National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KDLH 041147
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
547 AM CST Thu Mar 4 2021

.DISCUSSION...(Today through Wednesday)
Issued at 349 AM CST Thu Mar 4 2021

Main forecast concerns this morning include the stratus and the
effect they will have on max temps today, with similar concerns
for the next couple days with a ridge of high pressure over the
area. A shortwave moving through Manitoba and Ontario on Sunday
will produce our warmest day of the week. We have also been
watching the potential for a spring storm system in the Tuesday-
Thursday time frame.

Stratus clouds at less than 1 thousand feet have spread onto the
land from Lake Superior, and are affecting a large portion of the
MN Arrowhead as well as parts of NW WI this morning. I expect this
stratus to continue to expand or at least maintain through at
least sunrise, and from past experience is unlikely to clear until
late morning given the strength of the surface ridge axis, light
winds and steep low level inversion that is depicted on model
soundings. Models are not handling these clouds well, and worked
more with the 925-975mb RH off the NAM12 and RUC13 as a better
guide for what should happen with the stratus. This is going to
stifle the morning temperature rise, and have kept temperatures
cooler than yesterday where I expect the clouds to be most
persistent, but put more warming where there should be more
sunshine. There is a risk of having this stratus form and move
inland once again tonight but the wind trajectory may not work out
properly with the surface ridge axis shifting more directly over
the area and have decided to leave the stratus out for tonight and
early Friday and we will have to play things by ear tonight to
see if this changes. This should allow temperatures to get warmer
on Friday, and with the same pattern again on Saturday, high
temperatures both days should get into the mid 30s-mid 40s Friday
and slightly warmer Saturday.

The ridge axis shifts east late Saturday, and the strong upper
level ridge that we have for the latter part of the work week
flattens enough to allow a strong shortwave to move along the
US/Canada border for Sunday. A surface low develops over eastern
MT, moving east-northeast into Manitoba and then Ontario during
the day. This brings a surge over warm moist air into the area,
but with all the stronger dynamics up into Canada, the chances for
getting precipitation into the forecast area are pretty minimal
and have kept the forecast dry for now. However, if we get enough
moisture into the area from the south there may be some afternoon
showers. We will have to wait and see on this for now. The strong
surge of warm air should produce the warmest day of the week
though, and have put in high temperatures in the mid 40s to mid
50s for Sunday, which is on the high end of guidance.

Our next chance for precipitation moves into the area in the
Tuesday through Thursday time frame as the models are beginning to
show some consensus as bringing a strong deep trough axis across
the Rockies on Tuesday, moving east through the work week. For now
there is only general agreement on the 500mb heights, but the
details and lower levels still have pretty large spread and I
cannot say much more than we have a chance at some much needed
precipitation in the midweek time frame. For now, from the amount
of warm air pushed this direction, Tuesday and even Wednesday will
be on the warm side and the precipitation should start out with
rain, gradually switching over to snow before the system moves out
on Thursday. We will have to keep a close eye on this system, as
we could have some flooding concerns with precipitation falling on
top of the snowpack we have, even after we melt some of it off
this weekend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 547 AM CST Thu Mar 4 2021

IFR to low end MVFR stratus has overspread KDLH, KHIB and is
approaching KBRD as of issuance time. KDLH and KHIB should remain
in the stratus for at least the first few hours of the forecast
before the stratus lifts and dissipates, returning both sites to
VFR by 17z. The stratus should move into KBRD between 13z and 14z,
only to dissipate again around 16z. The stratus should stay out of
KINL and KHYR. Light winds of less than 10 knots and VFR
conditions are expected for much of the remainder of the time
range. With the warm conditions, light winds and melting snow, I
expect fog development tonight, and have included MVFR
visibilities for the most likely sites beginning at 10z, though
lower visibilities are possible.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  34  19  39  17 /  10   0   0   0
INL  42  15  40  15 /   0   0   0   0
BRD  45  21  43  22 /   0   0   0   0
HYR  43  14  42  14 /   0   0   0   0
ASX  35  16  38  14 /   0   0   0   0

&&

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

$$

DISCUSSION...LE
AVIATION...LE