Gulf Low Keeps Oil Onshore
Satellite Imagery, Gulf Low, Image: NOAA
Earlier today, an area of low pressure off the coast of Louisiana was looking fairly impressive. What I mean by that is thunderstorm tops were showing up on visible satellite imagery, and there was a lot of thunderstorm activity starting to fire up around the center of circulation.
In fact, hurricane specialists gave it a 60% chance of development into a tropical system earlier today. It has since moved closer to shore and it will not develop.
It is, however, increasing the wind and wave action off the coast of Louisiana, and more oil is being pushed onshore.
Wave heights are at about 3-4′. The east-southeasterly winds driving oil onshore would have subsided by tomorrow if it weren’t for another tropical disturbance in the northwestern Caribbean Sea.
I’ll have another update on that system tomorrow.
-Dawn Brown
95L Does Not Like Dry Air
Gulf of Mexico, Caribbean Sea Satellite Imagery, Image: NOAA
This is a current satellite image of the Gulf of Mexico, Caribbean Sea and the eastern Atlantic Ocean basin. Yesterday, we were watching an area of low pressure south of Louisiana for signs of tropical development. So far, nothing. Dry air has gotten mixed into the low, which is nice because it was actually pleasant in Southeast Louisiana today. Fireworks are popping without a hitch tonight because thunderstorm activity was limited due to dry air.
The biggest concern from the low, however, was the wind and wave action associated with a persistent southeasterly wind. Wave heights have been running about 5 – 6′. But as the low tracks west of Louisiana, heights will back down to 2 – 3′ by tomorrow.
I’m watching an area of disturbed weather in the Caribbean. I’ll have an update on that tomorrow.
-Dawn Brown
The Threat Invest 95L Poses to the Gulf Coast
Invest 95L Satellite Imagery, Image: NOAA
National Weather Service link tracking Gulf Low. (Click on the Gulf Low tab above the radar imagery.)
Meteorologists across the Gulf Coast are closely watching Invest 95L despite its lack of organization and poor chance of development. With oil still gushing from the bottom of the Gulf of Mexico, this low and its associated wind and wave action could drive more oil into sensitive marshes and estuaries along the northern Gulf Coast. Yesterday, hurricane specialists Lixion Avila and Chris Landsea identified the low and gave it a 10% chance of development. We’d already had our eye on it in the FOX 8 Weather Department. Today, Avila and Landsea give it a 20% chance.
Stalled Frontal Boundary, Image: Unisys
In early June and July, the main source of tropical development in the Gulf of Mexico is a low that forms off of a stalled frontal boundary in the gulf. You can see the position of the low is about 150 miles or so south-southeast of the boot of Louisiana. There’s a lot of wind shear and dry air affecting the low right now keeping it from developing into anything tropical. Wind shear is expected to remain fairly strong over the next couple of days. So, for this thing to develop, wind shear has to relax and the dry air will have to be replaced by a warm and tropical air mass.
Water Vapor Imagery, Image: NOAA
More troubling for Gulf Coast residents is the wind and wave action associated with a low pressure system east of Louisiana. With oil gushing offshore, a persistent southeast wind could drive the oil onshore. Wave heights are currently about 5 feet around the location of the Deepwater Horizon Incident. Wave heights are forecast to become 6′ offshore, keeping skimmers and other cleanup craft in safe harbor.
-Dawn Brown
Alex and the Oil Spill
Tropical Storm Alex forms off the coast of the Yucatan Peninsula in the warm waters of the Caribbean Sea.
Infrared Satellite, TS Alex, Image: NOAA
The current track takes Alex toward the Yucatan, weakening as it crosses the peninsula. Hurricane forecasters expect it to strengthen once again in the southwestern Gulf of Mexico, moving toward the south Texas coastline before possibly curving toward the west-southwest.
Official Forecast Track, Tropical Storm Alex
Most of the computer models agree on this forecast track. Hurricane specialists from the National Hurricane Center presented their post-season analysis of the 2009 Atlantic Hurricane Season at a meteorological conference in Miami this week. During their presentation, they announced the European Model, or the ECMWF, has delivered the most successful track forecast the past few years. That model takes Alex toward the southwestern Gulf of Mexico toward central Mexico. The ECMWF isn’t plotted on most computer model tracking maps, if you follow those.
You can find the link to the European model in my link to tracking hurricanes, but it’s hard to read for most people. Keep in mind that the hurricane specialists know which models are giving the best performance when they issue their track forecast, so you can be confident that when you are looking at the 5-day forecast from the National Hurricane Center, that is the most accurate information available.
This past week, two of the government models, the HWRF and the GFDL, were taking the disturbance in the Caribbean to the northern Gulf of Mexico. You can’t really follow computer models for tropical disturbances until there is a tropical depression, or a center of circulation. It’s hard to explain, but the mathematical models are set up to take a storm that has already formed and track it. They do a pretty good job of that. But, until a low, or depression has formed, you can’t rely on all those “spaghetti plots”, as they are familiarly called.
I walked up to Bill Read, the Director of the National Hurricane Center, and I said, “Hi, Mr. Read, I’m Dawn Brown from FOX 8 New Orleans. What’s up with the HWRF?”
Well, he smiled and said, “We initialized the model with a fake storm…, ” to try and give people battling the oil spill an idea of where Alex might go if it formed. Basically, the hurricane specialists had to input some numbers into the storm, such as maximum winds, etc., to run the model, because once again, these models are not designed to work unless there is a storm.
This is why last week, when most of the models were taking the tropical disturbance toward the west, the HWRF and GFDL were headed straight north. Now those two models are more in line with the other computer models and the official track from the National Hurricane Center reflects that.
Does that mean workers near the oil spill need not worry? No. We still have to watch Alex cross the Yucatan and see how it fares in the southwestern Gulf in the beginning of next week.
By the way, I really like Bill Read. Straight shooter, very smart, great communicator.
-Dawn Brown
Website Remodel!
I’m reworking myweatherlady.com to add videos and other elements to better aide educators and weather enthusiasts.
During this process I will not be updating my daily blog.
If you would like an update on the daily forecast and/or more information on weather phenomena, please go to www.fox8live.com and click on the link for weather.
-Dawn Brown
Red River Rises, Spring Flood Forecast
US Flood Risk, Image: NOAA
Sandbagging continues today on the Red River in Fargo, North Dakota. Residents in North Dakota can monitor the latest river stages. As of 11am this morning, the river was at 31′ feet in Fargo, 13′ above flood stage. It’s expected to crest at 38′ this Saturday. They can also watch the river rise through USGS (United States Geological Survey) web cams. Last year, the river rose to 40.8′, a record level for the Red River in Fargo.
24-Hour Snow Melt, Image: NOAA
Rapid snow melt is the main reason for the rising rivers. Near record snowfall across the Northern Plains caused the National Weather Service to put the Red River at a severe risk for flooding.
Red River Webcam, Image: USGS
This is an updated web cam image from earlier today. Look at the obelisk circled in the image. Two days ago, this obelisk was well above the banks of the river.
Red River Webcam, Image: USGS
You can clearly see the banks of the river, the obelisk and a walking trail. This is in Grand Forks, North Dakota.
Major Flood Crests, Grand Forks Image: USGS
Here’s a close up shot of the obelisk on the banks of the river. It marks the flood stage of last year’s flood, and the height of the river in 1897, 1979, 1882 and 1996.
To further monitor the situation, here’s a link to TV forecasters in Fargo and Northern Minnesota.
-Dawn Brown
A Rough Wednesday in Store
After tornadoes have already struck early this week in places like Oklahoma, another storm system will be swinging into the mid-section of the country with another bout of severe weather on the way for Wednesday and Wednesday evening. The Gulf of Mexico is now open for business, pushing dew points above the 60-degree-mark all the way up the southern Mississippi Valley, and more moisture is slated to crawl northward.
US Surface Dew Point Map, Image: Unisys Weather
The dew point is the measure of moisture in the air and it is this moisture that drives thunderstorms. Once the dew point exceeds 60, in combination with several other factors, the atmosphere is generally primed for thunderstorms and just waiting for a system to move in.
US Infrared Satellite Image, Image: Unisys Weather
It is the system circled above that will be that next system on Wednesday. Therefore, the Storm Prediction Center has extended an area of slight risk of severe weather all the way up the lower Mississippi Valley and into the mid-Mississippi Valley. The main threats are damaging winds, hail, and isolated tornadoes.
Severe Weather Outlook Wednesday-Early Thursday, Image: NOAA
Television meteorologists are talking about this elevated threat of severe weather in places like Mobile, New Orleans, and Little Rock.
Spring Has Sprung in the East For Now
After record setting snows and unseasonable cold across the eastern 2/3 of the United States this winter, the table have turned, at least temporarily. This weekend, sunshine is the main player across much of the East as fair-weather high pressure retains control, meaning a well-deserved respite with highs ranging from the pleasant 50s in the Northeast to near 70 degrees across the Gulf South! Place seeing the beautiful weather include Philadelphia, Raleigh, and New Orleans.
National Weather Service Advisories Map, Source: NOAA
Meanwhile, the “trough,” or dip in the jet stream, that was plaguing the East with precipitation and cold weather, has shifted to the West Coast, allowing in storm systems and markedly colder air. Here, one cold storm is expected to swing across the Pacific Northwest allowing for snow as low as 1,000 feet around the Medford, OR area d0wn to northern California on Monday. Here, Winter Weather Advisories are posted above 2,000 feet for up to 4″ of snow. Another storm is rotating through the Southwest, affecting high elevations above 5,oo0 feet around Flagstaff and Tucson, AZ with up to 14″ of snow through Monday.
Satellite & Surface Map, Image: Unisys Weather
Snow-pack, Continuous Cold Set Stage For Spring Floods
The National Weather Service has released its spring flood outlook, and once again the Red River Valley in North Dakota is threatened.
National Snow Depth, Image: NOAA
The snow-pack is approaching record levels and a cold, cold winter has limited melting and evaporation. The frozen soil in North Dakota will eventually melt, causing streams and rivers to swell.
1997 Red River Flood, Image: NOAA
In 1997, major flooding along the Red River near Grand Forks led to the evacuation of 50,000 people. The river inundated areas 2 miles away.
River Flooding, Image: NOAA
You can keep track of river stages online at the National Weather Service website.
-Dawn Brown
Gulf Coast Seiche
The recent Chilean earthquake at a magnitude 8.8 had some pretty far reaching effects and we’re not just talking about across the Pacific! Some effects were actually felt as far away as the Gulf Coast of the United States. Something called a seiche was actually observed in Lake Pontchartrain. What is a seiche? According to the American Meteorological Society Glossary, a seiche is an, “oscillation of a body of water at its natural period.” In other words, it is some additional amount of water, or a “standing wave,” on top of the normal tidal cycle or water level. In this case, this additional amount of water was caused by the seismic waves of Chilean earthquake 4,700 miles away traveling through the earth’s crust! It was actually measured that tides were running 5″ above their predicted levels in Lake Pontachartrain 11 minutes after the earthquake occurred. Seiches are nothing new. The term was coined in 1955 and the phenomenon has been observed as far back as 1755 in England.
In fact in history, due to the massive Alaskan earthquake of 1964, seiches also occurred in the Gulf Coast area; some reported as high as nearly six feet! This extreme height was probably aided by surface seismic waves that were in sequence with those moving through the earth’s crust. The same earthquake caused bodies of water as small as home pools to overflow as far away as Puerto Rico. Other seiches occurred in north and central New Mexico, eastern Kansas, and the region at the southern tip of Lake Michigan.
The occurrence of seiches seems to be more due to the make-up of the land that the seismic waves are traveling through, rather than the radial distance from the epicenter of the earthquake. The density of seiches appears to be roughly proportional to the thickness of surface sediments. For example, where there’s more opportunity for seismic waves to resonate through plenty of “loose” sediment and “rattle” bodies of water, like the Mississippi Delta region, there will be more seiches. In places like the New England where the surface is more stable, there will be far fewer or no seiches.
More on seiches can be found on the USGS site.
1960's Seiche in Baraga County, Michigan, Image: Baraga County Historical Museum