- Henri: The National Hurricane Center has issued hurricane and storm surge watches for portions of Long Island, Connecticut, Rhode Island and Massachusetts due to a further west shift and higher model confidence of this outcome. While the mean expectation is for a high end tropical storm at US landfall, there is an increasing possibility Henri retains hurricane strength at the coastline before weakening. A full discussion of implications for wind, storm surge and rainfall impacts is detailed below.
- Grace: Grace emerged overnight into the Bay of Campeche where conditions are favorable for intensification today. The NHC calls for landfall before sunrise Saturday morning as a category-1 hurricane with hurricane warnings posted from Puerto Veracruz northward to Cabo Rojo in eastern mainland Mexico. Heavy rainfall across the Yucatan Peninsula and Veracruz along with elevated mudslide potential are likely.
- Saturated soils and long duration winds: Henri is expected to make landfall as a strong tropical storm or possibly a category-1 hurricane, affecting portions of Long Island, Connecticut, Rhode Island and Massachusetts. While the winds are expected to remain at the lower end of the Saffir Simpson scale, an important consideration is the duration of the wind. The forecast calls for a significant slowing down of Henri prior to landfall, which means winds will impact a given area for a much longer duration, and rainfall totals could be very high. Portions of the New England coastline, including Cape Cod where the highest wind speeds are currently expected, had their rainiest July on record. Coupled with additional rainfall from the recent passage of Fred, the soils are extremely saturated. With a forecast of up to 8 additional inches with the landfall of Henri, flash flooding, urban flooding and treefall are all a major concern.
- Storm surge coincident with high tides: Henri is expected to approach and make landfall during the high astronomical tides on Saturday and Sunday nights. Consequently, significant storm surge flooding is likely. The National Hurricane Center forecast calls for 3 to 5 feet of surge from Rhode Island east to Nantucket and around Cape Cod. Additionally 2-4 feet is expected to the west of the track in Long Island and along the New Jersey coastline. Accompanying the rising waters will be large and destructive waves. Because of the complex coastline, any slight changes in track or intensity of the storm could have different storm surge outcomes.
- Increased risk of wind impacts to East Coast cities: On account of the further shift west of Henri, the probability for tropical storm and hurricane force winds has increased for most cities along the Eastern Seaboard from New Jersey to northern New England. There is still quite a bit of uncertainty in the windspeed forecast, as intensification in the next 24 hours is possible, followed by potential weakening as the storm slows over the cold waters off the coast of Long Island. Henri is expected to track due north over Massachusetts and New Hampshire, before making an eastward turn across the Gulf of Maine toward Maritime Canada.
The current peak storm surge forecast from NHC. Source: NHC.
The current rainfall forecast from NHC. Localized maximum rainfall may be higher than shown. Source: NHC.
Additional Items on Henri
- Intensification Today: As Henri makes the turn and accelerates to the north, wind shear will start to relax and Henri will track over the very warm Gulf Stream. Strengthening is anticipated, with a small but unlikely chance Henri intensifies rapidly to category-2 strength by tomorrow. This unlikely outcome would bolster the prospects of hurricane force winds on the coast Sunday of Long Island and southern New England.
- Henri in Historical Context: The last hurricane to make landfall on Long Island or the New England coast is Hurricane Bob in August 1991. The current 30 year stretch without a landfall in New England or Long Island is longest gap in the historical record dating back to 1851.
The current three day forecast from NHC. Please click on the image to view a movie of the three day evolution of the forecast since Tuesday August 17th, highlighting the westward movement towards southern New England. Source: NHC.
Maximum sustained wind forecast from the American weather model. Source: Everstream Analytics.
Timing and earliest likelihood of tropical storm force sustained winds with Tropical Storm Henri. Source: NHC.
Spread in weather model guidance for the forecast of Sunday evening August 22. The majority of weather model ensemble members now are projecting landfall along Long Island and the southern New England coast. Source: Tomer Burg, University of Oklahoma.
As Henri approaches the coastline of Long Island, NY and southern New England, sea surface temperatures drop below 26 degrees Celsius, the threshold usually required to maintain a hurricane. A key question in the forecast is how much further north Henri can maintain hurricane strength over cooler waters before landfall. Source: Tomer Burg / University of Oklahoma.