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Area forecast discussion 
National Weather Service Green Bay WI
229 PM CDT Thursday Oct 20 2016

Forecast discussion for routine afternoon forecast issuance

Short term...tonight and Friday
issued at 229 PM CDT Thu Oct 20 2016

The latest rap analysis and satellite/radar imagery show a large
high pressure system stretching from central Canada southward to the
Great Plains. Upper troughing is moving over the western Great
Lakes, with cold advection continuing off of Lake Superior
contributing to a widespread cu field. Partial clearing is
occurring over western WI, and some of this clearing should push into
parts of central WI later this afternoon. With north flow
continuing tonight into Friday, cloud trends are the main forecast

Tonight...high pressure will be slowly moving east over the northern
Mississippi Valley. Northerly winds will continue on the eastern
flank of the surface high, and produce clouds off Lake Superior.
Some clouds will likely dissipate over parts of eastern and central
with the loss of daytime heating. But then may see a surge of clouds
southward over central WI late. Low temps should range through
the 30s with a few upper 20s possible in the cold spots of north-
central WI.

Friday...the surface ridge axis will move across the state. As
light winds back to the west through the day, should see early
morning clouds retreat northward some, but think thermal troughing
should still lead to a persistent cu field over northern and
northeast WI. So will go with partly to mostly cloudy skies for the
morning, then increasing sunshine for the afternoon over central WI.
Temps near todays readings.

Long term...Friday night through Thursday
issued at 229 PM CDT Thu Oct 20 2016

Northwest flow will continue this weekend as a shortwave tracking
through the northern Great Lakes brings a small chance for showers
across the extreme northern cwa on Sunday afternoon. The models
seem to have converged on a solution in targeting this time period
which is coincident with peak heating, which when combined with
some added moisture from the lakes, should lead to better chances
than a nighttime window.

Other than the brief chance for rain across the north Sunday
afternoon, the weather should be relatively quiet through early
next week. The next chance for widespread rain does not arrive
until later next week when a more active pattern emerges for the
middle part of next week. The first chances arrive late Monday
night and into Tuesday as a warm front lifts north across the
western Great Lakes with a surface low tracking to our south on
Wednesday night. Although the models differ on the exact placement
of this low, the timing is in the ballpark. Also this run with the
low to the south the warm air does not seem to intrude as far
north with very little instability to speak of this far north.
Therefore will remove thunder from the forecast next week as the
best instability remains to the south. The main concern this run
is any further southward jog of this system to the south would
push the best rain chances further south, with smaller chances or
a dry forecast across the north in this scenario. At this point
will stay with the superblend and refine further in subsequent

Aviation...for 18z taf issuance
issued at 1204 PM CDT Thu Oct 20 2016

High pressure will be building into the region through
the taf period. However, cold north flow off Lake Superior will
continue to generate scattered to broken 2500-4000 ft cigs. Ceilings
will continue to be lowest over north-central WI.

Grb watches/warnings/advisories...


Short term.....Mpc
long term......kurimski

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