Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 160633
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
133 AM CDT Sat Sep 16 2017

.UPDATE...
Issued at 133 AM CDT Sat Sep 16 2017

Please see the 06Z Aviation Discussion below.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 333 PM CDT Fri Sep 15 2017

Concern for short term is showers and thunderstorm chances.

Current surface analysis indicates showers and thunderstorms over
most of northeast MN except north of the Iron range. However, the
precipitation will move into that area by 21z. This rain is
associated with strong WAA/moisture advection into the region out
ahead of a surface trough extending north from a low in the
central plains. This low will be the focus for the forecast
through the short term.

After this area of rain moves off to the northeast, a strong
shortwave wil move across mn overnight brining another shot of
showers and thunderstorms to the region. Most areas will receive
between 0.25 to 0.50 inches of rain. The rain areas will be
progressive and not train like yesterday. The chances for rain
decreases Saturday morning before another round of thunderstorms
develop in the afternoon. SPC has the region in a marginal risk so
there is a possibility of severe weather with them.

.LONG TERM...(Saturday night through Friday)
Issued at 333 PM CDT Fri Sep 15 2017

A fairly active weather pattern will build across the Northland,
with temperatures rising to above seasonal averages next week.

Saturday night into Sunday morning looks to have the best chances of
precipitation for the extended forecast period as a rather deep
shortwave trough advances eastward through the Dakotas and into our
neck of the woods, along with an associated sfc cold front. High
chances of showers and thunderstorms will result from this shortwave
given the isentropic upglide ahead of the wave, along with a strong
positive vorticity maxima. Some high elevated instability is progged
to be collocated with the shortwave, with MUCAPE values ranging
between 1500 to 2500 J/kg between the GFS and NAM models. There is a
Marginal Risk of severe weather during this time, mainly south of a
line from Aitkin to Castle Danger to Ironwood, mainly for hail and
damaging winds. The frontal boundary will move off to the east after
daybreak Sunday morning, leading to a dry Sunday afternoon, along
with decreasing clouds.

High pressure will then build into the region Sunday night and
Monday, bringing a brief respite from precipitation before a small
chance of showers arrives Monday afternoon into Tuesday morning. The
culprit appears to be another shortwave, which appears to be quite
weak. Southerly return flow from the sfc high pressure will bring
warmer temperatures for Tuesday through Friday, with highs in the
upper 60s to lower 70s expected across the Northland. Then, better
chances of showers and storms move in Tuesday night and Wednesday as
a more potent shortwave moves into the region. Deep lift will be
associated with this system, with upper-level divergence associated
with the wave. These chances will persist, but mainly late Thursday
into Friday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 133 AM CDT Sat Sep 16 2017

A complex forecast with low pressure lifting across northern
Minnesota into western Lake Superior through the period. This
will bring IFR conditions to HIB/INL with thunderstorms. Expect
visibility reduction to MVFR/IFR or lower as storms move through.
Northeasterly flow will continue advecting stratus into DLH from
Lake Superior, which will keep VLIFR visibility and ceilings until
winds switch to a southerly direction. BRD will see MVFR ceilings
develop as the surface low lifts northeast of the site. HYR will
remain VFR overnight with low level wind shear concerns until the
surface low moves into northeast portions of MN early on Saturday,
which will lessen the pressure gradient.

Expect MVFR/IFR conditions or lower to persist at all terminals,
except HYR, through the TAF period with a break in precipitation
Saturday morning. Additional shower and storm development is
expected Saturday afternoon. Tried to time this activity with the
latest HRRR/ARW/NMM and NAM. HYR should remain VFR through the
TAF, with some visibility and ceiling reduction between 02Z and
06Z when thunderstorms are possible.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  54  72  51  61 /  60  70  80  10
INL  51  64  46  56 /  90  50  50  10
BRD  63  70  48  61 /  60  50  40   0
HYR  60  79  54  64 /  50  70  80  10
ASX  58  80  55  65 /  50  70  80  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 10 AM CDT this morning for LSZ121-
     140>148.

&&

$$

UPDATE...WL
SHORT TERM...Stewart
LONG TERM...JTS
AVIATION...WL



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