Area forecast discussion 
National Weather Service Duluth Minnesota 
303 PM CDT Tuesday may 21 2013 


Short term.../now - Wednesday/ 


The focus in the short term is the periods of rain showers that 
are expected to continue through at least tonight and then begin 
subsiding Wednesday. The models are in reasonable agreement...so 
leaned on a blend. 


At 300pm/2000z...there was a large and nearly stacked low pressure 
system located near extreme SW Minnesota. Cloudy skies covered 
much of the northern plains and upper Midwest. There were clear 
skies farther north in Manitoba and northern Ontario due to high 
pressure over northern Canada. A stationary front stretched from 
the surface low in extreme SW Minnesota through southern 
Minnesota...west central and northern Wisconsin...and into the 
Upper Peninsula of Michigan. The majority of the Northland had 
cool temperatures in the upper 40s and 50s due to the northeast 
winds. Temperatures were in the 60s in the extreme southeast forecast 
area. Multiple potent shortwaves were embedded in the overall flow 
around the middle/upper level low. One of these shortwaves was 
centered near the twin ports and was resulting in widespread rain 
showers across northeast Minnesota. While much of the southern 
forecast area was dry...there were showers in central Minnesota 
and west central Wisconsin spreading northward towards the 
southern forecast area. 


Through tonight...the low pressure system in southern Minnesota 
will begin to move east. Rain showers in the deformation zone 
will provide relatively high chances of rain showers over much of 
the Northland overnight. The Borderland region near International 
Falls though should see some very late night clearing and drying 
out as the high pressure in Canada begins to move into the region. 
Overnight low temperatures will be in the low to middle 40s. 


Wednesday...the low pressure system will continue to move east. 
The Northland will likely have more rain showers in the 
deformation zone...at least in the morning...but there will be a 
drying and clearing trend from the north during the day as the 
high pressure moves into the region. High temperatures will be in 
the 60s across the northern and western forecast area due to the 
late day clearing...but will be cooler in the 50s across northwest 
Wisconsin and east central Minnesota dur to the cloudy skies and 
northeast winds off Lake Superior. 


Long term.../Wednesday night - Monday/ 


Canadian high pressure building over Hudson Wednesday night will 
allow for drier air to quickly spread westward across Lake 
Superior and into the Northland. A north to northeast flow from 
the high will will result in cold air advection and 850 mb temperatures dropping into the 
single digits by Thursday morning. The cool air aloft and steep lapse 
rates Thursday will allow for deep mixing and falling dew 
points/relative humidity through the afternoon. Expect locations in the Minnesota 
arrowhead and across northern Wisconsin to see minimum relative humidity values 
around 20 percent Thursday. 


Have lowered temperatures Thursday night as the surface ridge axis 
centers over the eastern zones and allow for clear skies...light winds 
and strong radiational cooling. Good model agreement that dew 
points fall into the 20s over the eastern zones...so overnight lows 
may need to be lowered further with later forecasts. The dry 
conditions will persist Friday. 


For the weekend...the forecast area becomes positioned in between 
middle level ridge anchored over the Great Lakes...and a transition 
to warm air advection over western Minnesota. Have small chances for rain showers/thunderstorms 
mainly for SW half of the County Warning Area through the weekend. Increasing rain 
chances into next week with the passage of a short wave. 


&& 


Aviation.../18z taf issuance/ 


Widespread -dz/br and low end MVFR/IFR ceilings with ceilings around 
1000 feet will prevail through the afternoon. Northeast winds will 
continue to be gusty around 30 knots at kdlh with weaker gusts 
elsewhere. Ceilings and visibilities will lower to generally IFR 
overnight with areas of LIFR. The exception will be in the kinl 
vcny...as drier air finally begins to filter into the Borderland 
overnight. Skies will clear out in the far north late tonight. The 
clearing line will push south across the region through the day 
Wednesday...reaching the kbrd to khyr areas late in the day/early 
evening. 


&& 


Point temps/pops... 
dlh 40 56 39 60 / 60 60 10 0 
inl 39 68 38 62 / 30 0 0 0 
brd 45 60 43 65 / 60 60 10 0 
hyr 44 56 40 61 / 60 50 10 0 
asx 40 52 38 54 / 60 60 10 0 


&& 


Dlh watches/warnings/advisories... 
Minnesota...none. 
WI...none. 
Ls...Small Craft Advisory until 11 am CDT Wednesday for lsz121- 
140>148. 


&& 


$$ 


Short term...grochocinski 
long term....graning 
aviation...graning