Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Duluth Minnesota
314 am CDT Sat Apr 25 2015
Short term...(today through Sunday afternoon)
issued at 300 am CDT Sat Apr 25 2015
Very quiet conditions in the short term with cloudy skies this
morning clearing out from NE to SW in the afternoon. A dry air
mass will move in from the north and persist across the region
through the weekend.
Showers and storms are moving eastward through the middle MS valley region
early this morning well south of the Northland...with the entire
forecast area enshrouded in low/middle level clouds. A cool NE wind
off Lake Superior will continue today and keep most of the
Northland in these cool conditions with highs in the 30s and 40s
around and adjacent to the lake...and into the lower 50s inland. A
surface high will build S/southwestward across western Ontario into NE Minnesota as an
upper ridge amplifies over northwest Minnesota today. The combination of these
two features and a drying air mass will produce clearing skies
later today and continuing into tonight.
The main challenge in the short term will be the NE winds off the
lake and resulting temperatures. Winds around the lake this
morning are blowing 15 to 20 miles per hour with occasionally higher
gusts...and these conditions will likely persist today as the pressure
gradient remains in place over western ls. The strongest winds will
likely exist over the water and around the periphery of the lake.
The clearing skies later today and lighter winds inland will allow
temperatures away from the lake to rise into the upper 40s and
lower 50s. However...closer to the lake temperatures will remain
in the upper 30s and lower 40s.
Temperatures tonight will fall into the middle to upper 20s as winds
diminish and skies remain clear. Mostly sunny skies expected on
Sunday with light NE winds allowing much of the region to warm
into the middle to upper 50s...with the exception being around the
very immediate Lake Shore locations...which will only see the 30s
and 40s again.
Long term...(sunday night through friday)
issued at 300 am CDT Sat Apr 25 2015
Upper level and surface ridging remain over the forecast area Sunday
night and Monday. Model differences persist Monday night. The GFS
brings a cold front into northwest Minnesota by 12z Tuesday. The 00z European model (ecmwf) is a
bit faster and more robust with the front into the area. The NAM has
the front on the western doorstep of the forecast area by 12z
Tuesday. Have used a blended approach which results in probability of precipitation over the
western third of the area. Model differences persist on Tuesday.
The GFS washes out the frontal boundary as a positively tilted upper
trough cruises by with no additional rain. The European model (ecmwf) has a
deeper/stronger upper trough which slows down as it reaches the upper
Mississippi River valley. The Gem is similar to the European model (ecmwf) with the
trough but has no precipitation. The European model (ecmwf) is consistent with its prior runs
and generates precipitation over the region. As a compromise...will have low
probability of precipitation over the forecast area. Tuesday night has high pressure
building into the area from the west while the primary upper trough
departs. Next upper trough clips The Arrowhead as it drops from
Ontario into the central Great Lakes. Have a small pop over the tip
of The Arrowhead and into Ashland and Iron counties as a result.
High pressure builds behind this trough as it departs on Wednesday and
covers the region through Thursday. Models diverge Thursday night
and Friday and have a blend for probability of precipitation.
Aviation...(for the 06z tafs through 06z Saturday night)
issued at 1218 am CDT Sat Apr 25 2015
A dry easterly flow has led to mostly VFR conditions as of late
evening with some MVFR ceilings toward kbrd. This is expected to
continue overnight and ceilings will then rise and become scattered
as we progress through Saturday.
Gusty easterly winds will continue around Lake Superior...especially
around the twin ports.
Preliminary point temps/pops...
dlh 39 29 49 31 / 10 0 0 0
inl 53 28 58 31 / 10 0 0 0
brd 52 28 59 33 / 10 0 0 0
hyr 51 27 55 29 / 10 0 0 0
asx 41 29 46 30 / 0 0 0 0
Ls...Small Craft Advisory until 10 PM CDT this evening for lsz146-147.
Small Craft Advisory until 10 PM CDT this evening for lsz141>145.
Small Craft Advisory from 10 am this morning to 10 PM CDT this
evening for lsz148.