Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 282352

Area Forecast Discussion
National Weather Service Duluth MN
652 PM CDT Sun May 28 2017

Issued at 645 PM CDT Sun May 28 2017

Am in the process of doing some updates to the forecast for the
lastest radar trends, that should be out shortly. Below is an
aviation update.


.SHORT TERM...(This evening through Monday)
Issued at 256 PM CDT Sun May 28 2017

There were numerous showers and storms across the northland this
afternoon and these will continue for most of the night and
Monday. But, I think we should see some decrease in coverage as
solar support is lost. The culprit is a deep low pressure area
over southern Manitoba and northwestern Quebec. Vort maxima will
be rotating around the low and over the northland. One went
through this morning and early afternoon and another is coming
through MN and a few more are still upstream, taking aim on the
Northland. With a low freezing level, these storms have been very
low-topped and especially productive small hail producers. Had a
pilot report of thunderstorm top over Duluth of only 20,000K feet.
Expect about the same type of weather Monday, but maybe not quite
so rambunctious as the temperature lapse rate won`t be quite as
strong with warmer 500 mb and little instability.

.LONG TERM...(Monday night through Sunday)
Issued at 256 PM CDT Sun May 28 2017

The closed upper low meanders around northwest Ontario Monday night
through Tuesday night. Several pieces of energy, along with a pair
of tight short wave trofs, will rotate through the forecast area
during this time. Periods of showers are expected, but will be
difficult to time. This leads to the chance pops that will be
carried in the forecast through Tuesday night. Much cooler temps are
forecast as 850mb temps drop to near zero celsius through this
period. The rain will end from west to east Tuesday night as high
pressure builds into the region. After a dry Wednesday morning,
model differences begin in the afternoon. The NAM/GEM are dry, the
ECMWF/GFS pop some showers over northern Minnesota. This continues
Wednesday night. Used a blend which led to small pops over the
Arrowhead early, then dry overnight into Thursday morning. Thursday
afternoon finds only the GEM dry, the GFS/ECMWF have some showers.
Have pops over the eastern third of the region to account for a
short wave trof dropping south from Canada. The last piece of energy
moves over northwest Wisconsin Thursday evening and have some small
pops in place. Dry elsewhere as high pressure arrives. Ridging
covers the area on Friday. Friday night through Saturday shows a
large model spread. The GEM has ridging, the ECMWF develops a
surface low over southern Minnesota and has a large swath of QPF,
the GFS is between. Used a blend which results in low pops Friday
night and Saturday.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 645 PM CDT Sun May 28 2017

Cyclonic flow both at the surface and aloft in combination with
diurnal heating and some weak impulses aloft will keep showers in
the terminal forecasts through much of the period. A surge of
colder air moving into the area from the northwest will sweep some
IFR ceilings into the terminals from west to east beginning around
06z, and continuing through at least 18z, slowly improving to
MVFR after 18z.


DLH  46  56  43  54 /  40  60  20  30
INL  47  54  43  54 /  70  60  30  40
BRD  49  57  45  57 /  50  40  20  20
HYR  47  57  44  56 /  40  60  30  40
ASX  48  59  45  56 /  40  60  40  30




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