All posts by Lei Zhao

NYC Weekend Weather – Hurricane Maria – Sep 22, 2017

We have a superb weekend of weather coming up. Temperatures will be anomalously warm for this time of the year, with highs ranging in the mid-upper 80s. It will feel more like late July than late September. Excellent beach weather, if not for the continuing coastal impacts of Jose. The warm spell continues into next week. Our eyes turn towards Hurricane Maria, which after devastating Puerto Rico and Dominica, is now heading up the East Coast. Maria is not expected to make landfall, but it could still bring coastal impacts like Jose.

Rest of today – partly sunny with high temperatures around 80°F.

Saturday – mostly sunny, very warm, temperatures 10-15°F above average for this time of the year.

Sunday – high pressure remains in place with lots of sun and high temperatures again in the upper-80s.

Monday – sunny, temperatures in the upper-80s yet again.

 

Hurricane Maria

You can now see both Post-Tropical Cyclone Jose and Hurricane Maria in the same satellite image of the continental US. Because Jose has eroded the high pressure over the northwestern Atlantic, Maria will have a path to move northwards up along the East Coast. It does look like Maria will get picked up by a frontal boundary late in the week that pushes it out to sea though.

NYC Weather & Tropical Update – Sep 18

Hurricane Jose will be the primary weather maker for us in the NYC region during the beginning of the week. Tropical storm watches are up for almost the entire the Northeast coast, except for NYC itself. The storm is expected to continue weakening, and while landfall on the US mainland is not expected, there will still be plenty of impacts from the storm.

Monday – isolated chance of showers, primarily this morning. Highs in the mid-70s with cloudy skies.

Tuesday – showers likely from the bands of what will probably a low-end Hurricane Jose or high-end tropical storm. Due to the track of Jose, it will look and feel much like a Nor’easter, with steady winds from the northeast between 15-20 mph. High temperatures in the low-70s. These winds will peak overnight into Wednesday around 25 mph.

Wednesday – rain is still possible from the influence of Tropical Storm Jose. Temperatures in the mid-upper 70s. Winds from the north between 20-25 mph.

Thursday – much more pleasant as Jose moves away from us and continues to weaken. Mostly sunny with high temperatures in the upper-70s.

 

Hurricane Jose

Hurricane Jose has been exhibiting signs of weakening over the past few days. In this latest satellite image, you can see the center of circulation is exposed and the primary convective areas are well to the north. This is due to strong mid-level wind shear from the south. The storm is also about to leave the warm waters of the Gulf Stream. Both these factors should continue to lead to steady weakening.

As the storm weakens, it has expanded in size, so despite its center not being forecast to make landfall, it is still expected to bring significant coastal impacts (beach erosion, coastal flooding, high surf) along with heavy rain.

As a side note – Hurricane Maria also bears watching with the potential to affect the East Coast next week.

 

NYC Weekend Weather – Eye on Jose – Sep 15, 2017

The main weather headline going into the weekend is the eventual track of Tropical Storm Jose. Depending on its proximity to land, we could see some nasty effects from the storm next Tuesday or Wednesday. The weekend itself should be rather uneventful, the veritable calm before the storm.

Rest of today – warm and mostly sunny. Small chance for an isolated PM pop-up thunderstorm especially inland and west.

Saturday – more clouds but still a nice day with highs around 80°F.

Sunday – probably the best day of the weekend with mostly sunny skies and a high around 80°F again.

Monday – pleasant enough to start the week. Increasing clouds, which will end the streak of above normal weather. With Jose approaching from the south we may also see increasing onshore winds cooling things off.

 

Jose an Increasing Threat to the East Coast

While Texas, Florida, and parts of the Caribbean are still reeling from the impacts of major hurricanes Harvey and Irma, Jose could pose a problem for us along the East Coast. Jose has been meandering aimlessly in the western Atlantic over the last few days and has done an anti-cyclonic loop. It’s now beginning to move west-northwest and there are a few forecast models that show it making landfall along the East Coast or coming very close to it.

It shouldn’t be too surprising that the cone of uncertainty in the official National Hurricane Center’s forecast is so large at day 5 given the substantial spread that exists amongst individual members of different modeling systems. Note that there is still plenty of time for this storm to curve out to sea with primary impacts being limited to beach erosion and coastal flooding. However, if the storm comes closer to shore or makes landfall, then we’re talking about a much more substantial problem.

Critical factors for steering this storm will include the strength of a blocking ridge (area of high pressure) which you can see in the upper right of the following image, and whether Jose gets picked up by a frontal boundary and pushed east. A stronger high pressure would block Jose’s eastward progress, and the timing of the frontal boundary passing over the East Coast will be crucial.

Jose is expected to intensify somewhat back to a minimal Category 1 storm over this time. On its approach to this area, it’s possible that it might begin the process of extratropical transition, where its center becomes less defined and loses a warm core. However, this process could also infuse some energy via baroclinic forcing that actually strengthens the storm, much as was the case with Superstorm Sandy. The concern for this storm is the long period it spends over open water where it has the potential to churn up storm surge. Even if there’s no landfall, it doesn’t mean it can’t affect coastal areas with surge or flooding.

This model run of the GFS shows Jose stalling out very close to Long Island, then brushing Cape Cod, much like a Nor’easter.

 

And don’t look now but we could be seeing the formation of tropical storms Lee and Maria in the Atlantic as well. The storm further to the west could pose a threat to the southern Lower Antilles next week.

NYC Weather Update – Sep 11, 2017

We will start this week that marks the 16th anniversary of the 9/11 attacks with excellent and seasonably warm temperatures in the low-80s for memorial services today. The pleasant weather should hold up through Thursday before the remnants of Irma begin to move into the region. Looking ahead, some forecast models have hinted that Hurricane Jose poses a possible risk to the East Coast.

Rest of today – pleasant, mild conditions with mostly sunny skies and high temperatures in the low-80s.

Tuesday – mostly sunny skies again with high temperatures much the same as today in the low-80s. High pressure will be in control of our weather during this period.

Wednesday – clouds begin to build in conjunction with the northward movement of the expansive cloud shield associated with Irma well to the south. This will cause temperatures to dip just a bit to about 80°F.

Thursday –  a touch warmer, mostly cloudy skies, high temperatures in the low-80s.

 

Hurricane Irma and Jose Updates

Residents of Florida’s west coast avoided what looked like it could be a worst case scenario for them. Irma weakened faster than forecast and moved just far enough inland such that the strongest winds of the eye did not hit Tampa. The weaker storm also reduced the risk of serious storm surge. Still, as you’ve probably seen from media reports, damage from the storm is widespread and of varying degrees of severity across the state. The dangers of the storm now move inland, with heavy rain and tropical storm winds into the Southeast.

While Irma spins down over the Southeast, Jose remains a wildcard for the East Coast next week. Several runs of the GFS have suggested a landfall for Jose somewhere in the Mid-Atlantic or Northeast. It’s far too early to know with any degree of certainty whether this scenario will pan out, since a lot of other forecast models show Jose curving out to sea, but it will bear watching.

Hurricane Irma Update – 5PM, Sep 9, 2017

Hurricane Irma has made landfall on the mainland of the Florida Peninsula at Marco Island. The eye is directly over Naples as of the time of this post. As the winds start to shift to the west and southwest in areas south of the eye of Irma, destructive storm surge will rapidly become a serious threat to life and property. The storm has weakened somewhat to a strong Category 2 with 110 mph winds. This does not diminish the wind threat, or the storm surge, flooding rain, and tornado threat.

Current Situation

Irma’s eye has filled in again as it’s interacting with Florida. It is a large, powerful storm which easily covers the entire state of Florida. There are still widespread reports of hurricane force wind gusts along the east coast of Florida, despite the eye being on the opposite side of the state.

Headlines

  • Storm surge has been flooding the streets of Miami all day. The storm surge threat will become very dangerous for southwest Florida in the next couple hours as the eye moves north along the west coast of Florida. This will bring onshore winds from the west and southwest and push the ocean over land.
  • Onshore winds along northern Florida and the Georgia/South Carolina coasts tonight will bring a storm surge risk there as well.
  • Wind threat is less serious than it was when Irma was still a strong Category 4, but a 110 mph Category 2 storm is still serious. Wind gusts recorded at Naples reached 142 mph. The northern eyewall is packing the biggest punch and this will continue to advance north along the west coast of Florida.
  • Next cities in line for a beating will be Fort Myers, Port Charlotte, and then the Tampa Bay area.
  • Tornado warnings have been popping up along the east coast of Florida with some of the stronger bands of Irma.

Forecast Track

It is pretty clear now that Irma will continue north to just west of north as it traverses the state of Florida along its west coast. Tampa Bay is the largest city at risk along this path.

Forecast Intensity

Irma is still expected to maintain hurricane strength until Monday. It should pass over Tampa Bay as a strong Category 2 storm. It will continue to gradually weaken during the next 48 hours followed by more rapid weakening.

Hurricane Irma Update – 11AM Sep 10, 2017

Hurricane Irma made landfall traversed the Florida Keys overnight as a powerful 130 mph Category 4 storm. As suspected, it was able to re-strengthen slightly over the warm waters of the Florida Straits. Landfall on the southwest coast of Florida somewhere near Naples is imminent. The forecast track is a worst case scenario for Tampa Bay, which could experience a direct hit from Irma’s eye as a Category 3 storm.

Current Situation

As of 11AM, Irma was a Category 4 storm with max sustained winds of 130 mph. It was located in the Gulf of Mexico between Key West and Naples and moving north or north-northwest.

Headlines

  • Landfall on southwest Florida will occur this afternoon as a Category 4. Devastating wind damage is expected.
  • Storm surge will occur on the southwestern side of Irma. As of now, offshore winds from the north side of Irma are pushing water out to sea. This water will return as a storm surge once winds shift to onshore on the backside of the storm.
  • Devastating winds impacts are expected for Tampa Bay with this forecast track. This will be the first direct impact of a hurricane of this magnitude in Tampa Bay since 1921.
  • Heavy, flooding rain is expected across Florida as well as much farther inland in the Southeast.

Forecast Track

Forecast models are tightly clustered on a solution that takes Irma right up the west coast of Florida. This puts the cities of Naples, Fort Myers, Port Charlotte, and Tampa Bay at high risk of experiencing the worst winds from Irma’s core.

Forecast Intensity

Irma is expected to weaken as it moves up through the coast of Florida. However, it will still be a dangerous Category 3 or strong Category 2 storm when passing Tampa Bay. It will also likely bring strong winds to large parts of Georgia.

Hurricane Irma Update – 5PM Sep 9, 2017

Hurricane Irma is moving away from the north shore of Cuba and entering the very warm waters of the Florida Straits. While it’s still moving west-northwest, it is still anticipated to finally make a turn towards the northwest as it’s rounding the southwestern periphery of the high pressure over the Atlantic that has steered it up to this point.

Current Situation

Irma’s eye shows some signs of organization and clearing up. The National Hurricane Center still pegs the storm as a Category 3 storm with 125 mph winds. As outlined in previous posts, the land interaction with Cuba has produced adverse effects on Irma, disrupting its core and causing it to weaken. However, now that it is clearing the island of Cuba and into the open waters of the Florida Straits, it should still have a window to re-intensify before hitting Florida.

Headlines

  • Forecast models are converging on a solution that takes Irma just inland and parallel to the west coast of Florida after a landfall near Marco Island.
  • First landfall could occur somewhere between Key West and Marathon Key.
  • Fort Myers, Cape Coral, Naples, Port Charlotte, and the Tampa Bay area are under serious risk of a direct hit from the eye of Irma, which could regain Category 4 strength. Storm surge is a major concern for the west coast of Florida and the southwest of the state in particular.
  • Miami and the South Florida region are less at risk from the worst of the winds, but other hazards like flooding, storm surge, and tornadoes persist. Again, the strongest winds of a hurricane in the northern hemisphere occur on the eastern side of the storm, which will impact the east coast of Florida.
  • Should the track of Irma inland but near the coast bear out, this would likely result in a slower decline in the hurricane’s strength. It would bring more risk of inland hurricane impacts to Georgia.

Forecast Track

Forecast Intensity

The National Hurricane Center forecast does call for some moderate re-intensification of Irma prior to landfall in Florida. This forecast calls for sustained winds of 140 mph prior to landfall. There are no inhibiting factors to the storm re-intensifying once it gets over open water. Wind shear is low. Sea surface temperatures are very warm.

Uncertainties

  • Internal fluctuations in the storm could still interrupt any re-strengthening.
  • On the other hand, there is a small chance for some rapid intensification if the storm gets organized again.
  • Since model forecasts haven’t changed since earlier today, this lends higher confidence to a track along the west coast of Florida.

 

 

Hurricane Irma Update – 9AM Sep 9, 2017

Overnight, Irma made landfall on the Cuban Keys off the north shore of Cuba. Land interaction with Cuba has eroded Irma’s circulation to the point where it is now a marginal Category 4 storm containing 130 mph peak sustained winds. However, it would be unwise for anyone in Florida to dismiss this storm for reasons discussed below.

Current Situation

Irma has been downgraded to a marginal Category 4 storm with peak sustained winds at 130 mph. Despite only barely touching the Cuban coast, it’s clear from satellite imagery that land interaction has disrupted Irma’s circulation. The eye is no longer clearly visible. The western side of the storm looks ragged.

Headlines

  • Track forecasts continue to shift slightly westward from overnight. This lowers the risk for a direct hit by the eye of the storm in the Miami area. However, since the strongest winds in a hurricane in the northern hemisphere occur on the east side of the storm, Miami can still expect strong wind impacts.
  • Hurricane force winds extend 70 miles from the eye on each side. Tropical storm force winds are 400 miles in diameter with this massive storm.
  • The risk to the west coast of Florida continues to increase. Southwest Florida could see the worst storm surge with surge of 6-12′ forecast.
  • It is not out of the question that Tampa Bay could take a direct hit from the eye of this storm at Category 3 strength.
  • Irma could still re-intensify over the very warm waters of the Florida Straits once it moves away from Cuba.
  • Tornadoes in the bands of Irma as it moves north will pose a limited but dangerous threat.

Forecast Track

The high pressure over the central Atlantic that has steered Irma to this point continues to remain strong enough to keep it on west-northwest motion along the northern coast of Cuba. Based on this latest track forecast, it is possible that Tampa Bay takes a direct hit from Irma. Portions of the Florida Panhandle are also at increasing risk. This track also enhances the risk of inland impacts in Georgia and southeastern states.

Forecast Intensity

Irma has been weakened by interaction with the north coast of Cuba. It is now a marginal Category 4 storm with sustained winds of 130 mph. While some further weakening is possible, once Irma emerges over the very warm waters of the Florida Straits, weakening should cease. It could even re-intensify over these waters before making landfall. Keep in mind that Category 3 winds would still be very serious.

Uncertainties

  • Any further motion into Cuba would mean further degradation to the storm’s core and circulation which could result in more weakening.
  • There is a window for some possible re-strengthening over the Florida Straits.
  • An eyewall replacement cycle could still occur bringing fluctuations to the strength of the storm.
  • The exact timing of Irma’s turn north is still not certain. When it turns north will have large implications for who sees the worst direct wind impacts from the eye of the storm.

Hurricane Irma Update – 5PM Sep 8, 2017

This update is based on information from the National Hurricane Center’s 5PM advisory on Hurricane Irma.

Current Situation

Hurricane Irma continues to persist as a large and powerful Category 4 storm with peak sustained winds of 155 mph. Its eye still appears somewhat ragged, suggesting that it’s still undergoing an eyewall replacement cycle. This will continue to lead to fluctuations in its strength.

Headlines

  • Track forecast continues to edge westward. This decreases the risk Irma poses in any direct way to Georgia and South Carolina coastal areas, though storm surge threat here is still significant.
  • The threat of a direct hit on Miami is decreasing. However, a track to the west of Miami would result in the South Florida region being on the more dangerous eastern side of the storm.
  • The risk of devastating impacts to the west coast of Florida is increasing.
  • Irma’s eye may be moving very close to or make landfall on the northern Cuban coast. The threat of catastrophic wind and storm surge damage to Cuba’s north shore is increasing.
  • Risk of damage from flooding rains and tornadoes also exists. See this 1-5 day map of possible rainfall totals:

Forecast Track

Forecast models continue to edge slightly westward on a track for Irma and as such the National Hurricane Center has also adjusted its latest forecast slightly more west.

Forecast Intensity

National Hurricane Center forecasts continue to call for Irma to make landfall somewhere in South Florida as a very dangerous and powerful Category 4 storm. Outside of possible internal fluctuations and interaction with Cuba’s high terrain, there are no other inhibiting factors on Irma maintaining Category 4 strength of even possibly intensifying. Irma is entering an area of very warm sea surface temperatures with basically no mid-level wind shear.

 

NYC Weekend Weather – Hurricane Irma Update, Sep 8 2017

We’ve got a wonderful stretch of below average but sunny, fall-like weather ahead of us over the weekend. The main weather story lies far to our south as Florida braces for Hurricane Irma over this same time period. Irma has weakened a bit but is still a large and dangerous Category 4 storm capable of wreaking havoc over the entire state of Florida.

Rest of today – our weather will be dictated by an area of high pressure anchored over the Great Lakes. This will give us mostly sunny skies with a cool high in the mid-70s.

High pressure firmly in control of the weather in our part of the world. You can see Hurricane Irma making its finally approach on Florida in the lower right.

Saturday – sunny with temperatures in the low-70s as the high pressure over the Great Lakes moves east a bit.

Sunday – more of the same as Saturday with sunny skies and high temperatures in the low-70s.

Monday – slightly warmer with high temperatures creeping back into the mid-70s with some more clouds.

 

Hurricane Irma a Major Threat to South Florida

Current Situation

Hurricane Irma has been weakening in the last 12 hours. It’s evident the storm is undergoing an eyewall replacement cycle, where the inner eye of the storm collapses and is replaced by a larger, outer eye. During these internal cycles, max wind speeds often decrease and fluctuate before the storm consolidates a new eye. It has been downgraded to a Category 4 storm with maximum sustained winds of 150 mph.

Headlines

  • Landfall somewhere in South Florida over the weekend is a near certainty. Outer bands from Irma are expected to reach South Florida overnight tonight. Life-threatening storm surge inundation and damage from winds of major hurricane force (115 mph) are a near-certainty for parts of South Florida.
  • Since midday yesterday, forecast models have trended slight back towards a westerly solution for the forecast track of the storm. This almost eliminates the risks to Georgia and South Carolina coastal areas from a direct hit from a major hurricane. However, the risk to these areas from storm surge and strong tropical storm force/marginal hurricane force winds still exists.
  • There is still a chance Irma could make landfall on Cuba. This would weaken the storm ahead of subsequent landfall on Florida.

Forecast Track

As mentioned above, the best performing forecast models have shifted back to a more westerly track for Hurricane Irma.

Several different forecast models take on Irma’s track.
Official National Hurricane Center forecast as of 8AM today.

Forecast Intensity

While Irma has weakened to a Category 4 storm due to an ongoing eyewall replacement cycle, it remains an extremely dangerous storm with an expanding wind field due to this cycle. Hurricane force winds extend 70 miles on each side of the eye and tropical storm force winds well beyond that. It remains possible that Irma can re-strengthen if it completes the eyewall replacement cycle before it interacts with land. Mid-level wind shear remains negligible and Irma will soon be passing over very warm seas with increasing depth. Both of these factors would suggest it maintaining Category 4 strength or possibly re-intensifying to Category 5.

Uncertainties

  • Any landfall on Cuba or interaction of the core of the storm with the high mountains of that island would disrupt the storm and cause weakening. This would be good news for Florida, at the expense of Cuba of course.
  • Should the core of the storm avoid Cuba and close off a new eye before too much time elapses, it would have the possibility of re-strengthening before landfall. A strong Category 4 or even a Category 5 storm making landfall on Florida is not out of the question.