791 
fxus63 kmqt 282332 aaa 
afdmqt 


Area forecast discussion...updated aviation discussion 
National Weather Service Marquette Michigan 
731 PM EDT Thursday Aug 28 2008 


Synopsis... 
a seasonably strong trough moving into the western lakes will allow 
a cold front currently extending from northwest Ontario through western 
Upper Michigan to move through the area early this evening. Showers 
and a few storms will accompany this front over central/eastern 
Upper Michigan this evening. Stronger short wave energy across northwest Minnesota 
along with low level surface convergence has allowed for adnl 
showers/storms to develop across northern Minnesota in northwest flow. Although 
these are mainly diurnally driven...there is a small chance that 
some of these will make it to the lake and even far western Upper 
Michigan this evening as the short wave passes through. 


&& 


Short term (tonight and friday)... 
the front should be east of the forecast area between around 03z...and 
any deep moisture and precipitation should move east with it. There has been 
an increase in shower/storm activity across eastern Upper Michigan 
over the past hour or two and this is likely in response to the 
daytime heating and steepening middle level lapse rates in response to 
the height falls aloft. With the front already through MQT...it 
looks like the best chance for showers/storms will be the eastern 
half of the forecast area and have opted to go with likely probability of precipitation 
early across the far east where the best coverage of precipitation is 
currently. As for the remainder of Upper Michigan...although the 
front has moved east...the showers and storms that developed over 
northern Minnesota may maintain themselves at least in part due to the 
steepening lapse rates aloft of 8.0 c/km and slightly enhanced 
convergence due to a secondary surface trough across Minnesota (seen by the 
wind fields). Although the thinking is that loss of daytime heating 
will keep coverage from becoming more than isolated...a mention of 
showers and storms seem warranted across the remainder of the area 
early this evening. 


By 06z...most of the area should be under strong subsidence and 
drying from the surface ridge building in from the west. A weak wave 
moves in the west-northwest flow into Northern Lake Superior later Friday afternoon 
and evening which may cause help to enhance the diurnal cumulus 
across the region and perhaps cause a shower late over Isle Royale. 
Otherwise it should be a pleasant day with mostly sunny skies and 
temperatures in the middle-upper 70s. 


&& 


Long term (friday night through next thursday)... 
main feature for much of the extended period is strong upper level 
building from the SW United States into the Great Lakes region by 
early next week. Only system of note early on is a weak disturbance 
passing across Ontario Friday night into early Saturday. Soundings 
indicate an increase of clouds over northern Upper Michigan into Lake Superior 
but no precipitation...except possibly on Isle Royale closer to the shortwave. 
High pressure building in Saturday leads to well developed lake 
breezes near Lake Superior Saturday afternoon. Highest temperatures Saturday into 
the lower 80s over south with warmer temperatures aloft and a low level west 
wind to start the day. Flow off the Lake Superior keeps northern Upper Michigan in 
the middle-upper 70s...still above normal. 


Heights in the center of ridge top out above 590dam over lower Michigan Monday 
afternoon. Given such high heights...possibly the highest of this 
Summer...and SW flow aloft into Upper Michigan...expect very warm and dry 
weather Sunday into Tuesday. 850 mb temperatures on ensembles up to +18c while 
GFS and European model (ecmwf) point to +20c 850 mb temperatures. Expect to see highs near 90 
degrees Sunday and Monday and maybe even Tuesday. Warmest temperatures away 
from the Lake Michigan shore with increasing south winds. Could set a 
record high on Monday at the National Weather Service office. Current record is 86 set in 
1973. Sampling of other record highs for Monday across the County Warning Area 
turned up readings from 90-93. 


Front that was supposed to be over Upper Michigan on Tuesday is now about a day 
slower in the latest runs of European model (ecmwf)/GFS and HPC hand drawn surface maps. 
GFS ensembles a bit faster...showing the front into the far west by 
Tuesday afternoon. Slower evolution of this front is reasonable with the 
strong ridge over the Great Lakes deflecting any upper troughs that 
move into northern plains into Canada as they bumps up against the 
ridge. Looks like the front with a narrow ribbon of moisture and 
perhaps some rain comes through area on Wednesday. So...it appears 
the general dry weather pattern seen across the County Warning Area the last month 
persists into first week of September as there are no large scale 
systems to bring widespread rainfall. 


Dry weather and very warm tempeatures and low humidities would lead 
to an increased wildfire risk with an increasing wind. Best chance 
for stronger winds would be late Sunday into Tuesday as pressure 
gradient due to surface high moving east of Upper Michigan cold front shifting 
into Minnesota. 


Finally...although areas in the western u.P. Received up to a half 
inch of rain late last night and early this morning...only a paltry 
hundredth of an inch of rain fell at the National Weather Service office. The monthly 
rain total is now 44 hundredths of an inch. So now we are definitely 
on track for this month to go down as the driest August on record as 
after today...no rain is expected through Sunday the 31st. Current 
record low rainfall for the month is 56 hundredths of an inch set in 
1970. 


&& 


Aviation (for the 00z taf issuance)... 
expect VFR conditions through the period. 


&& 


Marine (for the 4 PM marine issuance)... 
will likely need to keep the Small Craft Advisory early this evening 
for Lake Michigan due to waves being near 4 feet at the northern Michigan 
buoy. Otherwise...winds have diminished across Lake Superior this 
afternoon with the passage of the cold front and weakening pressure 
gradient. As the ridge builds in later tonight and into Friday the 
winds should stay less than 20 knots before the surface high moves east and 
southerly winds increase for the weekend and especially into Monday. 
The next cold frontal passage does not look like it will occur until 
middle week next week. 


&& 


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


&& 


$$ 


Synopsis...mrd 
short term...mrd 
long term...jla 
aviation...GM 
marine...mrd