Wednesday, October 24, 2012

Updated storm analysis from our Long Range Team

A Stormy Pattern Ahead?
Increasing likelihood of coastal and inland impacts to the 
Mid-Atlantic and Northeast from a significant storm next week

Several model projections have been showing a mean-looking 
post-Tropical system getting too close for comfort by Sunday

8:00 PM EDT 10/24 (Mid-Atlantic Team) You know the saying, "When it rains, it pours." In the weather forecasting business, we prefer to say, "When it rains, it's a monsoon." Even though Hurricane Sandy may over a thousand miles away, changes in the large scale atmospheric pattern are already beginning to take shape. The indicators our Long Range Team and meteorologists are watching suggest the Mid-Atlantic and Northeast may be increasingly facing very stormy weather in the 5-10 day period ahead. 

THE SHORT VERSION: What are the scenarios in consideration? For the Mid-Atlantic, here's what we are projecting as possible outcomes for the period Sunday into Tuesday of next week. There are still many factors at play which could keep either scenario from being realized. If you need an alternate look on what NOAA meteorologists are saying about this at the federal level, just glance at the first line of this link. 
  • Scenario A : Stormy along the coast, windy & rainy inland. Some remnants of Hurricane Sandy interact with an approaching upper level trough, pulling the energy toward the coast. Cold air working in from the trough, combined with tropical moisture, fuels the rapid development of a large coastal Low. Some beach erosion and tidal flooding would occur, but limited to the Atlantic coast.
  • Scenario B : Significant impacts both inland and along the coast. A considerable amount of tropical energy from the remnants of Sandy are incorporated into a developing Low projected to deepen along the Carolina coast by Saturday. As this Low gets pulled into the upper level trough, it explosively develops into a very large and extremely strong hurricane-like system. Winds of tropical storm to near hurricane force would impact a large area of the Eastern seaboard from southern New England to the Mid-Atlantic, including the I-95 corridor. 
WHAT IS OUR CONFIDENCE ON THIS? An assessment of the large scale atmospheric pattern in motion right now points to three major factors that are affecting this forecast. An overview of our confidence on how these factors will play out:
  • The North Atlantic Oscillation: A large scale measure of air mass movement in the North Atlantic. When the NAO is negative (as it is currently), the effect of colder air pushing south from Canada can block a storm's "escape route" up the coast. Our confidence the NAO will remain negative? HIGH
  • The Upper Level Trough: Currently in the upper Midwest, this is expected to move toward the Mid-Atlantic and remain "negatively tilted" or angled from southeast to northwest. This is one of the most important factors that will affect the intensity of the storm, if it develops. Our confidence the trough will be involved? HIGH
  • The Path of Hurricane Sandy: We expect Sandy to move into the western Atlantic as projected by models and the NHC. However, in advance of that, energy and moisture from a large plume of "outflow" ahead of the hurricane may begin to interact with the approaching cold front and eventually the upper level trough. The more that interaction occurs, the more likely Scenario B will verify.  Our confidence in energy from Sandy being incorporated into the trough: MEDIUM
NEXT STEPS? Our Mid-Atlantic Leadership Team in consult with our Tropical Team, will be holding a full collaboration this evening. Expect a late evening update on this page by 11:00 PM or sooner. (CEO Rich Foot & Mid-Atlantic Director Greg Jackson) 

Earlier analyses on this storm below. 

Examining Potential 
   For "A Big Storm" 

Water vapor flash loop of the Western Atlantic

10:15 AM EDT 10/24/12 (Long Range Team) With Tropical Storm Sandy now gaining strength and size as she moves north through the Caribbean, we can more closely examine  some aspects of storm potential which may affect the Northeastern U.S. next week. Below is on-going synopsis of the situation as prepared by our team. For those seeking more detailed information, a comparison of two recent computer model runs from Monday is also posted in our STORM section.

  • Tropical Storm Sandy is the "primary low" that would influence the possible development of a new hypothesized coastal storm, which others suspect may impact portions of the coastal Mid-Atlantic and Northeast by early next week.
  • Long range model runs currently project Sandy will move into the western Atlantic by this weekend. Some models show the storm transitioning into a post-Tropical state, and possibly starting to recurve toward the coast by Sunday. Other models project an entirely new system developing near the approaching front becoming an issue. One area of increasing concern for impacts is southern New England.
  • By Monday and Tuesday, one "middle-of-the road" scenario as presented in this HTML loop by the NOAA Hydrometeorological Prediction Center (HPC) suggests a post-Tropical low as the remnants of Sandy may approach the Mid-Atlantic. This scenario would produce gusty northeast winds and rain from the I-95 corridor of the Mid-Atlantic to the Carolinas and east to the coast and adjacent waters.

WHEN WILL WE KNOW MORE? With a number of large scale factors that will remain in play until the day this storm arrives, or does not arrive, in your area - it is still much too early to say where this system will go. We are preparing an "A versus B" scrimmage of scenarios which will be released Thursday night in the Storm section of this website. 

DO I NEED TO PREPARE? For readers along the East coast, if you're concerned about impacts on your property due to strong, gusty winds or heavy rain - this would be a good week to make some improvements, while the weather is warm. If there is a big storm, you'll be happy you cleared the gutters and storm drains. If not, at least you won't have to do that when the weather is much colder than today. 

Contributors to this storm investigation include: 
Connor Meehan, Lead Forecaster (MD)
Nic Roberson, Long Range Coordinator (NC)
Jason Mitchell, Tropical Coordinator  (MD)
Josh Owens, Affiliate Coordinator  (MD)
Greg Jackson, Mid-Atlantic Director  (PA)
 Ross Harris, Carolinas Winter Stormcaster (NC)
Zachary J., Metro New York Zone Forecaster (NY)

Greg Blumberg (OK); Alex Davies (DE); Daniel Ross (GA)

Rich Foot (CEO), Keith Krichinsky (COO)

Our previous report on this storm from 10/22 is below

Ah yes, "The Big Storm"

9:40 AM EDT 10/22/12 (Long Range & Winter Stormcast Teams)  Several long-range computer models have been show a variety of interesting and thought-provoking scenarios a potential large storm to affect several portions of the U.S. over the next 7-10 days, including the East coast. However, this East coast long range issue is not the "only game in town." Storm concerns currently on our team's agenda also include systems to impact the Sierra Nevadas, the Central Rockies and the Mid-West. 

For the hypothesized East coast concerns, a more specific overview of what we know and don't know is posted in our "STORM" analysis page.

The current 7-day forecast map from NOAA shows the generalized idea of what may occur by this coming Sunday:

There has also been a pandora's box of speculative reporting about this as-yet-to-form situation by a number of television and online media.  Our synopsis of the situation is as follows: 
  • YES, there is concern in the meteorological community for the potential of a major East coast storm which, if many factors come together, may occur in the 7-10 day period starting early next week. However, there is a greater likelihood of a major snow event in the northern Plains, followed by a sharp outbreak of cold weather for the Midwest and Southeast. 
  • NO, there is not enough information 7 days out at this time to make a reasonable determination of the timing, track and intensity of one or more storm possibilities, especially if the low pressure systems in question have yet to form.

1 comment:

Unknown said...

I hope no more terrible storms would happen around here. It's okay if there will be some light rain that kids can always prepare their childrens raincoats and that would be enough but if it's something heavy coupled with strong winds, that can be terrifying.