Thursday, October 25, 2012

UPDATED RISK ANALYSIS: HURRICANE SANDY

"She's Got The Look."
- Roxette in the 1988 single (YouTube video)



HISTORIC HIGH IMPACT EVENT POSSIBLE
FOR MID-ATLANTIC AND NORTHEAST

9:50 AM EDT 10/26  MID-ATLANTIC TEAM STATEMENT: The 8 AM NHC advisory showed that Sandy decelerated further overnight. Sandy is now tracking NW at just 10 mph.

  • The storm's slower forward motion is increasing the likelihood that it will be captured farther south on the Mid-Atlantic Coast.
  • The US Global Forecast System ensemble members must continue to be accounted for in the forecast, despite other models showing more extreme solutions.
  • Sandy could still make landfall somewhere from the VA Capes to northern NJ
  • Our projection is that the Delmarva to southern NJ offers the highest probability at this time.

7:15 AM EDT 10/26  The singer Roxette would agree that "She's Got The Look" seeing this this twitpic from NASA sent by Meteorologist Bob Ryan last night. If your frappuchino has not woken you up yet, then take a look at the 5:00 AM update by the National Hurricane Center. That'll froth your java, it sure did for us. 



What Are The Possible Hazards?


If this scenario continues to play out, weather hazards that would occur along the Mid-Atlantic include:  
  • Tropical Storm Force winds exceeding 40 mph may affect a large area of the U.S. coastline up to 150 miles inland, extending from New Jersey and eastern PA to North Carolina, including the I-95 corridor cities of New York to Richmond.
  • Heavy rainfall of 6-12" over parts of VA, MD, DE, PA and NJ - as well as Southern New England.
  • Extreme coastal flooding and beach erosion with significant tidal rises associated with the astronomical high tide and full moon. A long duration beach-pounding event with waves of 10-20 feet over a period of 24-48 hours is possible for Atlantic beaches.
  • Heavy snow later in the forecast period is possible from the Ohio Valley to the Central Appalachians and the Blue Ridge Mountains

COASTAL UPDATE FROM OUR MID-ATLANTIC SURF & SAIL PAGE 
"No big changes to the forecast from my update last night as the models are still trying to resolve the dynamics in play. The toughest physical question is when exactly will the system phase and move landward? It looks like to models are zeroing in on a landfall location somewhere between Norfolk, Virginia and New Haven, Connecticut."
"Again, the dynamics of the system are extremely complex so I do not expect the models to resolve everything, nor should you. I am certainly looking at each model run with a grain of salt, trying to figure out what exactly the model is doing in terms of dynamics and the question of when will the system phase and force the surface low pressure westward is something we may not know until Saturday night."

4:20 PM EDT 10/26/12 OVERVIEW OF POTENTIAL IMPACT RISKS FROM HURRICANE SANDY:  this system has the potential to produce widespread impacts over many heavily populated states. The image below is the projected rainfall to affect the Carolina coast in the next 72 hours as Sandy moves north from her current location in the Bahamas.



The Mid-Atlantic: What It Could Mean

5-day rainfall projections from NOAA HPC 
While too early to pinpoint the exact track of a storm still 1000 miles south of a particular point, long range indications suggest Hurricane Sandy becoming a post-Tropical system that could inflict large scale impacts on much of the Mid-Atlantic and Northeast in the Sunday to Tuesday period and perhaps longer. 

AN OUTLINE OF POTENTIAL RISKS BY STATE in the event one of the high impact scenarios were to be realized:
  • New Jersey: High risk of wind, flooding and heavy rain. A potentially high impact event with a direct onshore flow of Tropical Storm force winds, heavy rain and high level waves producing destructive beach erosion, possible storm surge along with inland and coastal flood.
  • PennsylvaniaPotentially high-impact rain event with a 24-36 hour feed of tropical enhanced Atlantic moisture surging across the entire state. Due to topographic enhancement in mountainous areas, rainfall amounts could far exceed that which occured in Ivan (2004) and Irene (2011). Downstream flooding on the Susquehanna and it's associated tributaries would be likely. 
  • DelawareHigh risk of wind & flooding. Potentially high impact wind, water and rain event to affect the entire state with NOAA HPC projecting over 6" of rain combined with Tropical Storm force winds in the Delaware Bay.
  • Eastern Maryland: High risk of a long duration wind event, with widespread beach erosion, coastal and inlet flooding concurrent with the astronomical high tide and full moon.
  • Central MarylandPower outage risk given many trees may have been weakened by storms earlier this year, including the Derecho. These trees could be more prone to collapse or produce downed limbs in a strong wind event. Coastal flooding would also be a concern for western shore counties.
  • Western MarylandHigh risk of heavy snowDepending on the track of the storm, an influx of cold air with moisture from either the storm or the Great Lakes could produce significant snow in from the Central Appalachians to the Blue Ridge Monday night into Tuesday. Will trees near full foliage this would produce significant power issues.


2:10 PM EDT 10/25 STATEMENT FROM OUR TROPICAL TEAM  (Forecaster Jason M. ) The latest NHC probability map for tropical storm force winds now places coastal portions of the Mid Atlantic in a 10-30% chance for sustained winds reaching tropical storm force from Sandy by early next week. While this is not a high chance, the NHC has stated at bottom of the 11:00 AM NHC Discussion in the latest NHC forecast track update:
"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."

With Sandy is expected to be become a large hurricane in size, and this is one reason why intense winds may not be confined to a small area.
EARLIER STATEMENT BY THE MID-ATLANTIC TEAM as posted in our Central Maryland Facebook page:
"Increasing potential for wind, rain and water impacts to Maryland from Hurricane Sandy. The latest National Hurricane Center forecast track places most of MD inside the possible path of Sandy in the Sunday-T
uesday time period. This does not suggest the storm will make a direct landfall in Maryland, but rather that effects such as heavy rain, strong winds and tidal rises are increasingly likely."

8 comments:

Triggerfoot said...

Foot's, you're the best. It's so cool to have such clear explanations backing up your forecasts. Thanks!

Andy, Southern York County Pa said...

Back to storm season and what a way to kick things off with a hurricane turning extra tropical and perhaps ending as some snow. This could be the worst storm since Agnes for our region.

Andy, Southern York County Pa said...

It's good to be back but this is really the time to start to prepare. This storm is really ugly with the wind and flood potential. Sure there might be a punch of snow at the end and that is a big might, but the story here is massive damage to the power grid and potential loss of life to the extent that this region has never experienced. I will track this very carefully but I recommend to take empty tea and milk jugs and freeze as many as you can to help keep your freezer cool for as long as possible.The main story here is severe wind damage, downed trees, flooding, and extensive power loss. A sub 940 MB storm is unbelievable and this threat is real.

ravensbbr said...

Andy, how's my fellow MD State worker bee? Looks like this one will be a doozy, we'll be leaving NE PA above NYC on Sunday AM, back here hopefully by noon or so in time for the fun...

Andy, Southern York County Pa said...

As always living the dream in dreamland! This is one storm that no one should take for granted. Be safe in your travels, and just be prepared to be without power for a very long time. I love a good winter storm, but there is nothing to love about this system despite a minimal winter component.

ravensbbr said...

Rog-o, good advice. Stay safe.

BioPat said...

Hello Andy and all, good to hear from you in the fall of 2012.
I have been following the storm closely with my students and it made it a point of discussion in today's Bio classes - which was great timing with the Water Cycle review. Also taled about potential dangers due to damages from the June storm. I have already prepared students for emergency mode in the early part of next week. Perhaps I have stimulated some good scientific inquiry among the new 9th graders. Looking forward to being in touch over the next few days and through this winter as well.

Foot's Forecast said...

Glad to see you all back in action once again!