Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 240327 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1027 PM CDT SAT JUL 23 2016

.UPDATE...

Line of weakening thunderstorms has exited to the southeast with
lingering showers and isolated thunderstorms expected to clear to
the east by midnight. How long a break in the precipitation we
get will be predicated on capping...700 mb temperatures around 12C
advecting in from the west...holding over the region overnight, or
if the cap collapses with mid level cooling with the short wave
trough. This would allow convection developing along cold front in
western Minnesota to drop southeast into southern Wisconsin late
in the overnight.

Will bring chance PoPs into the western forecast area after
08Z...and across the entire CWA through 12Z.

&&

.AVIATION/06Z TAFS/...

Expect lingering showers and a few storms to clear the east by
05Z. Could be some patchy mvfr fog with the moist atmosphere and
light winds. Hi-res models continue to show a band of showers and
storms reaching the western forecast area around/after 08Z and
crossing the CWA into Sunday morning. Will keep VFR conditions
until expected precip with MVFR cigs and vsbys moves in. Chances
for showers and storms linger until cold front moves east of the
state Sunday afternoon.

&&

.MARINE...

Will likely see some patchy fog over the nearshore waters after
showers and storms clear tot he east shortly after midnight. Then
another chance of storms returns late in the overnight into Sunday
morning as a cold front approaches. Showers and storms will end
with frontal passage by mid-afternoon Sunday. Southwest winds will
gust to around 20 knots ahead of the front.

&&

.PREV DISCUSSION... /Issued 249 PM CDT SAT JUL 23 2016/

SHORT TERM...

TONIGHT AND SUNDAY...Forecast Confidence...Medium

The first round of storms continues to move through, driven by some
warm advection, arrival of deeper moisture, and a weak shortwave.
Given these ingredients will continue to push eastward into the
afternoon, expecting these storms will make their way through the
rest of the forecast area through late afternoon.  Another round of
storms is possible this evening into tonight ahead of the main
shortwave. Main threats with the storms into tonight will be very
heavy rainfall and strong winds. Latest Day 1 has all but the
southeast forecast area in a Slight Risk, with a Marginal Risk in
the southeast.

Should be mainly dry Sunday, as the cold front moves through. Looks
like effective boundary will be south of the forecast area by the
time storms fire in the afternoon.

Will be a hot one again Sunday ahead of the front, with higher
dewpoints lingering. Will be cutting a few north and west counties
out of the heat advisory based on temps that were observed today and
what is expected tomorrow. Does not look like these areas will hit
the 4 straight days of 95-100 heat indices.

LONG TERM...

MONDAY and TUESDAY...Forecast Confidence...Medium

By Monday morning, zonal flow will set up in the upper and mid
levels. Cooler air will filter in behind the cold front in the lower
levels as high pressure builds into the region. 925 temperatures
will be in the 21-24C range, suggesting highs in the mid to upper
80s. The lower levels look to be fairly dry through this period.
This will result in dewpoints in the mid 60s, and mostly clear to
partly sunny skies before cloudier skies build in ahead of an
approaching shortwave on Tuesday afternoon.

TUESDAY NIGHT through SATURDAY...Forecast Confidence...Medium

Beginning Tuesday night, a series of shortwaves embedded in the
zonal flow will pass across the region. The models aren`t especially
well aligned at this time, but it looks like there will be at least
modest forcing for ascent each day through Friday. A more robust
trough will move through Thursday night and Friday. In the lower
levels, a low pressure system will begin to develop across the
northern Great Plains on Wednesday before trekking across the
upper Great Lakes on Thursday night and Friday. Southerly flow
will set up ahead of the low beginning on Wednesday. This will
bring about more moist conditions, which in conjunction with the
upper and mid level forcing, will result in rain chances each day
in the latter half of the week. Instability looks pretty modest on
each day, but given that it is the summertime, cannot rule out
thunder with any showers that do develop.

Broadly cyclonic and moist flow will remain in place through at
least Saturday, so will be extending rain chances into next
weekend.

AVIATION/00Z TAFS/...

Outside of thunderstorms, should see mainly VFR conditions through
Sunday. This first round of storms will continue to move through
this afternoon given latest radar and mesoscale model trends.
Another round of storms is then possible this evening into tonight
ahead of the main shortwave. Main threats with the storms into
tonight will be very heavy rainfall and strong winds.

It looks mainly dry then Sunday as the cold front moves through and
high pressure begins to build in behind the front.

MARINE...

Will see some fog at times into late afternoon, likely until
showers/storms move through.

Southwest to west winds will be gusty from late Sunday morning into
afternoon. May end up needing a small craft advisory...though looks
too borderline to issue at this point.

&&

.MKX Watches/Warnings/Advisories...
WI...HEAT ADVISORY until 7 PM CDT Sunday for WIZ058-059-063>066-
     068>072.

LM...None.
&&

$$

UPDATE...REM
TONIGHT/Sunday AND AVIATION/MARINE...DDV
Sunday NIGHT THROUGH Saturday...BSH


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