Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 211715

Area Forecast Discussion
National Weather Service Duluth MN
1215 PM CDT THU JUL 21 2016

Issued at 1215 PM CDT Thu Jul 21 2016

Updated for the new 18Z Aviation Discussion below.

UPDATE Issued at 1105 AM CDT Thu Jul 21 2016

Early morning severe squall line is now well east of northern
Wisconsin, but weak convection continues to bubble atop the
residual cold pool along the DLH/MPX CWA border region. Upper wave
to our north across Ontario continues to amplify this morning (60
meter/12 hour height falls), and the associated surface trof/weak
cold front will move slowly east into northwest Wisconsin by this
afternoon. While convergence along this boundary is expected to be
weak, there will still be ample instability in place this
afternoon/evening, and we have retained 20-30 PoPs across
northwest Wisconsin to account for this. Dewpoints may not be
quite as high as previously forecast, but with temperatures
reaching the upper 80s/lower 90s, heat indices should still reach
into the upper 90s in most areas from the Brainerd Lakes region to
Duluth and points south and east. With over 70,000 customers
without power/air conditioning and numerous outdoor recovery
operations ongoing due to the severe storms last night, we will
leave the heat advisory as is, as even if we do not quite
technically reach the minimum thresholds in a meteorological
sense, the hot and humid weather will have a very high impact
today across most of the region.


.SHORT TERM...(Today through Friday)
Issued at 219 AM CDT Thu Jul 21 2016

Early morning strong to severe storms are expected to give way to
another hot and humid day today, with the worst of the heat and
humidity focused across northwest Wisconsin. Overnight storms are
expected to have dissipated or moved through NW Wisconsin by mid-
morning today, with a wind shift to northwest winds across northeast
Minnesota today as the cold front moves in from the west. Cloud
cover still remains a question for today which impacts the heat,
but current thinking is that this convection will exit fast enough
to allow for plenty of diurnal heating during the day to allow highs
to warm up into the low 90s. Another round of isolated storms is
possible this afternoon mainly across northwest Wisconsin in what is
still expected to be a very unstable airmass ahead of the cold front
approaching from the west. Heat advisory still looks good, though
may be able to clip Cass and Crow Wing out of it depending on how
their dew points fare following the early morning storms. Heat
indicies in the 100+ range across far east-central MN and almost all
of northwest Wisconsin. The Twin Ports are a bit tricky because the
cold front may be right on our doorstep this afternoon with the
lower dew points being advected in from the northwest as temps
rise...but will continue the advisory since the front could always
lag behind slightly from the current progression resulting in an
hour or two of 100+ heat indicies.

Tonight an area high pressure will build in from the west resulting
in clearing skies and light to near calm winds. Dew points will fall
through the night as a drier airmass moves in from the northwest.
Widespread fog is not anticipated because of the drier air moving
in, but wouldn`t be surprised if some patchy fog develops in low
lying areas. Lows in the low to mid 60s, with some locations across
the MN Arrowhead falling to the upper 50s.

Friday will be sunny and very warm, but without the oppressive
humidity of the past few days as high pressure continues to build.
Highs in the upper 80s to low 90s similar to Thursday, but dew
point values only in the upper 50s to near 60 will feel a bit less

.LONG TERM...(Friday night through Wednesday)
Issued at 219 AM CDT Thu Jul 21 2016

Friday night appears relatively quiet still with the surface ridge
still keeping the weather west of the Northland.  Our next major
weather maker comes in on Saturday, mainly in the afternoon and
evening, and has some potential for severe weather as a warm front
lifts up into the area during the afternoon and evening. Have raised
pops during this period so there are some places with likely pops.

Sunday and Monday the heat and thunderstorm chances let up somewhat,
with highs by Sunday in the mid 70s and low 80s, warming only
slightly for Monday.

Model differences become ugly by mid week, with the GFS generating a
strong shortwave over the high plains of the western Dakotas, which
moves east across the upper Midwest on Tuesday and Wednesday. This
feature is either non-existent or very weak on the ECMWF.  As a
result there is high uncertainty in precipitation chances for the
Tuesday-Thursday time range and have had to go with some small
chance pops. Temperatures near normal during this time range.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1215 PM CDT Thu Jul 21 2016

High pressure will be moving into the Northland today and tonight,
likely maintaining VFR conditions through Friday morning. There is
a low possiblity of showers and storms near KHYR this afternoon
through early this evening.


DLH  90  63  88  65 /  10  10   0  10
INL  88  62  86  62 /  10   0   0  20
BRD  92  64  91  67 /  10  10  10  30
HYR  91  62  91  64 /  30  10   0  10
ASX  90  64  90  64 /  20  10   0  10


.DLH Watches/Warnings/Advisories...
WI...Heat Advisory until 9 PM CDT this evening for WIZ001>004-006>009.

MN...Heat Advisory until 9 PM CDT this evening for MNZ025-033>038.



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