Weather

427 
fxus63 kdlh 280804 
afddlh 


Area forecast discussion 
National Weather Service Duluth Minnesota 
304 am CDT Thursday Aug 28 2008 


Discussion...early morning surface analysis shows main surface 
trough stretched across The Arrowhead...Western Lake 
Superior...and northwest Wisconsin. Strengthening low level jet 
overnight has continued to fuel rain/thunderstorms along and ahead of this 
trough. Forecast soundings show minimal elevated instability with 
long and thin cape profiles. High fzl levels and precipitable waters  1.5 to 2 
inches support some heavy rainfall rates. Will need to monitor 
arrowhead area yet this morning...being in more of the pivot 
location as upper wave becomes more negatively tilted...and with 
kgna reporting almost two inches storm total so far. Good news is 
that radar loops is showing a persistent eastward progression to 
the heaviest rainfall. 


Upper trough currently over North Dakota/southern Manitoba per water 
vapor loop will continue to push east over the dlh today. While 
drier air does filter in behind departing surface trough...cold pool 
aloft and daytime heating will result in steep low level lapse 
rates. Will maintain isolated to scattered probability of precipitation through the afternoon 
accordingly. Tonight...high pressure will settle into the upper 
Midwest. Given the amount of rainfall much of the forecast area received this 
morning...and with light winds and clearing skies...added patchy 
fog tonight as well. Dry airmass looks to remain firmly in place 
through Saturday...and kept forecast dry despite expected trofpa 
during the day Friday. Warming trend looks in store for the 
weekend with upper ridge building over the central/eastern Continental U.S. 
And building low level thermal ridge...especially Sunday and then 
into Monday. 


Next week...models differ in timing and location of next strong 
southwest low ejecting northeast into the northern plains. Should 
see fairly significant cold frontal passage Tuesday into Wednesday. 


&& 


Aviation...thunderstorms in northwest WI at this time...with IFR conditions...will 
move east of the area by middle morning as a frontal boundary moves 
through. Areas of fog with IFR ceilings and visibilities is following behind 
the precipitation. High pressure building in behind the front this morning 
will erode the fog by middle morning and result in VFR conditions for 
the remainder of the forecast period. Patchy fog is possible late 
tonight with a light wind and clear sky producing local MVFR visibilities. 


&& 


Point temps/pops... 
dlh 73 50 77 53 / 20 10 10 0 
inl 71 44 75 45 / 30 10 10 0 
brd 76 48 80 48 / 20 10 10 0 
hyr 79 44 79 47 / 30 10 10 0 
asx 75 49 78 51 / 40 10 10 0 


&& 


Dlh watches/warnings/advisories... 


Minnesota...none. 
WI...none. 
Ls...none. 


$$ 


Liles/gsf