Scientific Forecaster Discussion
fxus63 kmkx 232023
Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
323 PM CDT Wed Aug 23 2017
Tonight and Thursday - confidence...medium
Overall dry and cool surface high will dominate this period. A
reinforcing cool front arrives later tonight into Thursday
morning. A potent mid level shortwave combined with this front
will try to fight the substantially dry column to kick off a few
showers. BUFKIT soundings do show various depths to the mid level
moistening so have some small chances mainly in the western cwa.
Cyclonic flow and low level thermal trough in place for much of
Thursday so after any lingering mid clouds move off should see
some more in the way of cumulus formation.
Thursday night through Saturday...forecast confidence is medium to
High pressure will hold in place over the Great Lakes late week
into the weekend. Moisture will be increasing from the west on the
back side of the high during this time. This could allow for a few
showers at times as weak waves rotate through the northwest flow.
It will be a battle between the higher moisture west and the much
drier conditions toward the center of the high in the east.
Confined highest pops mainly to the west as a result, with
eastern areas possibly staying dry through this time period.
Below normal temps are expected during this forecast period.
Sunday through Wednesday...forecast confidence is medium:
Models are developing a closed upper low in the area late weekend
into early next week. As is typical with these systems, models are
struggling a bit with the movement/strength of the upper low as
well as the resultant surface development. It does look like
showers and maybe a few storms are possible as this low moves
through the region, with Sunday and Monday having the higher
chances given the overlap among models. It should turn dry by
mid-week, though the European model (ecmwf) is slower to push the system out and
hangs on to shower chances through Wednesday.
Some uncertainty with exact temps given the different
possibilities with the low pressure system next week. Overall
though, temps should be near to a few degrees below normal.
Aviation(21z tafs)...VFR cumulus field should dissipate within
the cooling/dry airmass this evening. Small chance of shra very
late tonight into Thursday morning with approaching vigorous
shortwave and southward sliding cold front.
Marine...arrival of potent mid level shortwave combined with
lower level cold air advection may still lead to an isolated waterspout or two
overnight into Thursday morning. Passing cold front late tonight
into Thursday morning will shift winds onshore though winds and
resultant waves are expected to remain below small craft criteria.