Area Forecast Discussion
Issued by NWS Duluth, MN

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251
FXUS63 KDLH 280847
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
347 AM CDT Wed Jun 28 2017

.SHORT TERM...(Today through Thursday)
Issued at 345 AM CDT Wed Jun 28 2017

A more active day of showers and thunderstorms will develop later
this morning and continue into this evening. A potent system,
associated with deep lift as evidenced by upper-level divergence and
a mid-level shortwave trough, will enter the region today. In the
low-levels, a 35 to 40 kt low-level jet will intensify later this
morning, with the nose of the jet situated right over the Northland.
Enhanced moisture transport will result from this low-level jet,
with Pwat values in the 1.3 to 1.6" range, and sfc dew point
temperatures forecast in the lower to mid 60s this afternoon. NAEFS
analysis of these Pwat values continue to indicate well above
climatological averages for this time of the year, with these values
>90% of climatology. Heavy rainfall, with some localized flooding,
will be possible later this afternoon and evening, with the heaviest
amounts expected to be over portions of northwest Wisconsin, where
over one inch of rainfall will be possible. The focusing mechanism
for convection will be a low-level baroclinic zone that will develop
along a warm front boundary over our southern portions of the
forecast area. Corfidi forward propagation vectors indicate a nearly
due-east component of motion with this convection, which would be
right along the baroclinic zone, so training convection will be
possible. WPC`s latest Day 1 Excessive Rainfall Forecast has removed
the Slight Risk of excessive rainfall from the forecast area,
leaving only the Marginal Risk area over northwest Wisconsin and
points north and west into northeast Minnesota. Total precipitation
through Thursday morning across the area could range from one-half
of an inch in portions of northeast Minnesota to over one inch in
northwest Wisconsin.

There is an increased chance of strong to severe convection with
this system, albeit still a low risk. The 28.00z synoptic guidance
is now indicating the stronger axis of instability will be further
east over portions of the Northland, a bit further east than
yesterday`s corresponding model runs. There`s still some uncertainty
regarding the exact spatial displacement of the instability, but the
general consensus is for MLCAPE values to range from 300 J/kg up to
1500 J/kg by 21z today, much more favorable for strong to severe
storms compared to yesterday. Deep layer shear remains fairly low,
with values ranging from 20 to 30 kts over the area. Given this more
favorable set up for severe convection, the Storm Prediction Center
has expanded their Day 1 convective outlook to include areas south
of a Nisswa to Duluth to Bayfield line in a Marginal Risk of severe
weather. Due to the lack of deep shear, the most likely threats will
be large hail and damaging winds to go along with the larger threat
of heavy rainfall and localized flooding. The Slight Risk of severe
weather stops just barely into southeastern Price county.

Temperatures today will likely be cooler than they were yesterday,
due to the abundance of cloud cover and precipitation expected,
along with a northeasterly wind component off Lake Superior. Highs
today will range from the lower to mid 60s along Lake Superior, and
into the upper 60s and lower 70s further inland.

The system will depart the Northland late tonight. Some lingering
mid- to upper-level energy will continue to support some chances of
showers over portions of our northeastern forecast area. The
departure of the system will bring a cooler airmass over the region,
which will also help to scour out the better moisture, as evidenced
by decreased theta-e values. The better instability will also
decrease as the system departs to the east.

.LONG TERM...(Thursday night through Tuesday)
Issued at 345 AM CDT Wed Jun 28 2017

The atmosphere will be unstable into the weekend with showers and a
few thunderstorms possible through Sunday morning as a series of
shortwaves affect the region.  There will be some lingering showers
across areas mainly north of the Iron Range and the Arrowhead
Thursday morning before moving off to the east by midday. The next
round of precipitation will develop late Thursday night and
continue into early Saturday evening as a series of shortwaves
move through central MN and WI. The threat for precipitation will
finally end by Sunday afternoon as an area of high pressure
builds into the Upper Midwest. It will stay dry through Wednesday
night when another shortwave brings a chance for showers to the
region.

Temperatures will stay at or a little below normal through the
weekend but will increase to the 75-85 range with higher humidity at
the beginning of next week.  July 4th looks to be rain-free at the
moment.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1223 AM CDT Wed Jun 28 2017

A strong low pressure system to advance towards and across the
area during the TAF period. Strong south winds ahead of the low
and aloft has produced LLWS for several terminals which should
continue for much of the overnight period. Moisture surging north
along with a warm front has already generated showers and
thunderstorms in vicinity of KBRD, which will gradually spread
east to affect the remaining terminals through 12z. The initial
waves of showers and thunderstorms to bring MVFR conditions. As
the surface low gets closer expect a period of IFR ceilings and
MVFR visibilities beginning around 10z for KBRD, later for the
other terminals. The back edge of the precipitation should move
into KBRD around 21z, but lingering IFR/MVFR ceilings to linger
for a few more hours, followed by a return to VFR. The other
terminals to follow a similar pattern, though expect those
locations to remain MVFR or IFR through the remainder of the TAF
period.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  62  54  71  53 /  80  60  10  30
INL  68  55  71  54 /  80  70  20  30
BRD  73  56  77  57 /  70  20  10  40
HYR  71  58  74  55 /  80  60  10  40
ASX  69  54  72  53 /  80  60  20  30

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory from 10 AM this morning to 10 PM CDT this
     evening for LSZ140>145.

&&

$$

SHORT TERM...JTS
LONG TERM...Stewart
AVIATION...LE



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