Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Milwaukee/Sullivan WI
421 am CDT Monday Aug 31 2015
Today and tonight...forecast confidence high.
Dealing with areas of fog between 1/2 mile and 5 miles...with
locally dense fog. Of the Airport observation reporting the lowest
visibilities...most are bouncing between 1/4 mile and 1/2 mile. A few
locations have been staying at 1/4 mile but calls to local law
enforcement indicate dense fog not yet widespread. Will handle with
Special Weather Statement for now and continue to monitor.
Otherwise quiet weather with warming SW flow developing as surface
high and middle-level ridge axis slowly shift east. Models indicate a
cool pocket of 850 mb temperatures moves across the area this
afternoon...and 22c to 24c 925 mb temperatures do not quite make it into
the area until closer to 00z. Will trim back high temperatures a few
degrees due to early fog and stratus...and sun being filtered
through smoke aloft from western U.S. Fires.
Another round of fog expected to night but a little more gradient
flow should prevent widespread dense fog. Continued warm advection
will hold lows int eh middle to upper 60s.
Tuesday through Sunday...forecast confidence...medium
Surface high pressure and upper ridging is expected to generally
remain parked over the Great Lakes through this upcoming week. There
will be some minor day to day variations of ridge placement and
resultant temperatures aloft...but overall looks like a pretty persistent
pattern. Models are still trying showing some splotchy quantitative precipitation forecast...mainly
middle to late week. The moisture and instability will be there...but
hardly seeing more than a wrinkle in the flow. Have some low probability of precipitation in
there...but think it will likely be dry for much if not all of this
The GFS remains quicker with the eventual cold front...bringing it
into southern Wisconsin by Sunday evening. The European model (ecmwf) holds it off
until Monday night. Do have some probability of precipitation in there Sunday per the
The main story this week will be the warming temperatures. The consensus
blend of models does not seem warm enough given model temperatures
aloft...so bumped forecast temperatures up again. Offshore winds should be
strong enough Tuesday and at least into early afternoon Wednesday to
keep the lake breeze off shore. Looks like a much better chance for
onshore winds later in the week...so went with cooler temperatures near
Lake Michigan for that period.
Aviation/12z tafs/...IFR fog/stratus deck will begin to lift after
sunrise and should mix up/out to VFR levels by 15z. VFR conditions
expected through the day and evening hours...with fog developing
again later tonight. More of a gradient flow should keep visibilities at
MVFR levels...but cannot rule out IFR at a few spots if local
decoupling of surface winds occur.
Marine...issued a marine dense fog advisory until 10 am for
visibilities between 1/4 and 1 mile expected until mid-morning. After
that daytime mixing and more gradient wind than yesterday should
improve visibilities above 1 mile but with the cool water upwelling with
offshore flow could still see patchy/areas of fog through the
day. Expect the fog to thicken tonight and it may become dense
with below 1 mile visibilities after midnight.
Lm...dense fog advisory until 10 am CDT this morning for lmz643>646.
Today/tonight and aviation/marine...rem
Tuesday through Sunday...ddv