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
