We had a solid round of rain from some showers and thunderstorms that passed through the area overnight. Over the weekend, high pressure will start to build into the area, ushering in a period of calm, pleasant, and seasonable weather.
Saturday & Sunday – clouds will diminish later Saturday, and by Sunday we’ll see mostly clear skies. Both days will feature high temperatures around 80.
Monday – as you see below, by Monday an area of high pressure will be firmly entrenched over our region. This high pressure area will persist through the middle of the week, giving us fair conditions and pleasant highs in the low 80s.
High pressure firmly entrenched in the Northeast for the beginning of next week.
Tuesday & Wednesday will look and feel essentially the same with highs in the low 80s and mostly sunny skies.
Our next chance of rain will be later in the week, perhaps Thursday into Friday with the arrival of a cold front from the west.
In the Tropics
There’s a tropical disturbance currently positioned offshore of Puerto Rico that will very likely become the 2014 Atlantic Hurricane Season’s third named storm, Cristobal. You can already begin to see the storm organizing, as over the last day or so, a circulation has become evident, and strong thunderstorms are forming in the northern semicircle are also apparent (see the classic cauliflower tops). Outflow bands are also forming up (thin wispy clouds north and northeast of the center).
High resolution satellite image of the tropical disturbance
This storm will fell some negative impacts from the high terrain of Hispaniola and Puerto Rico. As you can see, the southern semicircle is considerably less organized than the northern.
As for the track of the storm, you can see the rather large spread between the different forecast models, which is not surprising given that the storm is still in its early stages. Note that there is an outlier model solution showing landfall on the Mid-Atlantic. This is unlikely at this point, but worth noting. It seems, given the conditions ahead of the storm, that this will become Tropical Storm Cristobal in the next couple days, and may become Hurricane Cristobal shortly thereafter.
I haven’t been active on this blog the past couple of weeks as I’ve been in Costa Rica, however, the unfolding situation with Hurricane Iselle warrants a posting. I’ve observed Iselle as it formed from a tropical wave and then a tropical depression along the Inter-Tropical Convergence Zone off of the coast of Central America where I’m currently staying. Now, Iselle is closing in on the Hawaiian Islands and is set to make landfall on the Big Island this evening.
Despite the fact that the Hawaiian Islands lie near an active area for tropical cyclones, they are rarely impacted, in part due to the sheer vastness of open ocean versus the relatively small land area of the islands. During most years, a semi-permanent high pressure area that resides near the Islands also precludes the formation, strengthening, and penetration of cyclones into the region. This changes dramatically when El Nino conditions prevail, as they seem to be currently. Iselle will be the first landfalling hurricane to affect the Hawaiian Islands in 22 years since the devastating Hurricane Iniki of 1992. Fortunately, Iselle will be making landfall as a much weaker storm than Iniki, but regardless, it will still pack a serious punch.
Satellite image of Hurricane Iselle with Hurricane Julio following behind. To the far left, you can see Hurricane Genevieve.
Track Forecast
With less than 24 hours before landfall, the forecast track for Iselle is essentially zeroed in. The official track forecast cone has Iselle hitting the Big Island straight on. The center of the current forecast track envelope, should it hold up, has Iselle potentially making a direct hit on the eastern portion of the Big Island, with the eye of the storm skirting just south or perhaps directly over the Hilo area. I would hope for a northward deviation of this track, as this would spare the region from the strongest quadrant of the storm’s winds and waves (in the northern hemisphere, the strongest quadrant of a cyclonic storm is generally the northeastern quadrant). In the case of Iselle, due to its forecast west-northwest motion, the strongest quadrant should actually be the northwest, since the forward speed of the storm is added to the winds in that area.
After making landfall on the Big Island, Iselle is forecast to move to the south of the rest of the islands, passing closest to Maui. Because of uncertainty in the track forecast, it is entirely possible that Iselle could end up making multiple landfalls on different islands. However, I would anticipate these subsequent landfalls to be less serious in nature as Iselle should weaken substantially due to the influence of interaction with the mountainous terrain of the Big Island as well as increasing vertical wind shear from the north and west. There could still be some damaging storm surge and high winds in the other Hawaiian Islands, especially if the center of Iselle passes to the south of them.
Intensity Forecast
Iselle has been stubbornly persistent in maintaining minimal Category 1 status. Forecast models have been giving conflicting signals as to whether Iselle will be impacted by increased wind shear. Forecasters had not anticipated that Iselle would enter into a col between two high pressure centers, essentially an area of very low wind shear, think of it as a calm spot between two swirling eddies. Different forecast models are providing two divergent scenarios: (1) that Iselle continues to move in tandem with the col, allowing it to maintain current strength, or (2) Iselle leaves the col and experiences much higher wind shear.
No matter what, Iselle will be making landfall on the Big Island as either a minimal Category 1 hurricane or a very strong tropical storm. The real impacts of either scenario will be hardly discernible. Wind over the Big Island should pick up substantially this afternoon and evening first from the northeast, then north, and then switching to the south and southeast overnight. Sustained tropical storm force winds in the range of 50-65mph are expected depending on the specific locale. Wind gusts of up to 90mph are also possible in some locations. Offshore waves will build from 6 feet to as high as 31 feet closer to the center of the eye. I hope all people on the islands are making adequate preparations. Wind speeds as high as the ones forecast could easily shred even a decently well constructed roof. I’m not sure if the local government has issued evacuation orders, but if so, I hope all citizens of Hawaii will heed the call and take every necessary precaution to secure life and property. Let’s hope this Iselle weakens some more before it makes landfall.
Notes
In contrast to the Atlantic Hurricane Season thus far, this year’s Pacific Hurricane Season has been quite active, in part due to the influence of anomalously warm sea surface temperatures over the Eastern Pacific. These temperatures are indicative of what could be the start of an El Nino event. Hurricane Iniki also formed during a very strong El Nino event.
Despite the fact that Typhoon Neoguri shares a name with a well-known brand of packaged ramen, it certainly is no joking matter, as you can see from the impressive satellite image captured recently. Although the storm has weakened from a Category 4 Super Typhoon, it is still a powerful Category 3 storm currently churning up the East China Sea.
This storm is bad news for Japan, especially the large populations living on the southernmost home island of Kyushu. Forecasters believe Neoguri will continue to weaken rapidly under the influence of increasing wind shear, but it is still set to make landfall on Kyushu some time Thursday as a Category 1 storm. The mountainous terrain of Kyushu will likely provide orographic enhancement for the rain bands coming off of Neoguri (the upslope side of the mountains facing Neoguri’s onslaught will have the tendency of squeezing out precipitation from the rain bands).
Hurricane Arthur is still being analyzed by National Hurricane Center as packing winds of 80mph. Although the inner core is still very symmetrical, you can see that the overall storm is beginning to lose some symmetry. In addition, central pressure has risen a couple millibar since earlier today, indicating the storm is continuing to weaken.
There’s still plenty of rain in store for Southeastern New England, though, as a couple bands of heavy rain are still moving their way onshore. The worst of the storm is yet to come, with the center of Arthur forecast to make its closest pass to this portion of the country in the next couple hours. Overnight, tropical storm conditions are likely over portions of Eastern Cape Cod.
As of 9AM EDT, Hurricane Arthur has weakened somewhat from its peak intensity as a Category 2, and sustained winds have declined to 90mph. However, its eye is still clearly visible, and as you can see below, the storm is maintaining a symmetrical appearance with good outflow in all quadrants, meaning this is still quite a powerful storm. As Arthur continues moving northeast, it is expected to weaken rapidly upon entering much cooler waters and with increasing vertical shear from the codl front seen below. Track Forecast
Forecast models are in very close agreement about Arthur’s track over the next 12 hours or so. As you see below, they are tightly clustered around the 40N, 70W benchmark. Hence, forecast reasoning has not changed much since yesterday night. Arthur is expected to continue its northeast track and speed up under the influence of the cold front depicted above, moving offshore of New England and into the Canadian Maritimes as it makes extratropical transition.
What This Means for Us
As expected, Arthur will be bringing multiple rounds of rain to the entire Northeast over the course of the day today. You can already see Arthur’s outer rain bands on our regional radar (you’d see it in the standard 124 nautical mile radar, but I’ve inserted an image of 248 nautical mile range radar image to see the storm better). As Arthur accelerates and makes its closest pass to this part of the country, we’ll see repeated bands of rain moving on shore. You can expect periods of heavy rain and thunderstorms, interspersed with some dry spells under cloudy skies.
The Rest of the Weekend
Once Arthur and the cold front clear the Northeast, we will see a return to a spectacular weekend with high pressure building back in. Sunny skies, mild, and dry conditions will prevail across the entire region with high temperatures in the low-mid 80s on both Saturday and Sunday. As the high pressure moves to our southeast, we’ll see a return flow from the backside of the high pressure ushering in another warm, humid airmass for the beginning of next week.
Hurricane Arthur has held steady with 90mph winds over the last 6 hours or so. The storm’s eye continues to grow more defined, with central pressure continuing to fall to 977mb. These signs point to further strengthening, and the National Hurricane Center is still forecasting Arthur to hit Category 2 strength as it makes its closest pass over North Carolina.
Track Forecast
Over the course of the day, Arthur has moved further north than originally forecast, and is only slowly beginning to make its turn towards the northeast. As a result, most forecast models have been pushed a bit further to the west. Most of the models now have Arthur making landfall somewhere over coastal North Carolina, and then passing inside the 40N, 70W benchmark offshore of the Northeast. The bottom line is that the updated forecast track increases the likelihood of adverse impacts to coastal areas all along the East Coast. This includes high surf, beach erosion, and dangerous riptides even in areas that don’t see direct impacts. This new track also puts portions of Southeastern New England under risk of experiencing tropical storm conditions, and heavy rain bands from Arthur as it passes offshore.
It’s a good thing that mandatory evacuations were placed for the Outer Banks and coastal North Carolina, as portions of these low-lying areas are forecast to experience storm surge inundation of greater than 3 feet during the peak of the storm.
Blue shaded areas = 1-3′ of storm surge Yellow areas = between 3-6′ of storm surge
Lots going on in the realm of weather over the coming weekend. First, to start off with today, the Storm Prediction Center has again placed our area under a slight risk of severe weather this afternoon and evening. We could see a repeat of the type of storms from last night as a cold front makes its approach from the west. Even though temperatures are lower today and sunlight limited, there’s still more than enough instability in the atmosphere to fuel a few strong to severe thunderstorms later today. Because we’re looking at another round of possibly torrential rain from today’s storms, many areas are under a flash flood watch. Part of this moisture is due to the influence of Hurricane Arthur to our south.
Hurricane Arthur
As of this morning, Arthur strengthened into the 2014 Atlantic Hurricane Season’s first hurricane and is currently sitting offshore of South Carolina with sustained winds of about 90mph. Forecasters are increasingly confident that Arthur will have enough time over warm water and low wind shear areas to grow into a Category 2 storm before getting recurved out to sea and making extratropical transition.
Track Forecast for Hurricane Arthur
Arthur is now forecast to brush by the Outer Banks of North Carolina sometime later today, and move to just about the 40N, 70W benchmark offshore of the Northeast by 8PM Friday. Given this current forecast track, confidence is increasing that we’ll continue to see heavy rain and showers through out Friday into Fridaynight, though not directly from Arthur itself. Rather, Arthur will be interacting with that cold front mentioned above to throw a wrench in everyone’s July 4th plans. Conditions should begin to improve rapidly Saturday as Arthur accelerates northeast, pushed by the cold front. We should see a return to sunny skies and seasonable weather Saturday with highs around the low 80s. Of particular concern are areas in Southeastern New England, which could see tropical storm conditions on Friday night into Saturday morning. Any deviation westward of this current forecast track would mean increased impacts on the Northeast, so this storm is worth watching closely. Regardless, high surface and dangerous riptides will be present on all Atlantic shorelines.
Current satellite imagery of Tropical Storm Arthur shows a storm that is increasingly organized, with well established outflow in all quadrants, a symmetrical appearance, and spiral bands around the whole storm. An eye feature continues to grow more clear. The National Hurricane Center current analysis of Arthur indicates a storm with sustained winds of 70mph, just below the 75mph criteria for a Category 1 hurricane.
Intensity Forecast
Current forecast reasoning shows low wind shear conditions over the next 48 hours, which should allow Arthur to continuously strengthen. Max winds are currently forecast at 85mph.
Track Forecast
As of right now, it seems Arthur has taken a jog to the west, so model forecasts have been pushed west as well. As a result, portions of the Outer Banks in North Carolina have now been placed under a hurricane warning. This slightly more westerly route also means increased potential for impacts in southeastern New England late Friday into Friday night. For NYC, we’ll be looking at soaking rains from the tropical moisture brought up by this storm tomorrow as well as Friday, however, confidence is decreasing that Arthur will rain out our fireworks in NYC.
A quick update on TS Arthur, before a more substantial post later this afternoon. Based on the latest satellite imagery, it appears that Arthur is continuing to gather strength. You can see below that a central eye feature is beginning to form, and that spiral bands have now begun wrapping around the west side of the storm. While Arthur continues to struggle with dry air on its western side, it does seem that this is gradually being overcome. The inner core of the storm is displaying relatively symmetrical outflows, a sign that the storm is strengthening.
As of 11AM EDT, the National Hurricane Center analysis indicated that Arthur now has sustained winds of 60mph, and is moving north.
As you can see below in a satellite image captured at 7:45AM EDT this morning, TD One is showing increasing signs of organization. You can clearly see overshooting tops (the bubbly looking clumps of clouds), which are clouds that are breaking up through the tropopause and into the lower stratosphere. This is a hallmark sign of intense thunderstorm updrafts, where warm, humid air is rapidly moving upwards in the atmosphere. You can even see the beginning of what may eventually become a spiral band forming directly south of the storm’s center.
National Hurricane Center has issued tropical storm warnings for the Eastern Florida coast. TD One’s sustained wind speeds are at 35mph, only 4mph shy of tropical storm criteria. In fact, as of this writing, TD One may have already become Tropical Storm Arthur, our first named storm of the 2014 Atlantic Hurricane Season.
Storm Track Forecast
TD One is forecast to begin a turn towards the north, then northeast over the period of the next day or so. Thereafter, it is forecast to steadily accelerate in forward speed towards the northeast as a cold front currently approaching our region from the west begins to steer the storm. It appears in the latest model runs that the storm may make a landfall in the Cape Hatteras area of North Carolina, and the move offshore of the Northeast Friday night into Saturday.
Intensity Forecast
Although the strongest thunderstorms are currently confined to the southern half of the storm, there is high confidence that the storm will continue to organize and become a tropical storm shortly. The National Hurricane Center is also now forecasting that TD One will have sufficiently good conditions to strengthen into a weak hurricane by the time it makes its closest approach to North Carolina. It will eventually get absorbed by the cold front mentioned above and make an extratropical transition somewhere off the coast of the Canadian Maritimes.
What This Means for Us
The tropical moisture from this storm is increasingly likely to throw a damper on July 4th plans for the area, when the storm and approaching cold front will interact to produce the chance for heavy rain, thunderstorms, and possibly some strong wind gusts. However, even though this is forecast to occur within the next 3-4 days, there is still a good deal of uncertainty as to the final track of this storm, especially as it approaches the Northeast. More updates soon!
