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Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
1103 PM CDT Friday Apr 18 2014
High pressure centered over the Great Lakes will be centered over
the eastern Great Lakes Saturday with south winds across southern
Wisconsin. Other than some MVFR visibilities around sunrise...expect VFR
conditions through the taf period.
Previous discussion... /issued 225 PM CDT Friday Apr 18 2014/
Tonight and Saturday...forecast confidence is high.
High pressure over the western Great Lakes this evening will slide
to the east side of the lakes by this time on Saturday. As a
result...look for quiet/dry weather through Saturday. Partly
cloudy skies and light winds will allow temperatures to cool to the
lower and middle 30s most locations. A southeast wind flow on the
back side of the high on Saturday will bring cooler lake effected
air from Kenosha County...through western Fond Du Lac/Green Lake
counties. Temperatures along the beaches will be in the upper
30s...climbing into the 50s inland...while areas West Madison will
see highs in the middle 60s.
Saturday night and Sunday...forecast confidence is medium.
The challenge this period has been how far an approaching cold
front/trough will sag south into the forecast area...before
another low pressure system moves in for Monday. This trough will
stretch from a low pressure system moving across south central
Canada...then connects with another low over western Kansas. That
Kansas low will eventually move up here. As the northern low over
Canada moves off to the northeast the front will drop south to
about an Iron Mountain to Eau Claire line by late Saturday night.
Some pre-frontal precipitation could drop into our northern County Warning Area by morning.
The front will have trouble moving south on Sunday as the
southerly winds begin to increase ahead of the Kansas low that
starts to head toward the area. In addition...it looks like by the
end of the day Sunday the front should be along a Fox Valley to
La Crosse line with precipitation mainly staying north of a Milwaukee to
Madison line through the day. Temperatures across the far south could hit
the lower to middle 70s...while to the north of msn/mke...where there
will be more clouds and potential rain...highs would likely only
reach the middle 60s. An off-shore wind should allow the far eastern
areas to enjoy some milder temperatures for a change.
Sunday night and Monday...forecast confidence is medium.
Rain should finally overspread all of southern Wisconsin later
Sunday night through Monday as low pressure moves through. The
soundings look pretty stable with respect to convection so will
keep it free of any thunder mention.
Monday night through Wednesday...forecast confidence is medium.
Strong cold advection kicks in in the wake of the departing low
pressure system. Any lingering rain should slip out of the
southeast Monday night with Tuesday and much of Wednesday looking
dry but much cooler. Tuesday will be the coolest under somewhat
brisk north winds. A high pressure ridge will slide over the area
late Tuesday night and Wednesday morning with southeast winds
returning on Wednesday. Warm advection late on Wednesday could
bring some showers to the west in the late afternoon. Of course
the cool southeast winds will keep it chilly near the lake on
Thursday and Friday...forecast confidence is medium.
A large low pressure system that is being handled by the GFS and
European model (ecmwf) reasonably well will move through the area during this time.
This will likely bring the area more rain and a chance for some
thunderstorms. Specific timing still needs to be worked out...but
its looking unsettled.
Look for VFR conditions through the taf period as high pressure
moves through the region.
tonight/Saturday and aviation/marine...mrc
Saturday night through Friday...Davis