Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 241755 AAB
AFDDLH

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
1255 PM CDT FRI JUN 24 2016

.UPDATE...
Issued at 1255 PM CDT Fri Jun 24 2016

Please see updated 18Z aviation discussion below.

&&

.SHORT TERM...(Today through Saturday)
Issued at 432 AM CDT Fri Jun 24 2016

The short term will feature chances for strong to severe storms
both tonight, but more so Saturday afternoon into the evening.

An upper ridge will build over the Northland today shifting east
tonight. This ridge will keep much of the Northland dry today with
highs from the upper seventies to lower eighties. A shortwave
will move through North Dakota today into northwest Minnesota this
evening and into northwest Ontario overnight. Warm air and
moisture advection will be on the increase through the day into
tonight across the region and that and the shortwave will combine
to produce showers and thunderstorms. The storms are expected to
develop late this afternoon or early evening over northwest to
north central Minnesota, with chances increasing further south and
east overnight. A chance will exist across the entire Northland
overnight with probabilities highest far north. Some of the storms
could become quite strong, mainly along and north of highway 2 in
northern Minnesota. The strongest storms will be capable of
producing large hail and damaging wind. PWAT values will rise to
or just over 1.5 inches by 12Z Saturday. Localized heavy rain will
also be possible tonight and NCAR ensemble forecasts show the
probability of 1 hour rainfall rates greater than 1 inch fairly
high over far northern Minnesota.

Overnight convection will have a big impact on the chances for
more severe storms on Saturday as it often does. Many of the
parameters look favorable for severe storms, mainly Saturday
afternoon into the evening and we do think the overnight
convection will dissipate or move out of much of the area through
the morning. A strong upper low will move from the southern
Saskatchewan/northeast Montana area early Saturday morning into
southern Manitoba by 00Z Sunday then continue east/northeast
overnight. Surface low pressure will deepen in response and move
into the Lake Winnipeg/Lake Manitoba area before moving into
Ontario overnight. A strong cold front will move across western
and central Minnesota through the day and through western
Wisconsin in the evening. Surface dewpoints will be in the upper
sixties to lower seventies leading to MLCAPE values from
1500-2500J/KG per forecast soundings. Morning convection and
clouds may limit the instability some and this is one limiting
factor on the severe potential in the afternoon/evening. Mid level
winds will be on the increase through the day causing favorable
0-6km shear and the 0-1km shear is forecast to be from 15 to as
high as 30 knots. The current SPC outlook for severe across the
entire Northland looks good for now and we think all modes of
severe weather will be possible with the most likely being large
hail, damaging wind, and heavy rain possibly leading to localized
flash flooding. Heavy rain will be a threat despite progressive
storm motions as PWAT values of 1.75 inches or higher are forecast
and this is near record levels for this time of year. If better
instability is realized, the 0-1km shear would also favor a
tornado threat.

We have highs only forecast in the lower to mid eighties (cooler
in the Arrowhead) despite the very warm 850mb temperatures due to
expected cloud cover.

.LONG TERM...(Saturday night through Thursday)
Issued at 432 AM CDT Fri Jun 24 2016

A strong low over southern Manitoba will exit to the east-northeast
late this weekend leading to cooler (and windy!) northwest flow
and a chance for light rain showers Sunday. Northwest flow aloft
will prevail through the rest of the work week leading to cool to
seasonable temperatures and a chance for rain showers mid to late
week as an upper level disturbance approaches the upper Great
Lakes.

After strong to severe storms exit Saturday night, the main concern
Sunday will be strong westerly winds in the wake of the low. Fairly
strong low/mid level winds will easily mix down due to steep low/mid
level lapse rates, with gusts to 30-40 knots possible. Rain showers
expected to develop in the the post-frontal environment mainly north
of Highway 2 in northeast Minnesota... but possible anywhere across
the Northland. Cloudy skies could continue through Monday as a mid-
level trough axis associated with the departing low swings through
from north to south Sunday night into Monday, but a clearing trend
is expected beyond that as a strong area of high pressure builds in
(1024+ mb). This high will be centered across northern Minnesota
Tuesday morning, gradually sliding southeastward through mid-week.
This high then remains fairly stationary over Wisconsin through the
work week resulting in sunny skies, seasonable temperatures, and
weak winds.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1255 PM CDT Fri Jun 24 2016

Not much change from previous set. Isolated to scattered
thunderstorms are expected to develop late this afternoon and
tonight. Usual uncertainty in timing and location of storms
warranted removal of prevailing -TSRA from earlier forecast.
Confidence in a period of storms affecting the HIB and INL
terminals is highest and introduced TEMPO for -TSRA during best
time period. Should storms affects any terminals this afternoon or
tonight...will likely see vsbys lower into MVFR or even IFR
categories through sunrise. Kept a short period of MVFR cigs/vsbys
at locations most likely to be impacted. Conditions should improve
as storms move out Saturday morning. Another round of thunder-
storms is expected to move through the region Saturday, which may
affect the terminals. Timing and confidence in those storms is low
and did not include a mention in this package. Overall confidence
in this set is average.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  80  61  79  57 /   0  50  80  60
INL  82  65  81  58 /  20  60  80  30
BRD  80  67  84  60 /  10  40  80  10
HYR  80  65  84  59 /   0  40  70  80
ASX  83  60  84  60 /   0  40  70  70

&&

.DLH Watches/Warnings/Advisories...
WI...None.
MN...None.
LS...None.
&&

$$

UPDATE...Huyck
SHORT TERM...Melde
LONG TERM...JJM
AVIATION...Huyck



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