Hurricane Joaquin’s nightmare forecast challenge

I would not want to be a forecast at the National Oceanic and Atmospheric Administration's National Hurricane Center this week.

What many consider the "nightmare scenario" for hurricane forecasters seems to be unfolding. It could be a passage out of a Michael Crichton science thriller. An intensifying hurricane moving erratically near the Bahamas. Forecast models show the storm is expected to intensify to major hurricane Category 3 status.

Winds forecast to reach 110 mph in 72 hours. The storm then forecast to suddenly accelerate toward the east coast of the United States, the most densely populated part of the U.S. with more than 100 million people potentially in harm's way. But the most trusted forecast models can't reach clear consensus on where or even if the storm will make landfall.

That's not fiction, that's reality today.

Joaquin is now officially Hurricane Joaquin as it continues to churn and strengthen near the Bahamas.

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BULLETIN

HURRICANE JOAQUIN INTERMEDIATE ADVISORY NUMBER 10A

NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015

800 AM EDT WED SEP 30 2015

...JOAQUIN BECOMES A HURRICANE...

SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION

----------------------------------------------

LOCATION...24.9N 72.2W

ABOUT 245 MI...395 KM ENE OF THE CENTRAL BAHAMAS

MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H

PRESENT MOVEMENT...SW OR 235 DEGREES AT 6 MPH...9 KM/H

MINIMUM CENTRAL PRESSURE...971 MB...28.67 INCHES

Intensification expected

Joaquin is slowly spinning near the eastern Bahamas. The warm water and low wind shear environment is favorable for intensification during the next 48 hours.

Most of the models bring Joaquin to Category 2 or 3 status on the Saffir-Simpson scale within two days.

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NOAA's official forecast for wind speeds with Joaquin reaches 110 mph in 72 hours.

FORECAST POSITIONS AND MAX WINDS

INIT 30/0900Z 25.4N 72.5W 60 KT 70 MPH

12H 30/1800Z 25.1N 73.0W 70 KT 80 MPH

24H 01/0600Z 24.7N 73.8W 75 KT 85 MPH

36H 01/1800Z 24.7N 74.5W 80 KT 90 MPH

48H 02/0600Z 25.2N 74.7W 90 KT 105 MPH

72H 03/0600Z 28.3N 73.5W 95 KT 110 MPH

96H 04/0600Z 33.0N 73.0W 85 KT 100 MPH

120H 05/0600Z 37.0N 73.5W 80 KT 90 MPH

Here's a great animation from NOAA on the types of damage expected at various categories of the Saffir-Simpson scale.

https://www.youtube.com/watch?v=sGaP58LfyO4

Rapid intensification?

Joaquin is passing into a favorable area for rapid intensification. Very warm water and light wind shear aloft may be a catalyst for rapid intensification in the next 48 hours.

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Here's more on the potential for rapid intensification with Joaquin from Weather Underground.

During its slow westward trek, Joaquin will be passing over ocean temperatures near 30°C (86°F)--the warmest seen there since record keeping began in 1880. Oceanic heat content--the amount of energy stored in the upper 50 meters (160 feet) of the ocean--is another index of potential strengthening.

Joaquin’s track should take it across the boundary into oceanic heat content values greater than 50 kilojoules per square centimeter by Wednesday. For tropical storms and Category 1 hurricanes, values of heat content greater than 50 kJ/cm2 have been associated with more rapid intensification rates, assuming that wind shear is less than 15 knots, mid-level relative humidity is greater than 50 percent, and SSTs are at least 28.5°C. Joaquin should meet most or all of these criteria over the next couple of days, which raises the possibility of robust intensification.

Forecast track: No model consensus yet

The eventual track for Hurricane Joaquin is still very much in question. The overnight and early Wednesday forecast model runs did not create a high degree of confidence on the storms path. Many of the U.S. models cluster around a possible landfall near the Virginia coast with a powerful storm moving up the Chesapeake Bay toward Washington, D.C.

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The Canadian model favors a storm making a potential double landfall. A first landfall near the Virginia coast, then a storm skipping along the Jersey shore with a second landfall near New York City or Long Island.

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And then there's the usually trusty model from the European Centre for Medium-Range Weather Forecasts. Remember the European model nailed the forecast of Hurricane Sandy days in advance, and it's eventual landfall along the Jersey Shore in 2012.

The last two runs of the European  model continue push Joaquin on the east side of the forecast envelope and take the storm out to sea, without a U.S. landfall. But the Euro is the outlier at this point.

Her's a good comparison look from Mike's Weather Page.

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NOAA's official NHC track splits the difference, taking a path between the eastern Euro solution and the more westerly (and landfalling) U.S. models. That's a tough choice. Follow the U.S. models and ignore the usually trusty Euro?

Here's a closer look.

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Giant storm?

Joaquin could be a very large storm by the time it approaches the U.S. east coast. It's critical to remember that the landfall is less important then the overall storm size and impact zone. The latest rainfall projections are stunning, a wide zone of 6 to 11 inches (or even 1 foot of rain) that could cause widespread and major flooding along a big swath of the eastern U.S. megalopolis.

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Bottom line:

• Hurricane Joaquin is forecast to reach Category 3 intensity with 110 mph winds in about 72 hours.

• Rapid intensification is possible as the storm passes over warm water and through light wind shear aloft.

• The storms eventual track and potential landfall location is still highly uncertain, but the majority of forecast models now favor an eastern U.S. landfall Sunday or Monday.

• All persons in the eastern U.S. from North Carolina northward should now be on high alert and making preparations for a possible landfall with a strong hurricane this weekend or early next week.

• A few (but not all) of the cities potentially impacted by Joaquin include Norfolk, Va., Washington D.C., Philadelphia, New York City and Boston.

• If a Category 2 or 3 Joaquin makes landfall along the U.S. east coast and moves north as many models are forecasting, it could become a very deadly hurricane and one of the costliest disasters in U.S. history.

• Stay tuned as models updates roll in Wednesday.