Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 282356
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
656 PM CDT SUN AUG 28 2016

.SHORT TERM...(This evening through Monday)
Issued at 350 PM CDT Sun Aug 28 2016

Warm/moist advective processes are well underway this afternoon
and continue to strengthen with time, with the surface warm front
now lying roughly from near Grand Forks, to just west of Brainerd,
to the northern suburbs of the MSP metro area. The airmass in the
developing warm sector across western MN and the eastern Dakotas
has undergone rapid/significant destabilization over the past 6-9
hours, with the eastern periphery of the instability gradient now
lying across the southwest sections of the Duluth CWA, just to the
north/east of the surface front.

Current objective analysis fields and visible satellite continue
to indicate increasing forced ascent within the aforementioned
frontal zone, due to the combination of mesoscale frontogenesis,
low level moisture transport into the frontal circulation and
large scale low level mass convergence maximized over NW MN/NE ND
as of 3 PM. Satellite imagery continues to reveal the presence of
shallow mid level convection along this arc from far NW Minnesota
to near Duluth - clear evidence of increasing ascent. Exact
timing on deep convective initiation is still not crystal clear,
but it seems to be only a matter of time before layer lifting of
very unstable air leads to the formation of thunderstorms across
NW MN this evening.

With sufficient deep layer shear, storms are likely to be
organized with the potential for large hail initially, with a
transition to a primary threat of damaging wind gusts as they move
into northern Minnesota later this evening and overnight.  although
the severe threat should eventually diminish somewhat with
eastward extent as storms move farther detached from the parent
instability axis, the threat for locally heavy rainfall will
persist into early monday morning as a 35+ knot low level jet
continues the flux of high PW air into the frontal zone and MCS
cold pool boundary.

There is some uncertainty regarding severe potential with the cold
front later Monday/Monday night, which is somewhat conditional on
the departure/dissipation of morning clouds and destabilization
in the wake of overnight convection. However, most model guidance
suggests 3000-4000 CAPE with 40+ knots of deep layer shear
along/ahead of the front over eastern MN/NW WI Monday afternoon
and evening, which would support a fairly robust severe weather
risk - including at least some potential for supercells and
tornadoes for a few hour window later Monday.

.LONG TERM...(Monday night through Sunday)
Issued at 350 PM CDT Sun Aug 28 2016

The cold front will continue to move through NW WI monday evening
continuing showers and thunderstorms through the region. There
will probably still be at least some threat of severe storms and
heavy rainfall through around midnight. The precipitation will
taper off west to east after midnight as the cold front moves out
of the area. On Tuesday, an upper level ridge will begin to
develop in the west and drift east over the upper midwest. It will
dominate the weather across the region into Friday with partly to
mostly sunny skies along with seasonable temperatures in the 70s
during the day and middle 40s to middle 50s at night will be the
norm. The next chance for precipitation will be Friday through
much of the Labor Day weekend as a slow moving upper level trough
approaches the region.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 643 PM CDT Sun Aug 28 2016

Convection the main concern for this TAF issuance. Initial storms
west of KINL to affect that terminal for the next few hours, but
are expected to slide southeast through 14z, likely affecting
KHIB, KDLH, and possibly also KBRD and KHYR during that time
frame. I expect needing to do updates to freshen up timing for
each terminal as trends clarify. As storms move through each
terminal IFR to MVFR conditions expected. A break and return to
VFR is expected from approximately 14z -18z, with new convection
expected after 18z. Have gone with only VCTS groups for now as
timing and placement are highly uncertain.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  62  83  57  75 /  70  70  40   0
INL  63  81  51  73 /  60  40  10   0
BRD  65  82  57  77 /  60  60  20   0
HYR  63  81  59  77 /  60  60  60  10
ASX  62  84  61  76 /  60  70  60   0

&&

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

$$

AVIATION...LE



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