Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 221725
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1225 PM CDT SUN MAY 22 2016

.UPDATE...
Issued at 1121 AM CDT Sun May 22 2016

Not a whole lot of significant changes late this morning as the
larger scale forecast is generally on track with an appropriate
theme of message. However, there are a few mesoscale details that
have required some attention. First, shallow morning inversions
evident on 12z area soundings (in particular KINL) have mixed
out over roughly the western half of the DLH CWA as of 11 AM, as
noted by the notable increase in wind speeds and onset of gusts.
We suspect that the burst of 30+ knot gusts over the far southwest
CWA is due to the initial burst of momentum as the max winds
withing the inversion layer was tapped, and as mixing continues
to deepen this afternoon into somewhat weaker winds, that the
gusts in this area may diminish a bit. Nonetheless, it is still
going to be very windy with the strong southerly gradient in place
and pressure falls to the west. Second, there is already some
evidence for a stronger Lake Superior marine layer push today with
stronger onshore flow evident at Grand Marais/Silver Bay/Sky
Harbor/Superior and the UMD buoy 5 miles offshore. We have made a
few adjustments to reflect these changes, but temps in close
proximity to Lk Superior may need to be brought down a little
more.

After coordination with WFO Green Bay and the State of Wisconsin,
we also issued a fire weather watch for Iron/Price/Ashland
Counties for Monday afternoon at their request.

&&

.SHORT TERM...(Today through Monday)
Issued at 401 AM CDT Sun May 22 2016

The warm and dry weather pattern, which has affected the Northland
since early this past week, will culminate today. Above normal
temperatures and gusty southerly flow will also contribute to an
elevated fire weather risk this afternoon. The weather pattern is
about to change though, with much more humid air pumping north
into the region tonight and Monday ahead of an approaching trough
boundary from the west. Showers and storms are possible late
tonight and early Monday, and will become more likely and
widespread Monday afternoon.

The axis of an upper level ridge over the Northern Plains, as of
early this morning, will shift to over the Northland by later this
morning. Plentiful sunshine and dry humidity will allow
temperatures to quickly climb into the upper 70s and low 80s by
early this afternoon, and good mixing will drawn down winds of 20
to 25 mph from aloft. Much of the Northland will see critical or
near critical fire weather conditions this afternoon and early
evening, through combinations of the dryness of the vegetation,
wind speeds, and humidity of 20% to 25%.

As for the temperature and humidity forecasts for today, leaned on
the models seeming to perform the best the past few days, namely
the bias corrected outputs of the Canadian-regional, consensus
mos, and SREF models.

A lake breeze from Lake Superior is expected today, but will not
likely move far inland because of the strong southerly flow and
heating/mixing overland. The lake breeze will keep areas near Lake
Superior a little cooler and more humid than areas more inland.

The winds will subside after sunset. However, it will be different
story aloft as low pressure approaches from the west in the Great
Plains. A SSW low level jet of about 40 to 45 knots will develop
by later in the evening and pump moisture into the Northland. The
NAM12, SREF, and GFS20 models and model soundings indicate there
will be building elevated instability from the west overnight. The
jet, slightly falling heights from the west, and late night
shortwaves in the SW flow could help develop showers and
thunderstorms, mainly over the western forecast area. Severe
weather is not likely, but the storms could be capable of
producing small hail.

Monday will be another warm, but much more humid day. Dew points
will climb to the upper 50s and lower 60s, and precipitable water
values will increase to around 1.5 inches. Cloud cover and
increasing chances of showers and storms from the west will mean a
bit cooler temperatures in the lower 70s across the western
forecast area, but northwest Wisconsin could still reach 80
degrees due to tapping into more sunshine and drier conditions.
The heights will continue to fall as low pressure approaches from
the west, providing the synoptic lift to help develop showers and
storms. More shortwaves could lift through the region, too, and a
trough boundary will move into the western forecast area later in
the afternoon or early evening. The models are not in good
agreement concerning pcpn and severe weather parameters, but the
nam12/sref is indicating mixed layer cape could reach around 1500
J/kg amidst 25 to 35 knots of deep layer (0 to 6 km) wind shear.
There is a slight risk of severe weather due to the potential
storm environment. Much of northeast Minnesota can expect
widespread rainfall of 0.25" to 0.50" by Monday evening.

.LONG TERM...(Monday night through Saturday)
Issued at 401 AM CDT Sun May 22 2016

The extended period will be unsettled with periods of showers and
storms possible.

A large upper level trough will be over the western CONUS through
the entire period with several shortwaves moving through the
Northland bringing chances for showers/storms. A trough/frontal
boundary will continue to move east through the Northland Monday
night into Tuesday. Showers/storms will be likely ahead of these
features Monday evening over the eastern half of the area,
diminishing overnight into Tuesday from west to east. Some of the
storms could be severe but there are questions on the amount of
instability that will be present due to expected convection that
should be occurring over western areas that will spread east
during the day.

A weak upper ridge will move over the Northland briefly on
Tuesday into Tuesday night which will lead to weaker forcing and
lower chances for any additional showers/storms for most areas.
The exception will be far eastern areas Tuesday morning which will
have a better chance for precipitation.

Both the GFS and ECMWF bring another shortwave into the area on
Wednesday with a surface low also lifting north. Shower/storm
coverage should ramp up as these features approach on Wednesday
into at least Wednesday evening then they will diminish as the
wave lifts into Ontario later Wednesday night.

Shower/storm chances will continue into Thursday, although at
this time there does not appear to be any strong features for
forcing so coverage should be lower than what is expected
Wednesday.

The GFS/ECMWF show an area of low pressure and another stronger
shortwave impacting the area Friday/Friday evening. There are some
timing differences, but both do indicate stronger forcing and
shower/storm coverage should increase once again.

Tuesday will be the warmest day of the period with highs in the
mid seventies to lower eighties, cooler around the lake. Wednesday
through Saturday will feature highs from the mid sixties to mid
seventies but it will be cooler around Lake Superior with a
persistent onshore wind expected.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1225 PM CDT Sun May 22 2016

VFR for much of the forecast. A cold front will move into
northwest Minnesota by Monday afternoon. Isolated to scattered
showers, with a few thunderstorms, will develop/spread across the
terminals through the morning. The exception being KHYR which will
remain rain free. Ceilings will drop into the MVFR range by mid
morning from KBRD to KHIB and KINL. VFR will remain in charge at
KDLH and KHYR. Gusty surface winds will diminish this evening and
then resume by mid morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  75  55  73  55 /   0  20  70  60
INL  82  59  74  51 /   0  50  70  30
BRD  81  62  74  56 /   0  50  70  40
HYR  81  57  80  58 /   0  10  50  70
ASX  78  54  80  56 /   0  10  50  70

&&

.DLH Watches/Warnings/Advisories...
WI...Fire Weather Watch from Monday afternoon through Monday evening
     for WIZ003-004-009.

MN...Red Flag Warning until 7 PM CDT this evening for MNZ010>012-018-
     019-025-026-035-037.

LS...None.
&&

$$

SHORT TERM...Miller
LONG TERM...Melde
AVIATION...GSF



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