Sunday, September 19, 2010

Sept 19: Return Of 90+ Degrees?

Notes:

- The 5-Day Forecast was updated for the area, including how warm it could get for the area between Wednesday and Friday. The poll for the hottest temperature during this time frame remains open until Tuesday, vote your thoughts if you have not done so yet.

- The tropics have been discussed today in the bottom of the post, where you will find details about hurricane Igor, potential Tropical Storm Lisa, and another tropical cyclone that could form next week in the Caribbean.

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Today was a rather mild day across the area, with high temperatures ranging from the upper 70s inland to the mid 80s in parts of the immediate NYC area. There are currently some isolated showers moving through, however these should only be isolated and light at best, with most locations staying dry. Tomorrow and Tuesday will be cooler, however a surge of warmth will bring much warmer temperatures for Wednesday through Friday, with some places potentially reaching the 90 degree mark once again.

Monday And Tuesday Outlook:

Tomorrow will be a mostly sunny day, with a cooler air mass expected. High temperatures will be in the lower 70s inland, mid 70s in the immediate NYC area, and lower to mid 70s for S CT/Long Island. Tomorrow night will bring very chilly temperatures as the cold air mass starts to exit, with low temperatures in the lower 40s and potentially upper 30s inland, mid to upper 40s with a few lower 50s for the N/W suburbs of NYC, mid to upper 40s for S CT, upper 40s to lower 50s in Long Island (with the exception of the cool spots in eastern LI), and lower to mid 50s in NYC.

Tuesday will start to warm up as a warm front approaches from the southwest, with high temperatures similar to, if not slightly warmer than those of Monday.

Wednesday-Friday : Two Storms, Big Surge Of Heat


**Note: I took my time to make a discussion for this time frame, discussing the likely scenario and the other possibilites. If this is too long for you to read, you can find the forecast temperatures for your area in the 5-Day Forecast page.**


On Wednesday, a warm front related to a storm well to our northwest will move through the area, bringing a much warmer air mass. 850 mb temperatures are likely to be near 18c, leading to high temperatures in the mid 80s inland and upper 80s in the immediate NYC area, with lower 90s also possible in NYC in the warmer case scenario. The GFS, however, is showing slightly cooler temperatures despite being colder than the rest of the models, with highs in the lower to mid 80s in NYC, and while this solution is not the most likely at this time, it also cannot be ruled out.

Overnight, the cold front will approach, and with a potentially favorable set up, scattered thunderstorms, potentially strong, are likely for the area. These storms, though, aren't likely to bring more than locally heavy rainfall, with generally light rainfall amounts likely.

On Thursday, it now appears that the warm air mass will stay far north enough to bring warm temperatures to the area, but how warm is the question as an east wind could limit the temperatures. The air mass, given that there is no rain expected, would support high temperatures in the lower to mid 80s inland and mid 80s for NYC, however this is in the warmer case scenario, and it could be cooler due to a SE-E wind and/or a slightly different placement of the stalled front. At this time, I am going slightly lower than the above, expecting highs in the lower 80s for NYC, and upper 70s to lower 80s inland with mid to potentially upper 70s for Long Island/S CT, but note that this is still subject to change.

Another storm will then organize to our northwest on Friday, however the models have trended slower and further north for this storm. While the models will still shift around a little over the next few days, I do think that a slightly slower and further north solution than yesterday's forecast is becoming more likely. 850 mb temperatures will rise into the 18c-20c range again, and with a SW wind returning, high temperatures could reach the upper 80s to lower 90s again in the immediate NYC area. The cold front, however, will be slow to reach the area, and will only start bringing rain by Friday night. With this, scattered showers and thunderstorms are expected.

The cold front could pass any time between late Friday night and Saturday afternoon, at this time I am going in between with a cold frontal passage during Saturday morning but note that I could shift it towards Saturday afternoon.

Weekend Outlook: Dry Saturday, Wet Sunday/Monday?

The cold front should move through on Saturday, bringing high temperatures closer to but still above average, potentially between the mid 70s to lower 80s. If the cold front on the models stays the same or trends slower, however, temperatures would likely be warmer, in the lower to upper 80s. By Sunday, the cold front should be to our south, however it is possible that the cold front nearly stalls, with a low pressure developing along the cold front, as some models have been showing. If this happens, there is uncertainty on where it forms and tracks and who gets rain, but any storm would be to our south, meaning that if we do get rain, it will likely be the steady, chilly type of rain. More details on this potential will be posted over the next few days, including who is likely to get rain and how much.


Tropics: Igor Weakening, Lisa And Matthew To Come Next


Hurricane Igor, currently a weak Category 1, has weakened faster than expected, and is barely a hurricane, though it is still producing strong winds and heavy rainfall in Bermuda. Despite this, however, Igor is undoubtedly one of the largest storms recorded in the Atlantic Ocean, leading to a greater impact on Bermuda than a typical Category 1 hurricane would have. Igor is then expected to move northeast and potentially weaken to a tropical storm, but then intensify again as it becomes an extra-tropical cyclone, absorbing the remnants of Julia at the same time.

Meanwhile, there are two potential tropical cyclone formations. An invest in the eastern Atlantic Ocean is becoming more organized, and could be named Tropical Storm Lisa over the next day or two. Lisa is currently not a threat to land.

The second potential, however, is a threat to land. All of the models are hinting at a low pressure developing into a tropical cyclone in the western Caribbean around Sunday or Monday the 26-27th. This is still in the longer range, and the models vary with the direction of this tropical cyclone, ranging from a hurricane in the Gulf of Mexico to a hurricane moving up the East Coast (which the GFS has been showing), however what we can take from this is that a tropical cyclone may form in the Caribbean and move north or NW, affecting land. If this potential stays, more details on it will come over the next few days.

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