Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 221746
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1146 AM CST Wed Feb 22 2017

.UPDATE...
Issued at 1114 AM CST Wed Feb 22 2017

Increased precipitation chances and amounts for this
afternoon/evening as a band of moderate to at times heavy rain
showers move from west to east across the region, tracking along
the Highway 2 corridor. Rain will changeover to snow as colder air
moves in from the north this evening, and it is possible a brief
period of moderate snowfall with some big wet flakes fall this
evening before precipitation quickly comes to an end. The best
chance for this quick transition to snow will be east of Grand
Rapids, including the Twin Ports and parts of the north and south
shores of Lake Superior. Just a quick few tenths of an inch
expected, though a few isolated spots could see up to an inch.
While some guidance does have a bit of elevated instability,
the chance for a rumble of thunder seems fairly low, with the best
chance across the I-35 corridor into northwest Wisconsin this
evening.

&&

.SHORT TERM...(Today through Thursday)
Issued at 317 AM CST Wed Feb 22 2017

Patchy to areas of fog will once again linger through the morning
hours today as sfc winds remain light, prohibiting boundary layer
mixing. As of 300 AM CST, some thicker fog has developed along the
southern periphery of our forecast area from Hinckley west to the
Brainerd Lakes as dewpoint depressions appear lower there than
locations along our north. Much like yesterday morning, there could
be some pockets of dense fog. Dense Fog Advisory issuance is not
expected at this time, but will continue to monitor through the
early morning hours.

The main short-term forecast focus for today will be a mid-level
shortwave that is expected to enter the region late this morning and
persisting through the early morning hours Thursday. The mid-level
isentropic lift has shifted farther south compared to the
corresponding model runs from yesterday, along with a very moist
atmospheric profile, as indicated from the 22.00z GFS/NAM model
soundings. Precipitation types look to be mainly a wintry mix across
our northern counties, with rain for the afternoon before turning
into a rain/snow mix later this evening. The Storm Prediction Center
has general thunder mentioned across our southern counties for
today, but inspection of the GFS/RAP soundings indicate very small
amounts of elevated CAPE for the BRD and HYR areas, with amounts
reaching as high as 20 J/kg. The NAM soundings indicated higher
amounts, but the NAM typically has a high bias when it comes to CAPE
amounts. Moreover, soundings are indicating broken to overcast sky
cover for today at this time, so destabilization doesn`t appear to
be likely. So, for now, left out mentions of thunder. Due to the
increased moisture, the models have increased their progged QPF from
previous runs, and I have adjusted the forecast accordingly. The
majority of the QPF will fall as rain as any snow amounts look to be
light. Through Wednesday night, only up to one inch of new snow
accumulations are expected, with the highest amounts falling over
the MN Arrowhead and Lake Superior snowbelt regions. Today`s highs
will be a bit cooler than what we have had the last few days, with
values in the lower 40s to lower 50s across most of the Northland.

Thursday is looking quiet and dry as the mid-level shortwave moves
off to the east, and a 850-600 mb dry intrusion moves in. However,
Thursday`s highs will return to closer to seasonal normals after
cold air advection occurs behind the departing system. Highs for
Thursday look to be in the mid 30s to lower 40s for most locations,
except for near freezing along the International Border.

.LONG TERM...(Thursday night through Tuesday)
Issued at 317 AM CST Wed Feb 22 2017

Model differences prevail for the potential winter storm Thursday
night through Friday night. The GFS takes the surface low center
into western Iowa Thursday night, through Iowa Friday, then through
southern Wisconsin Friday night. The ECMWF takes the surface low
center into northern Missouri Thursday night, then quickly through
northern Illinois into western lower Michigan Friday, finally
reaching Quebec Friday night. The GEM takes it into the
Nebraska/Missouri border area Thursday night, southwest Iowa Friday,
then develops a secondary low center in lower Michigan Friday night
with the main low center in western Illinois. Will issue a winter
storm watch for Pine through Price counties for Thursday night
through Friday night as this area seems to be primed for greater
than 6 inches of snow. Used a model blend to account for the model
differences. A positively tilted upper level long wave trof will
move through the forecast area Saturday night and Sunday. This will
push a weak cold front through the region. Moisture is sparse for
these features to work with and have chance pops. High pressure
follows behind for Sunday night and Monday morning. Model
differences remain quite large for Monday night and Tuesday and will
use a model blend for pops to resolve the differences.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1146 AM CST Wed Feb 22 2017

VFR conditions will deteriorate to IFR for a period this evening
across BRD/DLH/HIB with MVFR conditions at INL/HYR. An area of
rain showers changing over to snow will impact most sites, with a
period of moderate rain/snow at BRD/HIB and likely at DLH. A short
period of moderate snow is possible at DLH which could reduce
visibility down to a mile or less early this evening, but as the
precipitation quickly comes to an end ceilings should gradually
improve towards Thursday morning. MVFR ceilings may stick around
into the day Thursday at BRD/HYR, with a lower chance at DLH.

There is a very low chance for an embedded thunderstorm late
afternoon/early evening at BRD, DLH, and HYR, but these chances
seem to low to even mention in the latest TAFs.

Winds out of the north to north-northwest through the period,
possibly breezy with gusts around 15 knots for a period late
afternoon/early evening, then becoming light after midnight.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  44  26  35  21 /  80 100   0  50
INL  37  17  31  14 /  50  10   0   0
BRD  47  27  37  23 /  90  80  10  50
HYR  52  30  40  27 /  60  70  10  70
ASX  47  30  38  25 /  70 100  10  60

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Watch from Thursday evening through late Friday
     night for WIZ006>009.

MN...Winter Storm Watch from Thursday evening through late Friday
     night for MNZ038.

LS...None.
&&

$$

UPDATE...JJM
SHORT TERM...JTS
LONG TERM...GSF
AVIATION...JJM



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