Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 152050
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
350 PM CDT Thu Jun 15 2017

.SHORT TERM...(This evening through Friday)
Issued at 349 PM CDT Thu Jun 15 2017

A few showers and thunderstorms have popped up over mainly the
Arrowhead and northwest Wisconsin this afternoon in an airmass
with weak CAPE and shear and in cyclonic flow on the south side of
an upper low over east central Manitoba. These storms have been
worth watching, but ma not concerned for severe storms. There is a
very weak shortwave in the upper level flow that will help keep
this scattered activity going until after dark this evening, so
have kept pops going well into the evening. The upper low shifts
to northern Ontario by Friday afternoon, and while I expect a very
similar airmass, there will be a weak trough in the vicinity to
help generate additional shower and thunderstorm development
Friday late morning and afternoon. Temperatures Friday to be very
similar to today, with highs in the low 70s to low 80s.

.LONG TERM...(Friday night through Thursday)
Issued at 349 PM CDT Thu Jun 15 2017

The long-term forecast remains on track, with increasing chances of
showers and thunderstorms, mainly for Saturday afternoon and
evening, along with a return to more seasonal temperatures Sunday
through mid-week.

Friday night/Saturday morning - an upper-level low will continue to
churn over northwest Ontario Canada, but should eventually lift
northeastward over Hudson Bay. A 100+ kt jet streak will then
develop on the backside of the upper low, placing the Northland
under the influence of upper-level divergence. This jet streak will
strengthen and help to amplify and dig an upper-level trough, which
will set the stage for a active weekend. An associated mid-level
shortwave will then translate into the region Saturday afternoon and
evening. This shortwave will then pivot, keeping chances of showers
over the region for Sunday. For Saturday, the best chances of strong
convection will be in the evening as a sfc cold front boundary is
progged to sweep through the region. Environmental parameters
suggest that storms could be on the strong side, with MLCAPE values
between a few hundred up to 1000 J/kg between the GFS and NAM
models, along with 0-6 km deep layer shear of 35 to 45 kts ahead of
the front. The timing of the front may not be as favorable for
stronger convection as the front doesn`t really move through the
area until the evening and overnight hours, when instability is not
at its highest. The Storm Prediction Center Day 3 convective outlook
has a Marginal Risk stopping just short of our southern counties,
with a Slight Risk over Iowa, southern Wisconsin, northern Missouri,
and northwest Illinois where the much better instability and
stronger baroclinic zone is progged to set up. The strongest Q-
vector convergence is progged to remain south of the Northland as
well. So, storms may be on the strong side in the Northland Saturday
afternoon and evening, but not expected to become severe at this
time.

After the cold front passes through, temperatures will drop to more
seasonal values for the rest of the extended forecast period. Low
temperatures from Monday morning through Wednesday morning could
fall into the upper 40s and lower 50s. High temperatures Sunday and
Monday will range from the lower 60s to the lower 70s, which is
either at or below average for this time of the year. Monday is
looking mostly dry, except for areas of northwest Wisconsin where
some lingering mid-level energy may spark a shower or thunderstorm
in the afternoon. Another chance of showers and thunderstorms return
for Tuesday as a more potent mid-level shortwave and 850-700 mb
layer warm air and moisture advection moves in. Another wave moves
in for Wednesday night and Thursday, which could support another
round of showers and storms.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1239 PM CDT Thu Jun 15 2017

A mid-level shortwave trough will sweep eastward through the
Northland this afternoon, bringing scattered showers and a small
chance of a thunderstorm to the TAF terminals. A robust diurnal
cumulus field has already developed this afternoon, with SCT to
BKN ceiling heights of 4 to 5 kft. There is already some rain
showers that have developed too, mainly over the Iron Range and
Minnesota Arrowhead areas. This is expected to expand as the
afternoon goes on, with the best chances of seeing showers/storms
across the northern TAF terminals, including KINL, KHIB, and KDLH,
with lesser chances over KBRD and KHYR. The cumulus field and the
chances of showers should diminish by the evening, and especially
overnight.

A quiet night is expected, with only KINL seeing continued lower
cigs, while the remaining TAF sites should see mainly higher level
clouds or SKC. Another day of diurnal cumulus is expected for
Friday as we remain under the influence of this shortwave trough.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  53  78  56  72 /  40  30  20  60
INL  51  73  51  71 /  30  30  30  60
BRD  54  81  57  74 /  20  20  20  60
HYR  54  81  58  77 /  10  30  20  60
ASX  55  82  57  75 /  30  30  20  50

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

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



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