Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 182345
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
645 PM CDT Fri Aug 18 2017

.UPDATE...
Issued at 639 PM CDT Fri Aug 18 2017

Updated aviation section below for 00Z TAF TAF issuance.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 257 PM CDT Fri Aug 18 2017

An upper level trough was over the region this afternoon with a
weak low level trough near or just west of our CWA. Isolated to
scattered showers/storms have developed over/near the Walker/Pine
River/Brainerd Lakes region with more just entering Koochiching
County as of 1950Z. MLCAPE values are between 500J/KG and 1000J/KG
over the western half of Minnesota but deep layer shear is quite
limited. Some stronger storms have developed this afternoon but
they are short-lived due to lack of organization and stronger
forcing. The chance for showers/storms will move east through the
evening continuing into the rest of northeast Minnesota into parts
of far northern Wisconsin. They should dissipate late evening or
shortly after midnight. Fog will then be possible later tonight as
skies clear and winds go light.

High pressure will move in later tonight along with an upper level
ridge. Saturday will be a dry day under partly to mostly sunny
skies. Winds will become west to southwest and highs will climb
into the upper seventies to lower eighties.

.LONG TERM...(Saturday night through Friday)
Issued at 257 PM CDT Fri Aug 18 2017

The extended forecast is highlighted by above average temperatures
for Sunday, with a bit of a cool-down Monday through Thursday, as
well as a few shots at showers and storms, with possibly the return
of severe weather Sunday night.

Saturday night looks to be dry before a cool front boundary dives
southeastward, along with a mid-level shortwave. Some enhanced 850-
700 mb FGEN and enhanced low-level convergence will provide the lift
along this boundary. The best chances of precipitation with this
cool front will be Sunday morning. Not really expecting much in the
way of precipitation due to the low-level atmospheric moisture
profiles being fairly dry per the 18.12z NAM soundings. Highs Sunday
will range from the upper 70s north to the lower 80s over northwest
Wisconsin.

The best chances for precipitation for the extended forecast period
look to be from Sunday night through Tuesday morning. The
aforementioned cool front boundary stalls along our southern
counties Sunday night, and ultimately lingers over this area. The
baroclinic zone along the boundary remains stationary through
Tuesday morning before finally exiting the region. Consensus blend
POPs have low to some low-end moderate chances of precipitation.
With 925 mb temperatures in the upper teens and lower 20 degrees C
over the southern counties, along with a corridor of better
instability, these higher chances of precipitation appear
reasonable. There is a Day 3 convective outlook, with a Marginal
Risk south of a Poplar, MN to Hayward, WI line. The bulk of the
convective activity will remain to our south and west as the
environment is progged to be more unstable compared to over the
Northland. Some of the activity may creep northward into our far
southern counties, but there`s still quite a bit of disagreement
between the synoptic models, so still much uncertainty exists.
Leaned towards the consensus blend POPs for now. Temperatures will
gradually decrease Monday and Tuesday, with highs Monday in the mid
to upper 70s, and highs Tuesday in the lower 70s. Sky cover will be
the thickest over the southern areas due to this system, but other
portions of the Northland may potentially have an opportunity to
view some of the eclipse during the early afternoon, if some brief
clearing develops.

There may be some lingering small chances of showers and storms
Tuesday afternoon, but the trend in precipitation chances should
generally be downward as high pressure makes its way into the
region, which should set up for a drier stretch of weather Wednesday
through Friday. Temperatures remain slightly below seasonal
averages, with highs in the lower to mid 70s. There could be some
pretty cool nights during this period, as lows may drop into the
lower to mid 40s in some spots across our north, especially Thursday
morning.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 645 PM CDT Fri Aug 18 2017

Evening showers and thunderstorms in the vicinity of a few of the
terminals this evening, and have even included a tempo group for
KHIB as a group of cells is heading towards the site. Expect this
convection to die off by approximately 02z, leaving VFR
conditions at the terminals. Fog is expected to develop at several
terminals after 06z tonight, with MVFR or even IFR visibilities
between 09z and 13z. All sites should return to VFR by 14z and
remain so through the rest of the TAF period with generally west
winds less than 10 knots.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  55  80  60  80 /  40   0  20  20
INL  50  81  60  77 /  10   0  30  10
BRD  54  81  60  80 /  30   0  30  20
HYR  53  80  58  82 /  20   0  10  30
ASX  57  83  61  84 /  20   0  10  30

&&

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

$$

UPDATE...LE
SHORT TERM...Melde
LONG TERM...JTS
AVIATION...LE


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