Area Forecast Discussion
Issued by NWS Duluth, MN

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
000
FXUS63 KDLH 151130
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
530 AM CST Wed Nov 15 2017

.UPDATE...
Issued at 530 AM CST Wed Nov 15 2017

Please see the 12Z Aviation Discussion below.

&&

.SHORT TERM...(Today through Thursday)
Issued at 409 AM CST Wed Nov 15 2017

This morning there is a surface low over northwest Ontario, just
north of Dryden/Vermilion Bay.  South of this low there is a cold
front extending south into northern Minnesota before curving back
southwest into South Dakota.  A trough extends straight south along
the Minnesota/Wisconsin border into Wisconsin.  In the vicinity and
ahead of this trough axis dense fog has formed, affecting the
Arrowhead and portions of the Interstate 35 corridor early this
morning.  Elsewhere we have fog, but not as dense as in that area.
Will push the existing advisory east a little into northwest
Wisconsin this morning as visibilities are dropping in Douglas
county and surrounding areas.  Today, this surface low will shift
southeast and allow surface winds to turn northwest across much of
the forecast area by mid morning, ending the fog threat.  However,
steep low level lapse rates should keep some showers going over
northern Minnesota into this afternoon.  Tonight, the cold air will
continue to move into the area, and between that and the lingering
low level moisture we should have at least a short period of lake
effect snow showers along the south shore overnight.  Do not expect
much in the way of precipitation amounts as the time frame will be
short, but have increased pops from Bayfield county on east for
overnight.  Thursday to be our relatively quiet day in between our
current departing system, and the storm moving in for Friday  Have
some lingering light snow in the morning in Iron county as the lake
effect snow showers come to an end.  Then, in the afternoon the
leading warm air advection wing of the incoming system may produce
some mid and high clouds with just enough saturation to produce some
snow showers in my northwest late in the afternoon.  This may be too
fast, so have kept pops low to account for this uncertainty.

.LONG TERM...(Thursday night through Tuesday)
Issued at 409 AM CST Wed Nov 15 2017

A wintry mix to begin the extended as a warm front lifts through
Thursday night through Friday. The trailing cold front will slide
through Friday afternoon into Saturday morning. Initially
precipitation will be all snow Thursday night before changing over
to a wintry mix late Thursday night as warmer air advects in aloft.
Precipitation will become all rain across northwest Wisconsin, and
much of northeast Minnesota on Friday. Precipitation will gradually
change from rain to a wintry mix to all snow Friday afternoon into
Saturday morning from west to east as colder air moves in after the
cold front passage. A bit concerned that there may be more freezing
rain/drizzle than currently in the forecast late Thursday night
into Friday. If the latest NAM is correct there will be ice loss
aloft, while lower layers stay saturated supporting freezing
rain/drizzle. The current GFS stays more saturated throughout the
column, which supports a wintry mix/snowfall. Opted to go with the
GFS solution as the NAM ice loss aloft seems overdone.

Snow chances continue on Saturday in far northern Minnesota as a
shortwave slides in from central Canada. The south shore of Lake
Superior will see lake effect snow chances as flow becomes
northwesterly. Lake effect snow chances will linger into Sunday
before drier air moves in as high pressure builds in, and winds
aloft shift to a westerly direction. High pressure will slide
eastward on Monday, which will advect 0 to 8 degree Celsius air
aloft. This will bring the warmest readings of the extended with
highs in the 30s. The colder air will return for Tuesday and
Wednesday as a quick moving clipper moves across Ontario. There will
be chances of snow on Tuesday due to the clipper, before high
pressure builds in on Wednesday. Highs on Tuesday and Wednesday
range from the upper teens to the low 30s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 530 AM CST Wed Nov 15 2017

LIFR conditions will gradually improve to MVFR as fog dissipates
and ceilings lift. Low pressure will move eastward from the Upper
Mississippi River Valley into the central Great Lakes. As the low
departs the pressure gradient will tighten from west to east,
which will aid in dissipating the fog as winds increase and become
gusty. Expect an MVFR stratus deck to linger in wake of the low
as a trough axis extends into the Northland. Scattered diurnal
snow showers are possible with some visibility reduction in
heavier snow showers at all terminals except BRD.

High pressure will nudge into the CWA late this evening into
Thursday morning. This will gradually bring clearing skies and
potentially a return to VFR as ceilings scatter out. Leaned
heavily on the RAP/NAM guidance in the latest TAF set.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  34  19  31  28 /  50  10  10  30
INL  31  16  30  26 /  40  10  20  40
BRD  31  19  33  30 /  10  10   0  20
HYR  37  21  33  30 /  50  20   0  20
ASX  40  26  34  28 /  80  50  10  30

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Dense Fog Advisory until 8 AM CST this morning for WIZ001-006-
     007.

MN...Dense Fog Advisory until 8 AM CST this morning for MNZ011-012-
     019>021-037-038.

LS...Small Craft Advisory from noon today to 4 AM CST Thursday for
     LSZ121-140-146-147.

     Small Craft Advisory from noon today to noon CST Thursday for
     LSZ148.

&&

$$

UPDATE...WL
SHORT TERM...LE
LONG TERM...WL
AVIATION...WL



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.