Weather

738 
fxus63 kdlh 110226 aaa 
afddlh 


Area forecast discussion...updated 
National Weather Service Duluth Minnesota 
926 PM CDT Friday Oct 10 2008 


Update... 
substantially increased quantitative precipitation forecast in a band from northern Itasca County 
northeastward through the Snowbank Lake to Seagull Lake areas for 
tonight. Substantially increased probability of precipitation from the upper Saint Croix 
valley westward and northward. Lowered temperatures a few degrees. 
Substantially increased onshore winds in the Duluth area tonight 
and much of Saturday. 


&& 


Discussion... 
frontogenesis has hung itself up in a 20 km wide line from Cass 
Lake northeastward through the Snowbank Lake. The line passes 
exactly between Big Fork and Grand Rapids and happens to remain 
over remote areas just north of the Iron Range. Training and 
upwind redevelopment...over Cass Lake...seems to be finally 
falling apart. Radar estimated rainfall amounts are approaching 10 
cm over that part of Itasca County where the band lies. The 
Countryside in that area is numerous lakes and bogs...so for a 
while...very heavy precipitation can be absorbed. We ancpt that 
this intense rainfall will be over before really large amounts of 
water fill the wetlands and it takes a significant amount of time 
for excessive water to leave those basins. So...our advantages 
include the narrowness of the band...the flatness of the land... 
the nearness of high capacity bogs and lakes and adjacent areas 
that have not gotten excessive rain. 


Another situation is cold marine air being funneled down the lake 
with local sustained winds to 25 miles per hour continuing in and around 
downtown Duluth. Falling pressure to the west and resulting density 
gradients from temperatures near 5c in and just north of dlh with 
temperatures that approached 20c in humid air just south of Duluth 
along with the funneling of the hills behind Duluth and Superior 
have kept the winds up locally. Nearby buoys have not had winds of 
this sort and...without much fetch...waves have not grown much 
above a meter in height. 


The slowly moving surface warm front...just south of Duluth... 
will linger until an inverted trough pushes through late Sunday 
night or early Monday. Present indications are warm air will push quite far into 
inland areas west and south of Duluth. 


&& 


Previous discussion... /issued 219 PM CDT Friday Oct 10 2008/ 


Discussion..short term concern for forecast is ending of rain 
tonight. Next concern is rain for Sunday and Monday. 


Current surface analysis indicates an area of rain north of dlh- 
Walker line with only widely scattered showers south. This area is 
associated with a low level jet of 3-40 kts along with frontogenesis moving 
across the area. Models indicate this rain will continue to move 
north and decrease in coverage. Will keep likely probability of precipitation across 
north for this evening before ending by midnight. There will be a 
short break before the next system affects the forecast area. 


The area of low pressure will move into the Central Plains tonight 
and Saturday and move north into the Dakotas by Sunday. This will 
spread another area of precipitation into the forecast area through 
Monday. It looks like rainfall amounts will range between 0.50 to 
1.00 inch before it ends on Monday. The low pressure moves through 
ND on Sunday night and into Canada on Monday. This will drag a 
cold front across the forecast area late Sunday night into Monday. 
The rain will end from across NE Minnesota Monday morning and northwest WI by 
Monday evening. An area of high pressure builds into the area on 
Tuesday before a clipper brings a possibility of precipitation to the 
area wedneight and Thursday. 


Aviation...in the vicinity of showers...expect MVFR conditions. 
Otherwise...VFR through the taf period. Some br may form between 
06-12z at kdlh/khib/kinl with MVFR visibilities and ceilings 


&& 


Point temps/pops... 
dlh 39 56 48 58 / 40 40 40 50 
inl 38 59 45 65 / 40 60 60 60 
brd 41 65 52 68 / 40 40 60 70 
hyr 46 73 53 74 / 10 10 20 40 
asx 45 65 51 73 / 10 10 20 40 


&& 


Dlh watches/warnings/advisories... 


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


$$ 


Eom/tl