Posts

John Homenuk

Heavy rain, gusty winds likely on Wednesday

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The interaction between tropical moisture — remnants of Hurricane Patricia — and a strong mid level atmospheric disturbance over the North Central US will aid in the development of steady rain on Wednesday. As forcing for precipitation increases during the morning hours, steady rains will develop from southwest to northeast throughout the area. Atmospheric moisture content will increase throughout the day, as a psuedo-warm front moves through New Jersey and New York.

Precipitable water values between 200 and 300 percent above average are a testament to the tropical moisture involved in Wednesday’s rains. During the late morning and afternoon, a low level jet stream is expected to strengthen, further aiding in the potential for heavy rains. While heavy rain isn’t expected to be constant, sporadic heavy rains could cause localized flooding, despite the moderate drought conditions in much of Northern New Jersey, New York and Connecticut.

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John Homenuk

Heavy rain, thunderstorms likely tonight into Thursday

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An approaching strong cold front, and associated mid and upper level disturbance, will bring heightened chances for rain into the area from tonight into Thursday morning. However, the event will be made more significant by a plume of moisture, surging northward along and ahead of the frontal boundary. Forecast models indicate a strengthening low level jet stream and transport of this moisture. Precipitable water values (the amount of water in the atmosphere) will be high — in the 95th percentile for October.

The moisture will begin surging northward later this afternoon and evening. Forecast models indicate the best lift for precipitation will remain to our west until the latter part of the afternoon. At that point, from west to east, chances for showers and thunderstorms will increase. Initially, downpours will be scattered. But over time tonight, the support for heavy rain will expand and moisture will continue surging northward. Rain will develop from southeast to northwest, with widespread heavy rain likely throughout the area overnight.

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Doug Simonian

Foggy Friday followed by heavy rain Friday night

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A slow-moving cold front, along with a weak warm front that crossed the region on Thursday, will combine to create interesting changes to our weather — namely the potential for heavy rain on Friday afternoon. The warm frontal passage brought the introduction of a warmer, moist airmass — increasing dew points and precipitable water values. As the cold front shifts toward the area during mid-day on Friday, lifting in the atmosphere will gradually increase which will help to generate heavy rain and even the chance of a thunderstorm come Friday Night.

A large ridge in the Western Atlantic will act to provide plenty of clockwise flow increasing our warmth and moisture. Additionally, to the west, we have a potent trough and associated cold front with plenty of lift. The large ridge is what initially makes the front slow to move eastward, prolonging our fetch of moisture. This is a weather pattern we had often during the beginning of last summer, which is why we had such humid conditions. The initial slower movement of the cold front will keep the heaviest rain to the west of our area during the morning on Friday — but a slow shift eastward is expected.  Read more

Doug Simonian

Bouts of heavy rain expected through Thursday

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Although it has been quite the grey, dreary, chilly day, rainfall throughout the area has not been all that heavy yet. The main reason for this is because the surface pressures are still quite high, thanks to a large high pressure system north of Maine, which is wedging in very high pressures into the area. Higher surface pressure is an indicator of downward motion in the atmosphere, which is not conducive to precipitation.

This afternoon's NAM valid for 5:00pm shows a large high pressure system to the north, with high pressures still wedged into our area. This is why a lot of the rain has broken up as it has headed east (weather.cod.edu).

This afternoon’s NAM valid for 5:00pm shows a large high pressure system to the north, with high pressures still wedged into our area. This is why a lot of the rain has broken up as it has headed east (weather.cod.edu).

The image above explains it well — note the blue isobars of higher pressures that are being “pushed” into our area. The lower pressures are relegated to the west, southwest, and northwest, while the higher surface pressures are to the north and northeast. The station pressure at Rutgers Gardens is 1027mb. That is certainly not conducive for heavy precipitation. This is further augmented by the fact that an associated warm front is still well to the south of the area. If the atmosphere is going to generate lift for precipitation with high surface pressures, we need forced ascent from a frontal boundary, which will finally be approaching the area on Wednesday.

Moving forward through 11:00pm tonight, the surface pressures remain high, and the warm frontal boundary is still well to the south. This most likely means the Yankees will play baseball tonight (weather.cod.edu).

Moving forward through 11:00pm tonight, the surface pressures remain high, and the warm frontal boundary is still well to the south. This most likely means the Yankees will play baseball tonight (weather.cod.edu).

However, over the next several hours, notice how the strongest temperature gradient associated with the warm front is still well to the south, and the high surface pressures are still being wedged in. This combination leads us to believe that any rain that falls this evening and tonight will be very light, and not enough to cancel the Yankee game. As time goes on, the warm front will slowly be approaching the area, and the easterly winds from the cold, yet moist ocean will finally be enough to moisten the atmosphere and generate the necessary lift for precipitation.

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