps lower 80s, depending upon whether we see any
sunshine during the afternoon.

.SUNDAY THROUGH THURSDAY...Confidence is medium.

A few showers could linger into Sunday morning before mid-level
heights rise during the afternoon. The elongated ridge axis
remains to our south throughout the extended, with southern
Wisconsin located along the northern ridge periphery. Weak high
pressure is expected for the Great Lakes and Ohio Valley, but with
periodic chances for a ridge riding shortwave here or there.
Predictability for these is low, so left slight chances for
precipitation where the consensus of deterministic guidance hint
at this possibility. 925 hPa temperatures averaging 20 to 24
degrees celsius support highs in the lower 80s, with lows mostly
in the 60s.



VFR conditions should prevail at all TAF sites through Friday
afternoon. The only questions revolve around high clouds. Satellite
trends and model guidance suggests that the scattered to broken
clouds that have overtaken the area this afternoon should clear out
in the early evening, giving way to mostly clear skies tonight.
Tomorrow morning, those high clouds may push back into the CWA,
along with some typical afternoon cu.



Winds and waves will remain fairly calm through Friday afternoon
thanks to high pressure passing the area. By late Friday night,
most of the guidances brings a low pressure system into the region,
bringing chances of showers and thunderstorms through Saturday night.


.MKX Watches/Warnings/Advisories...


Friday NIGHT THROUGH Thursday...SPM is the U.S. government's official web portal to all federal, state and local government web resources and services.