UPDATE OCTOBER 2, 2015. 5 AM CDT (10 UTC). Joaquin – now a Category 4 hurricane – has been slowly pounding the Bahamas and is only now slowly moving away from there. Meanwhile, local National Weather Service offices now believe that flooding caused by Hurricane Joaquin this weekend could be “historical” in parts of the U.S. Southeast and Mid-Atlantic. Flash flood watches have already been issued for parts of Northeast Georgia, South Carolina, North Carolina, and northwards into the Mid-Atlantic including Washington D.C. through Sunday night. Meanwhile, the hurricane will also likely impact broad swaths of the U.S. Northeast, including New York City and New Jersey. Heavy rain and flooding should start Friday and last through the weekend, possibly into early next week.
Along the coast, expect rip currents, beach erosion, and coastal flooding. Gusty winds thanks to tightening pressures will be able to knock over trees and power lines. I honestly think the biggest impacts will occur across South Carolina and North Carolina through the weekend. NOAA’s Weather Prediction Center (WPC) is forecasting at least 10-15 inches of rain with isolated areas receiving nearly 20 inches. Rain this quickly in a short period of time will likely result in flash flooding.
The good news is that Hurricane Joaquin will likely stay offshore, with landfall in the U.S. looking increasingly unlikely.
Over the past week, we have already seen several inches of rain in parts of the Southeast, Mid-Atlantic, and into the Northeast from separate storms. With saturated grounds, it won’t take much rain for flooding to develop. Several areas have already received over three inches of rain in the past seven days. Also, winds are likely to increase as the jet stream becomes negatively tilted and tries to interact with Joaquin.
The combination of saturated soils and wind will also likely create a threat from falling trees and power lines.
Joaquin has been moving slowly over the Bahamas, as a Category 4 storm with sustained winds of 130 mph. No doubt in my mind that parts of the Bahamas have been heavily damaged. Imagine how horrifying it would be to experience hurricane force conditions over 12 to 24 hours. And it’s not over yet. The National Hurricane Center advisory this morning (October 2, 5 a.m. EDT) said:
…EXTREMELY DANGEROUS JOAQUIN MOVING SLOWLY NORTHWESTWARD AS IT BATTERS THE CENTRAL BAHAMAS…
…HURRICANE CONDITIONS TO CONTINUE OVER THE CENTRAL BAHAMAS TODAY…
This is the first Category 4 storm to affect the Bahamas since Hurricane Frances in 2004.According to Philip Klotzbach, Joaquin is the first Category 4 hurricane to track through the Bahamas in October in 149 years (1866).
Joaquin is expected to push to the north later today and eventually push to the northeast away from the United States. While some models still hint at a United States landfall, the majority of the models have trended much further east and towards Bermuda. If this solution occurs, then Bermuda will likely have to get ready for some kind of impact from this storm by late this weekend and into early next week.
Hurricane Joaquin by itself is not responsible for the heavy rain threat. We can thank the upper level low that will spin away across the Southeast for that. It will help bring moisture in from the Atlantic. As the low spins away and is cut-off, it will likely remain stationary. It means that moisture will continue to push from west to east off the Atlantic and train over the same spots Friday into Saturday.
Several models show this fetch of rain developing somewhere across South Carolina. The influence of the cut-off low could drag some of the moisture from Joaquin into the U.S. Southeast.
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