Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 290558
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1258 AM CDT WED JUN 29 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 402 PM CDT Tue Jun 28 2016

Warming trend into Wednesday as a cold front approaches from the
north resulting in increasing clouds and a chance for showers and
storms.

On the synoptic scale the northwest flow pattern across the northern
Plains and upper Midwest will continue through mid-week due to a
ridge over the Rockies and a longwave trough over Appalachia. A cold
front will approach from the north Wednesday, but not before warmer
air can advect in from the west ahead of the front result in a
slightly warmer day. Upstream observations in Canada show some
locations around 80, and this certainty seems plausible for parts
of northern Minnesota. Winds will also be breezy especially along
the international border just ahead of the cold front, out of the
west-southwest at 5-10mph with gusts to 15-20mph due to deep mixing.

Isolated to scattered thunderstorms are expected Wednesday afternoon
along and ahead of the cold front approaching from the north. With a
deeply-mixed inverted-V-looking sounding gusty winds are possible
with any storms. With only 15-20kts of speed shear through the 0-6km
layer do not expect much organization with these storms, though
towards the late afternoon some guidance suggests upwards of 1000
j/kg MLCAPE develop which could result in some heavy downpours.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 402 PM CDT Tue Jun 28 2016

Main concerns with this forecast package are thunderstorm chances
Wednesday night and Thursday, and again during the holiday weekend.

Low pressure at the surface and aloft will be centered over far
northern Ontario Wednesday evening, with a cool front poised just
north of the International Border. The front will advance southeast
across much of northern Minnesota overnight and through northwest
Wisconsin Thursday morning. Along and ahead of the front, showers and
thunderstorms are expected. Diurnal instability will likely linger
into late evening keeping a few thunderstorms around. Of course,
there is a small possibility a few isolated thunderstorms may persist
all night. Severe weather is not anticipated at this time. However,
the most vigorous storms will produce frequent lightning, brief heavy
rainfall, small hail, and wind gusts to around 40 mph.

The upper trough will slowly rotate farther eastward Thursday
afternoon through Sunday morning while a surface ridge of high
pressure drifts across the western Great Lakes. Fairly quiet
conditions are expected in the wake of the front through the first
half of the weekend. A subtle shortwave trough and associated vort
max may generate a few showers or a thunderstorm over my western
zones on Saturday, but guidance is split with only the GFS carrying
much of a risk. Opted for low chance POPs until Saturday evening.

Increasing southwesterly flow behind the departing ridge will push a
warm front northward into Minnesota Saturday night and Sunday. A few
storms are possible Saturday night near the warm front and on the
nose of the low level jet. The front is forecast to stretch from
near Winnipeg to near Duluth to Green Bay by late Sunday afternoon.
Another compact shortwave trough will dive southeast across the
Northland Sunday evening, which should support showers and
thunderstorms.

The frontal boundary is expected to linger near the Northland
through Monday into early Tuesday with several more rounds of
thunderstorms possible, especially Monday night.

Shear and instability parameters for this weekend into early next
week seem somewhat subdued for early July. Think there is a
potential for a few strong thunderstorms, at least, from Saturday
night through Tuesday morning.

Temperatures through the period will trend near to slightly below
seasonal averages. Look for highs in the upper 60s Thursday then
warming into the 70s to low 80s for the remainder of the period.
Lows are expected to range from the upper 40s to low 60s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1258 AM CDT Wed Jun 29 2016

Main concern overnight is the potential for radiation fog at all
terminals, due to clear skies and light winds. Per the latest
observations and HRRR/RAP, think that there will be too much
cloud cover at KINL for radiation fog to develop. Expecting lowest
visibilities between 8-11 Z. Most confident in the lowest
visibilities at KHIB/KBRD and tempo in IFR conditions, but lower
is possible for brief periods. Less certain at KDLH/KHYR so keep
visibility in the MVFR range. After radiation fog dissipates VFR
conditions expected for the rest of the TAF cycle.

A cold front will move southward through northern Minnesota late
in the afternoon/evening. This will bring showers and storms to
all terminals except for KHYR. Most confident in thunderstorms
impacting KINL, but still uncertain on coverage so kept in as
VCTS. For all other terminals left in as VCSH.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  51  77  59  69 /   0  30  40  50
INL  51  77  56  66 /  10  60  40  20
BRD  52  79  59  73 /   0  20  40  40
HYR  47  77  58  71 /   0  10  40  60
ASX  48  78  59  68 /   0  20  40  60

&&

.DLH Watches/Warnings/Advisories...
WI...None.
MN...None.
LS...None.
&&

$$

SHORT TERM...JJM
LONG TERM...Huyck
AVIATION...WL


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