Tropical Storm Cristobal forms in the Southwestern Atlantic near the southeastern Bahamas islands. Airforce Reserve and NOAA Reconnaissance aircraft found tropical storm force winds in Cristobal earlier this morning. This is after Tropical Depression Four formed over the Turks and Caicos islands yesterday and strengthened this morning. As of the 11am eastern (12pm local) time advisory, Cristobal had maximum 1-minute sustained winds near 45mph and a minimum central pressure near 1001mb. Tropical Storm Warnings are in effect for the central and southeastern parts of the Bahamas.
Cristobal is expected to track slowly north-northwestward or northwestward today. This motion is in response to a weakness in the Bermuda-Azores ridge to the north of Cristobal. This weakness is associated with the same trough related to the front that brought strong thunderstorms to Bermuda yesterday morning that produced gusts over gale force, over an inch of rain, and rain-cooled air led to a record low of 70.7F – beating the old record of 71.6F set in 1999.
Two potential scenarios then appear possible. The first, Cristobal turns more northward in response to a weakness in the Bermuda-Azores ridge because of a trough to the north. Cristobal then accelerates northeastward, passing to the northwest of Bermuda on Wednesday. The second scenario is the trough to the north of Cristobal doesn’t pick up Cristobal and the storm continues moving slowly northwestward, or even turning back to the west for a time, until the next trough creates a weakness in the Bermuda-Azores ridge on Wednesday and then takes Cristobal northward and then northeastward, passing further to the northwest of Bermuda later in the week. This second scenario could potentially take Cristobal fairly close to the United States before turning the storm out to sea. Hazardous rip currents are likely along the US East Coast in both scenarios. Because of the uncertainty in the track forecast, and the very different conditions that are possible as a result, it is important to monitor official updates issued regularly every 6 hours, or every 3 hours when watches or warnings are in effect. (See: National Hurricane Center | Bermuda Weather Service)
Similar to both scenarios, initially, Cristobal is expected to slowly strengthen as it moves northwest and then northward away from the easternmost Bahamas. Then a faster pace of intensification is possible Monday through Wednesday as Cristobal moves into an area where upper level winds are more supportive of intensification. During this period, early next week, Cristobal is expected to become a hurricane. As he passes northwest of Bermuda, the outer fringes of the storm could bring tropical storm conditions to the island – likely intermittently in squally rain bands. These impacts, and their timing, will vary significantly depending on Cristobal’s track in the short term and how close Cristobal comes to Bermuda. Meanwhile, showers, thunderstorms, and patchy rain are still on and off in Bermuda as yesterday’s front lingers nearby today.