Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Duluth Minnesota
743 am CDT Friday Oct 24 2014
issued at 649 am CDT Friday Oct 24 2014
Cut back on the dense fog advisory to the south as most of the
webcams and surface observation have continued to report improving conditions.
Will keep the advisory going from the twin ports along the North
Shore through 10 am at this Point. May need to be cancelled before
Short term...(today through Saturday afternoon)
issued at 331 am CDT Friday Oct 24 2014
Areas of dense fog this morning and above average temperatures
today and tomorrow...with gusty northwest winds Saturday are the main
concerns in the short term.
A dense fog advisory remains in effect for the eastern half of the
forecast area until 10 am this morning. Visibilities across The
Arrowhead...southward through the twin ports and into northwest WI have been
below 1/2 to 1/4 Michigan this morning and will likely continue through
Strong warm air advection in the middle levels...combined with a cool and moist
near surface layer is creating a favorable inversion across the
Northland this morning...conducive for fog formation. This layer
of clouds and fog will be met with the warm and slightly drier air
from the west later this morning and into the afternoon. There
should be enough deep mixing to scour out the low clouds over the
entire region today...but a thin layer of high clouds may
persist through this evening. There is a chance that the low
clouds over north-central WI may just end up lifting and persisting
through the day. This could keep temperatures in WI on the cooler side.
Even still...this bubble of abnormally warm air...850mb temperatures
+12-13 degree c should be able to mix down to the surface to produce
afternoon high temperatures in the middle to upper 60s over a large
section of the Northland...with a few lower 70 readings not of
the question in central Minnesota. The other concerns today will be the
potential for gusty SW winds in the afternoon. Depending on the
amount of mixing...wind gusts could reach into the 20 to 25 miles per hour
Conditions tonight will remain mild with temperatures only
dropping into the 40s. The quiet weather will persist tonight as
well with high pressure building in across the northern plains.
On Saturday a shift in the conditions will occur with the passage
of a cold front through Manitoba and western Ontario. As the high
builds in across the SW and the trough slides eastward to the
north...the winds will shift to the northwest and increase through the
day as the pressure gradient tightens and bl mixing transports
30-40 miles per hour winds aloft down to the surface. As the winds shift a cooler
air mass advects in as well and drops temperatures into the upper
40s and lower 50s to the north...and keeps temperatures in the middle to
upper 50s to the south. Winds will be quite strong as well with
sustained northwest winds around 15 to 20 miles per hour and gusts up to 30 miles per hour.
Long term...(saturday through thursday)
issued at 331 am CDT Friday Oct 24 2014
A 850 mb ridge axis moves into western Minnesota Saturday evening...gradually
shifting east over the Northland through Sunday. The combination of
the surface high and low dew points in the 20s Saturday night will bring
conditions favorable for strong radiational cooling. Have lowered
temperatures close to maximum/mex guidance values...generally in the upper
20s...but cooling trend may need to be continued if dew points
are expected to be lower.
A broad 850 mb/surface low positioned ahead of a deepening h50
wave...translates across the Dakotas Sunday. This will result in a
southerly flow with 850 mb temperatures warming into the low teens across the
southern zones by Sunday evening. The system slowly becomes a stacked low
centered over northern Minnesota/Ontario by Monday night/Tuesday.
Although models differ in timing and amplitude of the wave this far
out...the latest GFS/ecm are suggesting convection develops along
the 850 mb/surface boundary positioned over the Northland Sunday evening
into Monday. Wrap around precipitation and cooler temperatures will arrive
as the stacked low retreats over the Great Lakes/Ontario through
Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 732 am CDT Friday Oct 24 2014
Lingering morning fog with will be found around kdlh and khyr.
Otherwise...VFR conditions will prevail through the taf period. A
cold...but dry...front will quickly sweep over the region this
evening. The dry air mass will limit any low clouds or
precipitation with this front for most areas. The exception will
be over northern Wisconsin...possibly impacting khyr...where MVFR
ceilings may develop ahead of the front this evening. The frontal
passage will bring a transition from southerly winds today...to gusty
west/northwest winds by Saturday. Winds aloft will increase out
of the northwest at 35-40 knots overnight. Low level wind shear may be
possible...depending on near surface inversion.
Preliminary point temps/pops...
dlh 67 46 56 32 / 0 0 0 0
inl 68 42 52 28 / 0 0 0 0
brd 71 43 58 32 / 0 0 0 0
hyr 67 44 57 29 / 0 0 0 0
asx 67 46 57 33 / 0 0 0 0
Minnesota...dense fog advisory until 10 am CDT this morning for mnz020-021-
WI...dense fog advisory until 10 am CDT this morning for wiz001.
Ls...dense fog advisory until 10 am CDT this morning for lsz140>145.