Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 180830
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
330 AM CDT THU AUG 18 2016

.SHORT TERM...(Today through Friday)
Issued at 330 AM CDT Thu Aug 18 2016

Scattered to numerous showers and thunderstorms will develop today
into tonight along and ahead of a cold front approaching from the
northwest. While it appears the best chance for severe storms will
be to the south in central Minnesota, it`s possible a few strong to
severe storms producing large hail and gusty winds are possible in
the afternoon, with the threat transitioning to sporadic damaging
wind gusts and locally heavy rainfall in the evening. Strongest
storms are likely to be along and south of Highway 2 in east-central
Minnesota, with the heavy rain threat likely transitioning into
adjacent areas of northwest Wisconsin tonight. By Friday morning the
cold front will be through the Twin Ports and much of northwest
Wisconsin, but post-frontal showers and perhaps a thunderstorm are
possible mainly in northwest Wisconsin. Hot and humid today with
highs in the low to mid 80s and dew point values in the mid 60s, but
cooler tomorrow with highs in the low to mid 70s behind the cold
front.

On the synoptic scale the zonal flow in the wake of a weak mid-level
ridge axis moving east across the upper Great Lakes will give way to
southwesterly winds aloft as a longwave trough begins to deepen over
the northern high plains Friday. This developing trough will be
associated with a mature cyclone gradually moving east across
northern Manitoba towards Hudson Bay Thursday into Friday. As the
trough deepens, a sfc low will develop over the northern high plains
and traverse eastward, centered over central South Dakota this
afternoon. South/southwesterly flow at low levels ahead of this front
yesterday has resulted in a mild and moist airmass ahead of the
front. Nothing abnormal for mid-August with 850mb temps topping out
around +20C and PWATs solidly in the 1.50 to 1.80 range - just a few
outliers scratching at the 2.0" threshold at a few grid points
across the Northland, with a slightly higher band of PWATs in
southern MN along the poorly-defined warm frontal zone this evening.
Instability ahead of the will be decent as depicted by the scattered
ongoing convection early this morning across parts of North Dakota,
with an area of 500-1500 j/kg MUCAPE across east-central Minnesota
by 00z this evening. Wind profiles will be favorable for
multicellular clusters a possibly a supercell with the 30-45 knots
of 0-6km shear this evening, with stronger winds aloft possibly
providing a window for a bowing line segment to produce damaging
wind gusts. However, the threat for both large hail in the afternoon
and damaging winds in the evening seems to be on the low side, and
thus agree with the latest SPC Convective Outlook which has a
marginal risk along and south of Highway 2, limiting the slight risk
to areas south and west. With the east-northeast storm motions and
clustered nature of storms there could be a threat for locally heavy
rainfall, highlighted by the NCAR WRF Ensemble depicting a 70%
chance for > 2.0" QPF from Aitkin east to the Twin Ports and south.

Late tonight storms are expected to diminish in coverage and
intensity as they track further into northwest Wisconsin as the cold
front moves through. On Friday showers and perhaps a few storms are
possible mainly across northwest Wisconsin as storms redevelop in
response to diurnal heating. Instability looks very limited, and
with a somewhat drier airmass moving in behind the cold front there
is uncertainty to just how much post-frontal showers will develop.
While skies will clear out behind the front late tonight, expect
widespread cu to develop in the post-frontal environment across
northeast Minnesota Friday in response to diurnal heating and cooler
air moving in aloft.

.LONG TERM...(Friday night through Wednesday)
Issued at 330 AM CDT Thu Aug 18 2016

The cold front will clear eastern WI by Friday evening as the upper
level trough moves through the region.  However...enough moisture
will remain across the forecast area and will combine with a cooler
NW flow and solar hating to cause showers to develop across the
region. There also could be some isolated thunderstorms possible in
some of the stronger cells.  The NW flow will also bring in below
normal temperatures with highs in the 60s.  An area of high pressure
will build into the region Sunday bringing in drier air and near
normal temperatures for the beginning of the week.

A warm front will lift north through the region Tuesday night and
wednesday and will cause thunderstorms to develop.  the front will
pass back through later Wednesday as a cold front kicking off
another round of showers and thunderstorms.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1229 AM CDT Thu Aug 18 2016

High pressure will gradually move off to the south and
east overnight, as an area of low pressure emerges into the Dakotas.
Showers and a few thunderstorms will largely remain out of the TAF
sites overnight, although there is a chance we could see some
showers and thunderstorms reach KINL late in the night. Fog will be
less of a problem tonight, but there could be some patchy fog with
CIG and VSBY restrictions. As the low pressure system and complex
frontal boundary moves into the western Great Lakes on Thursday and
Thursday Night, it will bring the chance of thunderstorms eastward
into the region. The best chance for seeing the storms would be
later in the day and into the evening.|


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  83  62  73  56 /  50  80  20  20
INL  82  56  72  52 /  70  60  10  10
BRD  83  62  72  56 /  80  90  20  20
HYR  83  64  75  58 /  20  80  50  50
ASX  86  65  77  58 /  10  80  50  40

&&

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

$$

SHORT TERM...JJM
LONG TERM...Stewart
AVIATION...Stewart



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