Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 221726

Area Forecast Discussion
National Weather Service Duluth MN
1226 PM CDT Mon May 22 2017

.SHORT TERM...(Today through Tuesday)
Issued at 422 AM CDT Mon May 22 2017

Closed upper low was centered over northwest Ontario early this
morning with several shortwaves rotating cyclonically around the
center. An area of rain showers was over much of northwest
Wisconsin and portions of east-central Minnesota, with another
area of showers in the Red River Valley. A surface low was over
Lake Nipigon with a trough arcing westward into southeast

The combination of several shortwave troughs rotating around the
upper low today and tonight and periods of cold air advection
should keep showers in the picture for today and this evening.
Shower coverage and intensity will likely increase this afternoon
with weak instability developing. Isolated thunderstorms will be
possible, as well, and may produce pea-size hail. Rainfall amounts
will be lower today than the past few days with up to two-tenths
of an inch of rainfall expected and most locales receiving only a
few hundredths. Precipitation should trend down tonight with the
rain chances becoming more scattered.

The upper low will shear overnight resulting in the low dividing
into a progressive open wave and a lingering western cutoff low.
The cutoff portion of the system is forecast to drift south into
northern Iowa by late Tuesday afternoon. Cyclonic flow aloft and
several embedded shortwaves will keep shower chances in play
through Tuesday afternoon. Think there will be increasing sunshine
during the late morning and early afternoon for some locales,
including northwest Wisconsin. However, the increasing sunshine
and solar heating should lead to a dense cumulus field and
numerous rain showers. A few thunderstorms are possible, but they
will be weak with pea-size hail not out of the question given the
cool temperatures aloft.

.LONG TERM...(Tuesday night through Sunday)
Issued at 422 AM CDT Mon May 22 2017

A longwave upper trough is forecast to extend from Quebec
southwest through Lake Superior into the Southern Plains Tuesday
evening. An upper level ridge is forecast to stretch through
California northeast toward Hudson Bay. These features will move
slowly east with the upper ridge moving over the Central CONUS
Wednesday night into Thursday. Showers will linger into Tuesday
night but coverage and chances will be diminishing overnight.
Light winds will develop Tuesday night over northern Minnesota
with clearing skies. Temperatures may fall to near freezing in
spots over far northern Minnesota. A dry period will finally occur
Wednesday into Thursday as high pressure dominates. Highs
Wednesday and Thursday will be in the sixties for most areas but
it will be cooler around Lake Superior with off lake winds
occurring. Cool temperatures will again be possible Wednesday
night, especially over the eastern half of the Northland which
will see the lightest wind. Frost will be possible inland from
Lake Superior.

The upper ridge will be pushed east by an upper level trough
Thursday night into Friday. A trough of low pressure will move
east into the eastern Dakotas/western Minnesota area by 12Z Friday
continuing east Friday into Friday night. There will be a chance
for showers Thursday night into Friday evening. There will also be
a chance for a few thunderstorms, mainly on Friday. Highs Friday
will range from 60 to 70 but again be cooler around Lake Superior.

The models diverge later in the weekend with the GFS having a
stronger shortwave in the Central Plains which moves into Iowa
then through Wisconsin Sunday night into Monday night. A surface
low deepens as a result of the stronger wave and brings a better
chance for showers/storms to the Northland Sunday night into
Monday night. The ECMWF and CANADIAN models are in better
agreement and are more progressive. We do have a chance for
showers and some thunderstorms from late Saturday night through
Monday night but overall confidence is lower than average. High
temperatures are expected to remain in the sixties into Monday.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1226 PM CDT Mon May 22 2017

MVFR ceilings are expected through much of the forecast. There
will be some pockets of VFR prior to 00Z. With low pressure
lingering nearby, will continue to have showers in the vicinity of
all terminals. Confidence is low in having a predominate light
rain mention. Some areas of BR will occur after 05Z until about
15Z with vsbys in the MVFR/IFR range.


DLH  56  39  53  39 /  40  30  60  20
INL  51  41  58  36 /  60  50  30  10
BRD  58  43  57  41 /  70  40  50  10
HYR  58  39  60  41 /  40  20  50  20
ASX  58  38  52  39 /  30  20  40  20




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