The National Hurricane Center announced that Tropical Depression Eighteen has formed over the northwestern Caribbean Sea just south of Isla de Juventud in Cuba. The formation of TD Eighteen has implications on the forecast for Sunday’s storm as a complex scenario is set to unfold.
Impacts: forecasters are anticipating a high wind, and heavy rain event coming up. Storm total rainfall of 2-4″ and possibly higher could lead to urban and small stream flooding. The amount of rainfall over a short period of time has led our local forecast office to issue flash flood watches for much of the region. Winds will pick up as well, backing from the south to southeast, east, and eventually to north and northwest. Wind gusts could become a problem for local airports and for poor travel conditions in general. Thunderstorms are a possibility as well.
Timing: Winds are already increase today, and cloud cover will do so as well as the day progresses. Chances for rain will increase in the overnight hours, probably after 2-3AM. The strongest wind gusts will actually come on the back side of the storm going into Monday as it intensifies and the pressure gradient increases.
Discussion: a complicated set up is unfolding with a longwave trough (on the left) draping from the Great Lakes into the Gulf of Meixco interacting with a developing closed low over the Tennessee Valley, and TD Eighteen. TD Eighteen is likely to strengthen into a tropical storm, which would be named Phillippe if it did form. The effect of this will be to provide a conveyor of warm and moist air from the tropics up to our area. This will help feed the developing non-tropical low forming over the southeast. This low will become the primary rainmaker, and the tropical system (whether a depression or storm) will eventually merge with it. Plenty of instability to fuel a growing storm! The pressure gradient will tighten as this storm strengthens and departs eastward, and that will be the reason for a gusty start to the work week.
The first half of this long weekend will continue the warm summer feel we’ve had since mid-week. Some much needed rain arrives Sunday going into next week in conjunction with the anticipated remnants of Tropical Storm Nate. This does literally mean that it will rain on the Columbus Day parade.
Rest of today – mostly sunny. Warm with highs around 80°F.
Saturday – partly sunny, not a bad day though with high temperatures in the low-80s. The stationary front depicted above that’s sitting close to the city will push north of us as a warm front. This will open the door to an increasingly tropical feel with higher dew points and more moisture in the air.
Sunday – mostly cloudy. Rain chances increasing in the afternoon with thunderstorms possible. Rain that develops could be heavy with tropical moisture flowing into the area. Still warm, with temperatures in the low-80s. An advancing cold front will push up precipitation partially fueled by Tropical Storm Nate (which is anticipated to make landfall on the New Orleans/Mississippi coastal area this weekend. This precipitation will be moving in on our area well in advance of the actual core of the remnants of Nate.
Monday (Columbus Day) – rain and thunderstorms as the bulk of the remnants of Nate move into the area. Rain heavy at times. Cooler with highs dipping into the mid-70s. With Nate approaching to the southwest of us, we should see more steady rain and clouds, keeping temperatures suppressed.
Tropical Storm Nate
Tropical Storm Nate is expected to strengthen into a minimal hurricane after it crosses near or over the northeastern Yucatan Peninsula this weekend and into the Gulf of Mexico. From that point, it’s expected to accelerate towards the Gulf Coast and make landfall in the vicinity of New Orleans, the Mississippi Delta and coastal Mississippi. Even though this storm will pale in comparison to Irma and Maria, it has already claimed 20 lives in Central America due to heavy rains and flooding.
Hurricane Maria will not be coming our way this week. The cold front that will be responsible for pushing Maria out to sea arrives late in the week and induces a return to fall weather. Until then, it will continue to look and feel like summer.
Rest of today – warm, sunny, high temperatures well into the mid and upper-80s
Tuesday – some patchy fog over night. Any fog should burn off early and high temperatures should reach in the low-80s with mostly sunny skies.
Wednesday – could see some more clouds, and possibly some rain along a frontal boundary passing through. High temperatures in the low-80s.
Thursday – clouds and sun with temperaturea around 80°F.
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.
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.
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.
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.
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.
This is one of an upcoming series of special posts dedicated to Hurricane Irma. I’m hoping these posts will keep those of you who are either in areas at risk or have friends and family there informed and prepared as this historic storm bears down on the US mainland.
Current Situation
Hurricane Irma remains an impressive Category 5 storm packing sustained wind speeds of 175 mph. It is nearing the Turks and Caicos Islands as of this time.
Headlines
The threat Irma poses to South Florida as a strong Category 4 storm continues to increase
There is a risk to the Georgia and South Carolina Coasts. This risk would increase if there’s eastward movement of the storm track, as was the case in previous track forecasts.
Major impacts are expected to the Turks and Caicos and Bahamas archipelagos
The threat to the northern coast of Cuba remains high. Hurricane watches have been upgraded to warnings.
This is a large hurricane – the larger the size of the storm, the larger the storm surge it can generate. Even if the eye of the storm misses Florida to the east, the entire state could still feel the impacts of tropical storm and hurricane force winds.
Forecast Track
Here is the National Hurricane Center’s latest official forecast with a 5-day cone of uncertainty reflecting the spread in forecast models. Models have been wavering between a more westerly and easterly track in the past 24 hours which would have big implications (see below).
Here are some actual forecast model outputs on the storm’s track.
GFS model run showing Irma very close to or making landfall on the Miami area on Sunday at 8AM
Forecast Intensity
Unless the core of the storm interacts with the high terrain of Cuba by making landfall on it, it is unlikely that Irma would weaken significantly.
Wind shear is expected to remain low at the mid-levels, which means basically zero disruption to the core of the storm. Sea surface temperatures are very warm in the Florida Straits and Bahamas. This will support the storm maintaining itself as a very powerful hurricane.
Irma is expected to approach South Florida as a dangerous Category 4 storm (sustained winds over 130 mph). Even with some interaction with Florida, Georgia and South Carolina could still expect a strong Category 2 (sustained winds > 95 mph) or a Category 3 (sustained winds > 115 mph).
Uncertainties
The critical component of forecast track uncertainty is the timing and degree of influence a mid-level trough (the dip in that solid black line in the image below) on initiating Irma to begin a turn to the north as it rounds the western periphery of the Bermuda high that has been steering it thus far. The effect of a mid-level trough is both to weaken the Bermuda high and also to exert a pull on Irma to the north.
The timing of Irma’s northward turn is significant as an earlier turn would result in a more easterly track, and a later turn would result in a more westerly track. A small deviation either way could either spare an area from a direct hit by the devastating eye of the storm or bring it right into the eye.
A track to the east that takes the center of the storm away from South Florida would result in a stronger impact on the Georgia/South Carolina coasts
A track to the west would reduce the possible dangers to Georgia and South Carolina but increase the threat to the entire Florida Peninsula. This would still result in serious impacts to South Florida.
Another factor to consider is that landfall on Cuba and any significant interaction of the core of the storm with the high mountains of Cuba would result in a weaker storm affecting Florida and other US locales
Irma’s Impacts Thus Far
Overnight into today, Hurricane Irma made landfall on several small Leeward Islands including Barbuda and Saint-Martin/Sint-Maarten. These islands took a direct hit from the eyewall of Irma, which packed sustained winds of 185 mph. This resulted in catastrophic damage to Barbuda that the prime minister described as rendering the island barely habitable. Below, you can watch some footage captured by a camera at Princess Juliana International Airport located in Sint-Maarten, the Dutch side of Saint Martin as the eyewall impacted that location.
As on Barbuda, scenes of widespread damage were to be found on Sint-Maarten as well. Here’s an infrared satellite image of Irma as its eye swallowed Anguilla and Saint-Martin/Sint-Maarten last night:
Hurricane Irma has smashed an all-time record for longest duration of winds at 185 mph in the satellite era (1970s or so onward) with these winds lasting for 36 hours. This is truly incredible considering that the strongest tropical cyclones are typically found in the Western Pacific where these storms have ample time over warm water to grow.
The unofficial end of summer does indeed bring us a last gasp of summery weather. A cold front passing through mid-week brings rain and signals a return to more fall-like conditions. Later in the week, we will see high temperatures 5°F below normal. Turning towards the tropics, the risk Irma poses to our region is diminishing, but it now appears Irma will be a threat to Florida.
Rest of today – clear, with ideal conditions for outdoor activities of all kinds. High temperatures in the low-80s.
Tuesday – highs in the low-mid 80s as warm air surges ahead of an advancing cold front. Mostly sunny with increasing clouds late in the day. Some possibility for a spot shower or thunderstorm in the afternoon.
Wednesday – thunderstorms are possible overnight Tuesday as the leading edge of the cold front advances through the area. More rain is expected to ride along the frontal boundary after it passes through, bringing periods of showers throughout the day. High temperatures will be much cooler in the mid-70s with the clouds and rain.
Thursday – mostly cloudy to start with a chance for lingering rain. High temperatures will be cool again in the low-70s.
Friday – mostly sunny skies, much improved conditions as high pressure takes hold. Cool, with high temperatures in the low-70s.
Hurricane Irma an Increasing Threat to Florida
Over the weekend, Irma has been fluctuating in strengthen as it has negotiated marginal conditions for strengthening (mostly the influence of some dry air at upper levels). The National Hurricane Center still forecasts Irma to attain Category 4 strength at some point later this week (130 mph sustained winds or higher) as it encounters more favorable conditions for strengthening, and maintain at least Category 3 strengthen (sustained winds > 115 mph) throughout the forecast period.
The track forecast for Irma has continuously shifted west and south over the weekend due to the influence of an area of high pressure over the Atlantic now, and a faster forecast for the passage of the cold front mentioned above. This frontal boundary lifting out of the East Coast at a faster rate than in prior forecasts would mean that it does not influence Irma to make a turn to the north-northwest and threaten the East Coast. This has two consequences: 1) The chance for Irma to make landfall up the East Coast is diminishing, 2) On the other hand, the risk to Florida is increasing.
This run of the GFS forecast model suggests Irma making landfall on South Florida as a powerful Category 3 hurricane in one week’s time.A “spaghetti” plot of multiple model runs of GEFS, one of the forecast models that forecasters are using to analyze Irma.
It is important to note that with a week to go before Irma nears the US mainland, there could still be room for changes to the track and intensity forecasts. The National Hurricane Center specifically cautions against drawing premature conclusions about the storm’s impact on the rest of the US, while singling out Florida as an area of concern. More updates to come as we continue to watch the development of what could be a very dangerous storm.
