Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 241310 AAA

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
810 AM CDT Sat Jun 24 2017

Issued at 810 AM CDT Sat Jun 24 2017

Update for 12Z Aviation Discussion below.


.SHORT TERM...(Today through Sunday)
Issued at 409 AM CDT Sat Jun 24 2017

Cycloninc northwest flow continues over the Lake Superior region
this morning, with an embedded shortwave moving southeast across
eastern North Dakota. Showers associated are associated with this
shortwave, as well as with the frontogenesis band extending along
the 925-850mb baroclinic zone in the vicinity of the 850mb low
center and surface weak cold front/trough axis. These features to
continue moving southeast across the forecast area today, bringing
precipitation chances to the forecast area today and tonight. This
extra cloud cover is going to keep temperatures on the cool side,
with some sites along the International border staying in the 50s
during the day. This trend to continue into Sunday, with the
lingering inverted trough serving as a focus for convection as a
secondary weak shortwave moves across the area. Have highest
precipitation chances with highs only in the 50s across the tip of
the Arrowhead for Sunday.

.LONG TERM...(Sunday night through Friday)
Issued at 409 AM CDT Sat Jun 24 2017

Summary: Broad longwave trough will depart to the east early in the
period with a progressive quasi-zonal flow for much of the week.
Periodic chances of showers and thunderstorms are expected with
temperatures remaining near to below normal.

A broad upper level trough will remain over the region Sunday night
with scattered showers and isolated thunderstorms continuing through
the evening. The cool cyclonic flow aloft should continue to support
isolated showers into the wee hours of Monday morning. Another
shortwave trough will move across the Northland Monday morning and
afternoon. Deterministic guidance is split between several dry
members and a few with showers or isolated storms. Most of the GEFS
members over the past two runs include some QPF. The ensemble
guidance plus the passing shortwave seem to support at least low
chance POPs during the afternoon. Have nudged precip chances in the
Arrowhead higher than the consensus blend to better capture the
potential. Temperatures remain 5 to 10 degrees below normal on
Monday with highs in the low 60s to around 70 degrees.

The upper level trough will drift eastward away from the Northland
Monday night and Tuesday. A mid-level ridge will gradually flatten
as it pushes into the Dakotas with surface high pressure sliding
southeast across the eastern Dakotas and western Minnesota. Expect
increasing sunshine and slightly warmer temperatures for Tuesday in
addition to a break in the precipitation chances. As the surface
ridge axis moves through the Northland, winds will turn southerly
ushering in a warm and moist return flow. A warm front will lift
across Minnesota during the day Tuesday ahead of an approaching
shortwave trough and surface low moving into the Dakotas during the
afternoon. Highs will be near normal with values in the middle 60s
to upper 70s.

The chance of showers and thunderstorms returns to the picture
Tuesday night through Wednesday night. Falling heights ahead of the
approaching shortwave trough and additional forcing for ascent on
the nose of a strengthening nocturnal low-level jet should support
the development of showers and thunderstorms Tuesday night. MUCAPE
values overnight of 500 to 1000 J/kg and 0-6 km bulk shear of around
25 knots indicate a potential for a few strong or severe storms
overnight. A better chance of severe thunderstorms will develop on
Wednesday afternoon ahead of the surface low and attendant cool
front. Increasing northward moisture transport on south to
southwesterly low-level flow will lead to moderate destabilization
across the southern half of our CWA by Wednesday afternoon. The
strengthening winds aloft will increase 0-6 km bulk shear to 35 to
45 knots with MUCAPE increasing to 1500-2500 J/kg. Strong to severe
thunderstorms will be possible, mainly south of US Highway 2 likely
beginning in central Minnesota and pushing east into northwest
Wisconsin during the evening.

The shortwave trough and associated surface low will continue
eastward on Thursday with showers diminishing during the early
morning hours. Deterministic guidance diverges on Thursday with the
GFS bringing another cutoff upper low into the Canadian Prairies
while the ECMWF and GEM are less amplified and more diffuse with the
upper trough. In either case, a shortwave trough is forecast to
rotate through the base of the approaching trough by Thursday
afternoon. The consensus blend would keep the Northland generally
dry, however, the GEFS members support at least a chance of showers.
Have decided to increase POPs Thursday afternoon through Friday to
bring a chance of rain to most of the Northland. With the
approaching upper trough and cool cyclonic flow developing, think
the rain chances will be diurnally driven and should diminish
overnight into Saturday morning.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 810 AM CDT Sat Jun 24 2017

Broad upper-level trough continues to loiter over the region with
a compact but potent shortave trough passing through the eastern
Dakotas and Minnesota. Scattered rain showers are likely across
the area today into this evening. Along with the showers, MVFR
ceilings can be expected this morning. Conditions should begin to
improve this afternoon as the shortwave moves away from the


DLH  64  48  60  45 /  40  30  70  30
INL  58  48  60  43 /  50  70  70  20
BRD  64  49  64  45 /  40  30  30  10
HYR  65  48  63  44 /  50  30  50  30
ASX  66  48  62  46 /  40  40  60  40




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