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FXUS63 KMKX 060223
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
923 PM CDT Fri Jun 5 2020

.UPDATE...

High pressure begins to build into the region with skies staying
mostly clear tonight. Lows bottom out in the 50s with a noticeable
change in humidity as drier air continues to filter in. The
current forecast is on track and no changes are needed.

&&

.MARINE...

The cold front has pushed south of the lake with high pressure
starting to build in behind this front. One change was to add low
pops for a few isolated storms moving across the far northern
portion of Lake Michigan. Otherwise, the rest of the forecast is
on track.

&&

.PREV DISCUSSION... (Issued 559 PM CDT Fri Jun 5 2020)

UPDATE...

Confidence in any shower/storm development this afternoon/evening
continues to decrease based on satellite imagery. With drier air
filtering in behind the cold front MLCAPE is decreasing and other
than some weak convergence we lack any real forcing. So, at this
time no changes are needed to the forecast.

AVIATION(00Z TAFS)...

Cold front is now south of all terminals with breezy NW winds.
Expect winds to drop below 10kts tonight. VFR conditions are
forecast through the period as high pressure begins to build into
the region. Winds stay out of the N/NW for Saturday.

PREV DISCUSSION... (Issued 328 PM CDT Fri Jun 5 2020)

SHORT TERM...

Tonight Through Saturday Night...Forecast Confidence Is High.

Cumulus are getting smaller and more spaced out afternoon, with
decreasing confidence in any thunderstorm development through late
afternoon. Winds have become west/northwest across the forecast
area too, with dew points beginning to fall in the northwest.

Should see clearing skies this evening into tonight, with mostly
clear skies continuing into Saturday under high pressure. Could
see some mid/high level cloudiness arrive from the northwest
Saturday night. Temperatures are expected to be within a few
degrees of normal tonight through Saturday night.

Sunday Through Monday Night...Forecast Confidence Is High.

Models are in good agreement with taking an amplified 500 mb ridge
axis over the area Sunday and Sunday night slightly to the east
Monday. Warm air advection will steadily occur during this
period, with temperatures warming Monday away from Lake Michigan
as winds shift to the south. Cooler temperatures near the lake are
expected Sunday and Monday, with onshore winds. Highs should
reach the upper 80s to around 90 on Monday inland, given expected
925 mb temperatures. Dry conditions should linger into Monday
night, as the 500 mb ridge axis moves well east of the region.

LONG TERM...

Tuesday Through Thursday...Forecast Confidence Is Medium.

The biggest impact in the forecast will be the remnants of
Tropical Storm Cristobal and possible heavy rainfall and
areal/river flooding during this period.

The operational 12Z GFS and Canadian models are about 6 hours
quicker and a little further east with the track of the remnants
of Cristobal than the 12Z ECMWF. They are generally taking a
deepening low north northeast through the area Tuesday afternoon
or Tuesday night. This is when the heaviest QPF would occur.

The ECMWF and Canadian then show a secondary area of strong 500
mb vorticity advection through the area Wednesday, with subsequent
additional QPF across the area. The GFS only has a little more
QPF Wednesday, as a cold front passes through the area. Still,
there is pretty good agreement with trends this far out in the
forecast.

The GEFS plumes for Madison and Milwaukee are suggesting around
1.50 inches of QPF for Tuesday into Wednesday. The NAEFS is
showing anomalous precipitable water potential for Tuesday into
Wednesday over the area, not surprising with a remnant tropical
system. There is a fair amount of spread in the NBM v4.0 24 hour
QPF and extended period MOS products. However, the 90th percentile
amounts have trended upwards and are now over 2 inches, and thus
the signal for heavy rainfall, despite being several days out.

Given this, and the operational models all showing a bullseye of
2 to 3 inches of QPF in a 6 hour period somewhere in or close to
the area, feel that leaning toward the higher end of the ensembles
for QPF would make sense at this time.

Because of the uncertainty with QPF amounts, will not message
exact QPF amounts at this time. However, there is good potential
that heavy rainfall and subsequent river and areal flooding are
possible Tuesday into Wednesday, with impacts perhaps lingering
Wednesday night into Thursday morning or longer. Will need to
monitor for increasing confidence trends for this period as it
gets closer, and ramp up messaging accordingly.

Thursday Night And Friday...Forecast Confidence Is Medium.

Models are trending toward cold air advection occurring with high
pressure to the northwest of the area. This may bring cooler and
drier air into the region.

AVIATION(21Z TAF UPDATES)...

Confidence is increasing in any further shower/storm development
this afternoon, but not out of the question for some isolated
activity. Should stay VFR through Saturday, especially once the
clearing moves in late this afternoon into early evening.

MARINE...

Winds will vary from west to north through tonight as low
pressure drags a cold front through the region. High pressure will
build over Lake Superior Saturday, shifting towards the eastern
Great Lakes on Sunday. Winds will generally stay below 20 knots
through this weekend.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

Update...Stumpf
Tonight/Saturday and Aviation/Marine...DDV
Saturday Night through Friday...Wood
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