Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Duluth Minnesota
1055 am CDT Thursday Oct 23 2014
issued at 1055 am CDT Thursday Oct 23 2014
Updated for fog along the Northshore and backing off of the precipitation
ending in northwest WI. The clearing in the west is on target.
Update issued at 915 am CDT Thursday Oct 23 2014
Updated to slow movement of rain showers in The Arrowhead and northwest
WI due to present trends. Also...delayed clearing by an hour based
Short term...(today through Friday afternoon)
issued at 337 am CDT Thursday Oct 23 2014
Main concerns in the short term remain focused around the rain
showers moving through the Northland this morning with patchy fog
on the back edge of the rain through the middle morning...
temperatures 4 to 8 degree warmer than yesterday this afternoon...and
even warmer conditions on Friday.
Upper trough and nearly Colorado-located surface cold front currently situated
north-S from southern Manitoba through southern Minnesota...with a eastward track and areas of
rain showers along and ahead of the front. The band of heaviest rain
is currently aligned from inl to Lake Mille lacs and slowly
transitioning to the E/NE. This corridor of rain will move through
the twin ports between 4 and 8 am this morning and eventually
through The Arrowhead and across northwest/N-cntrl WI. Rainfall amts will
likely be limited to two tenths of an inch or less. The effect of
rain falling into the surface layer will saturate conditions enough to
produce patchy fog behind the rain this morning. Warm enough air
aloft and light winds at the surface will allow for favorable
conditions for fog.
Ridging aloft and weak high pressure at the surface building in behind
the exiting front will combine with a much drier air mass to allow
conditions to dry out this afternoon. Fairly steep 1000-850mb lapse
rates will mix this dry air down to the surface and work in unison with
robust warm air advection in the layer aloft to produce highs in the lower to middle
60s over much of NE Minnesota. Slightly cooler conditions will exist
further to the east where cloud cover into the early afternoon will
inhibit the amount of heating. High pressure will continue to
dominate the region tonight with mostly clear to partly cloudy
skies. The +12 degree c air advecting in aloft tonight will create a
very strong inversion in the bl...and as surface temperatures cool into the
40s the threat for fog arrives again tonight. Winds will remain
light around 3-6 miles per hour from the south-southwest and could inhibit the
development of fog due to mixing.
Friday will be a very pleasant day with a few clouds in the sky and
temperatures warming into the 60s...with a few 70 degree readings not
out of the question over central Minnesota. The quiet weather conditions
will continue into the weekend.
Long term...(friday through wednesday)
issued at 337 am CDT Thursday Oct 23 2014
A series of fast moving short waves will translate across the
Northland through the extended period. A vorticity maximum will bring
increasing clouds Friday...mainly to the eastern half of the County Warning Area.
However...the dry air mas is expected to limit any precipitation. A
more organized wave will drop over the Lake Superior region
Saturday...but at this time the main area of precipitation is
expected to remain to the east of the County Warning Area. Small probability of precipitation may be needed
in the tip of the Minnesota arrowhead Sat if the track of the low trends
any further west. Long range models are in good agreement that a 850 mb
ridge axis moves into western Minnesota Saturday afternoon...gradually shifting
east over Wisconsin Sunday...keeping the Northland dry and mostly
sunny through the weekend. The exception may be some low
clouds/drizzle that may develop along the western tip and North
Shore of Lake Superior late Sunday afternoon as the pressure
gradient increases and the marine winds become onshore.
However...have kept probability of precipitation out Sunday at this time as anticipate a
slower arrival of the moisture and higher dew points to support
saturating the low levels until the evening and overnight hours.
A southerly flow will bring a return to warm air advection across
the region Sunday night/Monday ahead of the next wave. Although
models differ in timing and amplitude of the wave this far out...the
latest GFS/ecm are suggesting convection develops ahead of the h50
trough...along a surface boundary positioned in the Northland vicinity
Monday. At this time have continued to carry small probability of precipitation through the
Sunday night/Tuesday time frame.
Aviation...(for the 12z tafs through 12z Friday morning)
issued at 700 am CDT Thursday Oct 23 2014
A frontal boundary will move eastward across the region
through the morning. The front will bring rain showers and
prevailing MVFR cigs/vsbys. IFR ceilings with fog will be found
over the Minnesota zones through 15z. Drier air will move in from
the west and bring clearing skies this afternoon.
Preliminary point temps/pops...
dlh 60 44 66 44 / 50 0 0 0
inl 63 43 67 41 / 10 0 0 0
brd 65 43 68 42 / 10 0 0 0
hyr 57 41 66 43 / 50 0 0 0
asx 56 42 67 44 / 60 0 0 0