Scientific Forecaster Discussion
fxus63 kdlh 301141
Area forecast discussion
National Weather Service Duluth Minnesota
641 am CDT Tue may 30 2017
issued at 633 am CDT Tue may 30 2017
Please see the latest 12z aviation discussion below.
Short term...(today through wednesday)
issued at 347 am CDT Tue may 30 2017
At 330 am, skies were cloudy across the Northland. Regional radar
shows scattered showers moving southward across the cwa, and
temperatures were generally in the 40s to around 50.
The focus for the weather over the next couple days will be the
potential for rain showers, along with temperature trends. An
upper level low over Ontario will continue to affect the Northland
weather today and tonight, before moving out of the region on
Wednesday. Today is shaping up to be another gray day, with
scattered rain showers across the region. A shortwave rotating
around the main upper low will swing south to southeast across the
Western Lake Superior area today, before moving out of the area
later tonight and on Wednesday. The best chance of showers should
be in northern Minnesota today.
For today, will carry highest pop's in the north, with rain
showers likely from the Iron Range northward. Scattered showers
are expected elsewhere. Highs will generally be limited to the
50s. The rain showers will decrease from west to east tonight,
with high pressure moving in on Wednesday. Lows tonight will range
from the upper 30s to lower 40s, with highs on Wednesday ranging
from the mid 60s to the lower 70s. There should be plenty of
sunshine across the area on Wednesday.
Long term...(wednesday night through monday)
issued at 347 am CDT Tue may 30 2017
The extended fcst period looks to be overall fairly dry, with
temperatures returning to more seasonal values.
The long-term forecast period begins with Thursday and Friday
looking dry and warm, with highs ranging in the upper 60s and into
the 70s, with the coolest temperatures expected along Lake Superior.
An upper-level closed low is progged to remain situated over
northeast Ontario Canada, keeping the Northland under the cyclonic
flow. The consensus blend low temperatures Wednesday night/Thursday
morning seemed to be a bit too warm, seeing as we should see some
mostly clear skies and very light winds during this time to enhance
radiational cooling, so decreased the lows by a few degrees. Lows
during this time are expected to be in the lower to mid 40s. It's
still a bit too warm for any frost concerns, but any further
reduction in temperatures may lead to a mention of frost given the
favorable set up. A weak trough with some low-level isentropic
lift may support a brief rain shower over the Minnesota arrowhead
region Thursday afternoon, but there is still a good bit of
disagreement between the synoptic models to put much stock into
Chances of rain showers then develop Saturday morning through Sunday
night, which is the only decent shot at precipitation for the entire
long-term period. The main driver of these chances of precipitation
looks to be a mid-level shortwave, with an associated sfc warm
front. Lift looks to be pretty strong as the GFS model is
indicating some good isentropic lift with this shortwave. Pwat
values are also approaching one inch, so there could be some
wetting rainfall from these showers. The caveat is that there is
some disagreement between the GFS/ECMWF/CMC models at this point
regarding the timing and location of these rain showers. The European model (ecmwf)
and CMC are closer to agreement than the GFS, with the European model (ecmwf)
shifting the track of the sfc low a bit further north, leading to
higher confidence in the precipitation, especially across our
southern areas. So, did increase the pops along the southwestern
counties Saturday morning.
Monday and Tuesday next week look to be mostly dry, with only a few
scattered chances of a rain shower.
Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 641 am CDT Tue may 30 2017
A mid-level shortwave will continue to bring scattered to numerous
rain showers over the Northland today. The rain showers and a
moist low-levels will support MVFR to IFR conditions, with mainly
reduced ceiling heights being the biggest concern, with heights
between 0.5 to 2.5 kft expected. There could also be some MVFR
vsbys possible at the kinl terminal, which may persist through
much of the morning. There is also a possibility of IFR vsbys at
kinl as well through the morning, but confidence is much lower on
this, so will keep the 5 to 6sm MVFR vsbys in the taf.
The shortwave should move out of the area by this evening and
overnight, which will help to improve the ceiling heights over all
of the taf terminals.
Preliminary point temps/pops...
dlh 53 40 68 46 / 50 30 0 0
inl 54 38 70 43 / 60 30 0 0
brd 56 42 71 45 / 30 10 0 0
hyr 55 43 70 42 / 30 40 0 0
asx 55 43 67 44 / 50 30 0 0