Weather

949 
fxus63 kdlh 280231 aaa 
afddlh 


Area forecast discussion...updated 
National Weather Service Duluth Minnesota 
931 PM CDT Wednesday Aug 27 2008 


Update... 
no sig change to forecast. Updated zone forecast product for time references. 


&& 


Previous discussion... /issued 340 PM CDT Wednesday Aug 27 2008/ 


Discussion...a cold front will slowly move across the upper 
Midwest tonight and tomorrow. This front...along with an upper 
level shortwave...will be the main forcing mechanism for the 
development of shower and thunderstorms across our forecast area 
through tomorrow. All of the operation models generate a swath of 
heavier rainfall across our central and eastern zones during this time 
frame...although the GFS differs from the others somewhat by 
shunting the precipitation off to the east more quickly. Some models are 
forecasting rain amounts of over an inch. But feel more confident 
in mentioning 0.5 to 1 inch amounts since these higher amounts 
should be localized. The front will propagate east of our County Warning Area by 
Thursday night...although a few showers may linger across the 
Northland as the upper level wave rotates over the County Warning Area. Drier air 
will filter in across the region by Friday as high pressure from 
the plains moves over the upper Midwest. 


Extended...sun through Tuesday..medium range guidance supports general 
idea of large scale ridge amplifying over eastern Great Lakes. This occurs 
in response to a progressive M/l trough over northern rockies.Some 
difference between ec/GFS with ec maintaining ridge over County Warning Area 
longer..allowing warming to continue into Tuesday afternoon.GFS 
is about 12hrs faster breaking down ridge...allowing precipitation to push 
farther east. Ec/CMC in strong agreement on slower movement of main 
features. GFS ensemble members are much less pronounced with trough 
amplitude by 12z Tuesday...supporting ec/CMC solution of holding off 
on precipitation until early Tuesday over western County Warning Area...and then edging east by 
Wednesday morning. Have tossed mex MOS considering it is too 
cool..and leaned more with ec/HPC values...considerably higher maxes 
Monday. 


Aviation...mainly MVFR-IFR conditions can be expected through 
this evening and overnight...except west of a line from 
kcdd...to kgpz..to kpwc...where VFR will prevail. Plenty of low 
and middle level moisture will continue to feed north and east along 
a cold front that will only slowly progress eastward...resulting 
in ceilings generally 2k feet above ground level or below. While precipitation will 
be minimal through 00z...rain and thunderstorm chances will 
increase early tonight as an area of enhanced lift and instability 
approaches the region in response to the shortwave currently over 
North Dakota. While timing is a bit of a challenge...the highest 
risk for shra/tsra...and the lowest ceilings...appears to be from 
04z-10z. However...areas of fog may develop during the overnight 
hours and persist through about 13z...resulting in local LIFR- 
vlifr conditions. Expecting improvement to VFR in much of NE 
Minnesota by 14z Thursday...while showers will still be possible 
over much of northwest Wisconsin including khyr through about 18z. 
The potential for convection will also persist in this 
area...especially due to strong flow aloft/shear...but the highest 
SBCAPE...lifted indices...and greatest ascent will likely be just 
to the south over central and southern Wisconsin. 


&& 


Point temps/pops... 
dlh 54 72 52 75 / 70 20 10 10 
inl 48 72 46 75 / 20 30 20 20 
brd 54 75 48 77 / 60 20 10 10 
hyr 56 76 48 77 / 70 30 10 10 
asx 58 76 52 77 / 70 30 20 10 


&& 


Dlh watches/warnings/advisories... 


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


$$ 


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