Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kdlh 190511 
afddlh

Area forecast discussion
National Weather Service Duluth Minnesota
1211 am CDT Thu Oct 19 2017

Short term...(this evening through thursday)
issued at 433 PM CDT Wed Oct 18 2017

We have had a very dry and windy day today with a few fire starts
reported around Grand Rapids and areas farther west. West winds are
sustained in the 15 to 25 mph range with gusts in the 30-35 mph
range over a fairly large portion of the northern Minnesota
arrowhead. After coordinating with Minnesota dnr partners, the red flag
warning has been expanded to a few additional counties, where we are
making criteria consistently this afternoon. Winds should diminish
rapidly this evening with sunset as diurnal effects help decouple
surface winds from the strong westerlies aloft. Relative humidity values will
remain low overnight as the incoming airmass is very, very dry. The
west winds will stay up in the 5 to 10 mph range overnight, which
should help keep air temperatures overnight in the upper 30s to low
40s. This will set the stage for another warm and dry day tomorrow.
Winds will not be as strong tomorrow, as at the surface we will have
weak ridging and winds will not be as strong aloft so that even
though we should mix fairly well, the speeds are not there to mix
down. Have raised Max temperatures tomorrow into the middle to
upper 60s for everywhere except the tip of The Arrowhead, where
values closer to 60 will be found. Fire weather conditions will be
dry, but without the wind do not anticipate the need for any
headlines at this time.

Long term...(thursday night through wednesday)
issued at 433 PM CDT Wed Oct 18 2017

The dry and warm weather pattern that has dominated over the
Northland for the last few days will continue through the day Friday
as high pressure remains in control, which will be situated over the
eastern one-third of the United States. However, we finally start to
see a break in the flow pattern as a longwave trough develops over
the Pacific northwest. This wave will bring chances of rain showers
Saturday, with a small chance of thunderstorms possible as well in
the afternoon. Some decent moisture will be transported into the
region, given an enhanced low-level jet and an increase in Theta-E
advection. Amounts through Saturday afternoon are not looking too
high at this time, but some places might get a wetting rain, a
welcome occurrence considering the dry conditions from this week.
Temperatures Friday may be the warmest day of the week yet, with
high temperatures expected in the upper 60s in The Arrowhead region,
with lower 70s elsewhere.

Chances of showers and thunderstorms will continue into Saturday
night before coming to an end during the day Sunday. There is a bit
of model disagreement, with the GFS/European model (ecmwf) keeping the trough
progressive and moving it out by Sunday morning, while the CMC
lingers the trough through the afternoon. Due to better consensus
with the GFS/ECMWF, leaned toward them for my Sunday pops, keeping
it a bit drier than what the consensus blends had. A secondary mid-
level impulse clipper system will quickly eject from Alberta. A good
maxima of isentropic lift will provide decent lift with this system,
but deeper moisture appears to be lacking. Temperatures will cool
down a bit with this system, with a gradual cooling trend from
Saturday to Monday, decreasing from the middle 60s Saturday to the
50s Monday.

The overall trend is to linger chances of showers and possibly some
snow showers Tuesday and Wednesday as the upper-level trough slows
down and deepens over the Northland. Cold air advection will be
enhanced within this trough, with a return to temperatures below
freezing - a return to seasonal temperatures.

&&

Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1211 am CDT Thu Oct 19 2017

VFR through the forecast. Low level wind shear is expected to affect the
terminals at the start of the forecast with another low level jet nearby.
Low level wind shear is possible again toward the end of the forecast at
hib/brd/hyr. Low level wind shear is questionable at dlh and have left out due to
lower confidence.

&&

Preliminary point temps/pops...
dlh 39 64 46 69 / 0 0 0 0
inl 37 65 46 73 / 0 0 0 0
brd 38 67 48 71 / 0 0 0 0
hyr 39 68 46 73 / 0 0 0 0
asx 42 69 47 75 / 0 0 0 0

&&

Dlh watches/warnings/advisories...
WI...none.
Minnesota...none.
Ls...Small Craft Advisory until 4 PM CDT this afternoon for lsz140-
141-146-147.

Small Craft Advisory until 4 am CDT early this morning for
lsz142>145.

&&

National Weather Service Glossary of Abbreviations