UPDATE: CENTER OF SANDY PASSING NEAR ELEUTHERA ISLAND IN THE NORTHWESTERN BAHAMAS
HURRICANE SANDY DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL
AL182012 500 PM EDT THU OCT 25 2012 SATELLITE IMAGERY SHOWS THAT
STRUCTURAL CHANGES ARE ALREADY OCCURRING WITH SANDY. DRY AIR ALOFT AND
SOUTHWESTERLY FLOW ASSOCIATED WITH AN UPPER-LEVEL LOW CENTERED NEAR
WESTERN CUBA ARE IMPINGING ON THE WEST SIDE OF THE CIRCULATION. AS A RESULT...THE OUTFLOW IS RESTRICTED IN THE SOUTHWEST QUADRANT AND THE CLOUD PATTERN IS BECOMING MORE ASYMMETRIC. HOWEVER...THE HIGHEST FLIGHT- LEVEL WINDS FROM THE AIRCRAFT WERE STILL 109 KT AT THE END OF THE LAST MISSION AND THE CENTRAL PRESSURE REMAINS AT 963 MB. THE INITIAL INTENSITY REMAINS 90 KT FOR THIS ADVISORY. SOME DECREASE IN THE MAXIMUM WINDS IS EXPECTED DURING THE NEXT COUPLE OF DAYS AS SANDY BECOMES MORE ENTANGLED WITH THE UPPER-LEVEL LOW...HOWEVER THE GLOBAL MODELS SHOW SANDY REMAINING A VERY DEEP CYCLONE AND THE WIND FIELD EXPANDING DURING THIS TIME. LATER IN THE PERIOD...SOME RE-INTENSIFICATION IS SHOWN AS SANDY DEEPENS AGAIN OFF THE U.S. EAST COAST WHILE IT INTERACTS WITH ANOTHER SHORTWAVE TROUGH. REGARDLESS...SANDY IS EXPECTED TO BE A LARGE CYCLONE AT OR NEAR HURRICANE INTENSITY THROUGH MOST OF THE FORECAST PERIOD. THE INITIAL MOTION ESTIMATE IS 360/17...AS SANDY HAS BEGUN TO ACCELERATE NORTHWARD DUE TO THE UPPER LOW. THE REASONING FOR THE TRACK FORECAST REMAINS LARGELY UNCHANGED. SANDY WILL BE PULLED NORTHWESTWARD AND SLOW DOWN ON FRIDAY WHILE IT INTERACTS WITH THE UPPER-LEVEL LOW. THEN A NORTH-NORTHEASTWARD ACCELERATION IS EXPECTED BY SATURDAY AS A LONGWAVE TROUGH MOVES INTO THE EASTERN UNITED STATES. MOST OF THE TRACK MODELS NOW SHOW A TURN BACK TOWARD THE NORTHWEST BY THE END OF THE PERIOD DUE TO SANDY INTERACTING WITH AN AMPLIFYING SHORTWAVE TROUGH OVER THE CAROLINAS AND MID-ATLANTIC STATES. HOWEVER...THERE REMAIN SOME SIGNIFICANT DIFFERENCES IN THE TIMING OF THIS INTERACTION...AS THE ECMWF HAS SANDY FARTHER WEST AND INTERACTING WITH THE SHORTWAVE SOONER RELATIVE TO MOST OF THE REST OF THE GUIDANCE...WHICH SHOWS A WIDER TURN AND A TRACK FARTHER NORTH. THE NEW NHC FORECAST IS CLOSE TO THE PREVIOUS ONE...AND LIES ROUGHLY BETWEEN THE ECMWF AND THE GFS ENSEMBLE MEAN. REGARDLESS OF THE EXACT TRACK OF SANDY...IT IS LIKELY THAT SIGNIFICANT IMPACTS WILL BE FELT OVER PORTIONS OF THE U.S. EAST COAST THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK. NOTE THAT THE TROPICAL CYCLONE WIND SPEED PROBABILITIES ARE NOT DESIGNED TO HANDLE THE TYPE OF STRUCTURAL CHANGES ANTICIPATED WITH SANDY DURING THE FORECAST PERIOD. AS A RESULT...THESE PROBABILITIES WILL UNDERESTIMATE THE ACTUAL RISK OF STRONG WINDS AWAY FROM THE CENTER OF SANDY. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 24.5N 75.6W 90 KT 105 MPH 12H 26/0600Z 26.0N 76.0W 85 KT 100 MPH 24H 26/1800Z 27.4N 77.0W 80 KT 90 MPH 36H 27/0600Z 28.3N 77.0W 75 KT 85 MPH 48H 27/1800Z 29.8N 76.0W 65 KT 75 MPH 72H 28/1800Z 33.0N 73.0W 70 KT 80 MPH 96H 29/1800Z 37.5N 72.5W 70 KT 80 MPH 120H 30/1800Z 40.5N 75.0W 55 KT 65 MPH...POST-TROPICAL
FOR GRAPHICS GO TO BOTTOM OF STORY
Thursday, October 25, 2012 6:45 am
by Rob Lightbown
Hurricane Sandy: Sandy underwent pretty rapid intensification during the overnight hours and almost became a Category 3 hurricane at one point late last night. As of early this morning, Sandy was positioned on the northeastern coast of Cuba as a 105 mph Category 2 hurricane. The hurricane was tracking almost due north at a forward speed of 18 to 19 mph and this northward track will bring Sandy right across the central part of the Bahamas including Cat Island, Rum Cay, Sandy Cay and San Salvador Island this afternoon into tonight. Hurricane conditions are likely from today through tonight and right into Friday across much of the Bahamas. Additionally, total rainfall amounts of 4 to 8 inches are expected across the Bahamas along with very rough seas and a storm surge of 6 to 8 feet across the central and northwestern Bahamas.
For Those Of You On Florida’s East Coast: Sandy is expected to affect much of Florida’s east coast with tropical storm conditions from Palm Coast and Daytona Beach southward to Miami and Florida City starting after midnight tonight and continuing through all of Friday and into Friday night. In this area, expect sustained winds of 35 to 45 mph with gusts to 60 to 70 mph especially right on the beaches. Additionally, rain will be on the increase later today and especially tonight with rain, heavy at times, expected across much of the east coast of Florida through Friday. Total rainfall amounts of 1 to 2 inches can be expected. Finally, a storm surge of 1 to 2 feet, especially at the time of high tide can be expected along the entire east coast of Florida from late tonight through Friday.
Once Sandy is past the Bahamas by Saturday a blocking pattern is expected to set up to the east of Newfoundland and prevent Sandy from turning out into the open Atlantic. Instead a small ridge of high pressure will develop over the Canadian Maritimes as a strong trough of low pressure digs into the eastern United States by late this weekend. All of this will cause Sandy to turn towards the northwest into either the Mid-Atlantic states or southern New England early next week. Where exactly Sandy tracks into the Mid-Atlantic or northeast United States remains somewhat in question. What is not in question is that there is likely to be a significant and potentially major wind and coastal flood and beach erosion impact from Sandy from eastern North Carolina on Sunday to the Mid-Atlantic states from Sunday night through Tuesday and New England from Monday night through Wednesday.
Run Down Of The Latest Forecast Guidance: The latest forecast guidance continues to diverge a lot with the latest European operational, GFDL and NOGAPS models tracking Sandy inland into the Delmarva Peninsula by Monday evening. The GFS model pulls Sandy north and northwestward across Nova Scotia on Wednesday and then right across northern Maine on Wednesday night. The Canadian model forecasts that Sandy will get pulled northwestward across Long Island and right across New York City on Monday night.
Now, the ensemble guidance (European ensemble, GFS ensemble and the Canadian ensemble) may be the way to go with a forecast track 4 to 6 days out is overall pretty similar with a track that pulls Sandy northwest and even westward somewhere between Cape Cod and the Jersey Shore on Tuesday.
My Thinking For A Track is a west-northwestward tracking storm that moves right along the south shore of Long Island during the day Tuesday and then curves more northwestward into western New York State and southern Ontario by Wednesday and Thursday. Now, we cannot and should not focus on the storm track as the wind field and huge seas that this storm will create will be very, very large and the amount of geography that will be affected will also be very large.
Potential Impact For The Mid-Atlantic States & New England: Strong Winds: Very strong winds, not only along the coast, but also inland will affect areas from eastern North Carolina to New England. Strong winds with gusts to 60 to 70 mph are forecast across eastern North Carolina starting on Saturday night and continuing through Sunday and Sunday night. These strong winds will impact the Mid-Atlantic states, including the DC metro, Baltimore and Philadelphia starting late Sunday afternoon and Sunday evening and continuing through Monday and Monday night before slowly abating on Tuesday.
Now for New England: Strong easterly winds of 35 to 50 mph with gusts to 70 mph are expected to overspread southern New England during Monday afternoon and continue through Monday night, Tuesday and Tuesday night before slowly winding down on Wednesday. These strong winds will not only affect coastal sections, but also a majority of inland sections of New England. This will be a region-wide significant storm for New England.
I highly recommend everyone from eastern North Carolina northward to New England to prepare for power outages, including fueling up and tuning up your generator, if you have one.
Coastal Flooding: As I mentioned yesterday, preparations to protect coastal property should have been started already. If you haven’t, I advise you to start your preparations today from eastern North Carolina northward to New England. These preparations should include protecting your property from battering wave and coastal flooding damage. Multiple days of coastal flooding at high tide are expected from Saturday to Monday in eastern North Carolina to Sunday to Tuesday along the Mid-Atlantic coast and along the south coast of Long Island to Sunday night to Wednesday along coastal sections of New England. Additionally, significant to major beach erosion is likely from eastern North Carolina northward to New England.
Mariners: This potential storm has the potential to build up large amounts of ocean water along the coastal and offshore waters from eastern North Carolina to New England and the Canadian Maritimes. Seas of 20 to 30 feet are likely over a huge area from coastal sections of North Carolina northward to the coastal and offshore waters of New England and the Canadian Maritimes. If you have a boat in the water, you should make preparations today to pull it out of the water. Any late season fishing trips should be postponed or cancelled as life threatening seas of at least 20 to 30 feet and very possibly 40 feet could impact coastal and offshore waters from eastern North Carolina to New England from this weekend through much of next week.
Heavy Rain Potential: Heavy rainfall with street and basement flooding seems likely starting on Sunday over eastern North Carolina and spreading northward across the Mid-Atlantic states starting Sunday night and Monday and then across New England by late Monday afternoon and Monday night. This heavy rainfall is expected to continue through Tuesday and Wednesday. River and stream flood potential will have to be monitored closely as we get closer to the event.
So, it is now likely that Sandy will bring a significant and possibly a major impact across areas from eastern North Carolina northward to New England. Power outages, severe coastal damage and inland flooding are all threats with Sandy.
For more on this story go to:
http://www.crownweather.com/?page_id=4557
