Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 231138
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
638 AM CDT Thu Mar 23 2017

.SHORT TERM...(Today through Friday)
Issued at 438 AM CDT Thu Mar 23 2017

A very complicated forecast for the next 24 hours, with some
sensitive fluctuations that will have a very large impact on the
forecast area, but that`s for tonight. As of early this morning,
yesterday`s ridge of high pressure has slid to the eastern Great
Lakes region, with a developing surface low over eastern Colorado
this morning, and an inverted trough extending north up into
Manitoba and Saskatchewan where a weak low was centered. A lobe of
mid level moisture over eastern Nebraska and Kansas this morning
is going to surge north today on a wave of isentropic lift, moving
into the forecast area this afternoon, and remaining over
northern Minnesota and Wisconsin through tonight before narrowing
and shifting back south again on Friday. Rain and even a little
embedded thunder is expected to spread into the forecast area from
the south this afternoon. The initial wave of snow/sleet from a
leading wave is moving across the area early this morning and
should move out of the area to the east fairly early this morning,
and expect a period of drier conditions for at least a few hours
before the next wave moving in from the south gets here. A fairly
major complicating factor are the temperature profiles associated
with this system. The warm air advection should bring our mid
level temperatures above freezing, and while we should warm above
freezing during the day today, tonight they are going to dip to
near or just below freezing for a large portion of the area. This
is going to produce a mixture of freezing rain, sleet and rain to
a fairly large portion of the area overnight tonight, and could
make for some significant travel problems for the Friday morning
commute. However, these temperature profiles are very dependent on
getting the temperatures at the surface and aloft right, and with
tonight`s Min temperature guidance ranging from the low to mid
30s  the Canadian- on the warm end, to the 20s  bias
corrected NAM12 - on the cold end, this puzzle is not making
itself easy this morning. For now, I have decided to go with a
winter weather advisory for portions of northwest Wisconsin,
knowing that it may need to be expanded to include portions of the
north shore as well, or dropped entirely depending on temperature
trends in the next 18 hours. It seemed to better to get the
notification of the potential out now rather than wait.

.LONG TERM...(Friday night through Wednesday)
Issued at 438 AM CDT Thu Mar 23 2017

While a vertically stacked upper/surface low meanders through the
Southern Plains Friday night, high pressure will be drifting through
northwest Ontario. An upper short wave trof with weakening area of
vorticity moves over western Lake Superior. This will be just enough
lift to continue to mention some mixed precipitation over much of
Pine county and northwest Wisconsin. Dry elsewhere due to the
surface ridge axis from the aforementioned high extending through
the area. On Saturday, upper level and surface ridging covers the
region. However, only the GFS is trying to back build some
precipitation into northwest Wisconsin as it has an embedded impulse
lifting into this area. Cannot rule it out completely and have small
pops for mixed ptypes in the early morning, then rain by mid morning
into the afternoon. The GFS continues to be the only model with
precipitation over the forecast area Saturday night, but is then
joined by the GEM. The NAM/ECMWF are dry. Used a blend for
ptypes/pops. The vertically stacked system departs Sunday, which
allows for the next pair of upper waves to affect the region through
Monday. Embedded impulses will cross the area between and with these
features, and will use a blended approach to pops/ptypes to resolve
differences in models and their thermal profiles. A Hudson Bay high
sets up for Monday night through Wednesday which will keep the
region dry. The only model bringing in any precipitation is once
again the GFS on Wednesday afternoon. Will have a small pop to
account for this option. Temps will be above normal.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 637 AM CDT Thu Mar 23 2017

VFR at the start of the forecast. From 16Z to 21Z, a gradual
spread of MVFR cigs is expected ahead of an area of light rain
that is forecast to overspread the terminals. There is a remote
chance of some thunderstorms affecting DLH/BRD/HYR around 00Z.
However, confidence is low and have left out for now. There is
also a small window for some light freezing rain to affect HYR
from 03Z to 05Z with IFR cigs. IFR cigs will eventually affect all
terminals but INL from 04Z to the end of the forecast.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  37  31  43  26 /  70  80  20  10
INL  43  29  40  23 /  50  50   0   0
BRD  40  32  47  28 /  70  70  20  10
HYR  39  33  45  29 /  60  80  60  20
ASX  40  32  43  28 /  60  80  30  20

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 8 PM this evening to 9 AM CDT
     Friday for WIZ002>004-008-009.

MN...None.
LS...None.
&&

$$

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


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