First accumulating snow this Saturday?

We first reported last week that it looks like this upcoming Saturday could yield the first accumulating snow of the season. (Click here to read it.)

snowIt still seems quite plausible that we’ll need the shovels and winter driving skills for Saturday as the GFS model is now showing a potential for 2-3 inches of snow. We do not pin down numbers for snowfall until we are within 24-36 hours of the event, so it wouldn’t be wise to hang your hat on this graphic or this forecast. We’re just putting it out there for ya. -ES

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Posted under snow

This post was written by qni_it on November 30, 2010

Greenland Block

850Record warmth is forecast for parts of ice-covered Greenland this week and next. Parts of Newfoundland and Nova Scotia will see temperatures in the 40s and 50s this week which is some 20-30 degrees above average! The map to the left shows the departure from normal temperatures across North America.

So, why are places to the south colder than locations to the north? Seems counter-intuitive doesn’t it? The reason is the presence of a “Greenland Block.”  A ridge of high pressure has been developing over Greenland the past week or so. This ridge of high pressure is pulling very warm air northward from the Gulf Stream into the Canadian Maritimes and Greenland. The jetstream has become so highly amplified that cold air is actually undercutting the warm air to the north. The technical jargon for this type of scenario is a negative phase of the North American Oscillation.

156340_10150133710524167_639419166_7846171_4399136_nThe bottom line with this type of pattern is colder than normal temperatures for the Northeastern and Great Lakes regions of the United States. Consequently, warmer than normal air will now work northward through the Rockies. As far as precipitation, this pattern does not allow for much! In fact, it is more than likely that most systems will be “clipper-type” systems that work from Alberta and Saskatchewan down into the Midwest. Each clipper system has the opportunity to bring a new chunk of cold air as well.

naoHow long will this pattern last? It’s really hard to say. However it appears from the models that this could be the middle of it…with a return to a neutral pattern by Christmas so get out the heavy jackets, scarves, and gloves!

p.s. We have added a new tag called #weathergeek that will be used for our more technical blog posts. Don’t forget you can search our blog for these tags by using the tag list on the bottom of the side-bar. -ES

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Posted under climate/climate change, weather geek

This post was written by qni_it on November 30, 2010

Our high and low temperature essentially flip-flopped

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If you were out earlier today and noticed a warm feel to the air and then stepped out later to feel things very different, you observed a quick cold frontal passage. Rockford’s temperature plummeted some 13 degrees within 2 hours today when things are normally warming up!

-AB

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Posted under weather

This post was written by qni_it on November 30, 2010

The front is through, can you feel it?

23If you were up early today, things actually felt pleasant outside as we enjoyed morning temperatures in the middle to upper 40s. Things are certainly different now as a cold frontal boundary makes its way to our east. Winds of 25 to 30 miles per hour are being reported in parts of northern Iowa as colder air continues to fill in. I do believe our temperatures will hold right around the 30 degree mark through the rest of the day with the continuing chance of snow showers through the evening.

-AB

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Posted under cold blast

This post was written by qni_it on November 30, 2010

Tornado hits Yazoo City again

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MORNING UPDATE (3:30am) -

(Associated Press) The National Weather Service says a strong weather system tore down power lines, uprooted a few trees and damaged property in parts of Yazoo City, but there were no immediate reports of injuries.

Severe weather swept through the area Monday evening. Meteorologist Daniel Lamb says there were reports of similar damage near Vicksburg and Valley Park.

Lamb says it couldn’t immediately be confirmed whether the damage was the result of a tornado, but it’s what’s expected based on what is being seen on radar.

Mike Womack, the head of the Mississippi Emergency Management Agency, earlier urged residents to prepare for the threat of severe weather.

 

10:37pm – Attala County, Mississippi (W

LBT) Mobile homes blown off blocks with reported numerous injuries along Sudduth Road/Co Rd. 4045 and Co Rd. 4171. Injuries also reported in rural areas southwest of Kosciusko, Mississippi.

10:34pm – According to WLBT-TV’s Facebook page: “buildings are still standing but windows blown out, roof damage, etc.” I’d call that good news.

10:15pm – You may remember back in April Yazoo City, Mississippi was struck by a very strong tornado. It was a long-track EF-4 that claimed the lives of ten people.

While the city is not back to 100% from that tornado, another one tore through the town of 15,000. According to WTOK-TV, damage was caused to structures, power lines, and trees. WLBT-TV in Jackson is reporting damage in Yazoo City because of a tornado. According to a local nurse there have been no reports of injuries at this time.

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Posted under tornado

This post was written by qni_it on November 29, 2010

What stormtrack brings the most snow?

149058_10150133028124167_639419166_7835600_7767767_nIt is about that time of year when we should expect our first accumulating snow. Now’s the perfect time to examine which stormtracks produce the biggest snows here in Northern Illinois and Southern Wisconsin and which bring rain, sleet, and freezing rain.

Stormtrack #1: Track goes west of Rockford. Because the circulation of wind around low pressure is counter-clockwise, a track to our west keeps most of the wind out of the south ahead of the system. This is usually enough to warm us above freezing which makes most of the precipitation fall in the form of rain. There are occasional tracks like this that do produce freezing rain at the beginning (before the warm air moves into the area).

154598_10150133028309167_639419166_7835607_864303_nStormtrack #2: Track goes right over Rockford. This puts us on the edge of the temperature change. For the most part, these types of events are non-events for us. Especially because dry air sometimes gets caught into the center of low pressure which doesn’t allow for us to get into the heaviest precipitation. This is usually a scenario where rain changes to snow around here…but the majority of the precipitation again falls in the form of rain ahead of the system. If temperatures remain too cool at the onset of the storm, this track is one that can produce ice storms (as cold air remains trapped in the low levels with a northeasterly wind). Upper-air winds are out of the south which cause the precipitation type to be rain. The rain then falls onto a sub-freezing layer at the surface which causes the rain to freeze on contact.

150051_10150133028494167_639419166_7835615_378240_nStormtrack #3: This graphic shows the “perfect track” if you’re a snowlover. The biggest snowstorms for Northern Illinois and Southern Wisconsin track from Southeastern Missouri into Northeastern Indiana. If the low is in a developing phase, they are able to easily transport moisture from the Gulf of Mexico right into the system. In any particular winter season we can expect one or two of these snow events. However in the past few winters we’ve seen three and four per season! A good rule of thumb is the heaviest snow occurs 100 to 150  miles to the left of the stormtrack.

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Posted under winter storm

This post was written by qni_it on November 29, 2010

Temperatures set to crash down

meteogramTake a gander at the current Meteogram for Rockford. This shows the output for temperatures from all of our available weather models (click to enlarge). Our current temperature is 46° but as you can see, temperatures will free-fall tonight and could be as low as the teens by wake-up! The warmest of the models gets us to 35° by the end of the week. The rain’s now falling in the Rockford area and the temperatures are set to fall in no time flat! -ES

p.s. Haven’t used the “End of the World” tag in a long time…so why not?

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Posted under end of the world

This post was written by qni_it on November 29, 2010

It’s Good to Know!

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Posted under weather

This post was written by qni_it on November 29, 2010

Similar weather pattern, very different result

110Most of us have some recollection of where we were one week ago. Maybe we were at work and the power flickered, or in the car and the sirens sounded. Today marks one week since a powerful tornado ripped through eastern Winnebago and northern Boone counties and as we look back at our atmosphere that day, there are actually some similarities to things today, only without the severe risk.

As an area of low pressure passed essentially over the Stateline last week, an attendant warm front was draped right near the border. Warm air to the south met cooler air to the north, and as storms fired up last week, they rode along that warm frontal boundary and began to rotate. Our surface map looks similar today but we are missing a few key ingredients for severe weather.

First, and most importantly of all, the front that will pass through our area is occluded, which means that the cold front “caught up” to the warm front. This will still give us a chance of a few rumbles this afternoon, but should keep things well below severe limits. Also, last week we were nearly 70 degrees at the surface with dew points nearly 60. Today, we will be lucky to get much above the lower 50′s. Finally, there isn’t enough vorticity or turning in the atmpsphere to get things moving.

Regardless, it is a bit odd that we will see an above average Monday followed by below average temperatures tomorrow just as we did one week ago.

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Posted under weather

This post was written by qni_it on November 29, 2010

Are we overdue for snow?

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I’ve been asked several times over the past weekend whether we’re overdue for snowfall. After all, we have not seen any measurable snowfall in the Rock River Valley thus far this season.

Do you remember how we started “winter” last year? It was with one wallop of a storm! We received 6.6 inches on December 8th, followed by 4.8 inches on the 9th! Click here to see our blog coverage from last year’s storm.

You can see in the graphic above that the average first inch of snow for the past six years is in the first week of December. While some of them have been BIG snows, most are usually in the 1-3 inch range.

For what it’s worth, it would take a lot to get an inch out of Tuesday’s snow. A light snow is possible in spots next Saturday. Could that be our first inch? We’ll see!

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This post was written by qni_it on November 28, 2010