Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Duluth Minnesota
414 am CDT sun Jul 13 2014
Short term...(today and tonight)
issued at 351 am CDT sun Jul 13 2014
The cold front that went through the Northland last night was
nearly out of the forecast area early this morning with the front
just on the verge of exiting Price County. Much cooler temperatures were
already being seen in northern Minnesota where temperatures were in the middle 40s...in
contrast to the lower 60s in northern WI.
Another in a series of S/waves rotating around upper low will affect
the Northland today and tonight. Scattered rain showers occurring
over southern Manitoba/northwestern Ontario will spread southward today and tonight.
The showers will also be aided by steep lapse middle level lapse rates
caused by cold air advection aloft. Sunshine this morning will gradually be
replace by the cold air stratocumulus in the wake of the cold
Long term...(monday through saturday)
issued at 351 am CDT sun Jul 13 2014
Anomalous middle level closed low and parent upper level trough will swing
across the region Monday...then gradually weaken as it shifts east
into the central Great Lakes midweek. The middle level pattern will then
transition gradually to a west northwest flow aloft during the end
of the week. This will be accompanied by an increase in warm air
advection in low levels and a chance of rain far north Friday.
Precipitation...clouds...and cold advection will ensure a much below climatology
day Monday across the County Warning Area. Based on latest forecasts of salient
features...middle level low and deep layer moisture...it appears the area
from the eastern arrowhead south to twin ports and northwest Wisconsin
will have the lowest maximum temperatures. Sref plumes show a mean temperature for dlh
of approx 57f..3 degrees above the record low maximum for the date.
Either way..temps will average about 10 to 20 degrees below climatology
over most of the County Warning Area. A challenge exists Tuesday regarding the
existing lower cloud deck left behind by the deep circulation. There
are some conflicting signals regarding placement of clouds Tuesday
as some nwp shows higher chance of instability cumulus developing over southern
County Warning Area late morning... and advecting south of the County Warning Area by afternoon.
General synoptic scale pattern would favor some amount of cloud
cover over the eastern part of the County Warning Area with closer proximity to moisture
associated with the Great Lakes circulation. Forecast 925h temperatures Tuesday of
14c to 15c should allow maximum temperatures to jump into upper 60s to near
70...and 70s area wide Wednesday. Warm advection pattern will
continue to push temperatures upwards late week with middle to upper 70s and a
few 80s by Friday. At this point the forecast strength of the surface high
over the region and the lack of sufficient deep layer moisture
should restrict precipitation chances to far north Minnesota zones Friday. Even that
potential may be overdone as GFS is only model driving a warm
frontal boundary precipitation pattern across the north. Of more confidence is
the approach of a frontal boundary with middle level trough during the weekend.
While both GFS/European model (ecmwf) agree on this general pattern there are timing
differences.The ec is faster in progressing the forcing/precipitation
eastward than the slower GFS/Gem. Will have to use generic chance
wording for now until later this week when model discrepancies
lessen and actual synoptic regime develops.
Aviation...(for the 06z tafs through 06z Sunday night)
issued at 1233 am CDT sun Jul 13 2014
Band of showers moving across the area are accompanying a cold
front. These are still affecting kdlh and kbrd...and will move
through khyr here in the next few hours. Conditions are mainly
VFR...and should return to VFR after the front passes and winds
turn northwest. After 15z Sunday morning northwest winds to
increase to 15kts with gusts to 20-25kts for most of the day.
Clouds to overspread the area from the north...with MVFR ceilings
expected to move in after 00z...but only affecting kinl and khib
through 06z. These MVFR ceilings to be accompanied by some -shra.
Confidence in timing not very high at this time.
Preliminary point temps/pops...
dlh 67 50 59 48 / 20 40 70 20
inl 65 47 63 47 / 30 50 60 10
brd 70 51 62 50 / 10 30 50 10
hyr 70 51 59 48 / 10 30 70 30
asx 68 49 58 48 / 10 40 70 50