Aug 14, 2013: September-Like Temps Today

Forecast Highlights:

northeastA strong trough for this time of the year entered the region today, bringing in mostly sunny skies, breezy NW winds and temperatures 5-10 degrees colder than average. Chilly temperatures will return again tonight with clear skies and lows falling into the mid 40s to mid 50s away from NYC and the coast. A gradual warming trend will return through the weekend and next week as temperatures gradually return to near and eventually above average, with 90s likely to make a return.


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Wednesday, August 14 Observations:

8.14.13 - CopyA strong shortwave moved through the region last night, with a westerly flow aloft bringing a cooler Canadian air mass into the region with 850mb temperatures near 6-8C. Along with a breezy NW wind, this resulted in temperatures 5-10 degrees colder than average despite mostly sunny skies in place, with highs peaking in the low 70s inland and the mid 70s for the rest of the area. While such temperatures were observed at times this summer such as on August 1 due to cloud cover and rain, it is less frequent to see such temperatures with mainly sunny skies. The highest temperature was 77 degrees in JFK, and the coolest high temperature was 70 degrees in Sussex, NJ and Port Jervis, NY.



Tonight – Friday: September-Like Conditions Continue

Although yesterday’s shortwave lifted back into Canada, the moderated cool air mass remains over the region, with current 850mb temperatures near 8-10C. Over the next two days, a weak trough will dig into the central US region, which will set up a southwest wind aloft. Given a relatively light mid-upper level flow, however, the cool air mass will not be quickly removed, and will slowly moderate over the next few days with 850mb temperatures warming up to 9-11C on Thursday and 10-12C on Friday. Meanwhile, the surface high pressure will remain stationed over the region, providing light winds, mainly clear skies and temperatures remaining cooler than average.

Clear skies are expected tonight with chilly low temperatures, falling into the mid to upper 40s in interior NW NJ/SE NY, low to mid 50s in the north/west suburbs of NYC, southern CT and eastern-central Long Island, and the upper 50s in NYC and the immediate coast. Slightly warmer temperatures are expected on Thursday, rising into the low-mid 70s inland and the mid-upper 70s elsewhere, warming up a bit again on Friday into the mid-upper 70s inland and the upper 70s to low 80s for the rest of the area. Mostly sunny skies are expected for both days.

Weekend – Next Week: Increasing Clouds, Some Showers

The high pressure over the region will continue to slide east over the weekend, allowing for a frontal boundary to slowly approach north into the southern Mid Atlantic region, spreading clouds and showers north into at least southern PA and NJ. Saturday is still forecast to remain dry, with partly sunny skies and highs in the low to mid 80s across the area. The high pressure is also likely to suppress Sunday’s shower activity to the south and east of the area, with highs expected to reach the mid-upper 70s in Long Island and the low 80s for the rest of the area.

Uncertainty slightly increases for early-mid next week as some models, particularly the GFS, show widespread showers/thunderstorms in the region on Monday and Tuesday, while the ECM keeps the rain entirely suppressed to the south. While the first half of August has been cooler than average, this pattern will fail to hold continuously through the entire month as a warmer and more humid air mass will gradually advect into the region, resulting in a continued increase in temperatures, reaching the mid to upper 80s from Tuesday into the second half of next week; on the drier and sunnier days, low 90s are possible in parts of the area. At this time, I am siding towards scattered thunderstorms on Tuesday and Wednesday with otherwise partial cloud cover and mostly dry conditions for the week, although the outlook for next week is subject to some changes.

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