Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 231141
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
641 AM CDT Tue May 23 2017

.SHORT TERM...(Today through Wednesday)
Issued at 354 AM CDT Tue May 23 2017

A closed upper-level low was located over central Minnesota early
this morning with numerous compact vorticity maxima observed on
water vapor imagery. A surface low was centered over southwest
Wisconsin. Several areas of rain showers were noted near the afore
mentioned vorticity maxima from the Red River Valley through
southern and portions of central Minnesota and central Wisconsin.
They were generally orbiting slowly cyclonically around the
primary closed low.

Expect rain showers to continue lifting northward into northwest
Wisconsin early this morning with another area of showers pushing
southwestward into far northern Minnesota. There are more breaks
in the overcast than last night at this time, and think the trend
for partial clearing will lead to increasing instability this
morning and afternoon. The closed upper-level low will drift
slowly southward today and into central Iowa by this evening.
Expect the showers to increase in coverage and intensity today,
with an isolated thunderstorm or two possible. Modeled instability
profiles are weaker than yesterday`s guidance, and focused lower
in the troposphere, so expect the potential is smaller. However,
should cloud cover break more than currently forecast, those CAPE
values will be buoyed by warmer boundary layer temperatures. While
there is plenty of cold air aloft, the equilibrium levels are
warmer than yesterday, topping out around -8C. Think this will
limit the hail potential with any storms which develop. A few
small pieces of graupel may accompany the strongest updrafts.
Temperatures should trend a little warmer in north-central
Minnesota, but cloud cover will keep temps similar this afternoon
for the rest of the forecast area.

With the closed upper low departing to the southeast tonight,
look for increasing clearing across northern Minnesota.
Temperatures should cool efficiently in the presence of light
winds, raising the specter of areas of frost north of the Iron
Range as temperatures dip into the low 30s. The clearing may be
delayed until late in the night, which would limit the time for
the temps to plummet. Should skies begin to clear earlier in the
evening, the forecast lows will be too warm. Some of the higher
terrain areas near Lake Superior in northern Wisconsin may, too,
see a few patches of frost tonight.

Clearing continues on Wednesday with high pressure ridging
building across the region. With recent rainfall and the
increasing botanic activity across the Northland, expect
evaporation and ET to boost low-level moisture leading to cumulus
development by late morning into the afternoon. A few updrafts may
possess enough moisture and lift for isolated showers to develop.
A lake breeze may kick in for portions of the Arrowhead and
northwest Wisconsin Wednesday afternoon, keeping max temps
restricted to mid-afternoon temperatures.

.LONG TERM...(Wednesday night through Monday)
Issued at 354 AM CDT Tue May 23 2017

An upper level ridge will extend from the southwest CONUS through
the Dakotas into Manitoba Wednesday evening with a stronger upper
level low centered along the southern Alberta/Saskatchewan
border. The upper low will continue slowly east with the upper
ridge moving over the Northland Thursday then passing east of the
area Thursday night. Dry conditions will occur Wednesday night
into Thursday. Frost will be possible Wednesday night, most likely
across the Iron Range, Arrowhead, into parts of northern
Wisconsin. Highs Thursday will rebound to 65 to 70 for most areas
except around Lake Superior where off cooler off-lake winds will
occur.

The upper low will continue to move east and be over the area
this weekend, departing early next week. Several shortwaves will
move around this upper low/trough and bring chances for showers.
The first wave and a surface front will affect the area Thursday
night int Friday evening. There will be a chance for showers as
early as Thursday evening with the best chance occurring Friday
afternoon. There may be some thunderstorms as well Friday
afternoon.

There are some differences in the details over the weekend into
early next week with the upper low and low level features but the
big picture among them is similar. There will be periodic chances
for showers along with some thunder over the weekend into early
next week. As the upper low/trough passes east a better chance for
dry weather will develop over the Northland in northwest upper
level flow and low level ridging just to the west. Highs Friday
through Tuesday will mainly be in the sixties.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 641 AM CDT Tue May 23 2017

An upper low was over east central Minnesota this morning with
shortwaves rotating around it. Ceilings varied from IFR to VFR and
there were some showers in spots. Areas of fog was also occurring
over far northern Minnesota. We expect the showers to increase in
coverage today and there may be an isolated thunderstorm as well.
Ceilings should be a mix of mainly MVFR and VFR by this afternoon
into the evening. The showers will diminish or end this evening
for most areas.

An area of high pressure will start to move into northwest and
northern Minnesota late tonight. MVFR and IFR conditions are
expected to redevelop overnight in spots...most likely south of
Highway 2 including northwest Wisconsin.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  53  39  58  38 /  50  20  20  20
INL  58  35  68  39 /  40  10  10  10
BRD  57  40  65  42 /  50  20  10  10
HYR  59  40  64  37 /  60  20  20  20
ASX  53  37  54  35 /  60  20  20  20

&&

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

$$

SHORT TERM...Huyck
LONG TERM...Melde
AVIATION...Melde


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