918 
fxus63 kdlh 050835 
afddlh 


Area forecast discussion 
National Weather Service Duluth Minnesota 
335 am CDT Sat Jul 5 2008 


Discussion... 
high pressure sinking through the lower lakes and Ohio Valley will 
keep the area in a warm dry southwest flow through this evening. 
An approaching front will connect with Gulf moisture late tonight. 
Present indications are the front will be weak with a strong veering shear in the 
column and an upper flow normal to the front. So...the flow over 
the frontal surface will be down...with direction and low level 
speed convergence ahead of the front. Present indications are a series of convergence 
lines ahead of the front will form behind the last one and then 
weaken as they move toward more stable air with lower convective available potential energy. Until 
06z a strong east-West Cape gradient will be stationary just east 
of the Red River...then it will move east. Convective available potential energy as high as 5500 
near Buffalo Ridge will be capped...as we will...with the cap 
quickly breaking down as the equivalent potential temperature 
ridge and the axis of high convective available potential energy begins to shift east. Present indications are the 
cap will break quickly enough and far enough south for most of the 
energy release to be well south of US late this evening...with 
rapidly lowering convective available potential energy and stabilities remaining at or above -4c across our 
area. This...and moisture absorption in convection to our south 
would mitigate thunderstorm strength this far north early Sunday 
morning. Additionally...freezing level would be high and low level 
moisture would be enough to quickly melt hail stones as they 
approach the surface. Additionally...chilly air at the surface 
would require a lot of work from any downburst...greatly reducing 
windspeeds at the surface. With convergence lines ahead of the 
front...convective available potential energy will be lower...stabilities higher and convective 
activity weaker than one would otherwise suspect as the front 
passes late Sunday. Present indications are the front will push most of the moisture 
out of our area late Sunday night. Weak jet dynamics aloft imply 
that secondary circulations will not be all that supportive. 


Afterward...a wavy northwest flow aloft will end a current series 
of very warm afternoons cause a series of weak and somewhat moisture 
starved fronts quickly dropping down behind equally weak highs 
from Alberta and Saskatchewan during the coming week. We has 
scattered thunderstorms returning northward late Monday and 
continuing at least until the following weekend. We Don/T ancpt 
much wetting but we will have to be mindful that some rather cold 
air aloft may reduce stabilities significantly from time to time. 
Present indications are nothing looks particularly supportive of intense convection 
during the coming week. Winds should back as ridging develops 
aloft during the following weekend. 


&& 


Aviation... 
radiational fog will again be possible this 
morning....through 11z-12z...at kbrd...khyr...and especially khib. 
Otherwise...VFR conditions to prevail at all terminals through 6z 
Sunday before conditions gradually deteriorate from west to east shortly 
thereafter. As low pressure moves into the Dakotas on Saturday...the 
pressure gradient will strengthen as winds turn 
south-southwesterly and increase. Some areas...especially in the 
western and southern portions of our area...may experience 
occasional gusts to 30kts from 16z-00z Saturday. Otherwise...cumulus will 
again develop Saturday morning and continue through the afternoon 
due to daytime heating and instability. High clouds will increase 
toward the end of the taf period...in advance of the approaching low 
pressure system. Low and middle level moisture will increase rather 
substantially after 6z Sunday...and when combined with MUCAPE of 
1500-200 j/kg...and sufficient forcing aloft...will result in the 
development of showers and thunderstorms. The storms will first 
impact the northwest portion of the region...including 
kinl...between 6z and 9z Sunday...before spreading across the rest 
of northeast and north central Minnesota by 12z Sunday. 


&& 


Point temps/pops... 
dlh 84 62 84 55 / 0 30 40 20 
inl 87 63 82 55 / 0 40 20 10 
brd 86 67 87 61 / 0 30 30 20 
hyr 88 64 87 59 / 0 20 40 30 
asx 85 62 84 57 / 0 20 40 30 


&& 


Dlh watches/warnings/advisories... 


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


$$ 


Eom/liles/bettwy