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Area forecast discussion...updated 
National Weather Service Milwaukee/Sullivan WI
1036 am CDT sun Apr 26 2015

Update...

Quiet weather will continue for the next few days across the
region...under the influence of high pressure. Dry look to area
forecast soundings suggest little to no diurnal cumulus
development this afternoon. Northeast winds near the lake will be
gusty at times...with somewhat weaker north winds inland.

Temperatures today should reach the upper 50s to lower 60s well
inland...with 40s near the lake. Gradually warmer temperatures are
expected into the middle of the week...with onshore winds bringing
cooler values near Lake Michigan each day.

Wood

&&

Aviation/18z tafs/...

High pressure to the north of the area will continue to bring
quiet weather with VFR conditions for the next few days. Gusty
northeast winds are expected this afternoon at the eastern
sites...with somewhat weaker north winds at Madison.

Light north winds are expected tonight...with north to northeast
winds on Monday. May see some low to middle level clouds pass
southward through taf sites later tonight into Monday.
Otherwise...mostly clear skies are expected.

Wood

&&

Marine...

Modis imagery from Friday revealed Lake Michigan surface temperature around 41
degrees. Weak surge of low level cold air will sag south across
central and Southern Lake Michigan this afternoon and evening. However...forecast
soundings over the nearshore waters Show Low level inversion
persisting. This should prevent an extended period of higher winds
from reaching lake surface.

However...a few gusts may punch through this inversion. Will hold
off on issuing Small Craft Advisory at this point...due to infrequent
gusts expected. Will add exercise caution remark to nsh for this
afternoon and evening.

Mbk

&&

Fire weather...

Very low relative humidity values of 20 to 25 percent are expected
this afternoon across areas away from Lake Michigan. North winds
will be in the 8 to 11 miles per hour range...with some gusts to 18 miles per hour in
this area. Temperatures will top out in the upper 50s to lower
60s.

The very low relative humidity values should persist Monday and
Tuesday away from Lake Michigan...under the influence of high
pressure. Winds will be light each day...with gradually warming
temperatures.

Wood

&&

Previous discussion... /issued 317 am CDT sun Apr 26 2015/

Short term...

Today and tonight...forecast confidence is high.

An upper level trough across far southeast Canada extends back into
the upper Great Lakes. This trough drops south a little and builds
back into Wisconsin this evening. Little in the way of upper
divergence or 700 mb upward motion. There is some increase in 700
mb relative humidity this afternoon from the east that reaches the Lake Michigan
counties. 850 mb relative humidity also increases...but mainly later tonight.
However it is not saturated...so do not expect any extensive cloud
shield.

The main concern is the increase in 700 mb winds this afternoon...
and the 850 mb winds mainly tonight. While the 700 mb wind increase
occurs across southern Wisconsin the 850 mb wind increase is mainly
near Lake Michigan. With surface heating wind gusts...while not
strong...will likely be stronger than the weak surface pressure
gradient suggests.

With the northeast winds off Lake Michigan...expect typical
springtime cooling near Lake Michigan...with mild temperatures well
inland.

Long term...

Monday through Thursday... forecast confidence high.

Dry air and middle level ridging will nose into the western Great Lakes
early this week as a sprawling closed upper low over New England
shifts east. Surface high pressure will take hold of the upper
Midwest and Great Lakes through Thursday and bring a pleasant
stretch of weather to southern WI. There will be a steady breeze out
of the north through this period... but with the weak pressure
gradient we can expect a lake breeze to develop each day. Inland
temperatures will be in the 60s for this period while Lakeshore temperatures will
be stuck in the 50s.

A middle level shortwave will drop down through WI Tuesday afternoon/
evening. Both the European model (ecmwf) and GFS models now have a dry forecast for
Tuesday night and Wednesday. This upper trough will bring at least a middle
level cloud deck... with the possibility of some sprinkles.

Friday through Sunday... forecast confidence medium.

Another shortwave trough crossing the northern plains will bring our
next chance for rain Friday night. Thunder is debatable. There may
be some weak elevated instability to support isolated thunder. Left
it out of the forecast until there is more certainty.

The GFS and European model (ecmwf) take on slightly different upper level weather
patterns later next weekend... but both result in precipitation chances
Saturday night into Sunday. The GFS keeps temperatures slightly
cooler than the European model (ecmwf) due to a northwest flow pattern.

Aviation/12z tafs/...

Expecting VFR conditions through the forecast. Could see some
diurnal cumulus this afternoon...especially over eastern portions of
the forecast area away from the more stable effects near Lake
Michigan. Some clouds in the 5 to 8 thousand feet range may affect the
southeast later this afternoon and tonight from a weak trough axis
rotating around the back side of elongated upper trough centered
over the Canadian Maritimes. Dry air in place should limit coverage
to mainly scattered.

Northeast wind gusts will increase again with mixing but without the
gusts like Saturday.

Marine...

Winds are easing to below Small Craft Advisory criteria this
morning. A surge in stronger north/northeast winds later this
afternoon and tonight could push winds and waves back towards small
craft levels.

Fire weather...

Min relative humidity values will drop to around 25 percent well inland and especially
over south central Wisconsin...maybe down towards 20 percent.

The main concern is the increase in 700 mb winds this afternoon...
and the 850 mb winds mainly tonight. While the 700 mb wind increase
occurs across southern Wisconsin the 850 mb wind increase is mainly
near Lake Michigan. With surface heating wind gusts...while not
strong...will likely be stronger than the weak surface pressure
gradient suggests.

&&

Mkx watches/warnings/advisories...
WI...none.
Lm...none.
&&

$$

Update...wood/mbk
today/tonight and aviation/marine/fire weather...hentz
Monday through Saturday...mrc

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