Area Forecast Discussion
Issued by NWS Duluth, MN

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093
FXUS63 KDLH 211752
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1252 PM CDT Wed Jun 21 2017

.UPDATE...
Issued at 1234 PM CDT Wed Jun 21 2017

Updated for the new 18z Aviation Discussion below.

UPDATE Issued at 637 AM CDT Wed Jun 21 2017

Updated for the new 12Z Aviation Discussion below.

&&

.SHORT TERM...(Today through Thursday)
Issued at 326 AM CDT Wed Jun 21 2017

High pressure was centered over the forecast area at 0730Z with a
mainly clear sky. However, cirrus was beginning to stream into the
area from the Dakotas and southern Canada. This was ahead of a short
wave moving through Saskatchewan. Areas of fog were forming under
the high, but this may be tempered as the clouds work there way
across the region. The high will drift east of the region this
afternoon. Meanwhile, the aforementioned trof washes out as it
approaches Minnesota. Latest model runs have come in with a slower
timing to the onset of showers today and have adjusted accordingly.
Models also suggest that even through there will be a mid level trof
reaching Minnesota this afternoon, it appears it will be a bit
flatter than previous runs. As such, have adjusted pops quite a bit
from yesterday and aligned them more with the ARW/NMM while also
blending in the GFS/GEM, and to a lesser extent the NAM and ECMWF.
This keeps pops in the chance category and mainly over the northern
tier of the forecast area until late afternoon when an expansion is
made to the south. This is a blend of all models, but downplaying
the ECMWF which has way too much QPF and overall coverage. Kept out
the mention of thunder until very late in the afternoon and over the
Pine City to Siren areas where there is enough instability to include
a mention.

The mid level trof moves through the forecast area tonight. Will see
a few showers and storms with its passage. Kept the chance pops in
the evening, then lowered through the overnight as the trof departs.
Highest pops will continue to be along the northern tier of the
forecast area. This is where the best upper level divergence is
along the left entrance region of an upper jet. Surface/upper
ridging follows behind the trof.

The surface high covers the region Thursday morning. By afternoon, a
pair of vorticity maxes affect the northern and southern edges of
the forecast area. Have some pops in these areas and minimal pops
between with dry air from the departing surface high prevailing.
Have a thunder mention along the southern edge where the best
instability will be located.

.LONG TERM...(Thursday night through Tuesday)
Issued at 326 AM CDT Wed Jun 21 2017

The Northland will be in a cool weather pattern late this week
through early next week, bringing temperatures of 5 to 15 degrees
below seasonal normal. There will be near daily opportunities for
light showers, and a few periods for weak thunderstorms.

A vertically-stacked area of low pressure will be near the border
area between Manitoba and far northwest Ontario by Thursday evening.
Its cold front will trail back into southern Manitoba and northern
North Dakota and Montana.

The Canadian low`s cold front will swing through the Northland
Thursday night. A prominent upper trough with the accompanying cold
front could help develop some light showers over the Northland
overnight.

The Northland will then have several days of cool northwest flow,
Friday through Monday. High temperatures will primarily be in the
middle to upper 60s. This type of flow will promote scattered to
broken cumulus and breezy conditions in the afternoon, followed by
clearing overnight. There may be showers and weak storms in the
afternoon and early evening hours. Some passing shortwaves and could
help the development of those showers and storms, as well as
maintain some light chances of showers overnight. The most prominent
upper-level disturbance may be Friday night or sometime Saturday.
The GFS and ECWMF have a small upper-level low swinging down through
or near the Northland within that timeframe.

High pressure might finally move through the Northland late Monday
into Tuesday, providing a period of clearer skies. The cooler air
will probably shift east, so temperatures on Tuesday should warm up
to closer to seasonal normal.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1252 PM CDT Wed Jun 21 2017

VFR conditions to continue across the Northland TAF sites through
the afternoon hours today. Some diurnal cumulus has developed over
mainly our eastern areas this afternoon, along with some high-
level clouds moving across north-central Minnesota. The potential
for showers and thunderstorms then increases later this
afternoon/evening and overnight as a warm front this afternoon,
followed by a cold front tonight, moves through the region. For
this afternoon, -SHRA will be possible, especially across our
northern TAF sites as the warm front moves through. Then, as the
cold front passes through later this evening and overnight,
chances of thunderstorms will increase. Some of these storms
could be strong, with gusty winds and small hail possible.
Confidence is higher for stronger thunderstorms the further west
and north you go, so KINL, KBRD, and KHYR will most likely see
these storms.

For our southern TAF sites, moisture pooling ahead of the cold
front will help to increase dew point temperatures, making the
development of areas of fog more likely, which could reduce into
MVFR categories, possibly into high-end IFR. The highest
confidence will be over KBRD and KHYR to see this. Ceilings may
also drop into MVFR as the cold front moves through.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  71  54  74  52 /  10  60  10  20
INL  74  53  72  51 /  50  60  20  30
BRD  76  57  74  52 /  20  20  20  10
HYR  76  59  74  52 /  20  40  20  20
ASX  75  56  76  53 /  10  60  10  20

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

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



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