Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Duluth Minnesota
1220 PM CDT sun Apr 19 2015
issued at 945 am CDT sun Apr 19 2015
Rain will continue to affect the forecast area through the day.
However...there will be an hour or two when no rain is occurring
and tried to account for this in the forecast. Kept the maximum temperatures
the same for now...but will look into lowering later today. Rest
of the forecast in the ballpark.
Short term...(today through monday)
issued at 342 am CDT sun Apr 19 2015
The focus remains on the rain today and tonight. Refined the precipitation
chances by using a blend of the rap13 and hrrr model runs through
this morning since the two models seem to be doing pretty well
capturing the location of the current rain. Did not make any
dramatic changes to rainfall. Overall...much of the forecast area
can expect about 0.30 to 0.75 inches of rainfall through tonight.
At 330 am...an area of low pressure was over the border between
South Dakota and SW Minnesota. A frontal boundary extended
northward to another area of low pressure in southern Manitoba.
There was an upper level trough over the northern High Plains and
Saskatchewan/Manitoba digging and deepening towards the northern
plains and Ontario. A large area of rain was lifting to north-northeast
through the southern two thirds of the forecast area. This rain
was associated with a band of middle level frontogenesis ahead of the
low near the South Dakota/Minnesota border. There was additional rain in eastern
South Dakota and northwest Minnesota moving to the east in the wake of
the trough boundary and ahead of the upper level to the west. The
Northland had cloudy skies with temperatures in the upper 30s to
middle 40s. The Northland had light easterly to southeasterly
This morning...the surface low near the South Dakota/Minnesota border will lift NE
to the Aitkin area by this afternoon. The surface low in southern
Manitoba will dig to the southeast. The rain over the forecast area early
this morning will continue lifting to the north with the band of
middle level frontogenesis. Parts of the northern forecast could pick
up to around a half inch of rain through this morning. The cold
front in North Dakota will begin to move into the western forecast
area late this morning.
This afternoon and evening...the two lows will gradually merge
into one low over northwest Ontario. Cloudy and cool weather is expected
with highs ranging from the upper 40s over the north to the 50s
over the south. Most of the afternoon and evening rain will be
over the eastern forecast area ahead of the eastward advancing
cold front. A dry slot will move into the western forecast
area...and there could be partial clearing in the SW forecast
area. Also...a prominent band of low/middle level frontogenesis will
set up over northwest Wisconsin this evening which develop and intensify
a band of rain over that area. The upper level trough over the
northern plains and south central Canada will deepen and develop
into a well defined upper level over southern Manitoba this
afternoon and continue deepening as it approaches northern
Later tonight and early Monday...the cold front will finish
moving through the forecast area. The upper level low will
continue deepening over northwest Ontario. The low/middle level
frontogenetical band in northwest Wisconsin should exit to the east by
around dawn. Temperatures will drop into the middle and lower 30s
tonight. The synoptic lift from the upper level low will likely
result in light rain and snow moving into the northwest forecast area.
Little of any snow accumulation is expected since much of it
should melt...either on impact or later in the morning.
Monday...it will be much cooler day with blustery northwest winds.
Sustained winds of 10 to 20 miles per hour will develop by the
afternoon...and there could be gusts up to 30 miles per hour. The 850 hpa
temperatures will be about -5 to -6 degrees celsius. Heavy cloud
cover and the cool northwest flow will prevent highs from getting much
higher than the low to middle 40s. There will be increasing
chances of cold rain showers as the upper low deepens and moves to
just north of Koochiching County.
Long term...(monday night through saturday)
issued at 342 am CDT sun Apr 19 2015
A deep area of low pressure will settle southward into the Lake
Superior region Monday night and Tuesday. The closed 500 mb low will
reach Western Lake Superior by Tuesday afternoon. Numerous
showers will rotate southward around the upper low...generally in
the form of snow showers at night and rain or snow showers during
the day through the middle of the week. Definitely could be some
slushy accumulation at times...especially in the north. Would not
be surprised to see a couple episodes of up to a couple inches...
followed by some partial to full melting during the day. This
massive upper level trough will eventually lose its grip on the
area from the middle to the end of the work week. The Gem and to
some extent the European model (ecmwf) are the most aggressive in pushing the
upper trough eastward through the end of the week...with the Gem
bringing upper level ridging already into the County Warning Area by 12z Friday.
The GFS is much slower and deeper with the upper level low.
Strongly favoring the Gem/European model (ecmwf) solution...especially late in the
week and into the weekend. High temperatures will remain on the
cool side during the week...reaching back into the low to middle 50s
on the weekend.
Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 1220 PM CDT sun Apr 19 2015
Conditions varied from LIFR to MVFR across the Northland with
periods of rain/fog/drizzle moving through the area. These
conditions will persist through the afternoon into tonight. The
rain will be most widespread over eastern areas...especially
northwest Wisconsin tonight. Southwest areas including kbrd may go
VFR briefly later this evening...but as colder air moves back in
on the backside of the low...lower ceilings will once again return.
Temperatures may get cold enough for some snow over portions of
northern Minnesota later tonight. Gusty west/northwest winds will
also develop later in the period...especially on Monday.
Preliminary point temps/pops...
dlh 49 34 44 29 / 90 30 30 60
inl 49 32 40 28 / 100 40 60 60
brd 56 35 43 31 / 80 20 40 40
hyr 58 37 46 30 / 90 80 30 60
asx 58 37 47 32 / 90 80 20 60
Ls...Small Craft Advisory until 4 PM CDT this afternoon for