I forgot to post this this past weekend but I recieved this email forwarded through my mom on Friday Feb. 18th regarding the snow storm forecast. (Note she lives in Shorewood, MN which is in the southwest suburbs of the Twin Cities).
I thought The best part of this email was that it was written by a Geographer and not a Meterologist!
The weather models have settled on a decidedly major storm system for the
weekend over much of the region. The differences between the models are
still significant, but even through those differences one can see the
signal: this should be one of the winter's largest storms. The
precipitation amounts being generated by the models are both large, and
widespread, and the forecast amounts and the total coverage both keep
growing. The models are indicating that an area of 150-200 thousand square
miles (approximately twice the size of Minnesota) will receive over
three-quarters of an inch of precipitation, and that about 60-75% of that
area will see over an inch; that is enormous. We still have no clue what
kind of model errors will screw up the forecasts, and which way the models
will be wrong, but a big, wet, regional winter storm is on its way.
Perhaps an even more interesting question than, "how much precipitation
will fall," is, "what kind of precipitation will fall?" Indeed, this system
is big and sloppy, and some of its temperature characteristics, especially
early on, resemble what we used to see a lot of in mid/late March. Maybe
February is the new March. Anyway, it is clear that some places, probably
in southeastern Iowa, far southern Wisconsin, and northern Illinois, are
going to see rain, and even heavy rain, and maybe even heavy rain with
lightning and thunder. But even some of those areas may start as freezing
rain, sleet, or even snow, and they certainly should end as light snow when
colder air works into the system. Moreover, even areas that end up getting
a decent amount of snow and sleet may have a period of rain mixed in early
on Sunday before the colder pushes in.
This system does have some ice storm potential, but realizing that
potential is contingent on keeping temperatures at the surface below
freezing while pumping in much warmer air aloft. This looks most likely
over parts of South Dakota, northwest Iowa, far southern Minnesota, and a
stripe of southwestern Wisconsin. Again, though, areas that experience
mostly rain also may see a period of freezing rain, as may areas seeing
mostly sleet and snow; and even in places that do receive significant
freezing rain, a period of liquid-only rain is also a good bet, as is a
snowy ending.
Now for snow: the area north and west of the Twin Cities is the only one in
*all* the models to have almost all of its precipitation fall as snow. So,
St. Cloud is likely to see all snow, or almost all snow. Same with
Alexandria, and Pine City. One problem, however, is that those areas are a
bit more iffy for the big precipitation amounts; some models have them in,
some have them out. One model is coming in with 12-18 of snow in those
areas; another looks more like 6-12, and yet another is showing more like
3-6 inches. If you blend the models together, or take their average, Twin
Cities area has much higher precipitation amounts than those places, and a
correspondingly higher probability of what we call "warning criteria
snow"--snowfall amounts large enough to warrant a winter storm warning.
But, Minneapolis has some issues concerning precipitation type, with snow
totals ranging from 8 to up to 18 inches. Do note the range, though: no
model is showing less than 8 inches of snow in the Twin Cities, and the
lowest model is cutting into the totals with a period of sleet and freezing
rain at the beginning.
As with everything else, the models exhibit some differences regarding when
the precipitation begins, when the *heaviest* precipitation begins, when
the whole things winds down, and how long precipitation of a certain type
is falling at any given location. But again, some things are clear. The
precipitation will begin in most places on Saturday night--maybe early in
the night, maybe late. By Sunday morning, however, it will be game-on,
pretty much everywhere (Chicago may miss the bulk of this storm, but it
will be close, and in any case would be mostly rain). Don't look for signs
of this thing to the west on Saturday, because you won't find much. The
ingredients fueling the intensification of it are going to be materializing
overhead, and once the precipitation begins, it won't take very long to
reach maximum intensity. Expect the heaviest precipitation on Sunday and
into Sunday night, depending on where you are, with a band of
light-moderate snow persisting over much of the area into Monday morning.
Winds will become intense on Sunday, and this is going to have some
white-out and blizzardy elements in open areas.
Expect some changes to the finer points of the forecast, but unless the
system does a complete head-fake, I would expect a major winter storm over
the region on Sunday.
Kenneth A. Blumenfeld, Ph.D.
Dept. of Geography, UMN; Dept. of Nat. Sciences, Metro State Univ. (MN)
weekend over much of the region. The differences between the models are
still significant, but even through those differences one can see the
signal: this should be one of the winter's largest storms. The
precipitation amounts being generated by the models are both large, and
widespread, and the forecast amounts and the total coverage both keep
growing. The models are indicating that an area of 150-200 thousand square
miles (approximately twice the size of Minnesota) will receive over
three-quarters of an inch of precipitation, and that about 60-75% of that
area will see over an inch; that is enormous. We still have no clue what
kind of model errors will screw up the forecasts, and which way the models
will be wrong, but a big, wet, regional winter storm is on its way.
Perhaps an even more interesting question than, "how much precipitation
will fall," is, "what kind of precipitation will fall?" Indeed, this system
is big and sloppy, and some of its temperature characteristics, especially
early on, resemble what we used to see a lot of in mid/late March. Maybe
February is the new March. Anyway, it is clear that some places, probably
in southeastern Iowa, far southern Wisconsin, and northern Illinois, are
going to see rain, and even heavy rain, and maybe even heavy rain with
lightning and thunder. But even some of those areas may start as freezing
rain, sleet, or even snow, and they certainly should end as light snow when
colder air works into the system. Moreover, even areas that end up getting
a decent amount of snow and sleet may have a period of rain mixed in early
on Sunday before the colder pushes in.
This system does have some ice storm potential, but realizing that
potential is contingent on keeping temperatures at the surface below
freezing while pumping in much warmer air aloft. This looks most likely
over parts of South Dakota, northwest Iowa, far southern Minnesota, and a
stripe of southwestern Wisconsin. Again, though, areas that experience
mostly rain also may see a period of freezing rain, as may areas seeing
mostly sleet and snow; and even in places that do receive significant
freezing rain, a period of liquid-only rain is also a good bet, as is a
snowy ending.
Now for snow: the area north and west of the Twin Cities is the only one in
*all* the models to have almost all of its precipitation fall as snow. So,
St. Cloud is likely to see all snow, or almost all snow. Same with
Alexandria, and Pine City. One problem, however, is that those areas are a
bit more iffy for the big precipitation amounts; some models have them in,
some have them out. One model is coming in with 12-18 of snow in those
areas; another looks more like 6-12, and yet another is showing more like
3-6 inches. If you blend the models together, or take their average, Twin
Cities area has much higher precipitation amounts than those places, and a
correspondingly higher probability of what we call "warning criteria
snow"--snowfall amounts large enough to warrant a winter storm warning.
But, Minneapolis has some issues concerning precipitation type, with snow
totals ranging from 8 to up to 18 inches. Do note the range, though: no
model is showing less than 8 inches of snow in the Twin Cities, and the
lowest model is cutting into the totals with a period of sleet and freezing
rain at the beginning.
As with everything else, the models exhibit some differences regarding when
the precipitation begins, when the *heaviest* precipitation begins, when
the whole things winds down, and how long precipitation of a certain type
is falling at any given location. But again, some things are clear. The
precipitation will begin in most places on Saturday night--maybe early in
the night, maybe late. By Sunday morning, however, it will be game-on,
pretty much everywhere (Chicago may miss the bulk of this storm, but it
will be close, and in any case would be mostly rain). Don't look for signs
of this thing to the west on Saturday, because you won't find much. The
ingredients fueling the intensification of it are going to be materializing
overhead, and once the precipitation begins, it won't take very long to
reach maximum intensity. Expect the heaviest precipitation on Sunday and
into Sunday night, depending on where you are, with a band of
light-moderate snow persisting over much of the area into Monday morning.
Winds will become intense on Sunday, and this is going to have some
white-out and blizzardy elements in open areas.
Expect some changes to the finer points of the forecast, but unless the
system does a complete head-fake, I would expect a major winter storm over
the region on Sunday.
Kenneth A. Blumenfeld, Ph.D.
Dept. of Geography, UMN; Dept. of Nat. Sciences, Metro State Univ. (MN)
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