Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 211348
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
848 AM CDT WED SEP 21 2016

.UPDATE...
Issued at 848 AM CDT Wed Sep 21 2016

Minor update to adjust pops/weather/sky cover through today. Still
expecting showers and storms to develop late this afternoon across
central Minnesota and northwest Wisconsin along an east-west
oriented stationary boundary. Increasing the thunder wording a bit
as instability seems to be a bit more than originally anticipated
per MPX sounding, SPC Mesoanalysis, and short-range guidance.

&&

.SHORT TERM...(Today through Thursday)
Issued at 354 AM CDT Wed Sep 21 2016

The Northland will be under near-zonal flow aloft through
Thursday, with surface high pressure building into south central
Canada from the west, and a warm/stationary front across southern
Minnesota and southern/central Wisconsin. In addition, a
trough boundary will likely set up across part of northwest
Wisconsin tonight, providing a focus for showers (and maybe some
thunder) tonight into Thursday.

A weak shortwave will pass across far northern Minnesota this
morning, possibly bringing some light rain to the northern
forecast area. There will be cool, breezy (downwind of the tip of
the Lake Superior), east- northeast flow today, bringing drier air
from Canada into the region. However, there will be building
moisture from the south due to a warm/stationary front across
southern Minnesota into central Wisconsin. This will bring
increasing chances of showers and some thunder into the southern
half of the forecast area. The RAP13, NAM12, GFS, and SREF
soundings and modeled CAPE profiles, as well as lack of forcing,
do not indicate much potential for thunder, but cannot rule out
some embedded thunder. Therefore, downplayed the threat of the
thunder.

The chances of rain peak tonight. A trough boundary will likely
develop from southern Minnesota into northwest Wisconsin,
providing an area of enhanced low level frontogenesis. This
frontogenetical band will provide a focus for showers tonight,
possibly some thunder. However, models still are rather low on
CAPE, and in the absence of any other significant forcing,
continued to downplay the chances of thunder in the forecast.
However, it appears some shortwaves may pass near or just south of
the forecast area, which could bring a better chance of
thunderstorms to the most extreme southern areas of the forecast
area in northwest Wisconsin. The boundary will shift east and
south late tonight into Thursday, generally shifting the showers
and thunder to the south and east, as high pressure and drier air
build into the region.

There is the potential for significant rain across parts of
northwest Wisconsin late today into early Thursday. Widespread
rainfall of 0.5" to 1.0" is forecast, but there could be isolated
higher amounts. The 6-hour flash flood guidance is about 2.5 to 3
inches, but since this rain looks more stratiform with only
isolated weaker thunderstorms, it appears the flash flood threat
is rather low. However, the passing shortwaves tonight could clip
the border areas of the forecast area, bringing a better chance of
heavy rain from thunderstorms. Considered a flash flood watch, but
confidence in its occurrence for any significant portion of
Burnett to Pine Counties in northwest Wisconsin is too low at this
time.

.LONG TERM...(Thursday night through Tuesday)
Issued at 354 AM CDT Wed Sep 21 2016

A large area of high pressure will migrate over Ontario Thursday
night through Friday. Have continued to carry small pops across
Wisconsin zones during this time. However, the Canadian airmass
will bring dry and stable conditions into the western Lake
superior region, keeping the bulk of the moisture and best chance
for rain confined to locations south of the Hayward Lakes area.

Focus turns to the next low pressure system which will lift a
warm front across the upper midwest Friday night into Saturday.
This front and associated warm air advection is expected to be the
focus for showers and a few thunderstorms. There will be a breif
dry period late in the day saturday, as models suggest a dry slot
pushes into the Northland. However, the break will be short lived
as the cold front sweeps across the region, triggering another
round of showers and thunderstorms Sunday.

The rain chances will remain in the forecast into next week as a
slow moving upper level low tracks across northern minnesota. The
GFS bufr soundings show steep lapse rates associated with the low
as 850 hPa temps fall into the single digits.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 659 AM CDT Wed Sep 21 2016

A warm front will bring gradually lowering ceilings and increasing
coverage of rain showers across the forecast area through the taf
period. Expect terminals to remain VFR through the morning, with
MVFR ceilings developing late in the afternoon and persisting
overnight. Low confident on how widespread the thunder will be
across NE MN. Main threat for thunder and heavy rain will be at
KHYR near the front where there is more instability and forcing.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  64  51  62  52 /  40  60  10  10
INL  65  44  65  43 /  50  10   0   0
BRD  68  53  66  51 /  30  60  20  20
HYR  70  56  65  50 /  70  90  50  30
ASX  66  54  62  49 /  60  80  30  20

&&

.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 from 4 PM this afternoon to midnight CDT
     Friday night for LSZ121-144>148.

     Small Craft Advisory from 10 PM this evening to midnight CDT
     Friday night for LSZ141>143.

&&

$$

UPDATE...JJM
SHORT TERM...G2
LONG TERM...Graning
AVIATION...Graning



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