Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 181131

Area Forecast Discussion
National Weather Service Duluth MN
631 AM CDT Thu Jul 18 2019

.SHORT TERM...(Today through Friday)
Issued at 429 AM CDT Thu Jul 18 2019

Chances of showers and thunderstorms will continue to be in the
picture for today and Friday. An isolated strong to severe storm
can`t be ruled out today, but the chances appear to be low. Very
warm heat indicies are also expected for today and Friday.

The overall synoptic pattern will change today, with the upper-
level flow becoming more zonal. The upper-level jet stream will
strengthen, to magnitudes around 110 to 120 knots. Westerlies
will allow a couple of mid-level shortwaves to translate through
the region, with the first one being this morning and afternoon,
and the second one during the day Friday. This pattern will
provide weak large-scale forcing over the Northland, which should
be sufficient to support some showers and thunderstorms. For
today, the surface flow will be from the southwest, which should
keep a lake breeze mostly at bay. Today`s high temperatures will
be in the middle to upper 80s, with heat indicies ranging from the
90 to 100 degree range, so it will be quite warm and muggy,
especially over northwest Wisconsin. As far thunderstorm chances
are concern, there is a good bit of uncertainty as to where and
when they will form, given timing differences among the high-
resolution guidance. Instability will be fairly modest, in the 500
to 1500 J/kg range, so some thunderstorms will be possible. The
entire region is in a Marginal risk of severe storms, so on the
low end of possibility. If storms do become severe, some large
hail and damaging winds can`t be ruled out.

Thunderstorm chances should diminish overnight, only to ramp up
again during the day Friday as the second wave passes through the
region, with an attendant cold front. A perusal of model soundings
shows a strong cap in place to inhibit convection during the day
Friday, with any shower activity most likely farther north away
from the capped environment. There is a Marginal risk of severe
storms over northwest Wisconsin, but this will most likely be
Friday evening when the cap eventually erodes along the cold
front. Temperatures will be a bit cooler over northeast Minnesota,
thanks to the cold front passing through. However, there should be
a window of heating to allow highs to warm into the upper 80s over
much of northwest Wisconsin, with lower to middle 80s over
northeast Minnesota. Heat indicies on Friday could warm into the
90 to 95 degree range once again over northwest Wisconsin.

.LONG TERM...(Friday night through Wednesday)
Issued at 429 AM CDT Thu Jul 18 2019

A change in the pattern over the Northland is still expected to
occur over the weekend. The fast west-southwest flow aloft will
transition to northwest flow aloft Saturday night into Sunday. A
frontal boundary will remain near or south of the Northland into
the first part of the weekend then a stronger shortwave and the
veering upper level flow will push it further south.

We have generally low POPs Friday night through the weekend,
although far northern Minnesota is expected to be dry Friday
night/Saturday. The GFS and ECMWF are trending drier for Sunday and
if this trend continues will be able to reduce POPs. Highs over the
weekend will be near or even a couple degrees below normal.

Most of the period from Monday through Thursday will be dry with
an upper ridge west of the region. High temperatures are expected
to be near normal but warm a few degrees by late week.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 631 AM CDT Thu Jul 18 2019

An MCV was moving through central into northeast Minnesota this
morning with showers and thunderstorms accompanying this feature.
In addition to the showers/storms, there was dense fog and low
ceilings over the Northland. We expect the visibility to improve
at KDLH/KHIB when the rain arrives over the next 1-1.5 hours but
just how quickly is still uncertain. Fog and stratus elsewhere
will likely lift for most areas between 13Z-14Z. After this MCV
moves through the Northland this morning, we expect a period of
dry conditions before additional shower/storm development this
afternoon into this evening. Coverage/timing of the storms later
today is still uncertain and later forecasts will continue to
refine the timing.


Issued at 429 AM CDT Thu Jul 18 2019

An area of low pressure will move through northern Ontario today and
this will allow the wind to become southwest through the day. Winds
are then expected to remain southwest into Friday morning before
veering to west to northwest Friday afternoon into Saturday. Wind
speeds are expected to be 15 knots or less.

There will be periodic chances for thunderstorms through Friday.


DLH  86  65  85  58 /  20  30  30  20
INL  83  61  80  55 /  30  20  10  10
BRD  87  67  84  62 /  30  30  30  10
HYR  85  66  88  60 /  20  20  40  30
ASX  88  68  88  60 /  20  10  30  20




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