Sept 3, 2013: Much Cooler Ending To Week

Forecast Highlights:

nam_namer_060_850_temp_mslp_precipA cold front moved through the area today, removing the warm and very humid air mass that persisted over the last few days, while also triggering heavy thunderstorms, flash flooding and hail in eastern Long Island. Behind this cold front, drier and cooler conditions along with more sunshine will return for Wednesday and Thursday, with a quick yet strong trough bringing a much cooler ending to the week as lows fall into the 40s to low 50s away from NYC and the coast.


 << September 1 | September 2 | September 3 >>

Monday, September 2 Observations:

9.2.13A pre-frontal trough moved through the region, along with several shortwaves moving through, bringing an active day of storms to the region, ranging from moderate to locally heavy storms in the area, severe storms in western NY state, and a cold heavy rain in Maine. Early morning scattered storms were observed north of NYC, with a more widespread round of storms affecting the immediate NYC area and northern NJ between 12-3 PM, mostly dissipating by the time it got to Long Island. Despite this, a strong thunderstorm stalled over northern Queens for over an hour, resulting in heavy rainfall with over 1-2 inches of rain observed. Temperatures were slightly cooler due to the cloud cover and rain, peaking in the upper 70s to low 80s, but conditions remained very humid with dew points in the low 70s, reaching the mid 70s for some. The highest temperature was 84 degrees in Newark, NJ, and the coolest high was 76 degrees in Montauk, NY and New London, CT.




Tonight – Friday: Cooler, Drier, Less Humid

The highlight for the next few days remains the cooler and drier air mass moving into the region, with temperatures cooling back down to near average along with more sunshine and less humidity. Mostly sunny skies are expected for Wednesday with highs peaking in the upper 70s to low 80s across the area with a west wind at 5-10 mph. A strong upper level low will dive southeast through Canada, briefly entering the region on Thursday into Friday, bringing much cooler temperatures to end the week as 850mb temperatures fall to near 4-6C in the area and as low as -2C towards northern parts of the region.

Relatively strong cold air advection is expected on Thursday with mostly sunny skies and a north wind at 8-14 mph, with highs expected to peak in the low to mid 70s inland and mid to upper 70s for the rest of the area. The coolest temperatures are expected on Thursday night, with mostly clear skies, decreasing winds, and lows falling into the low 40s inland, mid 40s to low 50s in the north/west suburbs, southern CT and interior Long Island, and the low to mid 50s in NYC and the immediate coast. Mainly sunny skies are expected on Friday with highs in the upper 60s to low 70s inland and the low to mid 70s for the rest of the area.



Weekend – Next Week: Brief Warmth, Briefly Cooler, Then Warmer Again

The pattern for the weekend into next week will be relatively variable, with a brief warming trend on Saturday and Sunday as the high pressure providing the sunny and chilly late week conditions slides to the east, bringing a southwest flow into the region. After another night of chilly temperatures on Friday night but not as cold as Thursday night, mostly sunny skies are expected on Saturday with highs in the mid to upper 70s. Sunday was originally likely to feature more widespread 80s, although the cold front is now modeled to move through faster than previously shown, quickly suppressing the warmer air mass on Sunday with scattered showers and/or thunderstorms possible with the frontal passage, with highs likely at this time to reach the upper 70s to low 80s but subject to some changes.

Another strong yet short lasting trough will move into the area for Monday, although temperatures are not expected to be as cool as those of Friday, likely at this time to peak in the upper 60s to mid 70s for highs, with overnight lows again in the 40s and 50s away from NYC and the coast. Following this trough, however, a shortwave in the northwestern US will shift the ridge axis further east towards the eastern half of the US, likely resulting in another mid-week warm up which may be more sustained than the weekend warm up. There is more uncertainty in the longer range pattern, although the possibility is there for a warmer pattern to evolve in the eastern half of the US for the middle of September time range. Stay tuned for more information on the longer range outlook.

4 thoughts on “Sept 3, 2013: Much Cooler Ending To Week

    • NYC Area Weather Post authorReply

      The week ahead will be primarily dominated by high pressure systems, so not many rain chances are expected. A few spotty showers are possible towards eastern LI and south CT early on Thursday with a frontal passage, which should be mostly dry without much moisture. Another cold front will approach on Sunday which may also produce isolated showers/thunderstorms, but is not expected to produce widespread rain at this time as well given limited moisture. The rest of the days otherwise should be dry and mostly sunny. The next potential for a more significant rain event at this time does not appear to be until mid-late next week, beyond the 7-day range.

    • NYC Area Weather Post authorReply

      Western LI is less likely to receive showers on Thursday; a slightly higher chance of rain exists on Sunday, with at least isolated shower activity possible at this time as opposed to widespread showers.

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