Scientific Forecaster Discussion
fxus63 kmpx 221057
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
457 am CST Mon Jan 22 2018
Short term...(today and tonight)
issued at 451 am CST Mon Jan 22 2018
The winter storm remains on track for southern Minnesota and western
Wisconsin. The Hazards that were in place yesterday were left
untouched as the adjustments were mainly focused on tweaking the
northern gradient and adjusting the thermal profile from the Albert
Lea toward Eau Claire areas.
Early this morning, the deepening surface low was located over
extreme northwestern Missouri and will continue to deep and lift
into Iowa today. Meanwhile, the main precipitation band is taking
shape from Nebraska through northern Iowa, and is lifting into
southern Minnesota. Albert Lea continues to report rain falling, but to
the east a cooler thermal profile has allowed a changeover to snow
The hi-res models now cover the storm as it moves through and has
only increased our confidence in the forecast. The heaviest band of
snow of 8-14" remains in the same place; from near Fairmont through
Red Wing, Menomonie, and Ladysmith.
The Twin Cities Metro still looks to have a tight snowfall gradient.
With the rap, hrrr, and hopwrf now covering the temporal period of
the storm, confidence is increasing that the southeast Metro will
see 6"+ of snow and the gradient may be a few miles northwest of
earlier expectations. Did adjust the snow amounts upward along the
northern gradient. Further aiding in this decision was the fact that
overnight lightning across the state of Iowa wasn't all that
widespread. In addition, we've been watching a west to east band of
snow developing from Canby through the Metro toward Menomonie. This
will produce some light snowfall this morning before the main event
ensues for the Metro mid morning, with the heaviest snow expected
The hrrr and rap show the potential for a heavy snow band to impact
the Metro mid afternoon leading up to the evening commute. This
band could have 1-2"/hr rates given the strong mesoscale forcing
associated with it and make for a very slow commute this evening.
The winds will continue to strengthen as the low moves through Iowa
today, with blizzard conditions developing from south and west of
Mankato. Again, the heaviest snow will arrive in far southern Minnesota
early this morning, with the heaviest period of snow expected later
today in the Metro and western WI. The morning commute will be
impacted across far southern Minnesota by the onset of the snow, while the
Metro and Wisconsin will see minimal issues this morning for the
commute. The afternoon commute will be a completely different
Long term...(tuesday through sunday)
issued at 451 am CST Mon Jan 22 2018
No significant changes in the extended. Blended guidance shows a
slight cool down in the wake of today's storm, with highs in the mid
to upper 20s Tuesday and Wednesday, but this is still about 2 to 5
degrees above the seasonal average for late January. A weak
shortwave will embedded in northwest flow will slide southeast
across the region Tuesday night, and this should be strong enough to
produce some clouds, but not enough to precipitate other than
perhaps a few flurries.
Upper level ridging will ensue for Wednesday night and Thursday,
keeping the region dry and mild. On Friday highs could reach the
lower 40s across the region as the low level thermal ridge advects
across the region. A cold front will follow Friday night with cold,
but not bitterly cold temperatures for the weekend into early next
week. No significant precipitation is expected at this time.
Aviation...(for the 06z tafs through 06z Monday night)
issued at 1057 PM CST sun Jan 21 2018
Conditions will steadily deteriorate over all taf sites as the
overnight hours progress, especially over southern/eastern Minnesota
into western WI. Mkt/eau still look to be the most impacted with
msp/rnh/rwf right on the gradient line. Axn/stc look to receive
little to no precipitation so have maintained a dry forecast for
those 2 sites yet IFR ceilings do look likely. Frequent amendments
do look likely for the southern and eastern taf sites depending
on exactly where the tight snow gradient sets up and how intense
the snowfall is.
Kmsp...conditions will remain as VFR for much of the overnight
then ceilings will drop to near or just below MVFR thresholds at
the start of the Monday morning push. Precipitation may hold off
until right at the end of the push, but timing could be slightly
earlier than the 14z currently advertised. IFR conditions look
likely by late morning, including the potential for 1 in/hr rates
early-mid afternoon. Snowfall is expected to continue through the
evening push, which given the potential for 1 in/hr rates for much
of the afternoon could make the evening push more of a problem
than the morning, but with improving conditions such that VFR
conditions return by late Monday evening.
/Outlook for kmsp/
Tue...MVFR thru mrng. Winds northwest 5-10 kts.
Wed...MVFR/IFR cigs. Winds 5 kts or less.
Thu...MVFR/IFR cigs. Winds southeast 5-10 kts.
WI...Winter Storm Warning from 9 am this morning to midnight CST
tonight for wiz014.
Winter Storm Warning until midnight CST tonight for wiz015-016-
Minnesota...Winter Storm Warning from 9 am this morning to midnight CST
tonight for mnz060-062-063-067>069.
Winter Weather Advisory from 9 am this morning to midnight CST
tonight for mnz053-061-065-066-073.
Winter Storm Warning until midnight CST tonight for mnz075-076-
Winter Storm Warning until midnight CST tonight for mnz070-077-
Blizzard Warning until midnight CST tonight for mnz074-082-083-