Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 241735 AAB

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
1235 PM CDT Mon Oct 24 2016

Issued at 1235 PM CDT Mon Oct 24 2016

Please see the new 18Z Aviation Discussion below.


.SHORT TERM...(Today through Tuesday)
Issued at 337 AM CDT Mon Oct 24 2016

Surface high pressure extended south through the eastern Dakotas
and western Minnesota early this morning. An upper ridge was over
the Rockies. The upper ridge will move east and flatten with time
into Tuesday as a shortwave moves through the ridge toward the
Northland late Tuesday. The surface high will move to northwest
Ontario and extend through Wisconsin by 06Z then shift east of
the region Tuesday morning. There will be fog in spots this
morning as skies have cleared and winds were light. The fog will
lift by 10 am then expect some high clouds to move in through the
day with skies partly to mostly sunny. Highs will range from the
lower to middle forties across far northern Minnesota to the lower
fifties from the Brainerd Lakes into northwest Wisconsin.

High clouds will continue to move in tonight. The high will still
be close enough to provide light winds. We lowered temperatures
tonight, especially over the eastern half of the Northland. If
clouds are thinner than expected, temperatures will have to be
lowered further. We expect lows from the lower to middle twenties
in the Arrowhead to upper twenties to lower thirties most other

A broad area of low pressure will develop to the lee of the
Rockies Tuesday with increasing warm air advection developing as a
shortwave moves through the Northern Plains toward western
Minnesota. Winds will turn southeast on Tuesday and be stronger
near Lake Superior. Clouds will continue to thicken through the
day and there may be some rain that develops roughly along and
southwest of a line from the Leech Lake area to Siren. Highs will
mainly be in the forties.

.LONG TERM...(Tuesday night through Sunday)
Issued at 337 AM CDT Mon Oct 24 2016

A progressive pattern across North America will bring a fairly
steady ebb and flow of chances for precipitation through the long
term period, with temperatures remaining consistently above normal -
continuing the trend of the past few months. (In the past 90 days, a
full 75% have been above normal, with the median daily average temp
departure from normal being +4.35 degrees F.)

After a broad area of high pressure across the Upper Midwest to
start off the week, a warm front builds north up along the mid-
Mississippi river valley Tuesday night into Wednesday. A broad mid-
level ridge across the western half of the CONUS and southern Canada
is broken down by a few mid-level shortwave troughs traversing
eastward. In the Midwest, this leads a low deepening Tuesday night
into Wednesday, and with an ample supply of deep layer moisture
(PWATs approaching an inch - into the 90th percentile relative to
climatology) the large-scale lift introduced will lead to a broad
area of rainfall across the upper Midwest. The progressive nature of
the large-scale flow makes it difficult to determine where precisely
the low develops and thus where the most rain will fall, but for at
least east-central Minnesota and northwest Wisconsin rain is likely
Tuesday night in early Wednesday with around a half inch of
rainfall expected, lesser amounts in far northern Minnesota.

Rain tapers off late Wednesday, with chances for light precipitation
continuing for parts of northern Minnesota through Thursday as a mid-
level shortwave trough dives from central Saskatchewan towards the
upper Great Lakes. A broad mid-level ridge develops over the Rockies
Thursday, moving into the Mississippi River valley early Friday,
but is quickly broken down by another fast-moving mid-level
shortwave trough entering the Pacific Northwest late Thursday and
reaching the northern Plains Friday, quickly resulting in a
deepening surface low across the upper Midwest. This will result
in a chance for what looks to be mainly rain Friday
afternoon/night, with cooler air moving in from the north in the
wake of the low Saturday. However, the coolest 850mb associated
with the post-low airmass will be in -5C to 0C range- just about
average for this time of year.

Another longwave ridges tries to build across the Great Basin into
the Rockies late in the weekend, but not for long as the progressive
pattern just continues to bring in mid-level waves across the region
for the foreseeable future. As can be expected, the spread really
increases towards the 6-10 period as far as timing goes, but there
is high confidence in the continued mild conditions.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1235 PM CDT Mon Oct 24 2016

VFR conditions will continue through early this evening across
the area as a surface ridge of high pressure slides eastward. An
area of VFR stratus was found over northwest Ontario and portions
of southeast Manitoba this morning. Some of the higher resolution
models, including the HRRR and NAM, suggest those clouds will move
into the INL vicinity this afternoon and linger into this evening.
Winds will go calm for a time tonight at all terminals before
veering east to southeasterly for Tuesday. With veering winds at
INL, think the stratus will retreat northwestward into northwest
Ontario by 25.10Z. An approaching shortwave trough of low pressure
will bring a high cirrus layer into the area overnight. Meanwhile,
the period of clear skies and calm winds may result in areas of
fog. Should the mid and high clouds arrive earlier, the fog
potential would diminish. As winds over western Lake Superior veer
east and southeasterly after 25.08Z, low-level moisture at HYR and
DLH should increase. Think there is a potential for the
development of an MVFR stratus deck at both terminals, but
confidence is lower at HYR since trajectories required are more
complicated. Stratus deck should advect northeast into the
Arrowhead, eventually reaching HIB and possibly INL Tuesday

Confidence in this forecast package is above average through
25.02Z and average thereafter. Greatest concerns are visibilities
with fog development overnight and timing MVFR stratus


DLH  49  33  45  37 /   0  10  10  60
INL  46  30  46  36 /   0   0   0  50
BRD  51  36  49  40 /   0  10  30  70
HYR  52  30  50  39 /   0   0  10  70
ASX  51  33  48  37 /   0   0  10  50




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