Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
325 am CDT Friday Oct 9 2015
Today and tonight...forecast confidence is high.
Main challenge today is trending the cloud cover out of here. Early
morning satellite imagery shows the lower cloud deck covers a
majority of Wisconsin...clearing now across the far northwest. Some
broken clouds over the northeast are under a decent middle level
circulation. That circulation is part of a larger middle level trough
axis that will shift south Wisconsin by middle day. Much of the
guidance suggests that the subsidence behind the trough coupled with
neutral low level temperature advection should bring rapid clearing from
north to south by afternoon. The rap is more pessimistic in the low
level relative humidity...keeping it around until middle afternoon or so. Therefore
some uncertainty exists with respect to the clearing trends. A
fairly tight pressure gradient will bring the strongest winds this
morning...but that gradient relaxes as a surface high pressure ridge
leans over the area this afternoon. So...the afternoon is shaping
up to feature decreasing clouds and wind with temperatures in the upper 50s
to lower 60s.
Quiet tonight under clear skies and light winds. Could see some
patchy fog in the usual low spots.
Saturday and Sunday... forecast confidence high.
Southerly winds will increase across southern WI on Saturday as high
pressure shifts east and the pressure gradient strengthens. Dry west-northwest
flow aloft will allow for abundant sunshine. Low level warm air
advection will push 925mb temperatures up to around 13c yielding maximum temperatures
into the upper 60s Saturday afternoon. Cannot rule out a few
locations reaching 70. Elevated winds should keep temperatures from
dropping too far Sat night... so went with lows in the lower 50s.
A strong shortwave tracking through southern Canada and the northern
plains will lead to continued breezy southwest winds and even warmer
temperatures in southern WI on Sunday. 925mb temperatures will jump to 20c
by Sunday afternoon so we are looking at maximum temperatures in the upper 70s
to around 80 with plenty of sunshine. Expecting a low around 60 Sun
night with continued elevated winds ahead of the approaching low
Monday... forecast confidence medium.
That strong shortwave and associated surface low will track across
Ontario late Sunday night and through the day Monday. The cold front
could clear southeast WI as early as 12z/7 am but most likely around
15z/10 am. This is your typical strong fall season front... although
the precipitation associated with it is expected to remain well to our
north. There should be some low clouds with the front and just
behind it. Otherwise... dry air will dominate.
Look for gusty west-northwest winds Monday afternoon and falling
temperatures. The maximum temperatures Monday will occur during the morning
hours. 925mb temperatures will fall to around 4c by early Tuesday morning.
Lows Monday night will be in the middle 40s inland from the lake.
Tuesday through Friday... forecast confidence medium.
We will be in a prolonged period of northwest flow aloft. Weak
shortwaves in the flow will allow for temperature moderation so we
are not expecting any real cold snap. Highs should be in the lower
60s on Tuesday and through the remainder of the work week. The
models are generating light quantitative precipitation forecast here and there with the shortwaves
although the timing does not agree between them. There will at least
be periods of clouds. Kept the forecast dry.
Aviation/12z tafs/...MVFR ceilings this morning will gradually lift
and then clear out by early afternoon across most areas.
Thereafter...VFR conditions are expected. The strongest northerly
winds will be this morning...diminishing rapidly this afternoon as
surface high pressure builds in and relaxes the pressure gradient.
Marine...brisk northerly winds will gradually subside this
afternoon as high pressure builds into the area. The highest waves
will be found from Milwaukee south into the Illinois nearshore
waters. A Small Craft Advisory is in effect until about middle
afternoon for the Sheboygan area and through about middle evening
Lm...Small Craft Advisory until 10 PM CDT this evening for lmz646.
Small Craft Advisory until 7 PM CDT this evening for lmz644-645.
Small Craft Advisory until 4 PM CDT this afternoon for lmz643.
Today/tonight and aviation/marine...Davis
Saturday through Thursday...mrc