Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 171145

Area Forecast Discussion
National Weather Service Duluth MN
545 AM CST Sun Feb 17 2019

.SHORT TERM...(Today through Monday)
Issued at 321 AM CST Sun Feb 17 2019

Relatively quiet weather continues through the day Monday, with some
chances of light lake effect snow/flurries along the North Shore
south to the Twin Ports today and tonight.

An upper-level longwave trough will persist over the Intermountain
West states through the day Monday, along with a sub-tropical jet
rounding the base of the trough, over the southern United States. A
surface low pressure system will remain over the central Mississippi
River valley region today, well south of the Northland. However,
this will result in northeasterly flow over the Northland through
tonight, which will result in some chances of lake effect snowfall,
which should remain light in nature. Some of the models are hinting
at this lake effect snow, such as the NAMNest and WRF NMM models, as
well as the 17.00z GFS model. The latest MODIS satellite imagery
still shows a good bit of ice coverage over Lake Superior, with some
breaks along the North Shore, which should be sufficient enough for
some light snow to develop, along with 850mb-to-lake delta-T values
between 13 to 18 degrees C. The main limiting factor will be a lack
of deep-layer moisture, although some shallow saturation will be
available to promote ice crystal growth. For now, snow accumulation
will be light, with a coating to no more than a half inch
possible. This lake effect snow should continue into the evening
hours tonight, but will shift more southward due to a backing wind
profile in the low-levels, so some light snow/flurries could
linger near the Twin Ports and adjacent areas of the South Shore
this evening. Some flurries will also be possible over our far
southern counties due to forcing from the aforementioned large-
scale trough. Highs today will range from the upper teens to lower

Another chilly night is expected tonight, with some clearing skies
to the north, which will promote some radiational cooling. Overnight
lows will fall into the single digits to near zero south and lower
teens below zero north. Monday looks to be drier at the moment as
high pressure will slowly build back into the region, which will
push the mid-level wave to the east. Skies will be partly to mostly
sunny on Monday, with highs in the teens.

.LONG TERM...(Monday night through Saturday)
Issued at 321 AM CST Sun Feb 17 2019

Below to near seasonable temperatures this week with a chance for
measurable snowfall mid-week, then a prolonged chance for light
snow late week into the weekend.

On the synoptic scale, a fairly active pattern across North
America, but locally generally low sensible weather impacts as the
main storm track shifts to the south compared to earlier this
month. The week begins with a mid/upper level longwave trough over
the southwest with a few weak mid-level shortwave troughs across
the Great Plains. One of these waves located over the northern
Plains will track east towards the Great Lakes, leading to clouds
Monday night into early Tuesday, but a very low chance for any
precip. A broad area of high pressure builds across the Midwest on
Tuesday leading to decreasing clouds, with southerly low level
flow developing. The main longwave trough over the southwest
slowly ejects into the southern Plains and Mississippi River
Valley mid-week, leading to a broad area of large-scale lift
producing light snowfall over much of the Midwest. Guidance
continues to trend slightly east with the area of heaviest
precipitation, though the latest 00z ECMWF is a bit more
aggressive than the rest of the guidance suite. Generally around 1
to 3 inches of snowfall is possible, with the best chance for
snow in northwest Wisconsin. The greatest impacts from this snow
would likely be during the Wednesday morning commute, with snow
quickly ending towards Wednesday evening. Areas in north-central
Minnesota would be on the western edge of the snowfall, with
locations like Brainerd and International Falls possibly only
receiving a coating to an inch of snowfall.

Just as one mid/upper level longwave trough ejects out of the
southwest, another develops as a wave descends from the Pacific
Northwest into the southwest to replace it late-week. Like the
early/mid week pattern, this wave would also likely eject into the
southern Great Plains producing a broad area of precipitation,
though the track for this system would likely be a more southerly
track than the early/mid week storm. There is greater than usual
spread in terms of how far north/south the resultant precip may
develop along with the intensity, but the guidance consensus is
for a repeat of the mid-week snowfall, perhaps greater or less in
intensity - more likely to be the same or less in intensity. A
warming trend in temperatures with highs in the low 30s across
northwest Wisconsin by Saturday, which is near normal for this
time of year.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 545 AM CST Sun Feb 17 2019

Easterly flow will cause an area of IFR to MVFR ceilings across
parts of the Northland today, including at DLH. IFR ceilings
early this morning should lift to MVFR ceilings by mid-morning and
remain that way through the day and into the night tonight, with
MVFR ceilings spreading inland to impact HYR, BRD, and HIB later
today. Some light snow is possible at DLH, but visibility is
expected to remain VFR. Surface winds will be out of the east to
northeast and light today and tonight, less than 10 knots.


DLH  18   0  15  -2 /  30  10   0   0
INL  18  -9  11 -12 /   0   0   0  10
BRD  21  -1  15  -7 /  10  10   0   0
HYR  22   2  18  -1 /   0  10   0   0
ASX  19   1  16   0 /   0  10   0  10




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