Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Milwaukee/Sullivan WI
841 PM CDT Friday Oct 21 2016

upper level ridging is building into the western Great Lakes
overnight. This is accompanied by a surge of milder air that will
take US into early next week. The warm air advection is rather
strong overnight, but the deep moisture is lacking. Thus we should
only see a persistent mid level cloud deck across the area tonight
into early Saturday morning, then those clouds should begin to
move out. Lowest temps tonight should be in the east, and probably
dropping to their lowest around midnight. It's mostly clear across
the east right now, but those mid clouds will move in and put a
stop to the falling temps. Still just looking at mainly patchy
frost, but a few favored low spots could get hit a bit hard if the
clearing lingers too long. The forecast is in good shape.


Aviation/06z tafs/...
VFR conditions are expected through the taf period with winds
below 10kts.


high pressure will provide light winds and small waves through the


Previous discussion... /issued 328 PM CDT Friday Oct 21 2016/

Short term...

Tonight and Saturday...forecast confidence is medium.

Broken to overcast stratus/stratocumulus deck should continue to
linger into early this evening, before gradually shifting off to the
east. An upstream 500 mb vorticity maximum sliding southeastward
through the region later this evening and overnight should help
bring another scattered to broken mid level cloud deck into the
area. This deck should linger into Saturday morning, perhaps into
the afternoon in the eastern counties.

The clouds should limit lows to the 35 to 37 degree range in most
areas, with upper 30s along Lake Michigan. This should allow for
patchy frost development later tonight into early Saturday
morning, but do not think it will get more widespread than that.
Thus, will not issue a frost advisory in the southeast counties for
later tonight.

In general, our frost/freeze headlines will continue only for
Ozaukee, Waukesha, Milwaukee, Walworth, Racine and Kenosha counties.
These areas have yet to see conditions supportive of frost over a
wide portion of those areas. The rest of the area has seen a few
nights with near-freezing temperatures and frost, so will
discontinue issuing frost/freeze headlines in those areas.

Warm air advection develops over the area later tonight into
Saturday. This should bring some milder temperatures for Saturday.
Highs should range in the mid to upper 50s in the northeast half of
the area, to the lower 60s in the southwest half.

Saturday night through Monday night...forecast confidence high.

A weak area of low pressure will track from the nrn Great Plains
to ern Minnesota Sat night. Wswly surface winds will remain light ahead
of the low with clear skies and cool temps expected. However, temps
will remain mild enough to prevent much frost formation.

The low will then track across srn WI from late sun am through the
first half of the afternoon. Surface to 850 mb warm advection will
boost temps into the 60s followed by nwly winds and cold advection
by late afternoon. The frontal passage will remain dry due to little
available moisture and the shortwave trough tracking to the north
across the nrn Great Lakes. The nly winds and cold advection will
weaken by Mon am with low temps in the middle to upper 30s with
some frost expected. A large high pressure area will then slowly
move across the wrn Great Lakes Mon and Mon night. Full sunshine,
light winds, and high temps in the 50s for Mon. Another cool night
expected for Mon nt with some frost formation once again.

Long term...Tuesday through Friday...forecast confidence medium.

A shortwave trough and low pressure area will then slowly move
from the central Great Plains to across the WI/Illinois border for Wed
night. There will be good lift and moisture with the low with
rain showers becoming likely on Tuesday while becoming widespread
late Tue night and Wed. Cyclonic flow and passing shortwave
troughs may allow the rain chances to linger for Thu-Fri. The
clouds and rain could make for fairly cool high temps during this

Aviation/00z tafs/...

VFR stratus and stratocumulus should linger into early this evening
across taf sites. These clouds should then gradually shift off to
the east. North to northwest winds will remain light to moderate
until early evening, before weakening to light and variable by later

Another round of scattered to broken mid level clouds should move
southeast through the area later this evening and into Saturday
morning. May see scattered clouds linger into Saturday afternoon,
with winds becoming light and southwesterly.


North to northwest winds gusting to 15 to 20 knots should gradually
weaken into this evening, as the pressure gradient relaxes. This
should help waves subside to below 4 feet by early this evening
south of North Point lighthouse.


Mkx watches/warnings/advisories...


tonight/Saturday and aviation/marine...wood
Saturday night through Friday...gehring

National Weather Service Glossary of Abbreviations