30 October 2012

Superstorm Sandy managed to live up to the hype

For many, Sandy certainly lived up to the seemingly impossible forecasts of impacts. For starters, it made landfall with a central pressure of 946mb... the second lowest pressure ever recorded for any storm to hit the northeastern U.S. (first place was the 1938 Great New England Hurricane at ~941mb).  Maximum sustained winds were 80mph, and higher gusts were reported from Rhode Island down to North Carolina.

The center came ashore near Atlantic City NJ around 8pm EDT last night, though its effects were of course felt far from the center.  This satellite image shows Sandy at landfall on Monday evening.

In terms of a human toll, 84 lives have been taken by the storm (as of 9am today) across the Caribbean, the U.S., and Canada.

At least 7.5 million people in the northeast are without power.  The only silver lining there is that the temperatures after the power outages aren't sweltering or frigid, so it's generally not as life-threatening as it could be.

The Battery in downtown NYC ended with a peak water level of 13.88', which is about 2'8" higher than the previous record (set in 1821).  That, of course, resulted in a total catastrophe.  By around 8pm, the subways and automobile tunnels were filling with sea water.  And before that, both JFK and La Guardia airports had flood water pouring across the runways and into the terminals.  The flooded areas of NYC also experienced large fires, collapsed buildings, and the power company shut off electricity to the city before the flooding got too bad and damaged the equipment.  The iconic fishing pier at Ocean City MD has been completely destroyed.  The streets of Wildwood NJ became the beach as the storm surge inundated the huge beach they used to have.  The Atlantic City boardwalk is now rubble and the city flooded.  The full range of impacts across all of the states are too numerous to detail here, but you will undoubtedly see and read more in the news.

A buoy at the entrance to the New York Harbor recorded a peak wave height of 32.5 feet... but I'm not yet aware of what affects such large waves had on the immediate area.

As of this morning, the Potomac River reached its highest level since 1996 due to the heavy rainfall.  5-7" of rain fell in much of Maryland, Delaware, and northern Virginia; southern New Jersey received about 7-9", northern New Jersey saw about 2-4", while much of southest Pennsylvania was in the 3-5" ballpark.  Meanwhile, it's still snowing hard West Virginia and they are expecting 2-3 feet of very wet snow.

It's not over yet either.  Heavy rain is still falling over an enormous area, and storm surge and coastal flooding continues to be a very large danger.  This image shows the current radar depiction of the precipitation still affecting 17 states.  I also have very long radar loops covering Sandy available at http://andrew.rsmas.miami.edu/bmcnoldy/tropics/radar/

Sandy will certainly be a storm for the record books, and will also end up being a retired name.  Going back to 1953, the only storms so late in the alphabet to be retired were Stan (2005), Wilma (2005), and Tomas (2010).

29 October 2012

Sandy's historic landfall expected tonight

Hurricane Sandy continues to loom ominously off the U.S. east coast, bringing very heavy rain and tropical storm to hurricane force winds to many millions of people well before the worst arrives. The coastal flooding is already terrible, as expected (even as far south as Miami and Fort Lauderdale!). Locations from North Carolina to Maine will continue to see incredible coastal flooding/erosion, with the worst near and north of where the center crosses land (approximately southern NJ into NYC, Long Island, CT, RI, and MA). Inland flooding will also be a large problem in the coastal states as well as the inland states throughout the northeast. Finally, the 50-90mph winds that many places will experience can easily damage roofs, break tree limbs, and uproot trees, bringing power lines down with them.

At 8am EDT today, Sandy was a Category 1 hurricane with 85mph sustained winds, and a 946mb central pressure (it's that very low pressure that creates the strong winds at the surface).  The wind field is so large that tropical storm force winds (45mph+) extend 485 miles out from the center.  The center is located approximately 300 miles south of NYC and 300 miles east of Norfolk... heading for a landfall late tonight near Atlantic City.  I have multiple long radar loops available at http://andrew.rsmas.miami.edu/bmcnoldy/tropics/radar/index.html#sandy12

Perhaps the trickiest part of this system from a warning perspective is that Sandy may not technically be a hurricane by the time it reaches the coastline later tonight. It is interacting with a cold front that is draped on the coastline and is losing some of its tropical characteristics. It actually has a warm front forming off to its east and a cold front to its south... a sign that it's transitioning to an extratropical cyclone.

This absolutely does not make it any less dangerous! It has been intensifying (by both tropical AND extratropical mechanisms), and this interaction with the mid-latitude front is exactly what has been forecast to occur for days now. With or without a hurricane or a hurricane warning, this storm is extraordinary, unprecedented, and must be taken very seriously.  The storms it has been compared to are the 1938 Great New England Hurricane, Hurricane Gloria in 1985, and the "Perfect Storm" of 1991.  Sandy will join this crowd, and likely surpass some (if not all) of them in total impacts and damage.

This is truly a worst-case scenario that will cost tens of billions of dollars and claim hundreds of lives.  Huge unthinkable storm surges along the entire northeast U.S. coast (particularly in the New York City and northern NJ region), mostly reaching their worst at night and during a full moon (already higher-than-normal tides), large rainfall amounts over several states, 2-3 FEET of wet snow in the mountains of WV, and widespread power outages for perhaps 10 million people.

If you're in the affected areas, be aware of nearby streams/creeks/rivers that could quickly turn into white water rivers... large trees near your house... and be prepared to lose power for several days.  Also, remember to check up on family and friends who might be at a higher risk than you.

A good source of constant updates through the coming couple of days is the Capital Weather Gang's live blog... and for the latest local bulletins and warnings, check your local National Weather Service office.

22 October 2012

16 October 2012

Hurricane Rafael heading toward Bermuda

At 03Z today (11pm EDT last night), Rafael was upgraded to the season's 9th hurricane.  At the 21Z advisory, the central pressure was 985mb with 60kt sustained winds, then at the 03Z advisory, it was 974mb and 75kts.  Both advisory intensities were supported by aircraft measurements.  The last time a storm had such a low pressure at its first advisory as a hurricane was Alex in 2010 (973mb).

The satellite appearance is not the best anymore, but as of 11am EDT today, the intensity is 75kts and 971mb.  It is expected to gradually weaken over the next couple of days until it transitions to an extratropical cyclone.  It is forecast to make its closest approach to Bermuda later tonight as a hurricane, and the center should pass just 100-150 miles east of the island.

Rafael is already in radar range from Bermuda now, and you can find a growing radar loop at http://andrew.rsmas.miami.edu/bmcnoldy/tropics/radar/

15 October 2012

Rafael almost a hurricane

Since my previous post on Friday, Patty got smothered by the mid-latitude trough and front as expected, and the final advisory was written on it on Saturday morning. 

Meanwhile, the disturbance that left the African coast on October 5 was upgraded to Tropical Storm Rafael on Friday night based on aircraft reconnaissance.  This is the same wave that I mentioned last Thursday when it was east of the Lesser Antilles.  It is now about 350 miles due north of Puerto Rico, and is just shy of becoming a hurricane (should be later today).  This would make Rafael the 17th named storm and the 9th hurricane this year in the Atlantic. [We've still only had 1 major hurricane very briefly: Michael.  The last five seasons with 0 or 1 major hurricanes were 1990, 1992, 1993, 1994, and 1997.  So it's been a while, but the season isn't over yet...]

At the 11am EDT advisory, the maximum sustained winds are 60kts with a 985mb central pressure.  Tropical storm force winds extend 205 miles from the center.

The traditional satellite presentation is quite impressive, and in earlier overpasses by microwave instruments, it already has an eyewall and eye below the cloudtops.  I'm going to include a couple images to showcase some of the noteworthy features.  The first is a full-resolution visible image from GOES-14 zoomed in right over the storm.  The fine whispy cirrus outlow exists in all quadrants except the northeast, and the deep intense thunderstorms are firing up and wrapping around the center.  Then, in the enhanced infrared image below that, you can see the temperatures of the cloud tops, with the coldest highest cloud tops in black and light gray and the warm ocean on the other side of the scale, also in dark gray.

Assuming it does indeed become a hurricane later today, it would be the first hurricane we've had below 25N since Ernesto (briefly a hurricane in early August before hitting the Yucatan peninsula).  And even Rafael would sneak in below 25N by a very small margin.  That is certainly an oddity of the season!

Track models are all in very good agreement that Rafael will head north toward Bermuda, then gradually turn northeast, most likely passing slightly east of Bermuda on Tuesday evening before racing into the cold and hostile north central Atlantic.

It probably won't be able to strengthen too much more, but should remain in the 65kt ballpark (+/- 10kts) for the next few days before turning extratropical.

Elsewhere, there's nothing on the horizon, but this time of year, we need to keep a closer eye on the western Caribbean and Gulf of Mexico for quick developers.

11 October 2012

Two disturbances to watch across the basin

The first disturbance is an easterly wave that left the African coast back on October 5, and has been making its way westward.  It's now centered near 11N 56W (about 340 miles east of Grenada in the southern Lesser Antilles) and has an embedded 1007mb Low.

Fortunately for North American interests, models are in good agreement on this system turning to the north very soon, probably passing east of Puerto Rico (rather similar to Jose 1999). One exception is the ECMWF global model, which has a more northwest track, bring it over Puerto Rico, then the Bahamas, THEN recurves it on Monday over the Bahamas before it reaches Florida.

As far as intensity goes, it has a good chance at becoming a Depression and then Tropical Storm in the next few days, but then the vertical shear is forecast to become fairly hostile after about 3-4 days, putting a brake on whatever intensification might be happening.  The next two names on the list are Patty and Rafael, and depending on the timing of this disturbance and the next one I'm going to talk about, this could be either.

The second disturbance has been a trackable entity since about October 6, and appears to be very close to Depression status (I think it has been a Depression for a while already, but NHC hasn't officially upgraded it).  However, it now has less than a day to "make its move" because a large frontal boundary is encroaching on it and will envelope it shortly.  On the large-scale water vapor image shown here, the disturbance in question is the blob of purples north of Hispaniola (the bright colors denote cold cloud tops and higher upper-level humidity, while the browns and blacks denote much lower humidity in the upper-levels).  Being that close to a mid-latitude trough/front is bad news if you're a tropical cyclone.

An enhanced satellite image with a closer view of the system shows the two air masses very clearly.  In the low-level clouds (yellow), two features are worth pointing out: 1) the surface Low is mostly exposed and centered to the southwest of the deep convection (white), and 2) the frontal boundary between the warm moist tropical air and the cooler drier mid-latitude air is evident and runs southwest to northeast... very close to the disturbance/depression.

04 October 2012

Latest on Nadine, Oscar, and GOES-East

Just a short update today, since both named storms are weak and far from land.  The enhanced satellite image below shows the locations of the two systems marked with a red "O" and "N". 

This map shows the past, current, and forecast tracks of both storms... Nadine (AL14) over the Azores, and Oscar (AL15) south of the Azores.  Both are expected to become post-tropical within a day or so.

Nadine continues to lose its identity and is expected to become fully absorbed by a mid-latitude trough later today.  Depending on exactly when the plug is pulled, it will end up at about 22.5 days as a numbered system, which is enough to put it in fourth place for longevity in the Atlantic since 1851.

Shortly after my update yesterday, TD15 was indeed upgraded to Tropical Storm Oscar, the 15th named storm of the season.  As I pointed out in a previous post, historically, only about 8% of seasons ever reach the 15th named storm, so this is certainly impressive, but about a month too late to be considered for the record earliest formation date of the 15th named storm.

Today is the twelfth day since GOES-13's primary instruments failed, and the fourth day since GOES-14 has been allowed to drift eastward to take over the GOES-East "parking spot" at 75W (so today it would be centered over 102.3W).  For details on this manuever and the relative locations of the satellites, please see the last section in yesterday's post

02 October 2012

As Nadine fizzles, Oscar may be forming

Stubborn Nadine is still a strong tropical storm with 55kt sustained winds, and is expected to remain a tropical system for another couple of days before finally getting obliterated by a mid-latitude trough.  It has been on the books for 20 days... in yesterday's post I highlighted the longevity record holders for reference. 

One thing a storm does when it sits over the same area for a long time is upwell colder water from the depths of the ocean.  In some places, the surface water might be warm, but that warm water doesn't extend very deep, making it easy for a storm to mix it out.  Nadine has been in the vicinity of the Azores for a couple weeks now, and has generated quite a patch of anomalously cold water as shown here.  A 2-degree Celsius anomaly is pretty significant, and greatly reduces the potential intensity of a storm.

As you can see in the satellite image below, it is a respectable tropical cyclone with an eye, indicating that it remains well-organized... the Azores islands are the yellow outlines on the right side of the image.

Now, there's another disturbance getting organized.  It's an easterly wave that left the African coast back on September 28, and is now centered near 12N 39W (about 850 miles west of the Cape Verde islands) with a 1009mb central pressure.  It appears to be on its way to becoming Tropical Depression 15 and then Tropical Storm Oscar this week.

The majority of models do intensify this to a hurricane, but also agree on a sharp turn to the north very soon, keeping it far away from land.  Oh, and if you're in the Azores, you might get another tropical visitor this weekend... as if the current guest hasn't already overstayed its welcome.

Assuming it gets named this week, it will be the 15th named storm of the season.  That is impressive, but far from a record.  In 2005 and 2011, we saw the 15th named storm form on September 7, and then in 1936, the same thing on September 19.  However, only about 8% of years ever reach the 15th named storm, so it's still an outlier in that regard.

01 October 2012

October Ushers in Highest Likelihood of Hurricanes in South Florida

Today's update includes the latest on Nadine, Nadine's longevity, the drought of U.S. major hurricane landfalls, and a focus on south Florida's hurricane climatology.

You can read today's post on the University of Miami's RSMAS blog.  Thanks for reading!