Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
245 am CDT Mon may 28 2018
Today and tonight...forecast confidence is medium.
Convection within a decent h8 jet Max/warm air advection regime
across northern Wisconsin early this morning will generate a
decent outflow that will surge south through the morning. This
outflow will likely continue to fire off new convection with
persistent cold pool lift on the western/southern edge. This stuff
should begin to weaken as we approach sunrise, but would expect
some of the showers/storms to push into our northern counties for
a few hours this morning. We then quiet down by late morning with
deep layer high pressure generally taking control. The wind fields
this afternoon suggest some weak convergence boundaries possible
over the middle of the forecast area. Some guidance produces
activity along it, others don't. Soundings show a decent cap
within the ridge, precluding development given the lack of any
deep forcing. For now will keep it dry across the area for the
afternoon and evening, except for a small mention well north of
Milwaukee and Madison.
Temps should be cooler east today as winds should be onshore for
most of the day due to the outflow described above. Hot again
Tuesday - confidence...medium
influence of 582-585dm 500 millibar ridge will extend from Ohio
Valley northwest into Great Lakes. Meanwhile remnants of Alberto
will be heading north into the mid miss valley. In the low levels,
surface/850 millibar anticyclonic curvature persists with little
boundary of note to latch onto. Hard to see much in the way of
forcing, however Gem/GFS and European model (ecmwf) all generating precip in
southwest cwa while the NAM is dry. Subtleties prevail in this
regime so won't go all out dry but opt for a small afternoon pop
mainly west and southwest of Madison. Still very warm with 925
temps in the low to mid 20s celsius.
Wednesday and Wednesday night - confidence...
main focus will be on tracking track of the remnants of Alberto.
The Gem has shifted the heavier precip to our east while the GFS
has toned down the qpf amounts, but still suggest we will be
squarely on the western flank of the circulation. Meanwhile the
European model (ecmwf) and NAM are showing a fairly siggy dose of rainfall across
the eastern and central County Warning Area right into Wednesday evening. The
soundings show a deep saturated layer with some skinny cape noted.
Precipitable water values are over 2 inches. Per coord with lot
and grb have boosted the blended pops higher to account for some
consensus for our eastern cwa being in a favorable position with
respect to current forecast track of this low. Have also made some
upward adjustments to the qpf to account for the higher than
normal moisture content this system will be bringing with it. Of
course if this starts to trend east, like the outlier Gem is
suggesting, then this will throw a wrench into things, but again
that is an outlier and will go with a non-Gem approach to this
system for now.
Thursday - confidence...medium
while the remnants of Alberto will have shifted away a shortwave
and associated surface low will drop into the area from the
northwest. This will keep the chance of showers and a few
thunderstorms in the forecast. Thermal ridge amplifies ahead of
the cold front. Winds shift northwest Thursday evening with a push
of drier and cooler air eventually working in.
Friday through Sunday - confidence...low to medium
cooler pattern sets up with high pressure ridging into the state
from north of Lake Superior. At this time the European model (ecmwf) is an outlier
in bringing a trough through later Saturday into Sunday with
precip. The Gem and GFS show this feature being suppressed to our
south as it advances towards WI with the high being dominant. At
some point the small blended pops could be removed should it
appear clear that the high dominates.
Aviation(09z tafs)...VFR conditions are expected through the taf
period. Look for winds to shift to the north by around 12z this
morning, eventually shifting back to the south this afternoon.
Near the lake, those winds will be southeast due to the lake
Marine...winds and waves are expected to remain below Small Craft
Advisory levels through Thursday. Fog may develop over the next few
days due to the warm and humid airmass over the region.