Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 270533
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1233 AM CDT Sat May 27 2017

.UPDATE...
Issued at 1221 AM CDT Sat May 27 2017

Updated aviation section below.

UPDATE Issued at 722 PM CDT Fri May 26 2017

Have updated the forecast for the latest radar trends, as storms
are maintaining longer but are weaker than they were earlier this
afternoon.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 354 PM CDT Fri May 26 2017

A surface trof of low pressure was moving into St.Louis county
southwest through Aitkin county at 1920Z. A line of showers and
isolated thunderstorms were occurring along an ahead of this trof.
Followed the 17Z HRRR for timing of this activity through the
forecast area. The HRRR has been doing a reasonable job with this
activity for the last couple of runs. Storms should extend from Ely
to the Twin Ports to Pine City by 22Z/5pm, the Arrowhead to the
Hayward Lakes by 01Z/8pm, and come to an end by 03Z/10pm. The
surface trof will have moved east of the region shortly thereafter,
and with the loss of diurnal heating, no additional precipitation is
expected. After 06Z, look for fog to develop over the eastern two
thirds of the area with light winds and a clearing sky. The fog
should erode by 9am Saturday.

The forecast area will enjoy a break from the rain for most of the
day Saturday. By afternoon, showers are expected to develop in
response to a long wave trof that is progged to be found from
northeast Minnesota southwestward to eastern South Dakota by 00Z
Sunday. The showers will be found primarily from the Borderland
southwest to northern Cass county, with isolated thunderstorms
possible in the late afternoon. Max temps will be in the 60s near
Lake Superior, to the lower 70s inland.

.LONG TERM...(Saturday night through Friday)
Issued at 354 PM CDT Fri May 26 2017

A cutoff upper low will keep partly cloudy skies and occasional rain
chances in the picture Saturday night through midweek.

Scattered showers and isolated thunderstorms should be ongoing in
our western zones Saturday evening associated with an approaching
cool front. Showers will weaken overnight with another round of
showers and storms expected on Sunday. A few strong storms are
possible as NAM/GFS/GEM profiles indicate 1-1.5 kJ/kg of MUCAPE
during the afternoon. The strongest signal for potent thunderstorms
is over northwest Wisconsin, but portions of the Arrowhead may also
see a few strong storms. Most of the deterministic guidance features
a compact and relatively strong vort max and shortwave trough moving
through the Northland Sunday afternoon and evening. The GFS seems to
carry the best signal for strong storms with the vort max rotating
through the area during the late morning through mid-afternoon
timeframe. The GEM is similar, but a little slower and a few miles
farther north while the NAM and ECMWF has a much less defined
feature in the vicinity.

The closed low will wobble southeastward toward northern Lake
Superior Sunday night and Monday. Several vorticity maxima will move
across Minnesota and Wisconsin, and along with continued cold air
advection aloft, should support numerous showers Monday, and a
chance of isolated thunderstorms. A chance of scattered showers will
continue off and on through Wednesday night as the closed low
continues drifting toward New England and gradually fills. High
pressure returns Wednesday night into the weekend.

Temperatures will be near to slightly above normal with highs in the
upper 60s and low 70s and overnight lows in the 40s and upper 30s. A
lake breeze will be present some afternoons limiting temperatures
near Lake Superior.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1221 AM CDT Sat May 27 2017

Fog has developed at KHYR, with LIFR visibilities and ceilings
in stratus ahead of a trough axis advancing slowly through the
area. As this trough moves past KHYR in the next few hours and
drier air moves in from the west, expect a gradual improvement in
the conditions before sunrise, which is around 1021z. However,
rainfall earlier this evening may cause MVFR conditions to linger
after sunrise. Rainfall may also bring MVFR fog to KHIB and
KDLH. Conditions should return to VFR no later than 13z for all
terminals. A cold front will approach the area from the west after
00z, with additional convection expected to move into the
terminals after 03z. However, timing and location are uncertain
and have left it out for now.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  47  70  48  64 /  30  10  30  60
INL  46  71  46  63 /   0  20  30  50
BRD  48  72  49  67 /   0  10  20  40
HYR  48  72  49  68 /  70  10  30  50
ASX  48  71  49  66 /  70  10  30  50

&&

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

$$

UPDATE...LE
SHORT TERM...GSF
LONG TERM...Huyck
AVIATION...LE



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