Area Forecast Discussion
Issued by NWS Duluth, MN

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817
FXUS63 KDLH 200001
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
701 PM CDT Fri May 19 2017

.UPDATE...
Issued at 701 PM CDT Fri May 19 2017

Please see the 00Z Aviation Discussion below.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 314 PM CDT Fri May 19 2017

Conditions tonight will remain dry as sfc high pressure progged to
be over eastern Ontario/southwestern Quebec will dominate the
region. Some cirrus clouds will persist overhead, and even increase
some overnight ahead of the next system that will impact the
Northland. Model soundings show that the cirrus cloud levels will
lower some, but still remain fairly elevated. A broad mid- to upper-
level trough will build over the eastern Rocky Mountain states and
ascend into the region overnight and during the day Saturday.
Enhanced 850-700 mb warm air and moisture advection will accompany
this western system as well, providing the support for precipitation
during the day Saturday. This warm air advection and cloud cover
will keep temperatures elevated enough to avoid a repeat of
frost/freeze headlines tonight. Low temperatures tonight will range
from the mid to upper 30s across the area.

Rainfall with this system could be moderate in intensity as the
better mid-level isentropic omega will reach the Northland by the
afternoon. Analysis of the MUCAPE values show very little in the way
of instability, with values reaching up to 50 J/kg, so not much
thunder expected with this precipitation. However, Pwat values
between 0.6 to 1.1 inches, from north to south respectively,
indicate some better moisture for heavier precipitation. The NAEFS
precipitable water standard anomalies at 18z Saturday indicate Pwat
values between 1 to 2 standard deviations above climatology over
northwest Wisconsin, leading more credence to heavy rainfall in
these areas. Generally, QPF amounts between 0.10 and 0.45" are
expected, with the lightest QPF across the International Border
region, and the heaviest over northwest Wisconsin. The associated
sfc low pressure will advance over northwest Missouri/eastern Iowa
Saturday, placing the Northland underneath the inverted trough. This
inverted trough will bring a tightening sfc pressure gradient, so
winds could be a bit breezy as well, with gusts between 20 and 30
mph adjacent to Lake Superior. These winds will also be easterly, so
cooler temperatures by the lake are expected.

.LONG TERM...(Saturday night through Friday)
Issued at 314 PM CDT Fri May 19 2017

A cool and wet weekend on tap before a slow rise to warmer
temperatures with occasional chances for light precipitation through
the work week.

On the synoptic scale much of the long term period will be impacted
by north/northwest flow across the Northland as a low lifts north
from southern Wisconsin towards the U.P. Saturday night into Sunday
then northerly flow aloft remaining into the early part of the work
week. Most of the rain will fall over the weekend Saturday night
into early Sunday with low chances for light precipitation
continuing through Tuesday in the wrap-around flow. A few rumbles of
thunder possible Saturday night but otherwise just light rain
showers through the period with no significant impacts expected.

Mid-week a mid-level ridge builds in from the west leading to warmer
temperatures while a warm front associated with the warmer airmass
may produce some light precipitation Wednesday night. Late week a
more potent mid-level trough and surface low approaches from the
northwest which could bring another round of showers and
thunderstorms with another stretch of cooler temperatures in the
wake of this low into next weekend.

Highs in the 40s to low 50s Sunday, 50s to mid 60s Monday and
Tuesday, then closer to normal late-week as highs rise towards the
60s and low 70s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 701 PM CDT Fri May 19 2017

High pressure will build into western Quebec late tonight, while
an area of low pressure moves northeastward from the Central
Plains in the Mid Mississippi River Valley by Saturday afternoon.
This will spread in 10 kft to 20 kft clouds into the Northland
tonight, with VFR conditions expected per the latest
GFS/NAM/DLHWRF.

The pressure gradient will continue tightening across the region
due to the exiting high and incoming low. As a result, expect
gusty winds to develop mid Saturday morning and persist through
the day once the mixed layer develops around 14Z to 16Z. Rain will
gradually spread in from south to north during the afternoon. As
the lower levels moisten, expect ceilings to gradually lower to
MVFR/IFR with visibility reduction in areas of heavy rain.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  36  45  38  47 /   0  90  90  70
INL  37  58  39  48 /   0  60  80  70
BRD  38  47  40  52 /  10 100  80  60
HYR  38  51  43  50 /  10 100  80  60
ASX  34  47  39  50 /   0  90  90  60

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory from 10 AM Saturday to 10 AM CDT Sunday for
     LSZ121-140>143-146>148.

     Small Craft Advisory from 4 AM Saturday to 10 AM CDT Sunday for
     LSZ144-145.

&&

$$

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



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