The winter has been off to a very mild start but mid January into February we might be seeing some major changes. Almost as if on cue mother nature looks to be turning much colder. I should note that historically January 7th through the 16th has the coldest average temperatures here in Charlotte. When the average high is 50° and the average low is 29°.
Even though we currently have tropical storm Harvey heading into Central America. The main concern for the Caribbean and U.S. is Invest 97L.
Invest 97l is just a designation the Navy and hurricane center use to track disturbed areas of weather that could potentially develop into a storm or hurricane. This designation is important because the tropical models start running on these areas. This particular area has been showing up in the global model long before it got a designation.
Here are the latest “spaghetti” plots on Invest 97.
The intensity forecast shows a slow but steady intensification process over the next 5 days.
Yet there are many hurdles for this system to overcome before becoming a major threat. The first of which is the dry Sahara air layer(SAL) that can sap moisture out of these storms.
The second is some shear to the north and west of the system. Though this along with the SAL will be less of a hindrance once it gets into the Caribbean. Then of course if it tracks right over the larger islands of the Caribbean, Hispaniola and Cuba those too could keep it from intensifying rapidly. You can see the main steering currents below which is the huge subtropical ridge over the central Atlantic.
Wind Shear Steering Flow
It is interesting to see our RPM model and the high resolution look at surface winds. Based on our model the storm track looks to stay south of those islands. The one big caveat in all of this is there is next to zero upper air or surface data going into these models from the central Atlantic. We will know a whole bunch more when the recon plane gets out in this system Saturday.
Today some amazing photos came in from the coast where several waterspouts were spotted near Carolina Beach and Oak Island in North Carolina. Another report of a waterspout came in from the Charleston, SC area near Wild Dunes resort. Now these were not what we call tornadic waterspouts but more of the fair weather type. It doesn’t mean they weren’t dangerous just not as powerful as a supercell tornadoes. They usually are harmless unless you are in a small boat on the water or in this case when they come ashore. They can cause minor damage. A Tornado warning was issued when they hit the beach.
These are some amazing shots from twitter
Both of the above pictures are from Tony Burnett-Millage when it came ashore.
Below is the definition of a waterspout from NOAA.
Waterspouts are similar to tornadoes over water. Waterspouts are generally broken into two categories: fair weather waterspouts and tornadic waterspouts.
Tornadic waterspouts are simply tornadoes that form over water, or move from land to water. They have the same characteristics as a land tornado. They are associated with severe thunderstorms, and are often accompanied by high winds and seas, large hail, and frequent dangerous lightning.
Fair Weather waterspouts are usually a less dangerous phenomena, but common over South Florida’s coastal waters from late spring to early fall. The term fair weather comes from the fact that this type of waterspout forms during fair and relatively calm weather, often during the early to mid morning and sometimes during the late afternoon. Fair weather waterspouts usually form along dark flat bases of a line of developing cumulus clouds. This type of waterspout is generally not associated with thunderstorms whereas tornadic waterspouts develop in severe thunderstorms. Tornadic waterspouts develop downward in a thunderstorm while a fair weather waterspout begins to develop on the surface of the water and works its way upward. By the time the funnel is visible, a fair weather waterspout is near maturity.
Fair weather waterspouts form in light wind conditions so they normally move little. If a waterspout moves onshore, the National Weather Service issues a tornado warning as some of them can cause significant damages and injuries to people. Typically, fair weather waterspouts dissipate rapidly when they make landfall, and rarely penetrate far inland.
The best way to avoid a waterspout is to move at a 90-degree angle to its apparent movement. Never move closer to investigate a waterspout. Some can be just as dangerous as tornadoes.
Listen for special marine warnings about waterspout sightings that are broadcast on NOAA Weather Radio.
Watch the sky for certain types of clouds. In the summer, with light winds, look for a possible waterspout underneath a line of cumulus clouds with dark, flat bases. Anytime of the year, a thunderstorm or line of thunderstorms, can produce very intense waterspouts.
If a waterspout is sighted, immediately head at a 90 degree angle from the apparent motion of the waterspout.
Never try to navigate through a waterspout. Although waterspouts are usually weaker than tornadoes, they can still produce significant damage to you and your boat.
Invest area 93 has a good circulation but not much in the way of thunderstorm activity. It’s running out of time before getting to Central America. The main threat will be heavy flooding rains in central America. For the Carolinas we need to watch late next week. Many global models are pointing to SE tropic development. It’s WAAY early though for specifics.
Something to watch late next week:
Storm Water Services did a great job with the recent flood in Charlotte. Thought I‘d share with you their assessment. Here’s the write-up.
August 5, 2011 – Flood Damage Assessments Continue
More than 100 high-risk properties that flooded on Friday used to have buildings on them but are now vacant lots due to the Storm Water Services’ Floodplain Buyout Program. The land is returned to open space which is not damaged when it floods. More than 230 flood-prone properties have been bought and town down in the past 11 years.
How did the flooding affect people? Watch this video by the American Red Cross, Greater Charlotte Chapter.
A strong thunderstorm moved down from the foothills into the piedmont Sunday evening causing a lot of damage in Denver, Belmont and Mt. Holly in Gaston Co. There was even damage reported in Clover in York Co. All the Doppler radar data and pictures I have see so far point to a “wet microburst” as the cause of this damage. This type of downburst wind is the cause of the majority of damage from severe thunderstorms in the Carolinas. Take a look at the radar images from yesterday both showing high reflectivity crashing to the surface right over Belmont. The area in pink is likely really heavy rain & hail within the wet microburst. The left image is a volumetric 3d view the right is a 3d cross section view.
I wrote about the difference between tornadic winds and straight-line winds before you can reference that Blog post here. Here’s another great look at what a microburst looks like and should help explain why it can be so violent.
Here’s today’s First Warn Outdoor Index for Tuesday May 31, 2011
Here’s what it means:
Earlier this year I starting thinking about a way to help people to understand and deal with summer time weather. In particular kids going to the YMCA of Greater Charlotte summer camps. They had approached me about doing some summer heat education and safety talks. So I started to develop what I call the Outdoor Index. It takes 3 widely used indicies that are used most often during the summer months. The Heat Index, the Air Quality Index and the UV index. Now all of these can have significant impacts on your outdoor activities, but not equally in my onion. So I weighted them based on the biggest impacts to everyone.
The first is the Heat Index, which many people are already all too familiar with. This is your basic “Feels Like” temperature based on the combination of heat and humidity. This is the most important factor in the Outdoor Index because it affects everyone and really impacts your bodies ability to cool itself. Using the scale below I assign a numeric value from 1-10.
Next is the Air Quality index and a common problem when we get stagnate air masses during the summer months in the Carolinas. While I certainly don’t want to diminish the impacts of poor air quality. It most often only impacts those with poor respiratory health or the very young and old. On very rare occasions when it’s quite high it impacts us all. It gets the second highest weight in the Outdoor Index. Same as above a 1-10 scale is used to assign a value.
Last but not least in the UV index. Now everyone should be protecting their skin from the sun due to the increased risk of skin cancer. With that said the UV index on any given day during the summer is above 8 an often 10+. If it’s sunny you need to protect yourself. So not to constantly skew the Outdoor Index it was given the lowest weight. Plus no matter the number on the Outdoor Index you should always be safe and protect yourself form UV. It will be something I’ll try always mention in my forecast.
So after getting all those values above you use the formula below and you end up with our exclusive Frist Warn Outdoor Index.
So today is Tuesday and today’s Outdoor Index is a 6.4. This was based on taking a 106 AQI = 4 , Heat index 102 = 7 and UV index of 10=1. Plugging those number into the formula and getting a number that then will fall in the scale above. I will always round to the nearest whole number to simplify this.
Now this index is not to discourage people from doing outdoor activities. Just the opposite it’s to inform you so you can prepare and do it safely. Most people know what they can tolerate so knowing what to expect can help make a decision how what and how you do your outdoor activities this summer.
Weather radio’s can be life saver, especially after what we have seen this spring with the tornado outbreaks across the south. Smartphones though are quickly replacing this weather radio and now there’s an app that does exactly just that.
Now this app normally coast $9.99 and even at that price I would highly recommend it, but for one day only it’s free. They are only giving out 100,000 of these so get in their quick starting at 5:00am.
Android is coming soon.
With iMapWeather Radio you will receive critical voice and text alerts on life-threatening weather events. Your iPhone will "wake up" and also "follow you" with alerts wherever you go. Listen with ease to local weather forecasts while you are on the move.
Brought to you by Weather Decision Technologies, Inc. a trusted weather provider for most of the major weather brands in the U.S. Weather is our business and has been for more than 10 years. That means you can count on us to create a top notch app and continue to improve it.
Keep Friends and Family Safe
Not only can iMapWeather Radio follow your current location, but it lets you save an additional 5 stationary locations. That means you can make sure friends and family, at school, out of state, at a ballgame, etc. are safe as well..
The app is designed to conserve your battery even though it uses GPS to give you alerts for your current location. We can’t give away our secret sauce, just know we are careful to lijmit the GPS usage and we are dynamically able to reduce the usage to help extend battery life.
In markets where local media partners participate, you can get streaming video of severe weather coverage. WCNC is working on providing this video to the app so you can see our stream.
Unfortunately all the ingredients are coming together for severe weather here in the Carolinas today and again tonight. There will be 2 waves of storms we need to watch out for. The threat today will be just slightly lower than the one tonight but in both cases the shear profiles in the atmosphere will be conductive for supercell thunderstorms. These rotating storms not only can produce tornadoes which is likely but also large hail and damaging winds. Here’s a quick video run down of the set-up and timing. This a very dangerous situations please take all watches and warnings very seriously.
Video Part I
Video Briefing Part II
SPC Outlook Maps
As if this Spring hasn’t been active enough with severe weather this week might be the straw that breaks the back of many communities. We will see all the elements that Spring severe weather can bring to the table including Tornadoes, Lightning, Straight line winds, Hail and the most widespread of them all flooding. The reason? There’s a stalled frontal system that stretches from Texas to New England that has brought days of rain and severer weather to the Mississippi & Ohio river valleys. This we will get upper level support to spawn lots of severe weather even heavier rainfall. This system will slowly begin to move east as well spreading the severe weather our way.
Surface Features 5-Day rainfall (which is likely underdone here)
The combination of this stalled frontal system and a deep and plenty inflow of moisture from the gulf of Mexico and Atlantic will keep severe storms possible both Tuesday, Wednesday and even possibly Thursday morning for the Carolina. Here’s a look at the outlooks from SPC (Storm Prediction Center). Which by the way for the first time I can remember actually has a moderate risk in the Day 1,2 & 3 outlooks.
Here’s a look at a few of the models for when we might see our rounds of severe weather. Tuesday looks like scattered severe storms but then Wednesday looks much more organized. Especially late Wednesday night into Thursday.
5:00 pm Tuesday 8:00pm Wednesday
2:00 am Thursday
The fly in the ointment and something the models maybe missing is the left overs of tropical disturbance 91L. This disturbance could add shear, moisture and lift to create even more widespread severe weather depending on it’s track. something I’ll be watching closely.