It's time to prepare for Irene
Current watches, warnings and advisories.
Current watches, warning and advisories issued by the National Weather Service. Courtesy of NOAA.
Your Northeast Forecast
A strong early-season cold front is currently sweeping through Maine after producing a widespread severe weather outbreak across the Northeast on Sunday. There were multiple reports of flooding from training thunderstorms across New Jersey and Long Island yesterday as well as numerous power outages across Vermont, mainly in Rutland County, where strong thunderstorm winds toppled many trees. A much more comfortable airmass will be left in the wake of the front today through Wednesday before another front makes it way towards the region from the Great Lakes. This front will be one of several that will help to carve a trough across the Great Lakes region that will lift Atlantic Hurricane Irene up the Eastern Seaboard at the end of the week into the weekend. More detailed information on Hurricane Irene will follow the Northeast Forecast in the Tropical Update section of the blog. At this time it appears areas within 150 miles of the coast stand a good chance of dealing with Irene in some capacity. Flooding rainfall will be the most likely and widespread effect felt here in the Northeast but should this hurricane take a track further east than models currently indicate winds and storm surge will become an ever increasing threat. After Irene lifts into the Canadian Maritimes yet another trough/upper low will dig into the Great Lakes, sending another cold front towards the Northeast to begin next week.
Rain and embedded thundershowers will exit Maine during the morning hours as a strong cold front clears the region leaving behind a much drier and cooler regime over the next 36-48 hours. Outside of a few instability/orographic showers scattered across Upstate New York and Northern New England, the remainder of the region will see partly sunny skies with a crisp northwest wind of 10-20mph. Daytime temperatures will average close to seasonal normals along the coastal plain but will drop below normal across the higher terrain across the North Country as clouds and showers develop with the cold pool of air aloft and still strong August sunshine. Definitely a feel of autumn in the air today and even more so tonight. Skies will clear and winds will slacken as high pressure moves overhead. Temperatures will plummet under ideal radiational cooling conditions. Expect lows across the interior to drop into the 40's with a 38 or 39 degree reading possible in the normally colder locales such as Saranac Lake. Temperatures will not get as cold across the coastal plain with 50's likely for most and 60's in the urban areas.
A beautiful day is expected for Tuesday as high pressure crests over the region during the morning hours and slides offshore by afternoon. This high will bring mostly sunny skies and very comfortable humidity levels during the afternoon hours to go along with high temperatures right where they should be for late August; upper 60's across the higher terrain of the North Country with 70's across the remainder of the interior and low to mid 80's along the coastal plain.
Southwesterly flow increases Tuesday night and Wednesday as a cold front approaches from the Great Lakes. Warm air advection and increasing high cloudiness from the west will keep temperatures about five to ten degrees warmer than the night before. Likewise for Wednesday, as high temperatures push into the upper 80's along the coastal plain with increasing humidity levels, with upper 70's to mid 80's across the interior and mid 70's across the North Country. A couple renegade thundershowers may run far enough out ahead of the front to affect western Pennsylvania and New York before sunset but most precipitation will hold off till the overnight hours.
The next cold front will move into the Northeast Wednesday night but will not be nearly as strong as the front this weekend. Hence, more scattered precipitation is expected along its flakes with severe weather virtually nil Wednesday night. Most of the rainfall associated with the front Wednesday night will remain across the northwestern half of the region, where lows will dip into the low to mid 60's. The Southeastern half of the region will simply see increasing cloudiness with mild readings remaining in the 70's across the coastal plain with mid to upper 60's points inland.
The aforementioned cold front will slowly sink towards the coast on Thursday with scattered showers and thunderstorms, most concentrated across the North Country, closest to the parent area of low pressure. Severe weather will be isolated at best as morning cloudiness should stamp out most instability and winds aloft aren't all that impressive. With clouds and showers expected temperatures should run about 4-8 degrees below normal for afternoon highs but it will be quite humid in all areas but the far northwest. Upon reaching the coast the frontal boundary is expected to stall and eventually wash out Thursday night into Friday thanks to building heights over the Western Atlantic as deep-layer ridging anchored over Bermuda builds west. This will help to steer Hurricane Irene towards the US mainland and likely as a significant, if not, major hurricane. How strong the ridging is will ultimately determine its eventual track but all residents from Florida to Maine are not in the clear as of yet. With pleasant weather expected for much of the week leading up to the arrival of Irene, now is the time to get prepared! Residents living along the coast should pay extra close attention to the very latest on Irene's track as they will be directly affected by the worst of the storm (strong winds/storm surge). Residents away from the coast in low lying or flood-prone areas also need to start preparations now. It's been a very wet month thus far and many area rivers are running at above normal levels for this time of year. Additionally, water tables are quite high as are soil moisture contents so it will not take much more rainfall to initiate flooding. This needs to be kept in mind, especially if the storm makes landfall in the Southeast because the rainfall with this system will still cause flooding concerns despite the weakened nature of the storm overall. This is a very dangerous situation as the last hurricane to directly make landfall in the Northeast was Bob in 1991, a full twenty years ago. Plenty of complacency can build over twenty of years.
Should Irene continue on a path model guidance suggests the western half of the region should escape most of this storm. However, the eastern half of the region could be in store for a very wet and wild weekend. Indirect rainfall from Irene in the form of a 'pre-event' appears likely to develop on Saturday. A weak trough draped across the region will help to initiate showers and thunderstorms during the afternoon, which should be slow-moving and quite moisture-laden, hence, flash flooding is a good possibility. Synoptic set-up will favor areas from central Pennsylvania to central New England as candidates for these storms. Otherwise expect increasing high cloudiness as the outflow canopy associated with Irene advances on the region. Increasing easterly flow off the Atlantic will start to kick up some stronger breezes along the coast as the saltine air invades the region ahead of Irene. Showers directly associated with Irene will begin to increase during the afternoon hours across southern New Jersey and Delaware. Temperatures will be warm, with highs in the 70's and 80's region-wide, and humidity levels will increase as the day progresses.
Saturday night through Monday will be game on for Irene and the Northeast. A western track will spare the region most of the stronger winds and storm surge but sustained tropical storm force winds should be expected up and down the coast and occur inland in gusts. However, the big story would be the rainfall as the stalled trough over the region serves of a focusing mechanism for enhanced convergence. As the deep tropical moisture feed and strong forcing associated with Irene pull into the region rainfall will get rather intense. Preliminary estimates are for three to as much as eight inches along the coastal plain with one to five inches across the interior. This type of rainfall would easily send small creek and streams as well as main stem rivers out of their banks. A more eastern track to the cyclone, clipping the Carolinas, would send the hurricane barreling towards the region as a very strong entity. Should this occur it would be likely that a good portion of the Northeast Coast will see hurricane force winds, with strong tropical storm force winds extending inland a good distance. At this time it is the scenario of lowest probability but it is a distinct possibility. As mentioned earlier, it has been twenty years since the last direct hit from a hurricane in the Northeast and a hurricane of the potential magnitude of Irene hasn't been felt since Hurricane Donna of 1960. There's an outside chance of this being a generational storm so there's many alive today where this will be a first time event. Something to take note of.
As of the 9AM AST National Hurricane Center advisory, Hurricane Irene was located at 19.0°N, 67.2°W, or 90 miles west-northwest of San Juan, Puerto Rico. Maximum sustained winds are up to 80mph with higher gusts although the pressure has risen slightly to 990mb. Movement is to the west-northwest at 14mph.
IR Satellite image of Hurricane Irene.
Irene has made some strides overnight and subsequently become the season's first hurricane at 5:50 this morning, as per NHC updated statement. Radar presentation of the storm has greatly improved, with a distinct eye now visible on both radar and, occasionally, on satellite. Outflow is restricted to the west and southwest of Irene as the hurricane continues to encounter 10-15kts of wind shear across the western semi-circle of the cyclone. To the north and east outflow is extremely impressive. Excellent poleward venting of the storm is noted, which then dips rapidly into a strong upper-level low pressure developing in the wake of the system across the central Atlantic. This wind shear is allowing for some dry air to be ingested by the storm, as evidence by the pulsing convection in the inner-core and the inability, thus far, for Irene to build a complete eyewall. Currently, the storm is over sea-surface temperatures of 28.5-29°C, plenty warm enough to support continued slow intensification in the near-term, as long as the shear remains in the 10-15kt range. Now that it is apparent that Irene will steer north of Hispaniola, land interaction will be less of a deterrent as well.
Wind shear in the 10-15kt range will continue to affect the cyclone through Tuesday afternoon, disrupting any rapid intensification possibilities and keeping Irene a category two storm at most. At this time the cyclone will be entering the region of the Turks and Caicos islands and the southeastern Bahamas and slowing down in forward speed as it continues on its west-northwesterly course, so a prolonged period of hurricane conditions will begin to affect the island archipelago that should last up to 24 hours in any given location along the storm's path.
By Tuesday night and Wednesday wind shear will begin to relax as upper-level high pressure develops over the eastern half of the storm and deep-layer ridging in the vicinity of Bermuda builds west. This should signal a period of further intensification that should bring Irene up to major hurricane status by the time it reaches the central Bahamas. Steering currents should begin to direct Irene on a northwesterly course by this time as another trough dips into the Northeastern region of the country, providing a weakness for the storm to move into.
Irene will continue to remain a impressive, major hurricane as it approaches the Southeast Coast Thursday and Friday after lashing the northern Bahamas. Indications as that Irene will grow in size to occupy quite a bit of real estate off the Southeast Coast. As Irene moves into the weakness along the East Coast it will begin to take on a more northerly component in its forward motion but confluent flow to the north of the storm will further slow its forward speed to an agonizing crawl. Moisture streaming out ahead of the storm in the form of rain squalls will begin to brush the coastal areas beginning on Thursday across Florida and by Friday from Georgia to the Carolinas. From this point forward, where the storm moves will be determined by the strength of the trough dipping into the Great Lakes region of the country. A stronger trough will tend to recurve Irene quicker, lessening chances for a landfall from South Carolina to Florida, but increase chances from North Carolina to the Northeast. A weaker trough will allow Irene to continue to the north-northwest into Georgia or South Carolina. Florida isn't out of the crosshairs yet but enough of a weakness should be present to allow Irene to pass by to the east. Stayed tuned, Florida. Either way, chances of a landfalling hurricane somewhere along the East Coast is about 80%, so now is the time to commence preparations.
Radar: Northeast Region Loop
Radar loop of the Northeast region. Courtesy of Weather Underground.
Sea-surface temperatures off the Northeast Coast. Courtesy of NOAA.