198 
fxus63 kmkx 100955 
afdmkx 


Area forecast discussion 
National Weather Service Milwaukee/Sullivan WI 
355 am CST Wednesday Mar 10 2010 


Short term... 
today and tonight...forecast confidence...medium to high 


Currently seeing one band of rain pushing north out 
of the forecast area...as another area of rain moves in from the 
south. These periods of rain will continue to be the story through 
the end of the week as two areas of low pressure merge 
tonight...with a large low then lingering in the region over 
the next few days. 


Main concern today is how much the rain will effect eastern 
portions of the County Warning Area...as rain across the west is a sure thing. The 
NAM is really trying to hold things off close to the lake...with 
much weaker lift further away from the center of the low. NAM 
may be also overdoing effect of cooler air/lower dewpoints off of 
Lake Michigan...as quantitative precipitation forecast seems to erode near the lake. Band that 
moved through the night was not picked up well by the NAM...and 
given the current radar and 06z NAM run...it seems the NAM precipitation 
is already not far enough east. Opted then to go with wetter 
GFS/European model (ecmwf) across the east for today. 


Rain should wind down across the north this evening...as low lifts 
north through Minnesota. Little to no rain is then expected 
overnight...as the low continues to lift and weaken...while being 
absorbed by the next approaching system. With a moist airmass 
remaining in place...should see some more fog overnight under 
light winds. 


Thursday...forecast confidence...medium 


Best chance for moderate rain this week still looks to be Thursday 
into Thursday night...as potent wave rotates around the low parked 
to the southwest. Biggest issue with this period is the timing of 
the rain across southern Wisconsin. The GFS is the slowest among 
the various models...with the bulk of the rain only pushing into 
the southwest half of the forecast area by early Thursday evening. 
The NAM...ECMWF...Canadian...and UKMET vary a little with 
timing...but are all quicker with the rain pushing all the way 
through southern WI by Thursday evening. Went with the convincing 
majority in timing the arrival of rain...a bit faster than the HPC 
solution. 


Friday...forecast confidence...low to medium 


As upper low moves slowly southeast on Friday...the surface low fills 
a bit as it gets pulled along by the upper system. The GFS is 
showing a bit of quantitative precipitation forecast across the area...bringing a wave through 
during the day. The European model (ecmwf) and NAM keep things drier through...with 
the bulk of the precipitation north...so did not change high chance/low 
likely probability of precipitation already in place. 


Long term... 


Saturday and Sunday...forecast confidence...low to medium 


Models continue to suggest waves rotating through southern WI on the 
backside of the low as it pulls away east. Kept chance for rain 
right through the weekend...but could not raise probability of precipitation at all...as 
confidence in the timing of these impulses is fairly low this far 
out. 


Temperatures through the forecast period will continue to 
run above normal...with cooler temperatures near the lake 
persisting under onshore winds. Also...still think some rivers 
could approach or reach flood stage later this week...with recent 
snow melt and additional anticipated rainfall. 


&& 


Aviation...boundary layer winds and periods of rain this morning should 
keep dense fog at Bay. Occasional MVFR ceilings/visibilities associated with morning 
precipitation. Also increased convergence associated with stronger low level winds 
this morning along Lakeshore likely to result in lowering ceilings at least 
for a time...but could fluctuate between VFR and MVFR. Will need to 
watch for potential of dense advection fog forming upwind and 
overspreading southern WI. Otherwise...low level profiles favoring stratus 
development with modified Richardson numbers lt 0.025. Confidence on 
the low side for this taf set. 


&& 


Marine...webcams showing only light fog on the shore. Previous 
areas of dense fog have thinned in response to periods of -ra and 
increasing boundary layer winds. Would expect this scenario to occur 
offshore as well...hence will drop marine dense fog advisory with new 
forecast per coordinate with grb. 


Tightening pressure gradient in response to Iowa low pressure will result in 
stronger onshore winds this morning but steep inversion to prevent 
wind speeds from reaching Small Craft Advisory criteria for any length of 
time. Waves heights will be borderline. Due to brief period of 
stronger winds this morning...counting on significant wave heights to 
also be brief. 


Latest SST image from 18z/08 showed lake temperatures mostly in the 
middle 30s. With lighter surface winds tonight and dewpoints potentially 
reaching the middle 40s...potential for advection dense fog increases into 
Thursday morning. 


&& 


Mkx watches/warnings/advisories... 
WI...none. 
Lm...none. 
&& 


$$ 


Short/long term...ddv/07 
aviation/marine...mbk/11