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Area forecast discussion...updated
National Weather Service Duluth Minnesota
946 am CDT sun Apr 20 2014
issued at 941 am CDT sun Apr 20 2014
Only minor tweaks to existing grids/zfp. Fog has dissipated over
southeastern part of the County Warning Area as mixing layer increases from sunshine. Some
concern that nearshore maximum temperatures may be modulated by marine
boundary layer. For now...forecast 2k feet winds suggest enough offshore
push to lower probability of an early push inland. Only clouds of
note today will be over southeastern corner of the region where northern fringe
of clouds from southern frontal boundary are advecting northeastward.
Update issued at 636 am CDT sun Apr 20 2014
Updated for aviation section below.
Short term...(today and tonight)
issued at 357 am CDT sun Apr 20 2014
Main concerns in the short term remain centered around the on-going
rain showers over southern Sawyer and price counties this morning...the
potential for patchy fog this morning as well...warm temperatures
this afternoon...and the next round of light rain showers expected
A trailing weak cold front oriented NE-SW from Eastern Lake Superior
back toward southern Minnesota continues to interact with a moist and weakly
unstable air mass to the south and produce rain showers over the
extreme southeastern portions of the forecast area. This band of showers
will continue to slowly track to the east this morning as high
pressure at the surface builds in across northern Minnesota. The flow aloft will
continue to remain fairly zonal...however the presence of very dry
air from the surface ridge will allow skies to remain mostly sunny today
and also contribute to the warm temperatures expected this
In addition...through the rest of this morning there will be a
slight chance of patchy fog across the Northland...with the most
favorable area expected around the periphery of Lake Superior
where the near-surface air mass is more moist and closer to
saturation. Visibilities have been around 3-5 miles so far this
morning...and could possibly dip to around 1 Michigan in some locations.
No widespread dense fog is expected.
A relatively warm air mass will build in over the upper Midwest
today and combine with weak subsidence from the surface high and strong
solar heating from the sunny skies to produce high temperatures in
the 50s through The Arrowhead and well into the 60s for much of the
For tonight...conditions will start out warm and dry but change
through the night as two weak systems approach the Northland. One
low pressure system from the south will move from the Central Plains
northeastward into southern Minnesota/southwestern WI and continue to interact with the moist air
mass to the south...producing light rain showers over the southeastern
portions of the Northland once again. The other system will ride in
from the northwest in the form of a cold upper low. This system will be
slightly more dynamic...but not have the necessary moisture
available to produce any significant precipitation. The end result is a
chance of rain showers across the north and south...with mostly dry
conditions in between. Temperatures will fall again tonight into the 30s
and lower 40s.
Long term...(monday through saturday)
issued at 357 am CDT sun Apr 20 2014
Monday the cold front moving through the area is expected to
continue to generate showers both northeast and southeast.
However...the surface ridge will build into the area from the
northwest...and conditions should dry out by late afternoon. High
temperatures will be warm again with highs across the south in the
60s again...but the colder air building in from the northwest should
keep highs there back in the middle and upper 50s. The surface ridge
building across the area on Tuesday will keep the weather quiet and
clear...with highs Tuesday in the 50s.
Wednesday through Friday is our next major weather maker...as a slow
moving upper level low moves across the upper Midwest. This system
should start out with rain as the warm air advection pushes across
the area. On the southern flanks of this warm air advection Wing we
should also get some thunder...mainly on Wednesday night and
Thursday with some fairly steep middle level lapse rates and even some
weak low level cape. Models are in good enough agreement on
Wednesday and Thursday to have fairly good confidence on
this...though the European model (ecmwf) is cooler at this point than the GFS.
Precipitation should remain all rain showers through Thursday as
well...though timing is going to be quite tricky. Thursday night
and Friday the cold air is expected to surge into the area from the
northwest...with the European model (ecmwf) faster than the deeper and slower GFS.
For now have kept things fairly generic with a rain/snow mix
overnight and Friday...with all snow Friday night before the event
ends. Confidence is not very high on precipitation type or temperatures by
Thursday and Friday on this system. For now temperatures through
the period to be colder than normal throughout...but expect to be
making changes in upcoming forecasts.
Saturday chilly but quiet with highs in the 40s.
Aviation...(for the 12z tafs through 12z Monday morning)
issued at 636 am CDT sun Apr 20 2014
Lingering low level moisture will keep a potential for fog at
kdlh...khib...and khyr for a few more hours. Otherwise...expect
clearing skies today with light and variable winds. Few to
scattered cumulus are possible over northwest Wisconsin at or
above 3kft...but should not go broken. Some middle and high level
clouds will move across the terminals after 06z tonight...but
conditions expected to remain VFR.
Preliminary point temps/pops...
dlh 59 38 60 33 / 0 10 10 0
inl 60 40 52 31 / 0 30 20 10
brd 66 44 63 35 / 0 10 10 0
hyr 64 38 65 33 / 10 20 30 0
asx 58 33 62 34 / 10 10 30 0