Area Forecast Discussion
Issued by NWS Duluth, MN

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
000
FXUS63 KDLH 172025
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
325 PM CDT Sat Jun 17 2017

.SHORT TERM...(This evening through Sunday)
Issued at 325 PM CDT Sat Jun 17 2017

A closed upper low over northwest Ontario this afternoon will loosen
its grip on the forecast area by Sunday as the main low center moves
to southeast Ontario. Will see embedded pieces of energy in the fast
flow aloft rotate over the region this afternoon through Sunday.
These features will lead to showers and storms this afternoon
through tonight. The storms will diminish somewhat after sunset with
loss of daytime heating, except in northwest Wisconsin where
enough CAPE lingers to support convection into the late night.
Showers, however, will persist through the night and into Sunday.
Isolated thunderstorms are expected to form in the late afternoon
over the Arrowhead, near the Twin Ports, and much of northwest
Wisconsin. The storms will fire in the axis of MUCAPE of up to
1000 J/kg Sunday.

The upper flow becomes northwesterly on Sunday with cold air
advection ensuing. Some gusty winds are possible by the afternoon in
response to the arriving colder air. Max temps will be cooler as
well with plenty of clouds and showers around. Min temps
tonight will be in the 50s. Highs on Sunday will be in the 60s.

.LONG TERM...(Sunday night through Saturday)
Issued at 325 PM CDT Sat Jun 17 2017

Sunday evening with the surface low now well west of the forecast
area, we are in a regime of northwest cyclonic flow with cold air
advection going on.  Due to the resulting steep low level lapse
rates, we should get another round of diurnally driven showers and
thunderstorms during the afternoon that gradually diminish during
the evening and overnight hours.  Monday will be similar, though
with a little less convective activity due to the moderating cold
air aloft and warmer surface temperatures.  Monday night a shortwave
dives through the flow and should help keep showers going overnight,
though. Tuesday should be quieter, with a little drier air and
subsidence behind the Monday night wave to keep diurnal
convection reduced. Temperatures will be near to below normal
Monday but warm to near normal for Tuesday.

A stronger shortwave is expected to move through the area Wednesday
and Wednesday night.  Models have been struggling with this feature,
and the GFS remains stronger than the ECMWF, but on recent days the
ECMWF did not even have this wave at all. Have kept to the chance
pops for now, but confidence in it is increasing a little at this
time.  Confidence diminishes for anything beyond that though, as the
models are depicting an even stronger wave forecast to move through
on Friday, but there is little agreement beside the presence of a
strong shortwave in the upper level flow in this time range, but not
in strength, timing or track.  For now we are carrying some slight
to chance pops for pretty much Thursday through Saturday, but we are
going to have to wait until we are closer in before we can find some
drier periods in there.   Temperatures through this period should be
near normal, though would not be surprised to see an above normal
day or two depending on the track of the shortwaves.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1258 PM CDT Sat Jun 17 2017

Initial VFR conditions with scattered showers and a few
thunderstorms across the area. Under the showers and storms a
period of MVFR ceilings/visibilities can be expected. These
showers and storms are forming in advance of a disturbance and
associated weak cold front that is moving rapidly towards the
area this afternoon and will continue through the evening. The
highest confidence in coverage is across the southern terminals
from 20Z through 02Z, and have put in tempo groups for thunder
for KDLH, KBRD, KHYR and KHIB, but for a shorter time frame.
Behind the cold front winds will turn to light northwest, MVFR
ceilings are expected to spread into the area from the northwest
after 06Z. The MVFR ceilings...along with scattered showers
expected to continue through approximately 17Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  53  66  49  67 /  50  50  20  20
INL  52  62  47  65 /  30  50  20  20
BRD  55  65  50  70 /  70  30  10  20
HYR  56  67  51  69 /  80  60  30  30
ASX  53  67  51  68 /  60  70  40  30

&&

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

$$

SHORT TERM...GSF
LONG TERM...LE
AVIATION...LE



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.