Weather

867 
fxus63 kdlh 290819 
afddlh 


Area forecast discussion 
National Weather Service Duluth Minnesota 
319 am CDT Friday Aug 29 2008 


Discussion...main forecast concern is convective chances for 
today. Early morning surface analysis depicts high pressure axis 
stretched across the Northland...with a surface trough located 
across southern Manitoba...and western North Dakota. This trough 
is a reflection of approaching vorticity maximum /currently pushing over 
southern Manitoba per water vapor loop/ which will affect the 
northern half of the forecast area today. Airmass becomes moderately 
unstable...especially by this afternoon across The Arrowhead. 
Forecast soundings should steep low level lapse rates developing 
with strong surface heating and mixing this afternoon. Introduced 
higher probability of precipitation with this wave...expecting isolated to scattered coverage 
by this afternoon across the northern zones...as it progresses 
eastward. Given relatively low fzl heights of 8 to 9 kft per 
NAM...and strong deep layer shear of 50 to 60+ kts...a period of 
organized convection looks possible. Cannot rule out a severe 
storm as well...with gusty winds and hail the main threats. 


The surface trough and associated convection should push off 
quickly this evening...as high pressure and drier air builds in 
from the west. With mainly clear skies and light winds expected 
overnight...lowered overnight temperatures considerably...closer to 
latest guidance. Also maintained patchy fog with strong 
radiational cooling expected. Much warmer temperatures will advect into 
the region for the weekend with upper ridge amplifying over the 
central Continental U.S.. developing return flow and strong low level jet 
Saturday night into Sunday advects upper teens to near 20c 850 mb 
temperatures across the Northland. This warming trend will continue into 
Monday with surface temperatures expected to reach 10 to 15 degrees warmer 
than normal. 


Still some model differences for significant cold frontal passage Tuesday 
through Wednesday next week. With prolonged period of southerly 
return flow ahead of the front...atmosphere becomes moderately 
unstable...with a good chance of organized convection. Significant 
rainfall will also be possible with low level boundary becoming 
more parallel to southwest upper level flow pattern. 


&& 


Aviation...patchy early morning fog...with local LIFR/IFR 
vsbys/cigs...will erode quickly after sunrise as it is a shallow 
layer of fog. Meanwhile...an upper level short wave/surface trough will 
cross the international border area today. VFR ceilings of 7-10k feet and 
isolated showers or thunderstorms will occur in this area until 00z/30. 
Elsewhere...high pressure and a relatively dry atmosphere will mean 
few...if any cumulus today. Sky clear tonight. 


&& 


Point temps/pops... 
dlh 77 49 77 57 / 20 10 0 0 
inl 75 43 80 59 / 30 0 10 0 
brd 81 45 84 63 / 10 0 0 0 
hyr 80 43 85 56 / 10 10 0 0 
asx 78 46 80 55 / 20 10 0 0 


&& 


Dlh watches/warnings/advisories... 


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


$$ 


Liles/gsf