Sept 26, 2013: Seasonable, Dry Pattern Continues

Forecast Highlights:

gfs_namer_060_500_vort_htTemperatures warmed back up into the 70s earlier this week, although a back door cold front is keeping temperatures in the low to mid 70s through the rest of the week and the weekend, with continued mostly sunny skies expected through Sunday. The next cold front will move through on Monday with little to no rain, followed by another stretch of dry conditions and gradually warming temperatures (image credit: NCEP MAG).




Today – Weekend: Seasonable, Dry

The latest synoptic setup consists of a strong upper level low near Nova Scotia and Newfoundland, with strong ridging amplifying over the central US into southeastern Canada in response to a strong trough over the northwest US, which is currently bringing the first major snowstorm of the season to the higher elevations in the NW US. A shortwave trough is currently over the Ohio Valley, which will continue to dive southeast into the Atlantic Ocean as ridging builds up to its north. While this leads to a strong -NAO setup, the orientation of the ridging along with the western troughing (-PNA) blocks the region from any new cold air source, with the only cold air source available being the stale cool air mass over Atlantic Canada from the departing strong upper level low, which then slides southwest into the region with 850mb temperatures near 6-8C as ridging builds up to its north and keeps the stale cool air mass trapped over the region until the next cold front on Monday. This will lead to temperatures persisting in the low to mid 70s for highs through the late week and the weekend along with mostly sunny skies.

The forecast for the NYC area, as a result of the previously mentioned setup, consists of mostly sunny skies continuing through Sunday, with high temperatures generally in the low to mid 70s. Overnight lows will stay in the 40s inland and the 50s closer to the immediate NYC area and the coast.


Monday – Next Week: Still Dry, Gradually Warming Up

The next cold front will approach the area on Monday night; while the previous update noted a coastal low that was moodeled to track offshore but possibly approach the area, this looks to develop too slowly and too far east to reach the region, instead being quickly carried out to sea by the approaching through. The trough will gradually lift northeast into Canada as another trough enters the western US, with the front weakening and drying up as it reaches the area, with only isolated showers expected on Monday night. Behind the frontal passage, temperatures will barely cool down, instead likely to begin to gradually warm up; as the trough lifts north, it will be unable to pull down a stronger cold air mass into the region, and the slightly cooler air mass that does get pulled down will be quickly carried offshore by the coastal low pressure and the next approaching through in the western US as a +EPO pattern persists in the northeast Pacific while ridging in the western US is becoming less likely to materialize for early October.

Temperatures are likely to gradually warm up into the mid 70s by the middle of next week, with upper 70s not out of the question for some in the warmer case scenario, with continued dry conditions likely. The next chance of rain and a cool down in temperatures may be towards October 6-7, when the next trough and cold front may approach.

<< Sept 23 | Sept 24 | Sept 25 | Sept 26 >>

Tuesday, September 24 Observations:

9.24.13After the cooler than average temperatures on Monday, chilly temperatures were observed on Tuesday morning, with temperatures falling to 47 degrees in Central Park, making this the coolest September temperature since 2000, when temperatures reached 46 degrees on 9/27/00 and 43 degrees on 9/29/00. Other notable low temperatures include 33 degrees in Sussex, NJ and 37 degrees in Westhampton Beach, NY. Mostly sunny skies were otherwise observed for the rest of the day with temperatures slightly warmer than forecast, in the low to mid 70s for most. The highest temperature was 77 degrees in Teterboro, NJ, and the coolest high temperature was 67 degrees in Montauk, NY.

Wednesday, September 25 Observations:

9.25.13A high pressure remained in place over the region, with mostly sunny skies continuing while temperatures remained near to slightly below average, peaking in the low 70s across most of the area. The highest temperature was 75 degrees in Newark, NJ, and the coolest high temperature was 69 degrees in multiple locations.

3 thoughts on “Sept 26, 2013: Seasonable, Dry Pattern Continues

    • NYC Area Weather Post authorReply

      No showers are expected today as despite the unexpected widespread cloudy skies with a shortwave trough moving through, a high pressure is still in place with a relatively dry air mass. Aside from a few possible showers on Monday, no rain is expected until next Saturday/Sunday (10/5-6) at the earliest.

  1. Anonymous Reply

    Is the nor’easter expected to affect Long Island with clouds and showers on Monday?

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