Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 191140
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
640 AM CDT Wed Sep 19 2018

.SHORT TERM...(Today through Thursday night)
Issued at 338 AM CDT Wed Sep 19 2018

The main concern during the short term period through 12Z Friday
morning remains the potential for heavy rain over portions of
northwest Wisconsin and the I-35 corridor Thursday and Thursday
night.

Surface high pressure over the Northland this morning was wedged
between developing low pressure in the Plains and a weak area of
low pressure in southern Saskatchewan. A cool front was located
over northwest Ontario, northwest Minnesota, and North Dakota
while a nearly stationary front was found along the Kansas/
Nebraska Border east across northern Missouri. A broad area of
scattered showers and thunderstorms was found over South Dakota,
northern Nebraska, and portions of western and southern Iowa. The
showers and thunderstorms are forecast to advance eastward/
northward into eastern South Dakota, southern Minnesota, and
northern Iowa this morning, keeping the best rain chances south of
the Northland. A few showers were found in central and northern
Wisconsin, which are expected to slide farther eastward during the
early morning hours.

With this forecast package we`ve tightened the gradient in
precipitation chances through 12Z Thursday keeping the northern
zones dry while increasing rain chances across the south. As the
Plains low continues to strengthen today, the stationary front
will lift northward as a warm front. Isentropic ascent over the
boundary will lead to rain showers developing over central
Minnesota and central Wisconsin this afternoon which will
generally lift northward into our southernmost Minnesota zones and
much of northwest Wisconsin. Rainfall amounts through tonight of
up to three-quarters of an inch are anticipated. A few embedded
thunderstorms are not out of the question although the best
instability will remain well south of the area.

Attention then shifts to Thursday through Thursday night when the
main area of low pressure lifts along the warm front through
Minnesota and Wisconsin. There may be a brief break between the
rain and thunderstorms of tonight and the next round on Thursday.
Rain and storms will redevelop during the morning with the
greatest potential for rain over northwest Wisconsin initially,
expanding across the remainder of the Northland by late Thursday
afternoon. Precipitable water values between 1.5 and 1.75 inches
will build into Pine County and across northwest Wisconsin by
Thursday afternoon on strong southerly 850 mb winds. Limited
buoyancy of 500 to 1000 J/kg will be available for storms and will
gradually build late in the afternoon through the early evening
mainly from Hayward eastward. The limited areal extent of the
instability and relatively low magnitude should limit the flash
flooding potential. However, the long duration rain event may lead
to localized low-land flooding and ponding of water on roads.
Area streams will rise gradually and may result in additional
flooding.

The low pressure system lifts into northeast Ontario by 12Z
Friday. As the strongest forcing for ascent moves away from the
Northland, expect rain intensity to diminish. Northern Minnesota
will continue to experience light rain behind the departing low.

.LONG TERM...(Thursday through Tuesday)
Issued at 338 AM CDT Wed Sep 19 2018

Friday morning the strong low pressure system will pull off to
the east, with precipitation lingering in the morning hours across
the eastern portions of the forecast area, followed by a dry
afternoon. Breezy north winds in the morning will diminish during
the afternoon hours. Cold air moving in aloft should help produce
high temperatures in the 50s, and we will likely have a decent
cumulus field during the afternoon hours. This cumulus field
should clear during the evening, and with a ridge of high pressure
settling into the area, expect a rather chilly night Friday
night. Have gone with min temperatures on the cold end of
guidance, and it looks like we will have some concerns for frost
overnight. It is in the forecast, and will be mentioning it in the
HWO as well this morning.

We return to a strongly zonal upper level pattern by this
weekend, with some relatively weak shortwaves that move through
the upper level flow to bring some small chance pops to the
northern portions of the forecast area on both Saturday and
Sunday. Temperatures will warm slightly going through the weekend.

Early next week a stronger upper level trough moves across the
CONUS, which appears to bring us some greater chances for
precipitation Sunday night through Monday night, with near normal
temperatures. The troughing aloft remains over the area through
the middle part of the week, with some small precipitation chances
through Wednesday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 640 AM CDT Wed Sep 19 2018

A range of conditions from IFR at KHYR to VFR at KBRD...with some
fog reducing visibilities to LIFR at KINL. Expect visibilities to
slowly improve through 14z this morning at KINL. Expect ceilings
to also improve by 18z for KINL, KHIB, KDLH and KBRD to at least
MVFR. Deterioration is expected again for KDLH and KBRD, with
conditions lowering to MVFR after 04z and then to IFR in light
rain beginning around 07z. KHYR to remain in IFR ceilings, adding
in light rain with MVFR visibilities around 19z.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  59  51  58  48 /  40  60  90  80
INL  64  44  59  41 /  10  10  80  80
BRD  61  52  60  48 /  40  60  90  60
HYR  60  54  64  52 /  60  70  90  80
ASX  60  53  61  53 /  60  70  90  90

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement through this evening for WIZ001.

MN...Beach Hazards Statement through this evening for MNZ037.

LS...None.
&&

$$

SHORT TERM...Huyck
LONG TERM...LE
AVIATION...LE


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