Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 261743
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1243 PM CDT Tue Sep 26 2017

.SHORT TERM...(Today through Wednesday)
Issued at 343 AM CDT Tue Sep 26 2017

Another wet day is in store for the region today, as the band of
rainfall over the forecast area extends south across much of
Minnesota and into Iowa and eastern Nebraska and South Dakota.  This
rainfall is associated with a surface low that is over northeast
Iowa as of 3 AM, with a warm front extending northeast across
Wisconsin into western upper Michigan.  This surface low is going to
lift northeast into western upper Michigan by this afternoon,
keeping precipitation going across much of the forecast area through
the morning hours, then slowly diminishing from south to north
during the afternoon and evening and ending overnight tonight. The
clouds and rain will keep temperatures on the cold side, with highs
only in the 50s for Minnesota and in the 60s over Wisconsin.
Wednesday, a surface ridge builds in quickly behind the surface low,
and after a cloudy morning in the lingering low level moisture, I
expect mixing to produce steep low level lapse rates. This should
allow some gusty winds on Wednesday as well as a decent cumulus
field for the late morning and afternoon.  Winds will be stronger
than the last few days, but mostly gusty though the sustained winds
will not be so very strong. This pattern will also allow us to warm
back up again a little with highs in the mid 50s to mid 60s.

.LONG TERM...(Wednesday night through Monday)
Issued at 343 AM CDT Tue Sep 26 2017

A dip to more seasonable temperatures late-week, then a warming
trend to temperatures that will feel more like early September, not
early October. A low chance for spotty showers and perhaps a
thunderstorm Thursday afternoon, then dry Friday and Saturday. An
active weather pattern returns with the warmer temperatures
beginning with a chance for showers associated with a warm front
building in Sunday, then continued chances for rain Monday and
Tuesday. A low chance for storms Sunday into early next week, but
nothing like the repeat days of strong storms we had last week.

On the synoptic scale a brief brush with a northwesterly flow
pattern late-week as a mid/upper level ridge builds over the
Canadian Rockies. A mid-level shortwave trough moves through
Manitoba and northwest Ontario then across the upper Great Lakes
Thursday leading to increasing mid-level moisture and cooler air.
Diurnally driven showers and perhaps a few thunderstorms will
develop Thursday afternoon given steep low level lapse rates, though
guidance has been slowly shifting east with the best large-scale
forcing and coolest air aloft, so it is possible this disturbance
just brings some fair-weather cu to many locations. Highs in the low
to mid 60s on Thursday with breezy northwest winds given deep
mixing. Cooler Friday as high pressure builds in resulting in mainly
skies. With clear skies and a cool Canadian high pressure nearly
overhead Friday night temperatures may fall to the low to mid 30s by
Saturday morning. MOS Guidance trends have been up and down, with
the 00z gridded GFS MOS not as cool as some previous runs had been
with no areas at or below freezing. Still, this pattern seems to
support at least some frost, mainly in the elevated terrain of the
MN Arrowhead and northwest Wisconsin, south of the Gogebic Range.
Sunny Saturday with highs in the upper 50s to low 60s and a light 5
mph south wind - the perfect weather for getting out and checking
out the fall colors as they approach their peak!

Late in the weekend a change in the large-scale pattern as a compact
upper low moves across the Pacific Northwest and into the northern
Plains. Southerly flow will develop ahead of this trough as the high
pressure over the Midwest on Friday shifts eastward towards the
Northeast. A warm front lifts east across the mid/upper Mississippi
River Valley Saturday night into Sunday ahead of the mid-level
trough resulting in increasing clouds and warmer temperatures. The
00z GFS is very fast with this warm front, arriving in north-central
Minnesota by mid-day Saturday, but this is more than 24 hours faster
than other guidance and previous runs. Precipitation chances ramp up
Sunday afternoon into Sunday night with the possibility for
thunderstorms within the warm sector of the deepening low pressure
system to the northwest in southern Canada. The cold front
associated with this low then moves east across the region Monday
into Tuesday resulting in widespread chances for rain with southerly
flow at low levels resulting in the potential for moderate to heavy
rain rates at times. This southerly flow will also result in mild
temperatures with highs in the mid/upper 60s Sunday and Monday, into
the low 70s in some parts of east-central MN and northwest Wisconsin
on Tuesday. These highs are around 5-10 degrees above normal.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1239 PM CDT Tue Sep 26 2017

The light rain will finally end at all taf sites by late tis
afternoon. However...IFR to LIFR cigs will be likely overnight at
all all airports due to the abundant moisture leftover from the
rain. Dense fog is not expected due to the cloud cover overnight.
An area of high pressure will build into the region Wedensday
increasing conditons to MVFR to VFR by late morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  55  43  59  46 / 100  10  10   0
INL  51  40  60  44 / 100  60   0  10
BRD  56  41  62  46 /  50  10   0   0
HYR  61  45  60  44 /  80  10   0   0
ASX  60  45  62  46 / 100  20  10  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement until 8 PM CDT this evening for WIZ001.

MN...Beach Hazards Statement until 8 PM CDT this evening for MNZ037.

LS...Small Craft Advisory until 4 PM CDT this afternoon for LSZ121-
     140>147.

     Small Craft Advisory until 10 PM CDT this evening for LSZ148.

&&

$$

SHORT TERM...LE
LONG TERM...JJM
AVIATION...Stewart



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