Sept 23: Heavy Rain Possible Next Week

Notes:

- NYC Area Weather currently has two advisories in effect: Heat Alert for NYC tomorrow, and a Rain Watch for the entire area between Monday and Wednesday.

- The 5-Day Forecast has been updated for the area.

- A new poll has been added in the top right side of the blog, under the radar, about the potential rainfall amounts for the arae between Monday and Wednesday. Please vote your thoughts in the poll, which will close on Monday.

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After yesterday's storms moved through, causing wind damage across parts of the area, today brought much nicer conditions. Temperatures failed to reach the forecast high temperatures as the position of the stalled front provided a SE wind instead of a SW wind, which caused cooler temperatures, however with a SSW wind returning, tomorrow is going to be a hot and humid day, likely the last of those we'll see until next summer.

While the cold frontal passage on Saturday will bring much cooler temperatures, with highs dropping into the mid 60s to lower 70s, it will be a dry cold front, but the dry conditions will not last for long, as there is the potential for a significant rainstorm in the middle of next week, and Tropical Storm Matthew is also being kept an eye on in case it goes up the East Coast as some models have been suggesting.

Tomorrow's Outlook:

Tomorrow will be a summer-like day, with a very warm air mass and a SSW wind. High temperatures will reach the mid to upper 80s inland, upper 80s to lower 90s in the immediate NYC area, and due to an onshore wind, Long Island and S CT will reach the upper 70s to lower 80s, with a few mid 80s in western Long Island.

There will be a sharp temperature contrast across the Northeast. Virginia and Washington DC will see high temperatures in the upper 90s, to near 90 in NYC, to the upper 70s to lower 80s from northern New York into central New England, with a chilly heavy rain and 50s in Maine.


Weekend Outlook: Hot Start, Cold Finish


With the cold front approaching, Friday night will be rather mild, with lows in the lower to potentially mid 60s inland, upper 60s in S CT and the N/W suburbs of NYC, and in the lower 70s for NYC and parts of Long Island. Increasing cloud cover is also expected.

The cold front will move through on Saturday, however it will only be a dry frontal passage, with an isolated shower or thunderstorm possible but nothing like what we saw yesterday. The cold front, however, will be slow enough to allow for a SW wind during Friday afternoon just before it moves out, leading to high temperatures in the lower 80s inland, mid to locally upper 80s in NYC, and lower 80s in Long Island/S CT. Saturday night will be chilly, with lows ranging from the upper 40s inland to the upper 50s in NYC.

Sunday will be a rather chilly day, with partly sunny skies and a north wind expected. High temperatures will be in the mid to locally upper 60s inland, upper 60s to locally lower 70s for the immediate NYC area, and in thepper 60s to lower 70s for Long Island/S CT.


Monday-Wednesday: Heavy Rain Potential


By Monday, temperatures will be slightly warmer than those of Sunday, however there will be increasing cloud cover ahead of a storm. A cut off low pressure is expected to approach Tennessee and slowly move toawrds the area, bringing a surge of Gulf of Mexico moisture into the eastern United States. There is still a lot of uncertainty on the smaller details, such as the exact track of the low pressure, how much rain falls and who gets how much rain, but it is starting to become clear that a potentially significant rain event may be unfolding for early-mid next week, and in the wetter scenario, several inches of rain may affect the area. I have issued a Rain Watch for this storm, indicating a 40-70% chance of more than 1 inch of rain (more details in the "Weather Alerts" page). Stay tuned for more details on this storm over the next few days.


Longer Range: Significant Cool Spell For Early October?


The models have been consistent lately in showing a large trough dropping into the Mid Atlantic and Northeast between October 1 and 3, bringing the coldest temperatures yet this fall. There is uncertainty on this time period, especially if Matthew ends up affecting the East Coast, but this potential will be watched.


Tropics Update: Lisa Weakening, Matthew Intensifying


Other Areas In Tropics:

Tropical Storm Lisa, having weakened to a tropical depression earlier today, is back up to a tropical storm, but with an unfavorable environment, will likely weaken to a tropical depression again soon. All models show Lisa dissipating in the next few days, and Lisa is not a threat to land. Julia's remnants, meanwhile, are getting more organized, however at this time Julia is unlikely to regenerate.

Tropical Storm Matthew To Affect Honduras, Mexico

The tropical threat I was talking about over the last few days has developed into Tropical Storm Matthew today. Matthew, however, will not become a major hurricane at least as of now, as it formed later and is moving faster than I expected, and is slow to intensify, but will likely be a strong tropical storm when it reaches Honduras. Despite not being a hurricane yet, Matthew will produce flooding and strong winds for that region, potentially causing significant damage. Matthew will then slow down, and will likely stall close to the Yucatan Peninsula.

What happens afterwards is still a question. One set of models take Matthew northeast from there, moving near Cuba and Florida and potentially going up the East Coast, the other models take Matthew north into the Gulf of Mexico, and some models take it due WNW through the Yucatan and into the western Gulf of Mexico, however this solution is unlikely at this time. Stay tuned for more details on Matthew over the next few days, along with discussions and forecast track/intensity maps.