Archive for October, 2007

October 31, 2007

The green numbers are the dewpoint temperatures. Note how they actually drop into the upper teens and 20s to our northwest. This is some mighty dry air, which cools and heats up efficiently, though in the immediate future we’ll be focused on the cool side of things. This air is back behind a cold front that continues to move through. As it spills into our area and we dry out, some impressive lows will likely be reached. Tomorrow morning will be chilly but, by Friday morning, we’ll be cold and many locations stand a good chance of seeing their first frost. Low lying areas that are sheltered from the wind stand the best chance. We do look to warm quickly into the weekend only to see another temperature drop around Monday. Will November bring some snow?


Trick or Treat..Here Comes the Front
October 31, 2007

Happy Halloween to all of your ghouls and goblins! What a perfect fall afternoon. Warm southerly winds ahead of a cold front have allowed temperatures to climb into the 60s and 70s; however, cooler changes are on the way for this evening as the front will pass through. The good news of course is that the front will come through dry! Expect a breezy evening under a partly cloudy sky. Trick or Treaters beware as the temperatures fall into the 50s!

Take a look at the picture above. This is a surface map that depicts the cold front moving into northeastern Oklahoma. Over the next couple of hours the winds will shift from the south to the northwest. Notice the cooler temperatures throughout Kansas and Missouri. We will anticipate highs in the upper 50s to the low to mid 60s for Thursday afternoon.

October 31, 2007

Looking well ahead into the forecast, models are leaning towards pulling in some cold Canadian air for the next week. The timing of this strong Cold Air Advection (Cold air advection is the process in which the wind blows from a region of cold air to a region of warmer air) looks to either be Tuesday or Wednesday of next week. Moving into the month of November, weather patterns like this can take place. That means we should enjoy the weather for the weekend as highs will be in the 70s for the entire viewing area by Sunday afternoon!

October 30, 2007

The weather should cooperate with all of our outdoor plans for Halloween. Expect a nice warm up into the afternoon across the area. That will allow some mild temperatures for all the trick or treating. Not everyone across the United States will be so lucky. Florida will be dealing with Tropical Depression Noel, and there is a chance that it could be Hurricane Noel by Wednesday afternoon. The rainy weather will be taking place in portions of Michigan and western Pennsylvania. The Pacific Northwest looks to be very cold and rainy. So enjoy the weather and have a safe Halloween!

Fall Foliage Changes with the Temperature
October 29, 2007

It has been an unusually warm autumn so far. Look at the average highs and lows in early October for both Fayetteville and Fort Smith. In fact, throughout the first 10 days of the month, temperatures were in the 80s and 90s. There’s no coincidence that late fall temperatures are contributing to a late color change.

To get the sugars to change the colors to red you need cool overnight lows in the 40s. The cooler temperatures help to slow the sugars, allowing them to stay in the leaf for a longer period of time. The sugars are ultimately responsible for the vibrant color change!

Here’s the latest foliage report. The best colors look to come out over the next 2 weeks across Northwest Arkansas; however, most of the Ouachitas will have to wait until the middle of November for the great color display.

Northwest/North Central – Although there is not much color to see today, it is developing quickly in the Ozarks of northern Arkansas. Many hardwoods are 20% color now, and more changes should be visible with each passing day. Moderate color is forecasted for the weekend of October 26-28, but the peak will probably not occur until several more days go by. Future reports will recommend specific locations and highways that are near peak. Predicted peak of color: early November.

Central Arkansas/Ouachita Mountains – There is less color today than in northern Arkansas, but noticeable changes in fall foliage are taking place in this region too. Rapid progress is expected. Predicted peak of color: early November.

Southern/Eastern Arkansas – Early signs are appearing in this region, but more time is needed. Predicted peak of color: mid November.

The Ozarks of northern Arkansas will have moderate but incomplete color the weekend of October 26-28, with peak conditions unlikely until November. Central Arkansas and the Ouachita Mountains should follow quickly.

October 29, 2007

Tropical Storm Noel is currently spinning just the the south of Haiti. As it makes landfall it should weaken to a tropical depression. The good news is that Noel is showing no signs of strengthening and no signs of hitting U.S. land. As Noel moves just to the east of the the southeast coast, we could see some strong winds and high surf.

October 29, 2007

In 72 hours time, the latest model guidance takes TS Noel up to an 85 Kt. Hurricane, which would be a weak Cat 2 storm. The storm is slow moving so right now the biggest threat is flooding. Don’t forget flooding is the number one killer among weather related phenomena! The general track takes the storm east of Florida, though there still is uncertainty. Hurricane season is winding down and is considered over by the end of November.

October 28, 2007

Over the next few days the jetstream will be parked to our North and running more or less west to east, eventually dipping to the SSE as a ridge of High pressure builds in. With the exception of a few pushes of cooler air (weak fronts), keeping a major warm up in check, we look to be quiet into next weekend. Average highs over the upcoming week are about 65 up north and around 70 in the river valley. We look to remain very close to these numbers until a trough now in the middle of the Pacific shakes things up sometime close to next Sunday.

Enjoy the nice stretch of Fall weather!

October 27, 2007

The long range weather models are hinting at snow in the Great Lakes within the next 10 days. The first image you are seeing is a precipitation forecast for November 4. If you look over Lake Michigan, this model is showing some form of precipitation taking place. No you might be saying, Patrick…how do you know it’s snow being forecast? Well, when you forecast you can’t just look at just one thing and be done with it. You have to look at multiple models and levels of the atmosphere. When we are talking about winter weather you we have to see if temperatures will be cold enough to support snow or warm enough to support rain.

A good level of the atmosphere to look at is the 850 mb level map. It does a great job of showing the movement of cold and warm air (otherwise known as cold air advection and warm air advection). Here is the forecast at the 850 mb level for the exact same date. Notice the strong push of cold air moving into Wisconsin, Northern Illinois and Michigan. This is very far into the future and models are known to exaggerate, but this is something that I noticed and I thought I would pass it along. I love forecasting snow. I have doing weather in Yuma, AZ for the past two years where snow is unheard of, but now I can get back to the forecast that I learned a great deal about when I went to Northern Illinois University.

October 26, 2007

The low pressure system that has been stalled out to our south and southeast over the past 3 days is finally moving…this time to the north. It’s the closest this low pressure has been since it swept through the area on Monday. The good news is that this system should continue on a northerly path and take the clouds with it…just in time for the weekend!