Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 220603
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
103 AM CDT THU SEP 22 2016

.SHORT TERM...(This evening through Thursday)
Issued at 303 PM CDT Wed Sep 21 2016

Main concern for the short term will be the potential for heavy
rainfall this evening across parts of east-central Minnesota and
northwest Wisconsin. While the highest risk for flooding remains
further south, there is potential for heavy rainfall along the I-35
corridor in east-central Minnesota east across all of northwest
Wisconsin. Showers and storms will develop along a stationary front
late today and continue through Thursday in this area. In northern
Minnesota, high pressure building in across central Manitoba into
northwest Ontario should result in clearing skies late tonight into
Thursday. Temperatures near normal with highs in the low to mid 60s
across the Northland today and tomorrow, with lows tonight in the
low to mid 50s - except to the mid 40s along the international
border.

On the synoptic scale a fast near-zonal flow aloft is nearly on its
way out. Aloft a fast upper level jet has persisted over southern
Canada, with a 130 knot wind sampled at 300mb on the Pickle Lake
Ontario sounding this morning (CWPL - about 230 miles NNE
International Falls MN). At the surface, a well defined stationary
front across southern Minnesota into central Wisconsin is expected
to gradually move northward as a warm front late today into tonight
with convection developing along the front late in the afternoon. As
it moves northward, it will bring instability on the order of 1000
j/kg - slightly more than originally anticipated. The best deep
moisture will remain farther south, but in the 00z-06z timeframe
PWAT values may approach 2.0" across Pine/Burnett/Washburn county
per some models - but the majority of the guidance is lower with
1.60-1.75" PWATs across this region. Note, the highest PWATs is not
necessarily where the most rain will fall, and it is expected that
storms wil fire along the frontal zone. Some training is possible
due to the easterly storm motion along the front, but the window for
heavy rainfall will be rather small thus limiting potential for
flooding. By Thursday morning drier air moving in from the north
will push the frontal zone further south, and by 18z PWAT values
across northwest Wisconsin will be less than 1.50" - rain shower may
continue through Thursday in NW Wisconsin, but they will be much
less intense compared to the initial storms that develop this
afternoon and evening.

Overall guidance is in fairly good agreement for the heavy rainfall
potential, with the Northland on the northern periphery of the
heaviest rainfall. It`s possible that the storms fire along the
frontal zone earlier and/or farther south than currently anticipated
which would result in less precipitation than currently forecast.
It`s also possible (though less likely given current trends) that
the front surges a bit further north than currently anticipated. One-
hour flash flood guidance across east-central MN into northwest
Wisconsin is on the order of 1.50-2.10", with 3-hour guidance in the
2.00-2.50" range. While some high-res convection-allowing guidance
does indicate produce sort of rain rates in isolated spots (not
unexpected given model soundings), the large-scale parameterized
guidance is much, much less aggressive this far north with no 6-hour
QPF amounts more than an inch (and most less than a half-inch).
Localized flood risk does exist, but have decided to continue to
hold off on a flash flood watch as confidence is not high enough
that flash flooding will occur.

.LONG TERM...(Thursday night through Wednesday)
Issued at 303 PM CDT Wed Sep 21 2016

Upper level ridging will be building into the forecast area from the
west Thursday night and be over the area on Saturday. Below this
ridge, a warm front will be lifting northward through the forecast
area. Meanwhile, an area of high pressure will be over northwest
Ontario Thursday night and drift eastward through Saturday. This
will result in chances of showers mainly over the southern tier of
the forecast area Thursday night and Friday. With a lack of good
instability, have a mention of showers. Friday night through
Saturday night finds an axis of weak instability, around 0C at
850mb, advecting northward through the forecast area. With such weak
instability, have a mention of isolated thunderstorms with the
chance of showers wording. Also on Saturday night, a closed,
deepening, cut off low will begin to move from the Northern Plains
into northern Manitoba by Monday. This cut off low will become
vertically stacked with its surface low and punch a cold front
through the region on Sunday. Models begin to have large differences
with the handling of this system. Will feature showers with the
frontal passage to account for these differences and thus blend the
pops. Will maintain the blended approach for all elements through
Tuesday as the model differences persist.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 103 AM CDT Thu Sep 22 2016

A stationary front will gradually slide southeastward from
southern MN and central WI into northern IA and southern WI by
Thursday evening. This will result in showers and storms impacting
KHYR and potentially moving into KDLH/KBRD tonight. This will
bring MVFR to IFR ceilings or lower as the lower levels moisten
per the latest RAP/HRRR. In the heavier showers/storms expect
visibility reduction, with visibility lowering most likely at
KHYR. Kept in the MVFR range based on surrounding observations,
but lower is possible.

Will gradually see conditions improve to VFR at KDLH/KBRD/KHYR as
the front slides away allowing drier air to move in from the
northwest. Expect VFR conditions to develop late in the TAF period
for KHYR and around 12Z to 15Z for KDLH/KBRD.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  51  61  50  60 /  50  10  10  10
INL  46  64  44  64 /  10   0   0   0
BRD  51  66  52  62 /  50  10  10  40
HYR  55  64  52  63 /  80  40  30  20
ASX  55  62  50  64 /  70  40  10  10

&&

.DLH Watches/Warnings/Advisories...
WI...None.
MN...None.
LS...Small Craft Advisory until midnight CDT Friday night for LSZ121-
     141>148.

&&

$$

SHORT TERM...JJM
LONG TERM...GSF
AVIATION...WL


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