Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 280835
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
335 AM CDT Sun May 28 2017

.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 06Z TAFS through 06Z Sunday night)
Issued at 1226 AM CDT Sun May 28 2017

A cold front and shortwave aloft is moving into the northland as
of issuance time, which will bring scattered showers to the
terminals generally from west to east. So far observations have
reported mainly VFR conditions with this wave and have just put in
VCSH for most terminals as it moves in. Even as this wave is
moving across northwest Wisconsin around 15z, steep low level
lapse rates will generate additional showers and even some
thunderstorms along with lower cloud bases. KINL is most likely to
drop into MVFR so have put at least a short period of ceilings
14z-18z before allowing ceilings to rise back to VFR. After 00z
MVFR ceilngs are expected to move back into the area from the
north. Timing is uncertain, but generally after 03z.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  64  46  56  44 /  70  30  50  40
INL  61  47  54  44 /  60  60  60  50
BRD  66  49  57  45 /  60  40  50  30
HYR  68  47  57  45 /  60  40  50  30
ASX  67  48  59  45 /  60  40  50  40

&&

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

$$

SHORT TERM...Grochocinski
LONG TERM...Melde
AVIATION...LE


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