Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Duluth Minnesota
640 PM CDT Monday Aug 31 2015
Short term...(this evening through tuesday)
issued at 302 PM CDT Monday Aug 31 2015
A surface cold front was moving slowly eastward through northwest Minnesota and at 19z was
located near Roseau southwestward to whapeton ND. Only some cumulus/stratus was
found near the front with no rain. The clouds will spread a bit
further eastward tonight. The stratus in northwest WI persists...but still shows
some erosion. Some stratus/fog is hanging onto the North Shore from
near Lutsen to about Hovland...but has also shown some erosion.
Expect the fog to remain along the North Shore tonight and Tuesday.
Elsewhere...no mention of fog tonight or Tuesday as forecast
soundings indicate a dryer boundary layer than last night. The cold
front will wash out this evening as it attempts to move eastward into the
forecast area. With a lack of forcing...have removed the mention of
thunderstorms for tonight. This is in line with latest short term
On Tuesday...models offer differing solution with regard to
thunderstorm development over northwest WI. GFS/nam12 and arw are dry.
European model (ecmwf)/Gem/nmm bring in some storms in the afternoon with the nmm
holding off until 21z. With high pressure at the surface covering the
area...and embedded impulses in fast SW flow aloft...difficult to
time any storms. Did lean toward the nmm/arw/nam12 and pushed back
the mention of storms until 21z with a realignment of probability of precipitation. Expect
maximum temperatures to be quite similar to today and tweaked as a result.
Long term...(tuesday night through monday)
issued at 302 PM CDT Monday Aug 31 2015
A broad upper level ridge across the eastern US will flatten out over
the Central Plains/upper Midwest early in the extended period as the
main axis shifts to the east. A middle-level ridge will amplify over
the western Great Lakes on Wednesday and be a foreshadowing of a
stronger upper ridge expected to build across the central Continental U.S. On
Thursday. The presence of this broad high pressure will keep weather
conditions fairly quiet across the region. However...there will be a
series of weak short waves that ride along the northern edge of the ridge
and interact with the hot/humid and unstable air mass in place. The
potential convection will be hit and miss through Thursday...but if
there is an area that does develop it will be able to tap into quite
a bit of instability and moisture...and also be very slow-moving.
The ridge to the east really begins to move eastward on Friday as
the next upper trough begins to dig into the northern rockies and ejects
a series of more potent waves through the upper Midwest this
weekend. Could see fairly active weather this weekend with strong to
possibly severe thunderstorms.
Temperatures will remain very warm this week and into the weekend
with highs in the 80s...and overnight lows in the 50s and 60s. Will
start to see the beginning of a cool down period early next
week...possibly as early as Sunday.
Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 634 PM CDT Monday Aug 31 2015
A weak frontal boundary will move eastward across the Northland
overnight. South to southwest winds ahead of the front will be a
bit gusty early in spots...but quickly lose their gusts within the
next couple hours. Some sprinkles or even a few showers will also
accompany the weak frontal boundary...but generally not resulting
in a visibility restriction. There could be some light fog later
in the night...especially in northwest WI. Some MVFR or possibly even IFR
conditions will be possible in khyr and perhaps a few other
locations. Overall...conditions will be VFR for much of the taf
cycle and for most locations. Behind the front...drier air will
push across the Northland from west to east on Tuesday.
Preliminary point temps/pops...
dlh 66 82 64 82 / 10 10 10 10
inl 57 81 54 87 / 10 10 20 20
brd 64 84 65 86 / 10 10 0 10
hyr 67 83 64 84 / 10 20 10 20
asx 68 82 62 84 / 10 10 10 20