Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Duluth Minnesota
542 am CST Sat Nov 28 2015
Short term...(today through sunday)
issued at 346 am CST Sat Nov 28 2015
Very tranquil weather will prevail today through Sunday across the
Northland. Surface high pressure centered over southern Minnesota
this morning will translate very slowly eastward through
Sunday..with light to moderate southwest to west winds both today
and Sunday across the region. A weak middle level impulse will slide
southeastward across Ontario today..and will bring a few middle/high
level clouds across northern Minnesota today..but this will have
little affect on sensible weather. Weak warm advection will allow
temperatures to warm a few degrees from Friday..and a few more degrees
into the Lower/Middle 30s on Sunday. However..combination of light
winds/clear skies/long night and at least some snow cover should
allow for some rather cold readings tonight in many of the favored
cold spots..and across northwest Wisconsin where there is a bit more
snow. Chances of precipitation will be near zero until sometime late
Monday with the approach of the system from the plains.
Long term...(sunday night through friday)
issued at 346 am CST Sat Nov 28 2015
Quiet conditions are expected to continue Sunday night across the
Northland. A cut off upper low is expected to be located over the
central rockies with a trough of low pressure extending northeastward
into northern Minnesota. Middle-level moisture and cloud cover expected
to increase overnight ahead of the approaching system. A nose of
Theta-E advection and middle-level fgen may be able to squeeze out a
narrow band of snow during the morning hours on Monday. However...
any snow which develops is expected to sublimate in the very dry low-
levels before reaching the ground. Included a low-end pop in my
southwest to account for this possibility.
By Monday afternoon...the upper low will move into the Central
Plains with a surface low expected to develop in southeast Colorado
and move northeastward toward the upper Midwest. Deterministic
guidance in good agreement this morning with the handling of the
upper low and surface reflection through Monday evening. GFS
diverges slightly from the European model (ecmwf)/Gem/NAM consensus with placement
of low centers on Tuesday...trending farther south. Even so...all
guidance points to snow developing Monday evening and continuing
through Tuesday into Tuesday night. Both the 27.12z and 28.00z GFS
ensemble members show better agreement than yesterday at this time.
Taking all these factors into account...confidence in several inches
of accumulation Monday night through Tuesday evening generally south
of Minnesota Highway 210/US Highway 2 is increasing.
System pulls out of the area on Wednesday. Zonal flow aloft and a
broad surface ridge will be the main features across the northern
plains and western Great Lakes Wednesday night and Thursday. High
amplitude shortwave ridge will build into the region Thursday night
through Friday night...continuing the quiet conditions.
Temperatures will continue to trend near or above climatological
normals through the long term.
Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 542 am CST Sat Nov 28 2015
VFR conditions expected for this forecast period with surface
ridging in place and zonal flow aloft. Low level wind shear will
continue to be a concern for the next few hours at Minnesota terminals where
nocturnal low-level jet...indicated by kdlh vwp...is forecast to
persist. Wind speeds near aloft will quickly diminish after
sunrise. With clear skies expected once again tonight...the
potential exists to develop MVFR/IFR ceilings and visibilities.
However...forecasts clouds and diminished visibility did not pan
out this morning...so confidence is below average. Did include VFR
visibility reductions and scattered clouds to convey the potential fog and
Preliminary point temps/pops...
dlh 31 15 33 22 / 0 0 0 0
inl 30 12 30 18 / 0 0 0 0
brd 33 14 34 21 / 0 0 0 10
hyr 32 11 35 19 / 0 0 0 0
asx 34 15 35 23 / 0 0 0 0
Ls...Small Craft Advisory until 10 PM CST this evening for lsz140-141-