Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 220920

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

.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 06Z TAFS through 06Z Wednesday night)
Issued at 1150 PM CST Tue Feb 21 2017

Mainly VFR conditions observed for the beginning of this TAF
issuance, except for some MVFR vsby reductions near the BRD area.
Conditions are expected to deteriorate overnight as a mid-level
shortwave advances into the region, along with moistening low-
levels. Ceiling and visibility reductions are expected, with
mainly MVFR/IFR conditions and isolated LIFR expected. Vsbys down
to 1 SM are possible, along with cigs down to a few hundred feet.
Light winds will lead to areas of fog developing this morning,
along with chances of a mix of rain, snow, and sleet towards INL
as the better column moisture is expected to be. Highest
confidence in precipitation towards the INL area.


DLH  44  26  35  21 /  40  80   0  50
INL  39  20  31  14 /  50  20   0   0
BRD  48  26  37  23 /  50  50  10  50
HYR  52  29  40  27 /  50  70  10  70
ASX  51  29  38  25 /  60  60  10  60


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.



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