Hurricane Cristobal Still a Potential Threat


Cyclone Family Satellite Image_A
Snapshot of a Visible satellite image from Wunderground’s Wundermap. Image valid at 16:23z. Some of my annotations are in red.

Hurricane Cristobal strengthened slightly last night, and as of the 11am eastern advisory from the National Hurricane Center, Cristobal has maximum 1-minute sustained winds near 80mph, and a minimum central pressure near 983mb. Cristobal continued northwards overnight, with a slight jog to the left (west) of north early this morning. This jog to the left puts Cristobal a little further away from Bermuda than expected. However, the possibility exists for a jog to the right of the forecast track this afternoon, or tonight as Cristobal makes its closest approach and this could be enough to bring Cristobal close enough to Bermuda for tropical storm conditions (1-minute sustained winds greater than 39mph) to Bermuda an the marine area which extends radially 25 nautical miles from Bermuda. Because of this possibility, Bermuda is under a Tropical Storm Watch which means tropical storm conditions are possible in Bermuda or the surrounding marine area in the next 48hours.

These slight deviations from forecast track can add up and lead to significant differences in impacts. For that reason it is important to exercise constant vigilance with the latest forecast products from the National Hurricane Center and the Bermuda Weather Service. The latest forecast calls for near gales in Bermuda tonight with gusty showers. Gusts could reach 50kts in the northwestern marine area and in elevated and exposed locations on the island – especially in any heavier showers. This could lead to some minor vegetative damage and isolated power outages. It is also important to remember that there is an additional threat for tornadoes with any nearby Tropical Cyclone. The main threat from Cristobal, however, is very rough seas that are already affecting the island. Seas could exceed 15ft outside the reef  as Cristobal passes tonight and tomorrow morning leading to hazardous/dangerous beach and boating conditions. These rough seas will likely also result in heightened coastal erosion, mainly on south shore. Heavy showers from Cristobal are expected to dump between 1 and 2 additional inches of rain on Bermuda and could make August 2014 the wettest on record at the Bermuda Weather Service. Heavy rains the past seven days have added up to near 5.50″ and have led instances of localized flooding and several record and near record low temperatures in the upper 60s and lower 70s.

Atlantic 27 AUG 2014 12z Surface Analysis_A
Bermuda Weather Service Surface Analysis at 12z with my annotations. Low 1: Related to the low that formed near Bermuda on Monday with erratic winds, Low 2: Formed further northeast of Bermuda and continued northeast/eastward, and Hurricane Cristobal now to the West of Bermuda. All three low pressure centers somewhat connected by a front.

From a technical standpoint, Cristobal has behaved much like an occluding extra-tropical cyclone. On Monday Cristobal looked nearly in line with a stationary front that curved northeastward from the cyclone towards Bermuda and diffusely westward into eastern parts of the Gulf of Mexico, then Tuesday, Cristobal visually looked like a wave in the diffuse stationary front. And last night/this morning, Cristobal jogged westward into the decaying ‘cold’ sector to the west of the stationary front as it matured and strengthened. Similarly, two separate waves have developed along the stationary front to form an extra-tropical cyclone ‘family’. One of these lows was related to the mesoscale (small scale) low that formed near Bermuda on Monday, and another formed further to the east of that, potentially in the same manner. All three lows are tracking around the Bermuda-Azores High into the central north Atlantic.

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