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Area Forecast Discussion (AFD)

Issued by Duluth, MN (DLH)

FXUS63 KDLH 211720 AAA

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
1220 PM CDT Thu Jun 21 2018

Issued at 1220 PM CDT Thu Jun 21 2018

Please see the 18Z Aviation discussion below.


.SHORT TERM...(Today through Friday)
Issued at 359 AM CDT Thu Jun 21 2018

Continued dry conditions expected across the Northland through 
tonight as high pressure over southern Ontario Canada remains in 
control. Surface low pressure situated over northwestern Iowa this 
morning will continue to bring a shield of cirrus clouds north into 
the region, but dry air near the surface will keep any precipitation 
that moves northward at bay. Another lake breeze will develop today, 
so temperatures will be cooler lakeside, with highs ranging from the 
middle to upper 60s along Lake Superior, and into the upper 70s and 
lower 80s further inland. Clear skies and light winds will be in the 
picture for tonight, so looks like a good night for radiational 
cooling, so lowered overnight temperatures by a degree or two. 
Overnight lows will dip into the upper 40s to lower 50s lakeside, 
with middle to upper 50s further inland.

A weak mid-level impulse will then eject from a shortwave trough 
that is progged to develop over the Intermountain West states for 
Friday. The primary consequence of this wave looks to be an increase 
in cloud cover from west to east Friday afternoon. There are some 
small chances of showers and perhaps a thunderstorm as better 
instability develops due to steepening low-level lapse rates. MUCAPE 
values range between a few hundred up to 500 J/kg, so instability 
will remain on the low side, but still think there could be a few 
rumbles of thunder along the International Border region. New 
rainfall amounts should remain light as well, with only up to one-
tenth of an inch of QPF anticipated.

.LONG TERM...(Friday night through Wednesday)
Issued at 359 AM CDT Thu Jun 21 2018

The long-term begins with weak high pressure over the Northland; 
however, the quiet weather will only be brief as a cold front begins 
to move down from Canada. This front will slowly decay over the area 
but will bring a chance of rain showers throughout much of the 
weekend. Overall, quasi-geostrophic fields show a general large 
area of enhanced lift though instability is a limiting factor and 
the lack of upper level support also will limit shower 
development. Have only included pops up to about 50% throughout 
the weekend with timing of the front being the main uncertainty 
due to its decaying nature. 

High pressure builds strongly on Monday and Tuesday before another
low pressure system moves through the area by mid-week. This 
system also brings potential for more rainfall, but nothing too 
extraordinary. Overall very little impactful weather throughout 
the extended period.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1220 PM CDT Thu Jun 21 2018

VFR through the forecast with light winds as high pressure nudges
into the region from the Northeastern US. A few scattered showers
or thunderstorms may impact INL after 18Z on Friday as a cold 
front slides in from the north.


DLH  69  51  79  55 /   0   0   0  10 
INL  84  58  84  59 /   0  10  20  20 
BRD  80  55  80  59 /   0   0   0  10 
HYR  76  50  80  54 /   0   0   0   0 
ASX  64  48  75  51 /   0   0   0   0