Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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549
FXUS63 KMKX 240544
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1144 PM CST Thu Nov 23 2017

.UPDATE...

Some altocumulus brushing across the far northeast, otherwise a
slight increase in cirrus. Increasing pressure gradient, so
temperatures will not drop much.

&&

.AVIATION(06Z TAFS)...

VFR conditions expected for this TAF period. Increasing low level
winds will cause low level wind shear scenario late tonight into
Friday morning before surface winds become increasingly gusty.

&&

.PREV DISCUSSION... (Issued 906 PM CST Thu Nov 23 2017)

UPDATE...

A few altocumulus brushing across the far north, otherwise clear.
Increasing pressure gradient, so temperatures will not drop much.

MARINE...

Low pressure moving across southern Canada will result in a
tightening pressure gradient ahead of an associated cold front. As
a result, gusty southwest winds will develop late tonight and
continue into Friday evening. The gusty southwest winds will turn
to the northwest Friday night and continue into Saturday. A few
gale force gusts will be possible Friday and Friday evening ahead
of the approaching cold front. Small Craft Advisory starts up
late tonight and will continue into Saturday morning.

PREV DISCUSSION... (Issued 528 PM CST Thu Nov 23 2017)

UPDATE...

Mostly clear skies this evening. light southwest winds.

AVIATION(00Z TAFS)...

VFR conditions expected for this TAF period. Increasing low level
winds will cause low level wind shear scenario late tonight into
Friday morning before surface winds become increasingly gusty.

PREV DISCUSSION... (Issued 215 PM CDT THU NOV 23 2017)

TONIGHT AND FRIDAY - Forecast Confidence...Medium to High.

Expect to see some increasing mid/high clouds later tonight as
second surge of warm air advection moves across the western
Great Lakes.  Strongest push remains over northern WI where a
few light showers may get squeezed out from the mid-clouds.
Will continue dry conditions in CWA due to lack of saturation
below 6K feet across northern areas.  A breezy day is expected
on Friday. Expect early morning mid-high clouds to thin through the
late morning and early afternoon resulting in good boundary layer
mixing.  Inversion will set up around 2-3ft preventing strongest
winds from mixing to surface.  However still expect gusts reaching
28-33 knots from late morning through mid-afternoon.  925H temps
warm to 11-13C.  Considering mid-November more limited sunshine, and
potential for mid-clouds returning in the afternoon, still thinking
temps should peak in the mid 50s to around 60 before cold front
moves through during the late afternoon and evening. Column
precipitable water increases to over three quarters inch ahead of
approaching front.  Sloping frontogenetical forcing and enhanced
forcing from right entrance region may have just enough atmospheric
moisture to result in a few light showers near the cold front.
Hence added small pops from mid-afternoon into the early evening for
light showers.

FRIDAY NIGHT THROUGH SUNDAY - Forecast Confidence...Medium to High.

Light shower threat will end Friday evening as cold front exits the
area.  Then cooler, more seasonal conditions will return for the
weekend as 925H temps cool to the zero to 5 above range.  Upper
level steering winds remain WNW preventing any significant surge of
colder air.  Influx of drier air and passing high pressure will
result in quiet conditions to finish off the long holiday
weekend.

EXTENDED PERIOD...

SUNDAY NIGHT THROUGH THURSDAY - Forecast Confidence...Medium.

A short wave trof moving swiftly eastward across the upper midwest
will affect the region for the first part of the period.  Deeper
atmospheric moisture will continue to be cutoff as sprawling high
pressure blankets the southeast CONUS.  Mild southwesterly breezes
ahead of the surface cold front associated with the mid-level trof
will result in another mild day on Monday.  Daytime temperatures may
be just as warm as tomorrow. 925H temps warm to 9 to 11 degrees C
with the GFS about 2 degrees warmer than ECMWF.  Medium range
guidance in general agreement on carrying cold front through
southern WI on Tuesday, however disagreement on timing.  GFS
consistently faster with cold front passing through about 12 hours
earlier than ECMWF and GEM.  The slower movement of the ECWMF/GEM
solution allows just enough Gulf moisture to stream north on Tuesday
to result in showers along the passing cold front over eastern CWA
per GEM.  ECWMF keeps moisture a bit shallower.  WPC blended
guidance also favors slower movement emphasizing ECMWF blend. If
this trend continues, may need to eventually add some some small
POPS to Tuesday outlook.

Otherwise, seasonal conditions to continue around mid-week.  Another
short wave caught in the zonal flow looks to move through the upper
midwest in the Wednesday night/Thursday time frame, but moisture
return looks limited once again.

AVIATION(21Z TAFS)...No change to the ongoing forecast. VFR
conditions expected for this TAF period. Increasing low level winds
will cause low level wind shear scenario late tonight into
Friday morning before surface winds become increasingly gusty.

MARINE...Deepening low pressure moving across southern Canada
will result in a tightening pressure gradient ahead of an
associated cold front.  As a result, gusty southwest winds will
develop later tonight and continue into Friday evening.  The
gusty southwest winds will turn to the northwest Friday night
and continue into Saturday.  A few gale force gusts will be
possible Friday and Friday evening ahead of the approaching cold
front.  Lake surface temperature is around 43 degrees which will
limit the amount of low level mixing on Friday as the warmer air
surges into the region. Small Craft Advisory starts up late tonight
and will continue into Saturday morning.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory from 3 AM Friday to 6 AM CST Saturday for
     LMZ643>646.

&&

$$

Update...Hentz
Tonight/Friday and Aviation/Marine...MBK
Friday Night through Thursday...MBK



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