PM Update: Unsettled pattern remains in place

Autumn usually brings a trend towards more unsettled weather, with shorter-duration stretches of pleasant and dry weather. This autumn will be no different, but it may just feel like a slightly more dramatic change in the pattern as a result of the longer than normal stretches of dry and pleasant weather which our area en joyed to close out the summer. Regardless of that, the autumn pattern currently in place will offer chances for clouds and showers throughout the day as a result of an upper level low which is meandering near the area. Cooler weather is in place as well, with temperatures remaining in the 60’s and lower 70’s throughout much of the area for highs, and dropping even cooler at night. Showers and an isolated storm are possible on Sunday as the upper level low shifts closer to the area, bringing a mid-level disturbance through in the afternoon and early evening. Monday looks to be a transition day — and then by late Monday into Tuesday, a surge of warmer and more humid air, owing to the amplification of a ridge to our east, will bring more chances of showers and periods of steady rain as we work towards the beginning/middle of next week. All in all, the story continues to be defined by an unsettled weather pattern — with autumn now in full swing.

NAM Model showing the upper level low in the mid levels of the atmosphere near the area this weekend — causing the unsettled weather.

Saturday Night: Cooler night once again, with temps dropping into the lower 50’s inland and near 60 in the metro area (with even some cooler readings possible in the mountains and higher elevations). A chance of sprinkles in some areas, but definitely no steady or heavy rain is expected overnight.

Sunday: A bit warmer than the past few days, with highs rising into the middle and upper 60’s. But showers will become scattered by afternoon, with even a chance of isolated thunderstorms. The showers and storms should wane by evening with the loss of daytime heating. Could see some sun in the morning, but the presence of showers/storms should bring clouds to many areas by afternoon.

Sunday Night: Similar to Saturday Night with temperatures a few degrees cooler throughout most areas. Low temperatures dropping into the 40’s and 50’s throughout the interior and even into the NYC Metro area.

Monday: A break in between disturbances should keep Monday as the most pleasant day of the next few. Temperatures into the lower 70’s throughout most of the area. Clouds should increase throughout the day but the sun will show its face especially in the morning hours.

Long Range: Models hinting at “cutoff low” next week

On the heels of a developing unsettled weather pattern for late this week, which we detailed in a post on Wednesday Night, forecast models are hinting that the medium and long range pattern could remain unsettled. The main feature in the medium and long range guidance now appears to be a large upper level “cutoff” low, which will cut off from the northern stream (northern jet stream) in Canada and drop into the Great Lakes and Northeast States next week. Such an occurrence isn’t exceptionally rare, especially in the Autumn and Spring. The resulting weather won’t be too extreme, either, but the cutoff lows usually provide a continuing chance of unsettled weather including showers during the day and cooler/cloudier weather in general. So, in essence, the development of the cutoff low as medium and long range guidance suggests would provide a continuing pattern of unsettled weather through early next week. Not all is lost under a cutoff low, however, as the weather can still be pleasant and sunny at times — but the threat for showers will always linger. The other wild card with cutoff lows is the duration of their stay — they can sometimes meander in the area for several days. Luckily, the current pattern isn’t overly slow, so the cutoff low should be pushed out eventually by another trough.

GFS Ensembles showing mid-atmospheric height anomalies. Note the cutoff low over the Great Lakes indicated by below normal anomalies.

Beyond the cutoff low, long range forecast models are indicative of a near-average pattern..but there are some hints of below normal anomalies in the mid-levels of the atmosphere working into the Central and Eastern United States by Day 10, with a large ridge on the West Coast of the United States. This is especially prevalent on the GFS Ensembles this morning. The Euro hints at a similar pattern — which adds some credibility to the potential for a developing below normal height pattern. Such a pattern would provide continued chances for precipitation and below normal temperatures as we head into the first few weeks of October. We’ll keep a close eye on it, especially now that we’re heading into October, where the pattern begins to take its first steps towards a hint at what to expect for winter. Yes,  the magic word. More updates in a few weeks (we love a good cliffhanger).

Stay tuned over the next several days for more updates on the potential cutoff upper level low and its impacts on the weather in the NYC Area next week. And, of course, keep a close eye on our Facebook and Twitter accounts for constant updates on the near and short term weather late this week and weekend.

Evening Update: Dreary weather settles in

An unsettled and active weather pattern is upon us, putting an end to a long stretch of slightly above normal temperatures and very pleasant conditions with low humidity and clear skies. A frontal boundary near the area this evening will be the culprit behind the development of showers and isolated thunderstorms (although the storms appear pretty unlikely at this point with very little instability). These showers will remain in the area through the overnight hours as the disturbance moves along a mid level atmospheric gradient near our area. A break in the action is expected on Thursday, but we will be in between disturbances. By Thursday afternoon and evening, the chances for showers will increase yet again. Forecast models are hinting at the potential development of a low pressure area just south of Long Island very early Friday morning, which could bring some heavier/steadier rains to the area as well as a period of gusty winds especially on Long Island. Another system will move along the front and impact the area later in the weekend, from Saturday into Sunday with another chance of showers and steady rain. Temperatures throughout the period will run slightly below normal, especially on the second half of the weekend as the front sags south of the area and more cool/damp air is able to work in to the area.

Latest NYC-Area radar imagery courtesy of weather-underground shows the intensity and movement of precipitation over the last hour.

Wednesday Night: Continuing chances of showers throughout most of the night – but the front will begin to sink south of the area overnight. Temperatures will fall accordingly.

Thursday: This looks to be the most pleasant day of the second half of the week. In between disturbances – most models have partly cloudy skies and highs in the 70′s. Increasing clouds by the evening as the second disturbance approaches.

Thursday Night: Clouds increase and a chance of showers return ahead of a disturbance approaching the area. Low temperatures end up only near 60 degrees in the city and upper 50′s elsewhere due to the cloud cover.

Friday: More showers and clouds throughout the day with the area being affected by a mid level disturbance riding along a front which will be stalled near the area. Cooler and more damp with high temperatures in the 60′s in many locations.

Midweek weather takes an unsettled turn

An unusually long stretch of pleasant fall weather will come to an end on Wednesday, as mid level disturbances work towards the area, and a

Infrared satellite imagery from September 25th, 2012 showing the approaching disturbances that will affect our area Wed through Sun.

frontal boundary approaches and eventually stalls near or just south of the area. The result in sensible weather will be developing chances of showers and isolated thunderstorms. Temperatures on Wednesday will surge warmer than the past several days, ahead of the cold front, with high temperatures likely approaching 80 in spots. With showers and isolated storms around, the warm temperatures will mitigated somewhat. Beyond Wednesday, some clearing is expected on Thursday before the front returns on Friday — with our area sitting along a gradient with cold air to the north and warmer air to our south. Temperatures in the 60’s will return on Friday and Saturday with a chance of showers and clouds on both days. Beyond this, things should begin to look up a bit with clearing expected behind the disturbances.

Keep reading past the break for the daily breakdown of the forecast from our Forecast Overview!

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