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.
You may have heard from media reports that the dreaded polar vortex is set to make a return to the Eastern US during the middle of the coming week. I’ll discuss that in detail below. First, for the weekend forecast:
Today & Saturday – a very pleasant couple of days in the wake of the cold front that finally pushed through our area yesterday. You can feel a marked drop in humidity, and temperatures are much more comfortable. Saturday, high temperatures should top out in the mid 80s in NYC.
Sunday – a chance for afternoon thunderstorms and a high in the mid 80s, chance of rain increasing through out the day into the overnight hours.
Polar Vortex?
Forecast models are in good agreement that beginning Tuesday into most of the rest of next week, an upper air vortex (see below, the trough with an inclosed region surrounded by the blue arrows) will drop into the Midwest and Northeast from the northern regions of Canada. This vortex can be technically referred to as a polar vortex, a term that instantly revives media hype about how cold it will be. But keep in mind, during the summer, polar regions heat up as well, so even the coldest polar airmass and vortexes are much milder than their winter counterparts. Furthermore, the influence of the sun is quite strong as we just passed the summer solstice, so the sun is sitting at a very high angle each day and is highly effective at heating the air quickly. Hence, temperatures are expected to be much below normal for some areas, but we’re not talking about snow or ice.
Upper air forecast from GFS for Monday, 8PM EDT, 500mb absolute vorticity.
Next Week
There will be a good deal of energy traveling with the polar vortex, so we’re expecting a somewhat disturbed pattern of weather for the beginning of next week. Tuesday & Wednesday will see the best chances for rain and thunderstorms with a cold front approaching us from the west. Before the cold front, we’ll still see temperatures in the mid to upper 80s with a chance for thunderstorms Monday. Once the cold front passes, we’ll be right in the mix with the “polar” air mass, so our high temperatures will drop into the low 80s, and overnight lows will drop into the upper 60s for the latter part of the week.
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
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.
Lots to talk about on the last day of June, which brings with it the opening of a warm trend and possible mini heat wave. A stubborn low pressure system over the Plains States is pushing warm and humid air from the Gulf ahead of a leading cold front. As a result, Tuesday will feature warm, muggy conditions with highs in the upper 80s, maybe even touching 90.
Wednesday, that frontal boundary comes closer, and with the heat and humidity in place, we’ll have the right conditions for some pop-up showers and thunderstorms later in the day. However, coverage is expected to be widely scattered. Highs again will be in the upper 80s, possibly hitting 90.
Thursday -as the cold front makes its approach in earnest, a pre-frontal trough is forecast to develop, and this should help spark off more widespread showers and thunderstorms than on Wednesday. Expect high temperatures to be somewhat lower due to cloudy skies, but still warm and humid in the mid to upper 80s.
Friday (Independence Day) – A lot of weather forecasters were saying earlier this weekend that July 4th was going to be a nice day with no rain. Sadly, that doesn’t appear to be the case now, as the timing of that pesky cold front has slowed down somewhat. This does mean you could see rain and or thunderstorms during the day Friday and into Friday night, but at least the heat will break somewhat with temperatures only around 80.
Cold front right on top of us Friday could rain on your July 4th plans.
First Named Tropical System of the Atlantic Hurricane Season?
Over the weekend, a disturbance off the east coast of Florida began to show signs of increasing organization, to the point that the National Hurricane Center now gives the system an 80% chance of forming into a tropical depression in the next 2 days. If it does, then it will become the first named tropical system of the 2014 Atlantic Hurricane Season.
High resolution satellite image of the incipient tropical system off the east coast of Florida
Why does this matter to us? Well, as it currently stands, it appears this tropical system/possible storm may impact our weekend weather here in the Northeast. Some forecast models have this storm moving to the near offshore waters of the Northeast by Saturday (indicated in pink circle below). This could bring the potential for rain to parts of the Northeast, in particular, New England. Fortunately, it doesn’t appear as though this storm will strengthen much (below you see the lowest pressure at the center of 1012mb, for reference, normal pressure at sea level is 1013mb), and in fact, it will likely make a transition to becoming an extratropical cyclone/storm rather quickly after it moves north of Florida. Still, it’s a bit too early to tell just where this storm will go, so it bears monitoring.
Possible storm tracks as illustrated by several different forecast models
Two part update today – first to address NYC weather, and then to discuss the outlook for next week down in Brazil during the opening week of the FIFA World Cup.
Friday – the work week closes out with the wettest day so far with a warm front passing through tonight, and then a cold front following shortly thereafter tomorrow. This will translate to mostly cloudy skies, with a round of rain tonight, followed by a period of scattered rain showers and thunderstorms, and then ending with another round of heavier rain and thunderstorms Friday night. Temperatures will be much warmer than today after the passage of the warm front with highs in the low 80s.
NAM model output simulated radar image for Friday morning @ 5AM
Luckily for us, the cold front passes through quickly Friday and leads to a splendid stretch of weather beginning with a sunny, mild and pleasant Saturday and Sunday. High temperatures will be in the low 80s both days under clear skies. This is due to an area of high pressure building in from the west behind the cold front.
Warm Spell Next Week
This same high pressure area will track to the southeast during the weekend. By mid-week next week, the high pressure center will be offshore of the Southeastern US, and link up with the Bermuda High. As you may know, Bermuda Highs typically cause hot, humid weather in our region, and this will be no exception. Temperatures will steadily increase each day Monday, Tuesday, and Wednesday, such that by Wednesday, we’ll be looking at highs in the mid-upper 80s. This area of high pressure will also block any precipitation from impacting us until at least next Thursday into Friday when a low pressure system with a trailing cold front is forecast to pass through the Great Lakes.
GFS model output for next Tuesday
World Cup Weather
The World Cup is upon us!!! With opening kickoff just a few minutes away, I thought it’d be useful to talk about weather down in the host country, Brazil. As you know, it’s currently autumn in the Southern Hemisphere, but you wouldn’t be able to tell based on the forecast high temperatures for most of the Brazilian cities with games going on next week. High temperatures will range from the upper 70s-upper 80s depending on where you are.
The highest temperatures will be in Manaus, which not surprisingly sits in the Amazon basin. That’s also the city where you can expect the highest likelihood of rain and thunderstorms. Most of the coastal Brazilian cities that are hosting games will have pleasant conditions and high temperatures in the low 80s this week. Fair weather should be the story as high pressure will tend to dominate this week.
GFS model output for S. America on Tuesday
For your reference, here’s a map with dates of games being held in each host city. I’ll be keeping an eye on the weather and posting any relevant updates as they come up.
When air flows are blocked by obstructions, such as buildings, trees, mountain ranges, or in this case, a mountainous island, all sorts of interesting effects can occur. Just as flowing water hitting a rock will form swirling eddies, flowing air has the same tendency, which you can plainly see int he image above. We’re usually not able to see these effects so vividly, though you’ll often feel them in the form of turbulence.
One of the lead forecasters at WPC was taking a look at the visible satellite imagery in the Pacific near the Baja California Peninsula and noticed some swirly action. If you take a look, there’s several swirls being caused by a volcanic island called Isla de Guadalupe. There’s also one right next to the coastline. How many can you count!?
We have satellite and radar imagery on our webpage alongside the surface analysis–if you want to take a look, visit our website (www.wpc.ncep.noaa.gov) and take a look under the current weather!
