Added Bonus For Stargazers Tonight?

As Candice mentioned this morning on the blog, the Geminid meteor shower peaks tonight, and the forecast couldn't be any better for stargazers. But if we're lucky, we might see even more activity in the night skies over the Stateline.

Copyright © 1997 by Akimasa Nakamura

That extra activity could possibly come from the comet Wirtanen, better known to scientists as 46P/Wirtanen. This would be the first time debris from the comet would pass into Earth's atmosphere, so we're not sure yet if we'll see anything, but some people estimate it could produce an extra thirty meteors an hour around the same area as the constellation Pisces.

Even if we miss out on Wirtanen, the Geminids should more than make up for it. Look for activity to pick up later this evening, after 10pm. Even though the peak is tonight, you should still be able to see meteor activity through Sunday.

I also know that it's December and it's cold outside, so if you want to watch this amazing light show from your computer, we have you covered. NASA will be streaming live and taking questions starting at 10pm tonight. Here's the link.

Happy stargazing! -BA

Rain and thunder likely Saturday

While there's still a lot of progress that needs to be made in the rainfall department, this weekend's storm system will help some.  Low pressure moving onshore in central/southern California later tonight will quickly move northeast into Kansas by Saturday morning.  With more of a northwest track expected we'll remain in the warm sector of the storm with rain, not snow, falling through the majority of the weekend.  Winds will remain from the south Friday night and Saturday pulling in copious amounts of moisture from the Gulf of Mexico.  Latest model runs are depicting anywhere between a half an inch to near an inch of rain across Iowa and northern Illinois by Saturday night.  There may also be a few thunderstorms that develop south of here and lift north by Saturday morning and continue into the early afternoon which could aid in some of the higher rainfall amounts.

By Saturday evening the low will have moved into Wisconsin as dry air wraps in from the southwest in the mid-levels of the atmosphere likely cutting off the heavy rain with only drizzle lasting into the night.  By the time the cold air moves into northern Illinois and southern Wisconsin the majority of precipitation will have already fallen with only a light rain/snow mix expected by Sunday.  A few wrap-around flurries could continue into Sunday night but no accumulation is expected.

The pattern will remain active going into next week with another system expected to develop by midweek.  But as with past storms this looks to be a warm one as well.

Geminid Meteor Shower Peaking Tonight

If you're out late tonight or up very early Friday morning take a look up to the sky because you may just be able to catch a glimpse of one of the most brilliant meteor showers around!  The Geminid meteor shower is expected to peak tonight with the best viewing likely after 1am.

The Geminid meteor shower peaks for almost a full 24 hours from December 13th-14th.  It's composed from the debris field of the asteroid 3200 Phaethon and has increased in intensity from when it was first seen back in 1862.  With a new moon tonight the sky should be darker than previous nights with nearly 50 meteors per hour possible.

For the best viewing of the Geminid meteor shower, you want to make sure you get away from the glare of the city lights.  Optimum viewing would be out in the country.  Give your eyes time to adjust to the dark once you're out; usually about 20-30 minutes.  The Geminid radiant point is over the eastern horizon after 6pm and the early rising time for the radiant point is typically why the Geminid shower is worth catching in the evening; especially if you're not a late-night owl.  The peak time for the shower is around 1am/2am.  Skies should remain fairly clear tonight, although there may be a few of those wispy cirrus clouds around with lows around 29°.  Friday night don't expect much as cloud cover and rain are expected to move in.

Signs of a Mild Winter?

The National Weather Service has released some interesting information about our temperature trend over the last couple weeks. If you thought the snow drought was something, check this out!

Note: Current Streak is Ongoing

Heading into the start of winter, we have yet to see a high temperature below the freezing mark. The average first day where we see highs fail to hit the freezing mark in Rockford is November 11th. So not only are we way past due for some truly cold temps, but we're approaching record territory. With the current forecast, we could break our current "mild" streak next Tuesday, which would still put us solidly in third place on the all-time list.

Temps & Snowfall Compared to Average

So why is this important? For starters, it could give us a glimpse into what the winter has in store for us. In almost every other year on the list, Rockford saw warmer than average temps and below average snowfall through February. In some cases, like 2001 and 1998, our snowfall was 16" off from the norm!

A word of caution, though... this current temperature trend isn't a guarantee that we'll see another mild winter. But at this point, it sure feels like it.

Weather and the impact it has on aviation

Shortly before 8:30pm Monday evening a REACT helicopter flying from Rockford Memorial Hospital to Mendota crashed in a field just south of Rochelle killing the pilot and two flight nurses.  The Lee County Sheriff's Department has turned the investigation of the crash over to the Federal Aviation Administration and The National Transportation Safety Board this morning and they will continue with their investigation throughout the day.  During a news conference held earlier this morning we now know the helicopter had encountered weather while en route and radioed back indicating that it would be turning around.  Shortly after they lost contact with the pilot only to learn the helicopter had crashed.  Witnesses around the area Monday evening stated as the helicopter flew over it just didn't sound right, like there may have been something wrong.  Whether or not this was the case is yet to be determined.  There are many factors that the investigators will be looking at to help determine the exact cause, but weather can not be ruled out.  Often times when we think of aircraft accidents we think severe weather; for example strong thunderstorms or wind.  In the winter ice is a major danger for aircraft because it can alter the air flow around the wing of a plane or rotor of a helicopter.  Before we get into the dynamics of air flow I want to talk a little bit about cloud structure.

Thousands of tiny water droplets are found in a cloud from base to top.  Many of these water droplets are known as 'super-cooled' water droplets.  This means that the water droplet is in the liquid form despite the temperature dropping well below freezing.  The reason for this is because the droplet has not yet come into contact with a surface or particle for it to freeze on.  When a plane flies into this level in the atmosphere it can usually ascend or descend to get to a safer altitude.  If not, ice can build up on the wings, or rotor, causing the lift generated by the plane/helicopter in flight to decrease.  In order to get a better idea of the weather conditions around the area we look at the observations taken from the Rochelle airport because this is the closet airport to the crash site.  In the couple hours leading up to the event skies were overcast at about 3,000 ft and light snow showers had been falling on & off, visibility varied at the surface between 7 and 10 miles.

This is the upper air sounding from the National Weather Service in Davenport, IA (the closet upper air sounding to that location).  The red line indicates the temperature profile and the green line indicates the dew point throughout the atmosphere.  Just by looking at this sounding you're able to see that the atmosphere was saturated (when the two lines are very close to each other) not that far above the surface and the temperature was below freezing.  It's possible the helicopter could have been flying at a level where these super-cooled droplets were present, but it's important to note that we don't know the exact flight plan or altitude the helicopter was flying at and we certainly don't want to make any speculations.  These are just some of the things I'm sure the FAA and NTSB will also be looking at.

Now, back to the aerodynamics of an aircraft.  Aircrafts generate their lift by creating a difference in pressure from the top of the wing to the bottom of the wing.  If a plane or helicopter flies at a level where these super-cooled water droplets are present ice can build up on either a wing or rotor and it can alter the air flow reducing the lift and force that keeps that aircraft in flight by creating more drag, or resistance.  It's not necessarily a matter of weight on the aircraft.  Ice can be very dangerous and that's why de-icing equipment are found on planes (I'm not sure if it is also present on helicopters) and many hours are spend on the ground de-icing planes before takeoff.  The chemical that is sprayed on the plane helps to lower the freezing level of water so the water droplets can't accumulate on the wing or tail.  The Chicago National Weather Service has already gathered data from the surface and above to assist with the investigation and anything official will come from the FAA and the NTSB within the next few days.  Please keep the families and friends of those lost in your thoughts and prayers as they are greatly needed at this time. 

Further updates will be provided on the WTVO Channel 17 News at 5,6 and 10pm and our sister station FOX 39 at 9pm.

This time of year it's all about direction

The recent snowfall across the upper Midwest and Great Lakes this past weekend can, and often does, affect our weather locally.  This time of year it's all about wind direction.  As wind moves across a snow covered land mass the cold surface of the ground will help modify and cool that air mass often times keeping temperatures cooler than they normally would be if there were little or no snow on the ground.

These next few days we won't have to worry about a northwest wind.  A series of quick moving systems will move across the Midwest and Great Lakes keeping northern Illinois locked in a southwest flow.  This will allow temperatures to warm through the 40s by the end of the week.

Hope For Breaking Our Snow Drought?

To answer the question asked in the title of this post, let me start off by saying, "Very little.." At least anytime soon. As Candice posted earlier today, we had a small chance to break our drought this afternoon with a few light snow showers. That didn't happen. Now Rockford is setting its sights on number three all-time on the snow drought list. The last time we saw measurable snow was on March 4th. Here's a quick recap:

As of 12/9/12

If we see no snow through Monday, that would set the record here in Rockford (Chicago actually broke their own snow drought record today with 281 days without accumulating snow). A quick look at the seven-day forecast shows one shot at keeping us from entering record setting territory.

A storm system is currently forecast to roll through on Saturday, but much like this past weekend's system, it looks like it will be just far enough to our north that we'll see mostly rain, with some snow mixing in during the evening. A lot can change between now and Saturday, but at this point, don't be surprised if we're talking about a record snow drought before this is over. -BA