Posts Tagged ‘Hurricane Center’

 

Paula: If You Didn’t Know There Was A Hurricane There…

Wednesday, October 13th, 2010

From time-to-time people talk about the frequency of hurricanes claiming there are more hurricanes now than ever before. Please take that claim with a grain of salt.

I will let the Hurricane Center do my explaining for me. This is the lead paragraph in the current technical discussion on Hurricane Paula.

A HURRICANE IS CROSSING BETWEEN THE WESTERN TIP OF CUBA AND EASTERN YUCATAN…BUT WITHOUT MODERN TECHNOLOGY NO ONE WOULD KNOW IT WAS THERE.

This is not to say there aren’t going to be problems. I expect rain, flooding and even mudslides in Cuba. Still, if you didn’t know there was a hurricane there you wouldn’t know there’s a hurricane there.

Before the advent of satellites we might still be waiting for the “P” storm to form!

Is There Bias In Forecasting Hurricane Earl?

Monday, August 30th, 2010

My friend Bob at Florida State took all the official fixes for Earl (since Earl became a tropical depression through this evening) and plotted them on a map. Then he added the official Hurricane Center forecast. Click the map on the left to make it large enough to read.

There is an unfortunate inconsistency to this data. In nearly every case Earl tracked west of the forecast!

If this remains the case Earl snuggles a little closer to Connecticut than has been said. Not good!

The Hurricane Center is populated with some of the smartest minds in tropical weather. Hopefully they’ll catch on or there’s a method to their madness I just don’t see.

Respect For Hurricane Earl

Monday, August 30th, 2010

Radar — that was my first step this morning. I needed to check the radar from Saint Maarten. As I type this the southern eyewall of Hurricane Earl is touching the coast of Anguilla in the Caribbean. The eye is well defined on radar.

The Hurricane Center says the top winds are 125 mph. If that’s true they’re in an extremely small area. I usually feel NHC’s estimated maximum wind is higher than warranted. It’s all academic. You don’t need 125 mph to rip a Caribbean island to shreds!

There have been no official observations from the Anguilla airport since yesterday afternoon. In Saint Maarten just to the south winds are sustained at 33 mph with gusts to 53 mph. Anguilla is getting it worse.

At St. Thomas the wind is gusting to 49 mph. Earl isn’t there yet. The Virgin Islands and Puerto Rico get their run-in later this afternoon.

These storms tend to wobble. They are not fully symmetrical. There is uneven friction from nearby landmasses and the interaction with other weather systems. This current path is north of where I thought it would be as recently as last night, but reasonably close.

Hurricane Earl is definitely a threat to the US East Coast. Will it hit? Too early to say, but it’s certainly enough of a possibility that I’m watching its every move.

I am surprised by the Hurricane Center’s forecast. The ‘out days’ center of the track is well offshore though all of the East Coast from the Maryland shore to the Canadian Maritimes are within the cone of uncertainty. How helpful is a forecast when it has to alert Washington, Baltimore, Philadelphia, New York and Boston? There’s lots of fudge factor still at work.

Based on the GFS past few runs I’d shift the track even farther west (left) than they have. I’m sure there’s a little “better safe than sorry” in my thoughts as well.

From the latest Hurricane Center discussion:

EARL IS FORECAST TO TURN NORTHWARD...THEN NORTHEASTWARD AHEAD OF A MID-LATITUDE TROUGH THAT MOVES ACROSS THE GREAT LAKES AND INTO THE NORTHEAST UNITED STATES IN 4-5 DAYS. THE TRACK GUIDANCE HAS SHIFTED WESTWARD AGAIN AND THE OFFICIAL FORECAST HAS BEEN ADJUSTED IN THAT DIRECTION. THE UPDATED TRACK FORECAST IS NEAR THE MIDDLE OF THE TIGHTLY CLUSTERED GUIDANCE.

THIS IS A GOOD TIME TO REMIND EVERYONE THAT NHC AVERAGE TRACK FORECAST ERRORS ARE 200 TO 300 MILES AT DAYS 4 AND 5. GIVEN THIS UNCERTAINTY...IT IS TOO SOON TO DETERMINE WHAT PORTION OF THE U.S. EAST COAST MIGHT SEE DIRECT IMPACTS FROM EARL.

There’s a full workweek of this still to come! I will become enveloped in the storm. Actually I already have.

Not A Good Night On Saint Maarten

Monday, August 30th, 2010

I captured the radar image above a little before midnight. You’re looking at Hurricane Earl on the heretofore unknown St Maarten radar. St Maarten is in the middle. On the left is Puerto Rico. The Virgin Islands sit between the two.

Hurricanes are the Gisele Bundchen of meteorology! They are stared at and studied. They are incessantly photographed. They are penetrated by flying meteo labs. All the stops are pulled for hurricanes.

Hurricanes obey the laws of physics. All weather does. Still, hurricanes are distinct.

At its simplest a hurricane moves heat from the equator where there’s an overabundance to the poles where there’s a paucity. The Earth appreciates it. This would be a very different world without hurricanes to transfer heat.

Wind rushes inward toward the hurricane’s centerr. Yes–hurricane’s suck!

As the wind moves friction turns it right. That rightward turn translates into the storm’s counterclockwise spin. As the wind gets closer to the center it gets faster until it finally reaches the eye where it is carried aloft!

The base of a hurricane sucks. The top of a hurricane blows.

A BROAD UPPER-LEVEL TROUGH IS CURRENTLY SITUATED TO THE NORTHWEST OF EARL. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT THIS TROUGH WILL SHIFT WESTWARD AND WEAKEN. THIS SHOULD CREATE A ENVIRONMENT CONDUCIVE FOR INTENSIFICATION AND THE OFFICIAL FORECAST...LIKE THE PREVIOUS ONE...SHOWS EARL BECOMING A MAJOR HURRICANE OVER THE NEXT DAY OR SO. THE NHC WIND SPEED FORECAST IS ABOVE THE INTENSITY MODEL CONSENSUS BUT BELOW THE LATEST GFDL HURRICANE MODEL GUIDANCE.

Pretty standard stuff from Dr. Richard Pasch at the Hurricane Center. The storm is his responsibility tonight.

I keep looking at the long range guidance because this storm has been modeled to pass very close to Connecticut. The 00z (8:00 PM EDT) run of the GFS isn’t in yet, but yesterday’s 18z shows Earl brushing past Cape Hatteras then hooking northeasterly south of Long Island and possibly striking Cape Cod.

Right now on St Maarten the wind is out of the northnortheast at 14 mph. There’s a thunderstorm in progress–not unusual on a tropical island. Tomorrow will be different.

When Hurricane Earl hits (or goes a little south of the island) every single person on St. Maarten will feel threatened! No one goes through a hurricane in any kind of shelter without fear. It’s well founded.

Seasonal Hurricane Forecasts: Why Bother?

Friday, May 28th, 2010

The 2010 NOAA seasonal hurricane forecast is out. The prediction is for a banner year or in government speak: “active to extremely active.”

14 to 23 named storms (top winds of 39 mph or higher), including:
8 to 14 hurricanes (top winds of 74 mph or higher), of which:
3 to 7 could be major hurricanes (category 3, 4 or 5; winds of at least 111 mph)

This would be a very valuable thing if

  • There was a history of accuracy in this forecast
  • The numbers meant anything

The number of storms is inconsequential unless one hits you. Even then only one counts. Human tragedy doesn’t parallel the number of storms. 1992 was a very light season and the year of Hurricane Andrew!

Beyond that top wind speed is only one piece of the equation. As with real estate ‘location, location, location’ is the critical factor. A poorly placed tropical storm can do lots more damage than a monster out to sea.

A nameless friend, well known in the small world of tropical weather experts, likens NOAA’s wide range of potential storms to a gambler betting every number at roulette then bragging when he hits! He went on:

“14-23 storms are you kidding me? That must be 75% of the full distribution. I thought the point of a forecast was to narrow the possibilities from the full range.”

Usually an ensemble of computer models is run to produce a forecast like this. Then the outputs are pared to the most likely results. He’s complaining too many possible scenarios have been left in. The forecast deck is stacked so the forecaster can’t lose!

The Numbers Guy at the Wall Street Journal is similarly complaining.

It is possible that NOAA is keeping its estimates loose to avoid having egg on its face later: In the past nine years, NOAA’s May storm-count predictions have proved accurate about 40% of the time.

Why do they even produce these forecasts? Who benefits?

NOAA and the Hurricane Center do great public good when they forecast individual storms. However, these dubious long range projections only cause skepticism down the road. Just what we don’t need!

The Hurricane Center Did A Terrible Job On Ida

Sunday, November 8th, 2009

I was just having a discussion with a friend about Hurricane Ida. It’s difficult to remember a tropical system this poorly forecast.

Here’s what the Hurricane Center said in their technical discussion Friday night:

ALTHOUGH WATERS ARE WARM OVER THE NORTHWESTERN CARIBBEAN…VERTICAL SHEAR IS EXPECTED TO HAMPER MUCH INTENSIFICATION OVER THE NEXT FEW DAYS. THE GFDL AND HWRF MAKE IDA A HURRICANE OVER THE CENTRAL GULF OF MEXICO…A SCENARIO THAT DOES NOT SEEM PLAUSIBLE IN THE FACE OF WESTERLY SHEAR THAT IS EXPECTED TO INCREASE TO 50 OR 60 KT BY DAY 4.

ida-wind-fields.gifSo much for plausible! Ida was forecast to be a tropical storm now, not a powerful hurricane.

A blown forecast like this, even though the storm is far from the mainland, changes how preparations are made. When the forecast is less dependable storm preps become necessary earlier and for more storms.

Bad forecasting is costly.

That being said I can’t tell you who forecasts hurricanes better. I’m not sure anyone does. The Hurricane Center is stocked with very bright people. Most of their lead forecasters are PhDs.

I don’t know how well, or even if, NHC does post storm analysis. In cases like this I’d like to see some outside agency or (more likely) the academic community take a gander and see if there’s anything that should be done differently.

More accurate forecasting of tropical weather systems is a money saver, plain and simple.

Tropical Storm Grace Is Totally Unimportant And Proves A Point

Monday, October 5th, 2009

The Hurricane Center has christened Tropical Storm Grace. It’s in a very unusual place, off the coast of Portugal. The official forecast has Grace gone sometime later today or tomorrow.

THE CYCLONE IS HEADED FOR EVEN COLDER WATER AND WILL LIKELY BEGIN TO WEAKEN VERY SOON. THE GLOBAL MODELS SUGGEST THAT THE SMALL CYCLONE WILL BE ABSORBED BY A LARGER EXTRATROPICAL CYCLONE OVER THE NORTHEASTERN ATLANTIC IN ABOUT 36 HOURS…IF NOT SOONER.

This storm is not a threat to land. It’s nearly a ‘who cares’ situation.

Before satellites this storm wouldn’t have been named. It might not have even been found!

When you read about increases in hurricane or tropical weather system activity keep that in mind. Not every statistic is meaningful. Historical data points are sparse.

Every Part Of The Danny Forecast Relies On Guesswork

Thursday, August 27th, 2009

It’s a little early for the late guidance on Danny, but not too early to tell you my worry. All day long the Hurricane Center has had trouble finding the center of the storm. Here’s what they said at 11:00 AM.

THE EXPOSED LOW-LEVEL CENTER HAS BEEN MOVING ALMOST DUE WESTWARD FOR THE PAST FEW HOURS. IT IS UNCLEAR IF THIS IS REPRESENTATIVE OF THE ACTUAL MOTION OF DANNY OR A SHORT-TERM TREND. SO…THE INITIAL MOTION IS AN UNCERTAIN 310/11.

They’re saying it’s moving west, but they’re officially marking it as northwest. Got it so far?

The latest technical discussion just hit a few minutes ago.

THE CENTER MEANDERED ABOUT DURING THE DAY…BUT LAST-LIGHT VISIBLE IMAGERY AND DATA FROM THE AIRCRAFT INDICATED THAT A NORTH TO NORTH-NORTHWESTWARD MOTION BEGAN SEVERAL HOURS AGO. HOWEVER…THE CENTER IS NEARLY IMPOSSIBLE TO DISCERN ON RECENT INFRARED IMAGES. THE INITIAL MOTION IS AN UNCERTAIN 330/7.

When the initialization is bad everything that follows it is suspect. Take the forecast with a healthy grain of salt.

The only good news is Danny continues to be a wimp. It wouldn’t take much to knock him out… nor much for him to rapidly intensify.

Earlier this evening my friend Bob, a professor of meteorology and tropical weather expert said, “I think it either remains a TS or becomes cat 2/3. I don’t think there is an in between.”

He’s probably right, but that’s not much help either!

Hurricane Dean – Living Up To Its Billing

Friday, August 17th, 2007

At work, we’ve got new graphics computers and software. With Dean in the Atlantic, I’ve been giving them a workout… or at least better learning how to use them. These storms can be tracked, predicted and shown in a variety of ways.

Right now, the Hurricane Center says Dean has sustained winds of 135 mph. I’m more likely to agree with NHC tonight than last night. Dean has become a classic hurricane with a well defined eye.

I popped over to the San Juan, PR radar and watched the outer bands spin as the storm passed to the south. Later, the huricane will be visible from a radar at Guantanamo and a few (if they’re working) on Cuba.

It will not be a good weekend in Jamaica. The official call brings Hurricane Dean right over the spine of that mountainous island Sunday. In that scenario you get devastating wind and rain, storm driven tides and huge mudslides. The Caymans aren’t much better off.

It’s possible tonight’s 135 mph is near Dean’s peak. Even if he does strengthen (as forecast), there is a limit. It’s tough for a storm to maintain 150+ mph winds for long before internal forces begin to break down the storm.

There’s lots of watching to come. Dean will be ‘on the books’ until midweek next week.

Hurricane Dean – At The Antilles

Friday, August 17th, 2007

Tonight, the Hurricane Center deemed Hurricane Dean’s winds to be sustained at 100 mph. Sure, why not?

I actually don’t think they’re blowing that fast. I’m basing my estimate on the look of the satellite imagery, surface observations and the Martinique radar.

The chain of islands Dean is approaching, the Antilles, will be quickly passed. Though Dean might damage them, they won’t slow Dean much at all. That seems unfair.

The next two days will probably see significant strengthening of this storm as it enters the Caribbean. On TV, meteorologists and others will point out Dean’s well defined and circular eye. We can’t do that quite yet.

The official pronouncement from the Hurricane Center calls for a period of Category 4 winds. There’s no certainty, but that seems a reasonable call. Dean is entering an area primed to be hurricane fuel.

Jamaica, the Caymans and the Yucatan Peninsula are all under attack if Hurricane Dean follows the computer guidance (amazingly in agreement with each other right now). All three areas are quite vulnerable.

After Katrina, some people were left with a false impression. There aren’t many places that can flood like New Orleans. Certainly none of the places I just mentioned floods that way.

The major damage from Dean will be related to strong, destructive winds. If you want the Katrina analogy, that’s the kind of damage produced on the Mississippi Coast.

A less sexy story, Mississippi a whole lot less news coverage than New Orleans. The damage was nonetheless catastrophic. Let’s hope I’m wrong.