Tropical Weather Update-1: Hurricane Sandy on Course to Impact Monday/Tuesday with Winds/Rain
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Oct 28, 2012, 12:49:10 PM10/28/12
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TROPICAL WEATHER OUTLOOK
Hurricane Sandy is continuing to approach the DC region at this time, with the main threat still being strong winds, aided and abetted by heavy rain. Main updates to previous: Less rain today, clearer wind threat, and some changes in timing.
Advisories: We are still under a Flood Watch and a Coastal Flood Watch, and the High Wind Watch has been upgraded to a High Wind Warning. This means that wind gusts to 60 mph are likely or will be occurring with Sandy.
Timing: (+/- 6-12 hours)
Now (Sunday Afternoon/Evening): A few sprinkles may occur before, but Sandy's first main band is still off to our east pushing across the Western Shore of the Chesapeake and should arrive in areas east of DC this afternoon and should reach the I-95 corridor by evening. We are getting a few gusts of wind up to 20-25 mph, as expected, but we should not see anything particularly strong until tomorrow.
Sunday Overnight: Heavier rain moves in from the SE, with more intense precipitation to the east and less to the west of DC. Winds continue to pick up, with peak gusts in the 30-35 mph range, but should not be a major concern before 8AM.
Monday Morning/Afternoon: Heavy rain will begin to fall steadily, and wind gusts will continue to increase past 45 mph, which could bring down small branches and cause scattered power outages. By the afternoon, gusts could reach levels sufficient to bring down branches, limbs, and potentially trees and power lines.
Monday Evening/Overnight: The worst of the storm's winds and damage look to occur during this time, with sustained winds near 40-45mph and gusts of potentially 60-65 mph taking down trees, power lines, and impairing driving. Rain will continue to remain steady and relatively heavy, and power outages are likely.
Tuesday Morning/Afternoon: Strong winds will continue to occur, although peak winds should lessen by the afternoon. Rain continues to decrease, although light to moderate showers will likely continue.
Tuesday Evening/Overnight: Winds will diminish from south to north, although caution when driving is still advised. Rain should taper off to light showers as the storm pulls out.
Wednesday: The threat will finally be over as the wind and rain pulls out, although winds will likely remain breezy and skies cloudy for at least some time during the day.
Hazard Analysis: (In order of significance)
Wind Threat: I now expect at least a 60%-70% chance of tropical storm force (40+ mph) sustained winds, and gusts now look to be even higher than previously predicted, past 60 mph. Gusts have already been reported past 25 mph now, and tonight we will likely see wind gusts in the 30-35mph range, which could snap twigs, leaves, and small branches. Gusts in the 45 mph range should arrive in the 8AM-Noon period, which could take down some sizable branches and cause scattered power outages. Later in the afternoon we could see higher gusts, near 60 mph, which could fell trees and power lines taking down power across the region and making transportation quite hazardous. The strongest winds should come overnight, as peak gusts could potentially reach past 60 mph. Things gradually calm down during the day Tuesday, but gusts could remain in the 50-55mph range through noon, and stay above 45 until nightfall, potentially hazardous to anyone outside or driving. Secure all outdoor objects, prune trees, and remain indoors and on the ground floor during the period of highest winds, and we should pull through alright.
River/Flash Flooding (Heavy Rain) Threat: The amount of rain predicted to fall with Sandy has fluctuated somewhat over time, but I'm still betting on 5-6 inches for DC, 3-5 for areas west and south, and 6-8 for locations west and north. I still don't expect freshwater flooding of low-lying areas to be a major threat, but it could certainly inconvenience commuters late Monday and early Tuesday, as well as be potentially hazardous for anyone near creeks, streams, and--later in the week--rivers.
Coastal Flooding (Storm Surge) Threat: The threat for major flooding along the Potomac is still fairly low, but we could see waters rise 1-2 feet above normal during times of high tide, which could potentially affect some locations right on the Alexandria waterfront but be little more than a minor nuisance anywhere else.
Tornadoes/Severe Weather: As before, the risk for tornadoes/thunderstorms is virtually zero.
UPDATE...Brief (er) updates around 2PM and 5Pm today.
C. A. M. Gerlach
Hurricane Sandy is continuing to approach the DC region at this time, with the main threat still being strong winds, aided and abetted by heavy rain. Main updates to previous: Less rain today, clearer wind threat, and some changes in timing.
Advisories: We are still under a Flood Watch and a Coastal Flood Watch, and the High Wind Watch has been upgraded to a High Wind Warning. This means that wind gusts to 60 mph are likely or will be occurring with Sandy.
Timing: (+/- 6-12 hours)
Now (Sunday Afternoon/Evening): A few sprinkles may occur before, but Sandy's first main band is still off to our east pushing across the Western Shore of the Chesapeake and should arrive in areas east of DC this afternoon and should reach the I-95 corridor by evening. We are getting a few gusts of wind up to 20-25 mph, as expected, but we should not see anything particularly strong until tomorrow.
Sunday Overnight: Heavier rain moves in from the SE, with more intense precipitation to the east and less to the west of DC. Winds continue to pick up, with peak gusts in the 30-35 mph range, but should not be a major concern before 8AM.
Monday Morning/Afternoon: Heavy rain will begin to fall steadily, and wind gusts will continue to increase past 45 mph, which could bring down small branches and cause scattered power outages. By the afternoon, gusts could reach levels sufficient to bring down branches, limbs, and potentially trees and power lines.
Monday Evening/Overnight: The worst of the storm's winds and damage look to occur during this time, with sustained winds near 40-45mph and gusts of potentially 60-65 mph taking down trees, power lines, and impairing driving. Rain will continue to remain steady and relatively heavy, and power outages are likely.
Tuesday Morning/Afternoon: Strong winds will continue to occur, although peak winds should lessen by the afternoon. Rain continues to decrease, although light to moderate showers will likely continue.
Tuesday Evening/Overnight: Winds will diminish from south to north, although caution when driving is still advised. Rain should taper off to light showers as the storm pulls out.
Wednesday: The threat will finally be over as the wind and rain pulls out, although winds will likely remain breezy and skies cloudy for at least some time during the day.
Hazard Analysis: (In order of significance)
Wind Threat: I now expect at least a 60%-70% chance of tropical storm force (40+ mph) sustained winds, and gusts now look to be even higher than previously predicted, past 60 mph. Gusts have already been reported past 25 mph now, and tonight we will likely see wind gusts in the 30-35mph range, which could snap twigs, leaves, and small branches. Gusts in the 45 mph range should arrive in the 8AM-Noon period, which could take down some sizable branches and cause scattered power outages. Later in the afternoon we could see higher gusts, near 60 mph, which could fell trees and power lines taking down power across the region and making transportation quite hazardous. The strongest winds should come overnight, as peak gusts could potentially reach past 60 mph. Things gradually calm down during the day Tuesday, but gusts could remain in the 50-55mph range through noon, and stay above 45 until nightfall, potentially hazardous to anyone outside or driving. Secure all outdoor objects, prune trees, and remain indoors and on the ground floor during the period of highest winds, and we should pull through alright.
River/Flash Flooding (Heavy Rain) Threat: The amount of rain predicted to fall with Sandy has fluctuated somewhat over time, but I'm still betting on 5-6 inches for DC, 3-5 for areas west and south, and 6-8 for locations west and north. I still don't expect freshwater flooding of low-lying areas to be a major threat, but it could certainly inconvenience commuters late Monday and early Tuesday, as well as be potentially hazardous for anyone near creeks, streams, and--later in the week--rivers.
Coastal Flooding (Storm Surge) Threat: The threat for major flooding along the Potomac is still fairly low, but we could see waters rise 1-2 feet above normal during times of high tide, which could potentially affect some locations right on the Alexandria waterfront but be little more than a minor nuisance anywhere else.
Tornadoes/Severe Weather: As before, the risk for tornadoes/thunderstorms is virtually zero.
UPDATE...Brief (er) updates around 2PM and 5Pm today.
C. A. M. Gerlach
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