WeatherNation Blog

Hurricane vs. Oil

It’s official. We have now entered the 2010 Atlantic Hurricane Season. It’s always an interesting time and we are all left wondering what’s in store for us. One thing is for sure–we have experienced very quiet, docile seasons these past few years and the forecast is calling for an active season this year. NOAA certainly isn’t being shy with their forecast. They’re calling for 14-23 named storms, 8-14 hurricanes (3-7 major hurricanes). In an average season, we see 10 named storms. Joe Bastardi at Accuweather is expected 15 named storms, 7 landfalls, 5 hurricanes and 2 or 3 major hurricane landfalls. Dr. Gray is calling for 15 named storms, 8 hurricanes (4 major) with a 69% chance of a hurricane hitting the US coastline. There are two reasons for this “active” forecast: 1) El Niño is breaking down 2) Warmer than average sea surface temperatures in the Tropical Atlantic.

With this in mind, many of us are left wondering how the oil spill in the Gulf may impact a hurricane or vice versa. Have we ever experienced a hurricane and an oil spill in the same area? Yes, but the oil spill has usually been the result of the hurricane. Katrina and Rita in 2005 showed us that hurricanes can widely disperse oil. Of course a hurricane would be expected to steer the oil. There are two scenarios depending on where a hurricane or tropical storm will position itself. Air flows in a counterclockwise fashion around centers of low pressure–hurricanes and tropical storms are intense areas of low pressure. Which means that if a hurricane were to situate itself to the west of Louisiana, strong onshore flow could absolutely push the oil into the Gulf coast:

Scenario 1: Onshore Flow Pushes Oil Into Coast

Scenario 1: Onshore Flow Pushes Oil Into Coast

What if a hurricane were to position itself further east? Well, that would actually help out the Gulf Coast quite a bit pushing the oil away from the coast due to offshore flow on the west side of a hurricane or tropical system:

Scenario 2: Offshore Flow Pushes Oil Away From Coast

Scenario 2: Offshore Flow Pushes Oil Away From Coast

Either way, we’ll have to prepare for the oil slick to spread. The odds of us not having any tropical system in the Gulf is minimal. Let’s just hope that Scenario 1 doesn’t happen soon…

Another question to answer: Will the rain produced by a hurricane in this area contain oil? No. Remember that hurricanes are a lot larger than the oil slick itself. Most hurricanes span 200 to 300 miles of ocean–far larger than the slick. What I would be concerned with is the storm surge associated with a hurricane in the Gulf. If Scenario 1 pans out, oily water could absolutely be a big problem.

stormsurge

What is a storm surge?

If the oil slick remains relatively small (as compared to a hurricane), it should have no impact on the direction or intensity of a hurricane.

We’ll be waiting… and watching.

Susie Martin
WeatherNation Meteorologist

In Like a Lion, out Like a Lamb

Wow, what a difference a few weeks make when it comes to severe weather across the Plains.  There has only been about 30 storm reports total across the United States in the last 30 hours.

There are two storms I am watching across the US today.   I have marked them on the map below.   Water Vapor is a great tool to pick out the weak or strong areas of low pressure in the jet stream:

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One in the Southeast is going to bring TN and KY some pop up or air mass T-Storms today, but they are not expected to be severe.

The other low to watch is moving through the Northern Plains and will bring cooler weather to the Upper Midwest for Memorial Day.

If you are looking for Severe Storms today… head to KS or OK, but I don’t think you will see much.

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Tuesday is the day to watch for Severe Storms across IA, NE and KS, but it does not look like an outbreak quite yet.

Cold Lows and Hot Highs

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There are two major features on the weather maps this Friday.   Can you see them?   One is a Cut-Off area of low pressure over the Northern Rockies and the other is a hot and dry dominant ridge of high pressure extending from the Great Lakes to the Southern Plains.   A forecast map like the one I posted above is one of the first forecast products I will look at on a daily basis.   This is the air temperature forecast from the NAM model at the 850 millibar pressure level.   This is a good level to look to find the air masses or the hot and cold places.

JC_BLOG4It may be cold enough across the Northern Rockies, that we may see some snow at the higher elevations around Glacier National Park.   That is the only place in the lower 48 that Winter Weather Advisories have been issued.

NORTHERN ROCKY MOUNTAIN FRONT-EASTERN GLACIER-
INCLUDING THE FOLLOWING LOCATIONS...BROWNING...MARIAS PASS...
LOGAN PASS...CUT BANK
507 AM MDT FRI MAY 28 2010

...WINTER WEATHER ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO
6 AM MDT SATURDAY...

THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A WINTER
WEATHER ADVISORY FOR SNOW...WHICH IS IN EFFECT FROM 6 PM THIS
EVENING TO 6 AM MDT SATURDAY.

* TIMING AND MAIN IMPACT: SNOW SHOWERS OVER THE MOUNTAINS WILL
  CONTINUE AT TIMES THROUGH THE DAY BUT THEN INCREASE IN INTENSITY
  TONIGHT. OVER THE PLAINS RAIN AND SNOW SHOWERS THIS EVENING WILL
  TURN TO ALL SNOW SHOWERS BY LATE EVENING. SNOW SHOWERS SHOULD
  THEN INCREASE IN INTENSITY AFTER MIDNIGHT. TRAVEL WILL BE
  AFFECTED DUE TO LOWER VISIBILITIES.

* SNOW ACCUMULATIONS: AROUND 2 INCHES OVER THE PLAINS AND 5 TO 10
  INCHES OVER THE MOUNTAINS.

* WINDS AND VISIBILITY: NORTHWEST WINDS 10 TO 20 MPH THIS EVENING
  WILL INCREASE TO 15 TO 25 MPH AFTER MIDNIGHT. VISIBILITIES WILL
  BE REDUCED TO ONE MILE OR LESS AT TIMES.

* LOCATIONS AFFECTED INCLUDE: CUT BANK...BROWNING...MARIAS
  PASS...LOGAN PASS

The same area of low pressure that is going to put out that snow is likely to bring some severe storms to the Northern Plains later today.   Are you going to see an outbreak?  No, I highly doubt it, but we may see a few severe storms from ND to MT, with the main concern being large hail.   There is another slight risk area near the Mid Atlantic States, but if there were to be a tornado today, it is likely going to be in SW NT.

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Speaking of tornadoes, so far this year, the US has had a total of 544 tornadoes to date.  Who do you think has had the most?   Well, Oklahoma comes in first at 63 tornadoes, Texas a close second at 62 tornadoes and Kansas at 56 tubes.

JC_BLOG2Notice it has been fairly quiet for both MN and Iowa and when it comes to the next few weeks, I really don’t see an outbreak of severe weather coming any time soon.   The overall long range weather pattern looks kind of calm in my eyes.

Where ever you are this holiday weekend, I hope mother nature cooperates with you and you have a chance to get outside and enjoy the weather.

I almost forgot to tell you, there may be a showing of the Northern Lights this weekend, you can read about it at spaceweather.com

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A Look Back At Winter

It’s a bit of a stretch thinking about the cold days when a good half of the country has been battling hot, muggy weather. Apparently, this past winter proved to be an quite a roller coast ride. We started the season off with record breaking snow in various areas in the United States. Remember the Christmas blizzard in the Midwest?  The relentless snowstorms out west? Round after round of heavy snow began right around the Winter Solstice.  Cheyenne, Wyoming actually saw a very snowy season with over 103″ inches of snow. That managed to make it into the top 5 snowiest seasons on record. Additionally, winter 2009/2010 was colder than average for the nation. Despite a healthy start to the winter season, it ended quite abruptly for many. Spring decided to knock on our door early (hey, I won’t complain). By the end of April, North American snow cover had retreated rapidly. In fact, snow cover in the U.S. was at its lowest since 1967, according to the National Oceanic and Atmospheric Administration (NOAA). It’s just an interesting dichotomy.

April 2010 Snow Cover (based on MODIS data).

April 2010 Snow Cover (based on MODIS data).

NOAA stated the following: “Across North America, snow cover for April 2010 was 2.2 million square kilometers below average—the lowest April snow cover extent since satellite records began in 1967 and the largest negative anomaly to occur in the 521 months that satellite measurements are available.” Despite this, the west seems to be still hanging on to winter.

I was talking to my in-laws in Pollock Pines, CA (it sits at about 4000ish ft in elevation). They had attended their son’s law school graduation in Santa Barbara last week. It was a beautiful, warm, sunny day. Then they drove home only to find 3″ of snow on the ground. They asked me, “When is Winter going to end?!” Out west, winter still refuses to let go. Yes, it’s common to see snow in the highest of elevations, but snow has been invading more populated elevations in the Sierras and Rockies.  It’s now the end of May and more snow is expected to plague the Sierras:

Another winter storm plagues the Sierras

Another winter storm plagues the Sierras

Snow levels are expected to be at around 5000 feet with the storm out west (with some areas seeing snow levels dropping to 4500 ft). Three to six inches of fresh powder will drape the 5000 ft levels and even higher totals (over 8″) at the higher peaks. Gusty winds will accompany the snow too. Well, at least the skiiers won’t have anything to worry about. There still are some resorts open. Donner Pass is open for skiing this memorial day weekend. It’s looking promising:

Donner Pass on May 27th.

Donner Pass on May 27th.

Susie Martin
WeatherNation Meteorologist

Large Wedge Tornado Saturday

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Yesterday, Walworth County North Dakota got rocked by a large and violent tornado.   It’s hard to tell by video along, but to me, it looks like at times, it may have been at least a 1/2 mile wide:   Take a look for yourself:

http://www.youtube.com/watch?v=IgvU4XE935k&hd=1

This one really takes my breath away:

http://www.youtube.com/watch?v=ukT00pYQ39o&hd=1

Look at how large it is!   Not sure how strong the winds are, it’s hard to tell, but at least 150 mph from my experience.

Yesterday was only a slight risk of severe weather… but we still saw a violent tornado.   Just because the SPC issues a slight risk… it does not mean the storms will not be violent, just that there will not be an out break.

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Today, there is more of a hail risk, then a tornado risk.   Above is SPC’s thoughts on the tornado probability for today.

There will be another chase possibility Monday from South Dakota to Nebraska, after that… the pattern looks fairly quiet, until next Saturday, where we could see more severe storms returning to the Northern Plains.

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