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Area forecast discussion 
National Weather Service Duluth Minnesota
939 am CDT Tuesday Jul 28 2015

issued at 939 am CDT Tuesday Jul 28 2015

Scattered showers and an isolated storm in northwest WI will diminish
through the rest of the morning. The cold front remains well to
the west of the forecast area and is just entering the Red River
valley of the north at 1430z. The prognosis for additional shower
and storm activity this afternoon has diminished greatly per the
latest hrrr/rap runs. Have reduced probability of precipitation/quantitative precipitation forecast considerably for this
afternoon. However...the warm and humid conditions will prevail
until the front arrives. Adjusted for these trends.


Short term...(today through wednesday)
issued at 443 am CDT Tuesday Jul 28 2015

A complex forecast in the short term as two rounds of showers and
storms are expected to move across the region today...then becoming
very windy tomorrow behind a strong cold front.

An area of low pressure currently along the North Dakota/Canada
border this morning will progress northeastward today with a
secondary low along the central ND/South Dakota border this morning
progressing in a similar fashion towards northeast Minnesota
tonight. From this secondary low pressure extends a warm front which
by 18z will be lifting northeast towards the Brainerd lakes region.
Ahead of this warm front an mesoscale convective system was progressing eastward out of the
Dakotas into west-central to southwest Minnesota.

Focus for this morning will be the convection moving in from the
west ahead of the warm front...with the question of just how well
these storms hold up as they reach the Northland. Short-range
guidance and mesoanlysis indicate appreciable elevated instability
is in place as of 09z this morning across north-central Minnesota
with 500-1000 j/kg MUCAPE. Should storms sustain...which per latest
radar/lightning they do not show signs of weakening yet...widespread
strong thunderstorms producing intense rainfall will overspread much
of northeast Minnesota this morning. This first round of storms will
be in a very moist environment with precipitable waters approaching 2.0 inches
across the region...which is in the 99th percentile compared to
climatology for parts of the region. Think the quantitative precipitation forecast output from much of the
guidance is a bit underdone given the potential for downpours. Storm
motions should be swift enough to limit flooding risk...but
localized flooding is always possible with this type of environment.

Early this afternoon this convection is expected to run out of steam
as it progresses into northwest Wisconsin and the Minnesota
arrowhead as it moves ahead of the best elevated instability. Still
have some concerns with this...but think as soon as it cross the
state line we will see a rapid decrease in intensity as storms
weaken. Across the rest of the region the morning convection will
diminish...though the hot and humid conditions will make for a muggy
afternoon. Clouds are expected to linger through the day...though
any clearing this afternoon across north Central/Northeast Minnesota
will increase the threat for severe weather this afternoon.

This afternoon...the north-south oriented cold front will progress
eastward across northern Minnesota. While isolated convection will
be possible along the front...there will be a strong cap in place
due to the very warm airmass ahead of the front. However...storms
that do break the cap will rapidly grow due to extreme
instability...MLCAPE values 2000-400 j/kg per a blend of short-range
guidance. Wind profiles are not especially supportive of supercell
thunderstorms with only 20-30kts effective bulk shear and weak winds
around 3-5km producing a less-than-stellar hodograph. Should storms
develop think they could quickly be capable of producing large
hail...but not for long given the wind profiles...with gusty winds
possible as storms collapse. This threat will need to be re-
evaluated depending on how storms progress this morning...but at
this time think there is a conditional risk for severe thunderstorms
as the front moves east across northeast Minnesota late this

Tonight...front will clear through the County Warning Area by the evening hours with
a few isolated showers/storms possible across The Arrowhead and
northwest Wisconsin ahead of it...with skies clearing behind the
front. Cold air moving in aloft should result in some lows reaching
the upper 50s in northeast Minnesota...though winds are expected to
be 5 to 10 miles per hour out of the southwest throughout the night.

Wednesday...windy with a chance for showers along the international
border. As the main surface low progress northward through western
Ontario expect some wrap around showers to effect the international
border region...but otherwise mostly to partly sunny across the rest
of the region. Winds will be the main concern...deep mixing to
around 750mb will result in gusts to 35-45 miles per hour being mixed down to
the surface. Highs will be close to seasonable in the middle 70s to
near 80...and down to the low 70s across the international border
into the tip of the Minnesota arrowhead region.

Long term...(wednesday night through monday)
issued at 443 am CDT Tuesday Jul 28 2015

The extended period will feature a Pacific... almost zonal flow
early...then as the western ridge builds expect a more northwesterly
flow. All the while a closed upper low will become semi-permanent
over Ontario. It is this upper low that will push embedded S/waves
through the region later in the week. The Minnesota arrowhead will have a
chance of some showers Thursday night...but the chances of more
widespread showers and thunderstorms will come late in the weekend
and early next week as a stronger wave rotates across the western
Great Lakes.


Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 639 am CDT Tuesday Jul 28 2015

Showers and thunderstorms will be over the Minnesota portion of
the forecast area this morning. Ceilings will be mainly VFR...but a
few pockets of MVFR. More showers and storms are expected to
develop this afternoon. Some of the storms could have damaging
winds and hail. A cold front will move across the region this
afternoon and evening. Expect winds to be very gusty tomorrow.


Preliminary point temps/pops...
dlh 81 60 78 59 / 30 40 0 0
inl 84 57 72 54 / 30 30 30 10
brd 83 62 80 59 / 100 20 0 0
hyr 82 61 79 56 / 70 60 0 0
asx 84 63 81 59 / 40 50 0 0


Dlh watches/warnings/advisories...


short term...jjm
long term...clc

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