Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
254 am CDT Tuesday Sep 16 2014
Today and tonight...forecast confidence is high.
High pressure will slide across the area...with the center of the
high tracking just south of Wisconsin. Any morning fog will burn
off quickly with just some scattered afternoon cumulus expected. A clear
and cool night expected tonight with patchy fog possible again late.
Wednesday - confidence...high
upper flow proggd to be swift from the northwest. Vorticity axis
across northern WI within this flow looks highly sheared and in either
northern or central WI. Meanwhile gradually departing surface high
pressure will still influence southern WI. 925 temperatures rise into the
11-13c range so continued modification of surface temperatures.
Wednesday night and Thursday - confidence...medium
surface/925 back door cold front arrives. Barring any Rapid Lake
side accelerations the proggd timing of frontal passage is 00-06z time frame.
The NAM is showing a more aggressive push of cooler lake air with
a period of gusty NE winds possible. Otherwise a dry Thursday in
the works with cooler temperatures especially near the lake with the NE flow.
Low level relative humidity forecasts are showing stratus potential within the cooler
regime/thermal trough. So the NAM MOS may be on to something
showing a bit more cloud cover developing Wednesday night into at least
Thursday am. If this lingers then the NAM MOS temperatures may end up being
better...but for now will steer more in The Middle Ground.
Friday - confidence...medium
with the high well to the east a southerly flow will ramp up and
bring warmer air into southern WI. 850 moisture increases after 18z
though boundary and low level jet axis suggest precipitation will stay to our north
during the day. In fact 582dm ridge nudges into southern WI with the
main vorticity track and dynamics to our north. If this model trend
continues then probability of precipitation can be further scales back across the County Warning Area.
Saturday and Saturday night - confidence...medium
best shot at precipitation this forecast package. Upper trough draws closer
with surface/850 fronts coming into play as well. Decent moisture
will be in place with some MLCAPE as well...so thunder idea looks
good. 0-6km shear and middle level lapse rates not too impressive at
Sunday and Monday - confidence...low
substantial variation in upper flow pattern with the European model (ecmwf) showing
a much deeper trough swinging across the western Great Lakes. The Gem is
progressive with ridging taking hold for much of Sunday and Monday.
Meanwhile the GFS shows most of the energy to our northeast with
just an elongated shear zone swinging through. Will play it with
early rain showers chances Sunday with high pressure and drying taking hold
for Monday...much like the allblend solution.
Aviation/12z tafs/...any morning fog will burn off quickly after
sunrise. Thereafter...generally look for VFR conditions through the
period with few clouds. Some patchy fog is again possible late tonight.
Winds will be less than 10kts.
Today/tonight and aviation/marine...Davis
Wednesday through Monday...collar