Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 281333 AAA
AFDDLH

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
833 AM CDT Sun May 28 2017

.UPDATE...
Issued at 830 AM CDT Sun May 28 2017

Made changes to reflect current raar and cloud trends with showers
and a few thunderstorms moving over the Arrowhead and northwest
WI ahead of cold front. Lowered precipitation chances in the west
for much of the morning, then kept likely chances in for the rest
of the day.

&&

.SHORT TERM...(Today through Monday)
Issued at 335 AM CDT Sun May 28 2017

The Northland can expect a cooling trend and rain to begin the
week.

A cool front will continue moving east through the Northland
this morning, while an upper-level low over the Manitoba and far
northwest Ontario drops south towards the Northland today. Cool
and breezy west-northwest flow will develop in the wake of the
passing front. Scattered to widespread showers will develop by
later this morning due to the combination of the solar heating,
cold air advection, and the lift generated by the falling heights
from the approaching upper low and embedded shortwaves. There will
likely be enough surface based instability, anywhere from a
couple hundred to up to several hundred J/kg of MUCAPE, to
generate isolated to scattered thunderstorms this afternoon. The
threat of severe weather will be limited by the lack of deep layer
wind shear. However, brief strong storms capable of small hail and
gusty winds are likely considering the low freezing levels and 20
to 30 knots in the mixing layer aloft. Highs should range from the
middle to upper 60s in northwest Wisconsin, to only the low 60s in
north-central Minnesota.

The upper low will move to near the Arrowhead this evening, and
the showers and thunder will taper off this evening with the
setting sun. However, showers will likely continue over the
Arrowhead and near the Canadian border through the evening.
Showers will then likely drop farther south into the Northland
later in the night as a trough swings south through the Northland
with the rotating low. Tonight`s cloud cover will bolster
temperatures, with lows only in the middle to upper 40s.

The cool, breezy, and relatively humid west to west-northwest flow
will continue Monday. It will be a similar story of scattered rain
showers by the late morning through the afternoon. The threat of
thunder looks much lower, as compared to Monday. The GFS, NAM, and
SREF are suggesting there could be enough surface-based
instability in the Arrowhead and near Price County in northwest
Wisconsin to generate some rumbles of thunder with the more robust
showers. High temperatures will be in the middle to upper 50s.

.LONG TERM...(Monday night through Saturday)
Issued at 335 AM CDT Sun May 28 2017

An upper level low will be over northern Lake Superior Monday
evening but will lift north through mid-week. A couple more
shortwaves will rotate around the low before the flow becomes more
northwest Wednesday. There will be a chance for more showers
Monday night into Tuesday evening. Rainfall amounts during this
time will generally be less than a quarter inch. Highs Tuesday
will be in the fifties.

The models diverge from midweek through the rest of the period.
The differences are in how they handle a stronger shortwave which
moves south toward the Northland mid to late week and in how they
handle an upper trough along the BC/western CONUS region late in
the week and over the weekend. The ECMWF is quicker bringing a
shortwave south, as early as Wednesday night, and the GFS has a
deeper upper low moving toward Lake Superior late in the work
week. Despite these differences, we still have confidence that
chances for rain will either be low Wednesday through Friday or
any rain that does fall will be relatively light. High
temperatures will warm to the upper sixties to lower seventies for
most areas.

Model differences increase even further over the weekend. The 00Z
ECMWF has a 1002MB surface low over east central Minnesota at 12Z
Saturday and the GFS forecasts high pressure at this same time.
The ECMWF solution would bring a chance for heavy rain to portions
of the Northland versus a dry GFS solution. We followed closer to
the GFS which has shown better run to run consistency and has
some support from the Canadian.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 644 AM CDT Sun May 28 2017

An upper level low will be over the region into the early part of
the week. Several shortwaves will rotate around this low causing
periods of showers. A cold front will also continue to move east
through the Northland clearing the Arrowhead and northwest
Wisconsin by early afternoon. There will be scattered
thunderstorms this afternoon into the early evening. Conditions
will be mostly VFR into this evening with the exception of
portions of northeast Minnesota this morning which will see
ceilings around 1000 feet for a time. As the night progresses,
MVFR and IFR ceilings will become more widespread. The showers and
storms will decrease in coverage overnight for most areas. The
exception will be along the International Border.

Gusty west to northwest winds will occur today as steep low level
lapse rates are expected. Even stronger winds will occur with the
showers.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  64  46  56  44 /  60  30  50  40
INL  61  47  54  44 /  60  60  60  50
BRD  66  49  57  45 /  50  40  50  30
HYR  68  47  57  45 /  50  40  50  30
ASX  67  48  59  45 /  60  40  50  40

&&

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

$$

UPDATE...CLC
SHORT TERM...Grochocinski
LONG TERM...Melde
AVIATION...Melde


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