Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 221800 AAB
AFDDLH

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
100 PM CDT Wed Mar 22 2017

.UPDATE...
Issued at 100 PM CDT Wed Mar 22 2017

Updated for new 18Z Aviation Discussion below.

&&

.SHORT TERM...(Today through Thursday)
Issued at 419 AM CDT Wed Mar 22 2017

Large ridge of high pressure has built into the forecast area
this morning, which has brought clear skies and falling
temperatures overnight. Many locations are in the single digits as
of 3 am, and expect many below zero values before morning. Today
this surface ridge is going to shift off to the southeast,
allowing south return flow to pick up over the forecast area. This
south flow will bring warmth and moisture will surge back into
the area from the south, but how quickly it moves in is the
question. Strong warm air advection pushes in above 850mb late
this afternoon, which is likely to spread mid and high clouds into
the forecast area. Despite the strong warm air advection, the
clouds are likely to limit heating today, and have only gone with
highs in the upper 20s to upper 30s, with the colder values across
the north where even if we do get the most amount of sunshine,
the below zero early morning min temps are going to keep temps
near or below freezing. Some high resolution models are bringing
some small pops in as early as this afternoon and evening.
However, from other models it appears the low layers are too dry,
and we are more likely to get increasing clouds and virga for this
afternoon and evening before we get enough moisture and lower
level convergence to produce snow later tonight to mainly the
eastern portions of the forecast area. Again, the drier air is
going to keep the pops in the slight to chance pop range.

Thursday our next strong storm system begins to move into the
area from the southwest. The strong warm, moist air advection
continues through a deep layer on Thursday, which should produce a
band of rain that moves across the forecast area during the day.
The warm air advection should bring temperatures aloft above
freezing, and with most of the forecast area above freezing when
this precipitation begins, have put in a mainly rain forecast,
with a little bit of mixed snow and rain for the far northeast
before surface temperatures rise. Have some likely pops in the
south for now, but we may need to expand these if the isentropic
lift continues to look good going into Thursday morning.

.LONG TERM...(Thursday night through Tuesday)
Issued at 419 AM CDT Wed Mar 22 2017

A few mid-level impulses and temperatures near or above seasonal
averages highlight the long-term forecast.

Thursday night and Friday morning start with chances of
precipitation situated over the Northland. A mid-level shortwave
trough with a good PVA maximum associated with it will translate
over the region during this time. Coupled with a deep saturated
profile up to 750 mb as indicated by the latest GFS/NAM model
soundings should provide ample moisture for precipitation.
Analysis of the thermal profiles for both the NAM and GFS show a
bit of uncertainty as the GFS is showing mostly rain through early
Friday morning, where the NAM is indicating more of a wintry mix.
In any case, the thermal profile is very close to the 0 degree
isotherm, so a small change in the temperature profile would
change the p-types. The NAM is the most concerning, especially
over Price, Sawyer, Ashland, and Iron counties in northwest
Wisconsin as the thermal profile is indicating a period of
freezing rain. With sfc temperatures expected to be either at or
below freezing, and a shallow cold layer of approximately 2000 ft,
the NAM solution is the most bullish with freezing rain. If this
solution does come to fruition, there could be some decent ice
accumulation amounts across these portions of northwest Wisconsin.
However, aforementioned uncertainty still exists, especially
since it`s a few days out. Farther north along northeast
Minnesota, snow and sleet look to be the more common p-types due
to a deeper cold layer near the sfc.

POPs look to slowly decrease from north to south as the system
departs to the east. Precipitation should transition to all rain
during the day Friday as the low-level thermal profiles warm up.
Could be a lingering rain/snow mix over extreme southeast portions
of the forecast area Friday night into Saturday morning. Most of
the Northland looks to stay dry during the day Saturday before
low-level warm air advection and an inverted trough from a sfc low
pressure system that`s expected to translate across northern
Missouri and Illinois Saturday night through Sunday moves
overhead. This wave could bring another shot at some wintry mix
precipitation across a good portion of the Northland. A secondary
shortwave looks to develop out of Montana and bring yet another
shot at precipitation. This time, a rain/snow mix through Monday
night. Drier conditions are expected for Tuesday and Wednesday.
High temperatures into the lower to mid 40s are forecast for the
entire long-term period, with the only exception of upper 30s
across the tip of the Minnesota Arrowhead.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 100 PM CDT Wed Mar 22 2017

VFR conditions will continue this afternoon before lowering to
MVFR/IFR this evening and Thursday morning. A warm front aloft was
positioned over the eastern Dakotas this afternoon and will move
eastward into BRD late this afternoon or early this evening, and
through the remainder of the terminals by 23.06Z. Expect MVFR
ceilings along and behind the boundary. A relatively solid line of
snow showers accompanied the front early this afternoon. Expect
the snow showers to push into the terminals along with the front.
Visibility may decline to IFR where the heaviest snow showers
occur, most likely INL and HIB. BRD may experience IFR visibility,
as well, but confidence is lower at that site. The snow showers
will move out late overnight/early Thursday morning, but the MVFR
ceilings will linger.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  34  24  38  30 /   0  10  60  60
INL  35  27  43  28 /  10  10  40  40
BRD  37  30  41  32 /  10  10  50  50
HYR  38  27  39  32 /   0  20  50  70
ASX  38  23  41  31 /   0  20  50  60

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

UPDATE...Huyck
SHORT TERM...LE
LONG TERM...JTS
AVIATION...Huyck



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