Tuesday, September 30, 2014

Weather's Effect On Fall Colors

We've already been getting some great fall color pics this year, but have you ever wondered what causes the changing colors? Here's a quick science lesson:

Yellows and oranges are the most common colors we see and those are associated with decreasing sunlight during the day. Those colors aren't really affected by things like temperatures or precipitation. Your more vibrant colors, like your reds and purples, are different. You need specific weather conditions to see those colors. Namely, cool nights with dry and sunny afternoons.

There are things that can shorten the color season, like strong winds or rain. The dreaded s-word can also end the season early. One thing we won't have to worry too much about this year is brown leaves. You typically get those with drought conditions, and we haven't seen much of that this year.

For more information and updates on this year's fall color season, check out NWS Chicago's resource page here.

Chills set in late week

After several days of high temperatures in the 80's, this afternoon may be a little shock to the system.  Cloud cover and a chilly northeast breeze will likely halt temperatures from rising much past the upper 50's (if we're lucky) this afternoon.  After a brief rise into the low 70's on Wednesday and Thursday, look for temperatures to take another dip for the start of the weekend as low pressure helps dislodge a chunk of Arctic air.

A strong cold front will pass late Thursday night and early Friday.  Showers and thunderstorms are in the forecast for Thursday afternoon with a few wrap-around showers likely on Friday.  Dare I even say up north could have a few wet snowflakes mix in?!?  The bigger story will be the temperature drop.  Highs on Friday will have a hard time rising much during the afternoon and may in fact be reached early in the day with a steady, or falling, temperature throughout. 

Temperatures several thousand feet above will sit below freezing and this will help overnight lows Friday night fall into the 30's.  Saturday night could be just as cold if warmer air from a quick moving system is delayed.  With such a cool start Saturday morning, afternoon highs will struggle to make it out of the 50's for the afternoon!

Friday, September 26, 2014

September Lack of Rain

It has been a picture perfect first week of fall, with no rain and comfortable temperatures in the 70s. There isn't rain in the forecast for today, which makes it the fifth day in a row with no rain. But, with five more days in the forecast without rain, that will make this the longest dry weather stretch we've seen in almost exactly two years. The last time we went this long without rain was September 22nd through October 2nd of 2012. We did come come close this past July with nine days in a row.

Temperatures this weekend will climb to 80° with plenty of sun. We won't see rain until Wednesday afternoon. The better chance for rain though will be on Thursday. Temperatures will become more seasonable by the middle of next week.  -KC

Monday, September 22, 2014

Fall Begins Monday Night

Fall officially begins in the Stateline Monday at 9:29pm. This means a lot of things: Changing leaves, sweater weather... and a lot less daylight.

The start of fall, or the Autumnal Equinox, sees roughly the same amount of daylight and darkness. Over the coming months, though, our sun angle starts to lower and the amount of daylight we see goes down significantly. By the Winter Solstice (the shortest day of the year), our amount of daylight is cut down to about 9 hours.

We may be seeing less sun over the coming months, but at least we'll have plenty of sunshine this week. Enjoy the start of fall! -BA

Wednesday, September 10, 2014

UPDATED: Tuesday Night/Wednesday Morning Rain

Rain moved into the Stateline area Tuesday night and continued through Wednesday morning. Thunderstorms stayed to the south of the viewing area, but we still picked up decent rainfall amounts. Many of us saw 1-2" of rain. Here's a look at some of the rainfall totals as of Tuesday evening:

Rain Totals Reported to the NWS
Rain Totals from NWS Weather Stations

Sterling: 1.48"
Newark (WI): 1.35"
Dixon: 1.26"
Paw Paw: 1.18"
DeKalb: 0.86"

Just south of the view area, Mendota saw some flooding with water covering parts of Route 251 and Route 34.

Tuesday, September 9, 2014

Tuesday Night Severe Weather Update

We are still monitoring the chance for severe weather and flooding across the Stateline Tuesday night into Wednesday morning.

The latest satellite and radar has a few showers in the Stateline with the bulk of Tuesday night's storms still off to our southwest. Those storms are expected to move in closer to midnight.

The primary concern will be flooding. A Flash Flood Watch is in effect for the entire Stateline through Wednesday morning. Most areas are looking at 1-2" of rain through the morning. Areas with stronger thunderstorms could see locally heavier amounts up to 4-5".

The secondary concern will be damaging winds. Even if we don't see any severe-strength winds, it will be breezy throughout the day Wednesday.

Storms will start wrapping up Wednesday afternoon with no major weather events expected for the rest of the week. -BA

Monday, September 8, 2014

Big Changes Coming In Forecast

Don't get used to the quiet weather we saw to start the work week. Plenty of big changes are coming over the next 48 hours.

Storms will be possible overnight Monday and into the day Tuesday, but storms become likely Tuesday night into Wednesday morning. These storms have the potential for heavy rain and even severe weather. Futurecast has the bulk of these storms rolling through Wednesday morning with our next low pressure system.

The timing of these storms should help suppress the severe threat a little, but we'll still have to keep an eye out for a few stronger storms. Typically, severe weather is more likely during the afternoon when storms can feed off the heat and humidity of the day. Since our storms will be mainly at night or early in the morning, our severe chances are reduced. Tuesday's severe threat should stay mostly to our west. Wednesday's severe threat will be mainly to our south. If we do see severe storms, damaging winds will be the biggest concern.

Heavy rain will be the most likely problem with this next system. Models are indicating that a good 1.5"-2" of rain will be possible through Wednesday evening. If we do see severe storms, locally higher amounts will be possible.

After these storms move out, an incredibly chilly blast of air moves in for the rest of the week. Right now, Friday will be the worst of the cold with highs potentially not making it out of the 50s. -BA

Friday, September 5, 2014

Friday Severe Weather Update

2:00pm Update: Severe T-Storm Warning for central DeKalb County until 2:30pm. Warning includes the cities of DeKalb and Sycamore. 60mph winds are possible.

Thursday, September 4, 2014

September 90s

The forecast high for the Rockford area today is 90°. A warm front passing through the area combined with strong winds from the south and minimal cloud cover are all contributing to the surge in heat. There has been some cooling this morning because of thunderstorms and cloud cover, so temperatures could be held back a bit this afternoon if the clouds hold together longer than expected. Highs in the 90s are more likely to the south and west of Rockford with heat index values in the mid and upper 90s.

But how likely are 90s in September? Looking back at past climate data, you can see that last year we had four 90 degree days. That number decreases every year we go back. In 2009, we saw no 90 degree days in September. While it's not extremely likely, it does happen occasionally.

We still could still hit 90 degrees here in Rockford on Thursday, but we will have to keep an eye on the clouds to see how long they hold together. Either way it will still be a humid day. Dew points in the low 70's will make for a sticky afternoon. The heat doesn't last long, though, as we drop into the 70's for the rest of the week! -KC

Wednesday, September 3, 2014

Don't Be Fooled: Late Season Heat Can Still Be Deadly

We haven't seen much extreme heat this summer, so when Thursday's forecast calls for a high of 90°, it's important to remember heat safety. Most of the reminders are obvious. Drink plenty of water. Wear light-colored and loose-fitting clothing. But the most important tip to remember is NEVER leave children or pets in a car. We've heard national stories all summer long of children being left in hot cars. Here's another reminder why that is so dangerous.

Data Provided by NWS Chicago
When the outside temperature is 90°, the temperature inside a closed car can top 100° in less than 10 minutes. After 30 minutes, the temperature inside a car is already flirting with 120°. Give it an hour and that temperature is almost 140°.

If you're out and about Thursday, remember the dangers of the heat and prepare according. The heat may not stick around for long, but it can still be dangerous. -BA

Tuesday, September 2, 2014

Are You Weather-Ready for Fall?

We haven't promoted this much yet, but the First Warn Weather team is the official Weather-Ready Nation ambassador for the Stateline. That means it's our goal to keep you prepared for extreme weather all year long.

As you may know, Monday was the official start to meteorological fall. With the changing seasons comes changes to our weather pattern, but severe weather can happen at any time. The two biggest threats we deal with this time of year are flooding and tornadoes, but this is also a good time to start preparing for winter. Whether it's a weather radio or an emergency kit, there are many great tools you can have to keep you safe. Below is more information on how to prepare for all these scenarios so you can "Be A Force of Nature". -BA

Flood Safety: http://www.nws.noaa.gov/floodsafety/

Tornado Safety (Including where to go during a tornado): http://www.spc.noaa.gov/faq/tornado/#Safety

Winter Safety
Build Your Emergency Kit: http://www.ready.gov/build-a-kit
Weather Radio Information: http://www.nws.noaa.gov/nwr/

Changing Seasons Mean Changing Temps

As you may already know, Monday was the official start of meteorological fall. If you're not ready to let go of summer just yet, don't panic. Astronomical fall doesn't begin until Sept. 22nd. Either way, the seasons are changing, and that means changes to our overall weather pattern.

The biggest thing people will notice is how fast it cools off over the next couple of months. The average high for the beginning of September is right at 80°. As each month passes, that number drops significantly. By December 1st, the average high is struggling to hit 40°

By comparison, this week's roller coaster temperatures are pretty mild. We'll go from the upper 80s on Thursday to the mid 70s this weekend. The moral of the story here is to get out and enjoy the weather while you still can because the changes only get more drastic from here! -BA

Monday, September 1, 2014

Stateline Summer Recap

Labor Day weekend is considered the unofficial end of summer for many, but in the weather world, summer really is over as meteorological fall begins September 1st. Here's how our past summer shaped up for Rockford.

While our summer was cooler than normal, we weren't anywhere close to breaking any records. Our average temperature ended up being 1° below normal, making us the 37th coolest summer on record since 1905. We saw plenty of rain, though. Between May and July, we saw 16.28" or rain, making this summer the 19th wettest on record since 1905. -BA

Labor Day!

Temperatures today will climb into the low 80's with winds from the SW gusting at 25mph. Pop-up scattered storms are expected through the late afternoon and into the early evening. We could see some quick heavy downpours with these storms but the severe threat will be to the SE of our area. But is this a typical Labor Day forecast?

The forecasted high for today is 81° which is in the most frequent range of temperatures on Labor Day. Forty-four Labor Day high temperatures have fallen in the 80-89° range in the last 105 years. Forty days have been between 70-79°. After that only 12 days have been between 60-69 °, and 13 have been between 90-99°, so today's temperatures is right around normal.

But with scattered storms in the forecast for today, is rain typical on Labor Day? Since 1905 there have been 59 Labor Days with no rain recorded, while there have been 50 days with rain recorded. While typically there isn't rain on Labor Day it definitely isn't uncommon. Today's rainfall amouts should be in the .10"-.25" range.

                                                              *Graphics courtesy of NWS Chicago
Overall, not a lot of coverage for the storms today so if you want to fire up the grill just check the radar quick to make sure no rain is headed your way! The best chance for more rain will be in the late afternoon and evening today but it will be on the muggy side this afternoon. -KC