780 
fxus63 kdlh 212119 
afddlh 


Area forecast discussion 
National Weather Service Duluth Minnesota 
319 PM CST Sat Nov 21 2009 


Discussion... 
the models are in decent agreement...each showing some run to run 
differences. A dt/dprog of the European model (ecmwf) at 84 hours shows the low 
moving a bit quicker...into southeast Iowa. A blend of the models was 
used through Tuesday. 


Fog has dissipated this afternoon...with a few stations still 
reporting 4-5sm in haze. Overall...skies were mostly sunny...with 
more clouds over portions of Sawyer/price/Ashland/Iron counties this 
afternoon. 


Low level moisture is forecast to increase rapidly tonight...as low 
level winds increase. NAM forecasts southerly 925mb winds of 
40-45kt. Clouds have been surging north through MO/eastern 
NE/eastern Kansas into Iowa this afternoon. We increased cloud cover 
tonight for all areas...especially late tonight. There could be some 
drizzle or sprinkles later tonight over a portion of northwest 
Wisconsin west toward Pine County with better moisture and 
isentropic lift in this area. We added patchy fog for tonight...as 
low level moisture increases. 


Models also in decent agreement with placing their highest quantitative precipitation forecast over 
the North Shore...southwest through the twin ports and Pine County. 
This area under deeper moisture and some low level fgen. We have 
highest probability of precipitation there for tomorrow. 


We increased probability of precipitation for Sunday night...into likely for a portion of 
our eastern Minnesota zones. The low level inverted sharp sharpens 
Sunday night...with fgen present...especially in the low levels. 
Precipitation should be rain...as cloud cover will keep boundary layer 
temperatures above freezing and 925mb temperatures of 3-7c are forecast over our 
area. 


As the upper trough swings in from the west on Monday...the inverted 
trough is forecast to rotate to the west. We keyed our higher probability of precipitation 
on the inverted trough...and have them likely over a good portion of 
northeast Minnesota. 


The upper low will close off as it dives east-southeast toward southwest Iowa by 
12z Tuesday...then east during the day Tuesday. The inverted trough 
weakens Monday night into Tuesday...and we just have chance probability of precipitation at 
this time. There is weak isentropic lift present 
Tuesday...especially over southern areas. We could be in for a 
period of drizzle...but left just a chance for light rain at this time. 


Extended...Wednesday through Saturday 
brushed small probability of precipitation further into western zones and increased to middle/high 
chance for eastern zones Tuesday night through Wednesday night. Also increased temperatures 
a few degrees to account for strong warm air advection and models trending warmer. 
The GFS/ec struggling with the storm track through long term as a 
double barrel low pattern develops. The initial low will exits to 
the NE while an elongated middle level vorticity/100 knots upper level jet dives S 
over the Dakotas developing a secondary low. The 12z GFS suggests 
the eastern cut low tracks NE over Toronto/Quebec through 12z Thursday as 
the secondary wave digs over the northern plains and deepens into a cut 
off low at the base of Lake Michigan during this time. Meanwhile...the 
00z ecm merges the two vorts into a broad system over the eastern Great 
Lakes. Although timing and specific details will still be worked 
out...both models show sufficient moisture and persistent cyclonic 
flow over the forecast area through middle week with deformation zone setting up 
Tuesday night over northern Minnesota that could potentially bring greater quantitative precipitation forecast or a 
band of snow accumulation. 


&& 


Aviation... 
south winds will gust 15-20 knots with VFR ceilings through 00-03z. By 
06z...a 40 knots low level jet around 2 kft will spread low clouds nwrd over 
the forecast area ahead of an approaching trough. MVFR ceilings and visibilities 
will become widespread after 09z...persisting through end of period. A 
few -shra will also be possible sun...mainly along a line from 
kbrd to khib. Introduced low level wind shear into kdlh/khib terminals...while 
expecting surface winds to remain higher in western locations where 
gradient is best. 


Point temps/pops... 
dlh 37 47 41 44 / 10 40 60 50 
inl 30 46 28 41 / 10 10 10 50 
brd 35 49 37 47 / 10 30 50 60 
hyr 34 50 42 51 / 10 40 30 30 
asx 37 50 43 49 / 10 40 40 30 


&& 


Dlh watches/warnings/advisories... 
Minnesota...none. 
WI...none. 
Ls...none. 
&& 


$$ 


Melde/graning