Rejoice! The long awaited Labor Day Weekend is upon us. Although I’d love to say that the weather will be fantastic throughout, but unfortunately there will be a few disturbances traversing the region the second half of this weekend. Thunderstorms accompanying these disturbances may literally rain on the annual West Indian Day Parade in Brooklyn on Monday.
Friday – the remainder of today will be a picture perfect, fall-like day with high temperatures hovering right around 80. A pleasant, dry airmass is in place in association with an area of high pressure that’s currently sitting over us.
Saturday – essentially a repeat of Friday, but with a bit more cloud cover.
Sunday – high temperatures on Sunday will be considerably warmer than Saturday, since the area of high pressure sitting over us now will have moved to the east, building up southwesterly winds and allowing for an influx warm air to penetrate the region. Expect more humid and warm highs between the mid-upper 80s. A weak frontal boundary will be approaching Sunday, and transit the region late Sunday into Monday. This will be our first shot at rain and thunderstorms, some of which may deliver some heavy rain.
Labor Day – the timing of the aforementioned frontal passage will be critical in terms of sensible weather Monday. It currently looks like Monday will be partly cloudy, with highs again in the mid-80s. There will be an increasing chance of scattered thunderstorms later in the day Monday leading into Tuesday as another weakening cold front nears the area.
Tuesday – the return to the work week will continue to feature warm and humid highs in the mid-upper 80s and a continued chance of thunderstorms as that cold front works its way through.
We have a fairly straightforward weather week ahead of us leading into the Labor Day Weekend. Currently, our region is sitting under an area of high pressure, which will be sliding to the southeast. As it does so, winds will shift to the south and southwest, allowing the entry of a warm and humid airmass that’s been responsible for brutal triple digit heat in the southern tier of the country.
Tuesday – temperatures will continue to climb into the mid-upper 80s under clear skies due to the aforementioned atmospheric dynamics.
Wednesday – this will be the warmest day of the week with temperatures approaching, if not topping 90, in some spots around the region. Some clouds will start to build in ahead of a cold front that is forecast to push through the area late Wednesday or Thursday. There is some discrepancy between different forecast models as to whether there will be a significant chance for precipitation with this frontal passage. Given this set up, it is likely even if there is rain, it won’t be widespread in coverage or long in duration.Thursday – following the passage of the cold front, temperatures will fall back into the low-mid 80s for Thursday. Mostly sunny skies will return with high pressure moving in behind the cold front.
Friday – should be a similar day in most respects to Thursday, with slightly cooler highs around 80.
Labor Day Weekend – currently, Saturday looks like the best day of the long weekend, with high pressure still in control over the region. High temperatures should be around 80 again with mostly sunny skies. Unfortunately, it does appear that there will be an increasing chance of precipitation in the form of showers and thunderstorms Sunday afternoon and Monday. More on this later in the week.
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.
Today-Wednesday will feature essentially the same weather, sunny to mostly clear skies with pleasant high temperatures in the upper 70s and low 80s.
Our first and only real chance at precipitation this week will be on Thursday, and it’s a low chance at that with the passing of a weak impulse of energy through the area.
Friday – high temperatures will continue to drop into the mid-70s as winds coming from the east will allow for a cooler marine air layer to park over the area.
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.
