877 
fxus63 kdlh 212005 
afddlh 


Area forecast discussion 
National Weather Service Duluth Minnesota 
305 PM CDT Thursday Aug 21 2008 


Discussion... 
main forecast concerns in short term are rain chance in wis zones this 
evening...and increasing thunderstorms and rain threat Friday/Friday night. 


Current surface analysis show a strong pressure gradient over the upper 
Midwest...resulting in a breezy srly flow with most areas in Minnesota 
gusting into the 20-30 knots range. Although the thermal gradient 
will weaken overnight...winds will remain gusty as cold front 
approaches western Minnesota and allows for a 30-40 knots low level jet to shift east over the 
County Warning Area. This will also for increasing thicknesses and warmer overnight 
lows...with most areas remaining in the middle to upper 60s. Winds will 
increase rapidly again after day break Friday as the front 
continues to push east over the forecast area through Friday evening. Models 
are in good agreement with the synoptic features...with the surface 
low strengthening over southern Manitoba as it becomes vertically 
stacked with the cut-off upper level low. The cold front sweeps 
quickly east over the region with a strong baroclinic zone and Post 
frontal dry slot. However...models diverge somewhat in timing of 
the frontal passage and associated dry air intrusion...with the NAM being the 
model of choice with the slower progression. 


Conditions will be favorable for isolated severe storms Friday 
afternoon/early evening as the instability increases and can over 
come the weakening cap. At this time...the best threat for strong to severe 
storms will be over northern Wisconsin mainly after 21z. 


Impressive cold air advection regime sets up after the frontal passage bringing a cool 
down the weekend as 850 mb temperatures on the single digits sink into northern 
Minnesota. Decreased highs on Sat quite a bit...closer to met/mav 
guidance. 


&& 


Aviation... 
generally VFR conds expected through the taf period. The exception will be 
tempo MVFR ceilings in rain showers or ts...beginning this evening in the S and 
spreading northward overnight. Scattered thunderstorms and rain expected through the day on Friday as 
well...when visibility may dip briefly into the MVFR Cat. 


&& 


Point temps/pops... 
dlh 80 65 81 60 / 10 20 50 60 
inl 87 66 79 52 / 10 20 50 40 
brd 86 67 84 56 / 10 10 40 20 
hyr 82 64 82 63 / 40 50 30 60 
asx 82 64 82 63 / 30 40 20 60 


&& 


Dlh watches/warnings/advisories... 


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


$$ 


Graning/04