Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 241126

Area Forecast Discussion
National Weather Service Duluth MN
626 AM CDT Tue Apr 24 2018

.SHORT TERM...(Today through Wednesday)
Issued at 255 AM CDT Tue Apr 24 2018

Quiet conditions across the Northland early this morning, with only
some high clouds overhead. Surface low pressure situated over
central South Dakota is progged to dive southeastward today, keeping
the Northland away from any appreciable precipitation. However, a
mid-level shortwave trough will dive through the region from
Manitoba Canada later this morning and early afternoon. The biggest
impact from this shortwave is an increase in cloud cover over the
region, with very small chances of any precipitation developing due
to dry low-level air entrenched over the region. The RAP model
soundings is the most bullish for precipitation with robust
saturation between the 800 to 500 mb levels, but the NAM and GFS
models soundings indicate much drier air in this layer. Confidence
is high that very little in the way of precipitation will occur with
this wave, but cannot rule out a sprinkle, so included some slight
chance POPs for this morning as the shortwave initially moves in.
Today`s high temperatures will be quite a bit cooler compared to
Monday`s due to the increased cloud cover and cold air advection
behind the shortwave. High temperatures should range from the upper
40s over the BWCAW to the lower to middle 50s over the southwestern
half of the forecast area.

Very dry air will quickly move in behind the shortwave, which will
lead to cold temperatures tonight. I decreased the low temperatures
for Wednesday morning by a few degrees from the previous forecast
package as we should have a night of good radiational cooling with
clear skies, light winds, and surface high pressure overhead.
Tonight`s lows should dip into the lower to middle 20s.

The high pressure remains in control through the day Wednesday as it
slowly dives southward. Skies will be mostly sunny, with dry
conditions expected across the region. There could be a window of
conditions approaching critical fire weather over Koochiching county
Wednesday afternoon as southwest winds strengthen due to a
tightening pressure gradient, but it appears marginal for now. Highs
Wednesday will warm back up into the middle 50s along Lake Superior,
to the upper 50s and lower 60s over north-central Minnesota.

.LONG TERM...(Wednesday night through Monday)
Issued at 255 AM CDT Tue Apr 24 2018

Wednesday night finds a positively tilted upper level trof moving
toward the region. Its associated cold front reaches northeast
Minnesota by 12Z Thursday. Moisture is limited ahead of the front.
Behind the front, moisture increases enough to warrant small chance
pops over the northwest corner of the forecast area. Temps are warm
enough that rain is the expected precipitation type. The upper trof
moves through Minnesota on Thursday and pushes the cold front
through northwest Wisconsin. The GEM/GFS have more moisture and
subsequently more QPF affecting the area. The ECMWF has less
moisture, resulting in less QPF. Regardless, have chance pops. A
rain/snow mix is possible along the international border early
Thursday morning. All rain is expected elsewhere. The upper trof
departs northwest Wisconsin Thursday night. Enough forcing and
moisture lingers in the southeast corner of the region to warrant
some low chance pops. Much colder air filters into the area behind
the trof, leading to a transition from rain to snow overnight. No
accumulations expected. Model differences reveal themselves with
the handling of the weak surface low following behind the
departing system, and its precip potential Friday. A blend was
used which led to small pops over the Arrowhead. A rain/snow mix
may occur in the morning, then transition to rain in the
afternoon. Have a dry forecast Friday night through Sunday night
as upper level and surface ridging are nearby. On Monday, a change
to the overall pattern begins to usher in a summer-like
atmosphere that is much warmer and more humid. 850mb temps,
depending on the model, rise into the teens. The GEM has colder
temps near the Canadian border with single digits at 850mb.
Regardless, they paint some precipitation into the region as upper
level energy in a fast flow aloft, cruises past. Have some chance
pops to account for model differences.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 626 AM CDT Tue Apr 24 2018

A cold front will move past the terminals today. Mid and high
clouds will accompany the front with a few sprinkles near HIB and
BRD. Have a VCSH mention to account for this possibility. The
front should move past HYR by 21Z, with a clearing trend from
north to south behind the front.


DLH  54  28  57  38 /  20   0   0  10
INL  48  22  62  39 /   0   0   0  20
BRD  56  27  61  40 /  20   0   0  10
HYR  55  23  56  36 /   0   0   0   0
ASX  53  28  55  33 /   0   0   0   0




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