008 
fxus63 kmqt 191746 
afdmqt 


Area forecast discussion 
National Weather Service Marquette Michigan 
146 PM EDT Friday Mar 19 2010 


Updated aviation discussion for 18z tafs 


Synopsis... 


Water vapor imagery and RUC show a closed low off the South 
Carolina coast and a trough stretching from a low over Las Vegas 
northeast through the Dakotas and into Hudson Bay. A shortwave 
embedded into this trough is over northern Minnesota and western 
Ontario. Strong upper level divergence is just ahead of this 
shortwave and is over Western Lake Superior. Surface analysis 
depicts a low north of Lake Superior with a frontal system extending 
from this low southeast through the eastern u.P. And northwest lower 
Michigan. A large high continues to build over Alberta. Surface 
reports are showing scattered snow showers over western Ontario this 
morning. 
&& 


Discussion... 


A shortwave trough will remain over Western Lake Superior today. 
Another weak shortwave will follow through northwest Ontario. A 100 
knot upper level jet maximum will be over Eastern Lake Superior through 
today putting the western u.P. Under the right entrance region. The 
cold front will reach the lower Great Lakes by this afternoon as the 
dome of the large high slides out of Alberta into the Dakotas. An 
850mb thermal trough will deepen over Minnesota. A weaker thermal 
trough will be over Eastern Lake Superior. Between these two 
systems...the 850mb temperature will drop to -12c over Lake 
Superior. This will be marginal for les development. Models showing 
fairly moist at 850mb...but fairly dry near surface. A few flurries 
may be possible mainly over the west half of u.P. Today. Cold air 
behind the cold front will cause the temperatures to fall during the 
day as cold Canadian air sweeps into the area mainly over the north 
half of the u.P. 


The trough will remain over Western Lake Superior through tonight. A 
shortwave moving through the trough will speed off to the northeast. 
The upper level jet maximum will shift east into western Quebec. The 
cold front will sweep into New England allowing the Dakotas high to 
blanket most of the northern plains and spreading into the upper 
Mississippi River valley. This will bring cool dry air into the 
forecast area. 


The trough will finally shift to the east of the forecast area on 
Saturday. The upper level jet will shift south into northern Lower 
Lake Michigan. The surface ridge will settle over the area. Dry air 
will remain in place over the forecast area. Thus with more stable 
and dry air in place...I will continue with increase sun. This same 
condition will continue through Saturday night. 


Another shortwave will sweep through Ontario on Sunday...only 
touching lightly on the forecast area. A cold front will settle out 
of south central Canada...into northern Minnesota and Western Lake 
Superior. The forecast area will remain in the dry stable air mass 
ahead of the front. 


The weak frontal system will continue to weaken as it pass through 
the forecast area Sunday night reaching low Michigan by sunrise on 
Monday. A high will settle over the area again keeping the air mass 
dry. The high will continue to dominate conditions through 
Monday keeping the air mass dry. 
&& 


Aviation /for the 18z tafs/... 


MVFR conditions will persist through tonight...especially at kcmx 
where upsloping winds will cause lower ceilings. Winds will 
diminish through the period as a low pressure system continues to 
move away from the area. Winds will be strongest at kcmx due to 
favorable terrain enhancement. Ceilings will likely improve through 
the day on Saturday as high pressure builds into the region. 


&& 


Marine /for the 4 am Lake Superior forecast/... 


Expect gusty northwest winds to 30 knots today as a cold front 
pushes through the lake. Winds will subside below 20 knots late this 
evening as high pressure builds into the upper Great Lakes and 
remains through Saturday morning. By Saturday afternoon a low 
pressure trough moving toward the upper Great Lakes from Manitoba 
will begin to influence Lake Superior. By Saturday afternoon winds 
will increase out of the southwest to 30 knots and continue into 
Sunday. High pressure will build back into the upper lakes for 
Monday and Monday night...keeping winds 20 knots or less. On Tuesday 
low pressure moves into Minnesota from the southwest...ahead of it 
winds will turn southerly and may increase to 25 knots over Lake 
Superior. 
&& 


MQT watches/warnings/advisories... 
Upper Michigan... 
none. 
Lake Superior... 
none. 
Lake Michigan... 
none. 
&& 


$$ 




Synopsis...dlg 
discussion...dlg 
aviation...Titus 
marine...Pearson