800 
fxus63 kdlh 192055 
afddlh 


Area forecast discussion 
National Weather Service Duluth Minnesota 
255 PM CST Wednesday Nov 19 2008 


Discussion... 
short term forecast focus on arrival of Arctic air mass and les amounts 
along the South Shore of Lake Superior. No changes to be made to 
current les headlines which are in effect this evening through 
Thursday night. 


The western Great Lakes region will remain situated between surface low to 
the east and building high pressure from the west over the next 36 hours. 
This will sustain the gusty northwest winds through Thursday 
evening...weakening by Friday morning as the surface ridge reaches eastern 
Minnesota/western wis. The cold air will keep flurries or isolated -shsn over 
the forecast area...with little or no accumulation. 


The exception will be across northern wis where a nearly fetch and steep 
lapse rates will produce conditions favorable for les...late today 
through early Friday morning. This will be a prolonged snow event over 
a 36 hour period. Significant snowfall totals are expected of generally 
around 10 inches along the higher terrain and Gogebic Range of northern 
wis...with isolated higher amounts of a foot or more possible. 
Areas inland or sheltered form the lake effect...as Ashland...can 
expect storm totals on the order of 2 to 3 inches. 


Although Delta T values and forcing support moderate to heavy 
snowfall amounts...some concern in the h70-h50 dry pocket that is 
currently depicted on the visible Sat as clear skies over southern Manitoba/western 
Ontario. The NAM 850-700 relative humidity field shows this dry layer sinks S over 
northern Minnesota and Western Lake Superior overnight...just as the coldest air 
settles overhead. Although surface-850 mb layer remains saturated and 
instability is in place...some fear that this dry air may sink 
far enough into the low levels to result in a decrease in intensity 
or a total lull in snowfall...mainly during the 10-18z Thursday time 
frame. To account for this possibility will mention the shsn may 
weaken or end for a short time in the west-southwest product...but at this time 
threat is not enough to make sig changes to storm total snow 
amounts. The NAM shows that the middle level moisture does rebound by 
Thursday afternoon...so would expect the les to regenerate and produce 
a few more inches of accumulate late Thursday/Thursday night...before the 
high pressure shuts it off for good Friday morning. 


The NAM shows that the middle level moisture does rebound by Thursday 
afternoon...so would expect the les to regenerate and produce a few more 
inches of accumulate before the high pressure shuts it off for good Friday 
morning. 


&& 


Aviation...gusty winds behind an Arctic cold front will slowly 
diminish through Thursday afternoon...though remain gusty at times 
through the taf period. Broken to overcast MVFR ceilings will scatter out from north 
to south this evening...as high pressure begins to ridge into the upper 
Midwest from Canada. Scattered snow showers and flurries will taper off by 
late this afternoon. 


&& 


Point temps/pops... 
dlh 12 21 5 21 / 30 10 10 10 
inl 9 13 1 17 / 20 10 10 10 
brd 16 22 5 23 / 10 10 10 10 
hyr 15 19 4 20 / 40 30 10 10 
asx 20 20 12 20 / 70 60 70 30 


&& 


Dlh watches/warnings/advisories... 


Minnesota...none. 
WI...lake effect snow warning from 6 PM this evening to 6 am CST 
Friday for Ashland-Iron. 


Lake effect Snow Advisory from 6 PM this evening to midnight CST 
Thursday night for Bayfield. 


Ls...Small Craft Advisory until 6 am CST Friday for lsz121-lsz140- 
lsz141-lsz142-lsz143-lsz144-lsz145-lsz146-lsz147-lsz148. 




$$ 


Graning/melde/lonka