Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 200542
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1242 AM CDT TUE SEP 20 2016

.SHORT TERM...(This evening through Tuesday)
Issued at 331 PM CDT Mon Sep 19 2016

Breezy conditions this afternoon aided by strong westerlies aloft
being tapped into by deep mixing and relatively dry air across the
area this afternoon.  Model soundings are showing that we`re mixing
to over 800mb, where winds are ranging from 35-40kts.  This evening
these should gradually diminish as a weak ridge builds into the area
and allows us to decouple from the higher winds that will remain
aloft.  Between the clear skies and decoupled winds temperatures
should drop off into the 40s most locations, with some low 40s for
far northern Minnesota.  Cooler than normal, but not by very much.

At upper levels we remain zonal westerlies with fairly fast flow,
with little in the way of shortwaves in it.  A mid level convergence
zone that sets up over the North and South Dakota border overnight
and early Tuesday will slowly spread clouds in our direction during
the day.  This also brings a wing of weak warm air advection across
the southern flanks of the CWA, but it is much stronger south of the
forecast area.  For now it appears we will be too dry at low levels
to produce showers out of this, and most models are dry. However, a
few models are bringing showers through, and cannot rule out lots of
virga and some sprinkles. Have left forecast dry for now, though we
may need to put in those pops later.

.LONG TERM...(Tuesday night through Monday)
Issued at 331 PM CDT Mon Sep 19 2016

An area of low pressure will get organized over western Nebraska
Tuesday night with a warm front into southern Minnesota. A fast west
southwesterly flow aloft will be covering the region. Models differ
in their solution on the handling of any convection that may fire
up. The GFS/CMC keep the rain south of the area, the ECMWF is a bit
farther north and the NAM is in between. The ECMWF is the first
model to develop some activity along the Minnesota/Canada border
area late Tuesday night. Used a blended approach which favored the
drier solutions of the GFS/CMC. On Wednesday, the CMC leans toward
the ECMWF, the NAM is the farthest north with showers and storms,
the GFS is south. The models do agree on general placement of
baroclinic zone affecting the southern tier of the forecast area.
Will use a blended solution. This approach is maintained for
Wednesday night as the surface low center drops into Kansas and an
inverted trof takes the place of the warm front. Different model
placement of this feature and embedded pieces of energy lifting
northeast along the boundary, favors having higher pops over
northwest Wisconsin. With all of these differences, this will affect
QPF placement and amounts and will therefore hold off on any
potential flooding wording. This will be monitored in subsequent
runs to see if a stronger signal can be ascertained. Thursday finds
the NAM/CMC offering similar solutions, while the GFS/ECMWF offer
another. Maintained the blend of models which keeps the bulk of the
rain across the southern zones and leaned toward the ECMWF/GFS.
Thursday night finds upper level ridging moving into the eastern
Dakotas/western Minnesota border area. High pressure over northwest
Ontario is trying to push drier air over the region, but the CMC
lifts the inverted trof into southern Minnesota and turns it into a
warm front. As a result, highest pops will be along the southern
third of the area. Model differences continue Thursday night with
the upper ridging nearby and the high over Ontario. The front begins
to bend northward as the surface low moves north. Maintained the
blended approach. The GFS and ECMWF come into better agreement
Friday night with the warm front/baroclinic zone draped over the
region from northwest to southeast and have pops aligned
accordingly. The upper ridging moves overhead on Saturday with the
models pointing to rain ending Saturday afternoon. Saturday night
and Sunday finds the surface low center moving over the region
accompanied by a strong upper level trof. This will result in a
rainy end to the weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1241 AM CDT Tue Sep 20 2016

High pressure will gradually lose its grip on the Northland, as
strong warm air advection pushes into the region from the south. A
warm front is expected to develop across central Minnesota on
Tuesday, with a few showers developing in the vicinity of the front.
Have included vicinity showers in the KBRD TAF for a time Tuesday
Morning. Conditions are expected to remain VFR throughout the period
at all sites.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  52  65  51  63 /  10  40  40  10
INL  46  64  43  64 /  10  10  10   0
BRD  53  68  52  65 /  10  50  40  10
HYR  53  69  54  66 /  20  60  70  20
ASX  54  67  52  65 /  10  50  60  20

&&

.DLH Watches/Warnings/Advisories...
WI...None.
MN...None.
LS...None.
&&

$$

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



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