Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 172035
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
335 PM CDT Mon Jul 17 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 335 PM CDT Mon Jul 17 2017

At 330 PM, storms were rapidly developing just west of the CWA. A
new severe thunderstorm watch was just issued by the Storm
Prediction Center, for much of our northeast Minnesota CWA, the
western Lake Superior Nearshore waters and far northwest
Wisconsin. Temperatures had soared to near 90 in the Brainerd
Lakes region, although showers and storms north of the Iron Range
had limited temps into the 70s and lower 80s. Dewpoints were in
the low to mid 70s across much of northeast Minnesota, in the warm
sector ahead of the frontal boundary moving into western MN.

The obvious focus for tonight will be the threat of severe
weather. Severe Thunderstorm Watch 418 has just been issued until
11 PM this evening for much of the CWA. CAM`s continue to be all
over the place, as expected, but the consensus among them is that
there will be some agreement concerning mode, with storms starting
as discrete cells, and eventually evolving into line and bowing
segments. Large hail, along with damaging winds, appear to be the
main threat. There is some potential for tornadoes, but not enough
at this point for a TOR watch. Will be a warm and humid night
across the Northland, with lows ranging from the 50s in the far
north, to the upper 60s to around 70 in the far south.

The frontal boundary will begin to sag to a west-east alignment on
Tuesday, with the brunt of the precipitation stretching from the
Brainerd Lakes, to the Twin Ports, and points south. The heaviest
rainfall on Tuesday is expected from east central Minnesota into
northern Wisconsin. Some potential for severe storms across our
far southern areas on Tuesday, with the best chance just south of
our CWA. Highs will range from the 70s to lower 80s.

.LONG TERM...(Tuesday night through Monday)
Issued at 335 PM CDT Mon Jul 17 2017

The long-term forecast period is highlighted by temperatures near
average, along with a few off-and-on chances of showers and
thunderstorms.

Tuesday night, a mid-level shortwave will be passing just to our
south, which will support a chance of showers and storms, mainly to
the far southeast corner of our forecast area. Another shortwave
will arrive Wednesday afternoon and evening per the 17.12z NAM and
GFS model runs, which will linger through Wednesday night, so it
should be a quick chance of showers and storms. The 17.12z GFS is
hinting at potentially some strong to severe storms over our south
with MLCAPE up to 3000 J/kg. However, the NAM/ECMWF/CMC models are
nowhere near as high with the instability, so confidence in severe
potential for this time frame is very low. However, the Storm
Prediction Center Day 3 convective outlook does have a Marginal Risk
of severe weather just to our south over southern Minnesota. If the
models all trend toward the GFS, this convective risk would creep
farther north. High temperatures Wednesday through Friday will be in
the upper 70s and lower 80s.

A brief dry period will begin Thursday morning, lasting through
early Friday morning, due to sfc high pressure building into the
region from southern Manitoba Canada. However, another series of
shortwaves look to bring off-and-on chances of showers and storms
during the day Friday and through the weekend, especially for
Saturday afternoon and evening. There are some model disagreements
between the GFS/ECMWF/CMC models as the GFS and ECMWF has
precipitation occurring over the Northland by 00z Sunday, yet the
Canadian model has no on-going precipitation at that time. Similar
disagreement between the models exist for Monday, only the model
solutions have flipped among these three. Temperatures from Saturday
through Monday will be a bit cooler compared to the days prior, with
highs in the mid to upper 70s for this period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1243 PM CDT Mon Jul 17 2017

Shower and thunderstorm activity is expected to ramp up later this
afternoon as a push of southerly winds and warm air ahead of a
cold front boundary moves eastward through the region later this
afternoon and evening. Some storms could be strong to severe,
with the main threats being damaging winds, large hail, and heavy
downpours of rain. The high resolution model guidance indicates
the best chances of seeing these storms will be over KHIB, KBRD,
and KDLH. TEMPO groups in for best timing of storms, along with
some MVFR visibility reductions.

Winds will be gusting between 15 to 25 knots across much of the
Northland, with potentially stronger gusts within any
thunderstorms that develop or move over the TAF terminals. Winds
will also turn more westerly as the cold front boundary moves
through later this evening and overnight. There could be some MVFR
ceilings developing over some TAF sites overnight after the cold
front boundary passes through as well.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  63  77  57  80 /  80  30  10  10
INL  55  80  52  79 /  60  10   0  20
BRD  66  80  57  82 /  70  50  10  30
HYR  68  85  56  83 /  50  60  30  10
ASX  66  82  56  83 /  60  60  20  10

&&

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

$$

SHORT TERM...DAP
LONG TERM...JTS
AVIATION...JTS



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