Hurricane Sandy approaches


This is a generalized wind threat map based off of National Weather Service and National Hurricane Center Warnings and statements issued by Environment Canada and the Canadian Hurricane Center. Go to their websites to find the latest, more detailed, official information.

Sandy’s forecast track has changed little over the last day. The hurricane is expected to continue northeast or north-northeastwards today. A turn to the north should commence this evening or tonight, and a turn to the northwest tomorrow morning.  Landfall is expected in New Jersey Monday night. Further deepening of this system has occurred with pressures falling to 951mb. Sandy could either hold its own, or continue to deepen up until landfall.

Impacts:
Heavy Rain – Widespread areas of 3-8″ of rain with localized areas of >12″ of rain are likely along and to the left of this storm’s track as Sandy moves inland. This could lead to moderate-major river flooding in the Mid-Atlantic states. Near-coastal river flooding may be exacerbated by elevated tides.

High WindTropical Storm conditions have been reported in the Outer Banks  of North Carolina and gusts over tropical storm force have been reported in VirginiaDamaging winds to hurricane force are expected to occur along the immediate coast and in gusts inland to near coastal cities. Tropical Storm force/gale force winds (>39mph) are expected to occur well inland with damaging gusts over 50mph common. This could cause severe tree damage or defoliation and lead to power outages or even structural damage as far inland as southern Ontario and Quebec.

Storm SurgeA storm surge of 2-5ft is occurring along the North Carolina, Virginia, and Delmarva coasts, this could increase further as Hurricane Sandy continues an onshore flow in this area. Sound-side flooding is likely also occurring in Albemarle and Pamlico sounds. In Long Island sound and in New York Harbor, expect peak storm surges of 6-11ft.  Anywhere else with onshore gale force winds can expect storm surges between 4 and 8ft.  These are very serious heights above mean tide level and if combined with a high tide cycle, could produce disastrous coastal flooding and damage in a highly populated area. This storm surge will be accompanied by large battering waves that could produce erosion and additional structural damage. Records for storm surge values in this region could be threatened and the infrastructure in place put to the test.

On the Great Lakes, the prospect of lake length winds on Lake Michigan have prompted lake shore flood watches to be posted in Illinois and Indiana. High surf and onshore gale force winds there could cause localized lake shore flooding there, a similar threat exists for Huron, Erie, and Ontario.

Heavy Snow – In the middle Appalachians in West Virginia, a combination of tropical moisture, up sloping winds, and cold air filtering in on the west side of Sandy will mix to dump heavy wet snow and bring gusty winds. Near blizzard conditions are possible here and winter storm watches are in effect calling for 1-2 feet of snow in the highest elevations above 3000feet in altitude. 2-6″ are possible below 2000feet in altitude in West Virginia. In areas where deciduous trees still have leaves, the combination of snow and winds will produce significant tree damage that could lead to power outages, the weight of the snow may even lead to some roof damage.

Bermuda Weather Service radar image of a squally shower of the west end of the island that possibly produced a tornado at around 9am local time.

Bermuda: Bands of showers are expected to move through tonight and tomorrow. Squally showers in these bands could contain tropical storm force winds and tornadic activity is a distinct threat here. The Bermuda Weather Service expects 35-40mph southwesterly winds with gusts to 65mph late tonight – but this could be confined to the western marine area. Elevated surf along the south shore will produce dangerous rip currents and significant beach erosion, while making it hazardous to be out on the water.

Why no tropical storm/hurricane warnings for the Northeast/New England? Hurricane Sandy could transition into a post-tropical storm as it approaches. If the storm is no longer tropical, tropical storm and hurricane warnings cannot be in effect for it. In the event this happens, all warnings would have to be switched to those used for mid-latitude extra-tropical storms which could lead to confusion among the public. So to avoid confusion, they are starting warnings off as those for extra-tropical storms.

Useful links:
National Hurricane Center– Latest official updates and products for the track, intensity, and impacts of hurricanes.
National Weather Service – Latest local weather products for the United States.
Bermuda Weather Service – Latest weather products for Bermuda.
Environment Canada – Latest local weather products for Canada.
Canadian Hurricane Center – Latest official updates and products on hurricanes affecting Canada.

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