Aug 24, 2013: Storms Possible Next Weds

Forecast Highlights:

northeast4A trough will be in place for the weekend with temperatures generally slightly below average along with mainly sunny skies and north winds. Temperatures will slightly increase in the early-mid week but with a more noticeable increase in humidity as the region ends up in the eastern end of a strong ridge, with scattered thunderstorms likely on Tuesday and Wednesday followed by more dry and seasonable conditions until next week.




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Friday, August 23 Observations:

8.23.13Behind Thursday night’s frontal passage, drier conditions returned for the area on Friday; the day started out with mainly cloudy skies, clearing in the late morning-early afternoon but with some cloud cover persisting, especially towards western and southern areas as an weakening area of rain and thunderstorms passed through southern PA and NJ. High temperatures were slightly cooler than those of Thursday further west and warmer further east, peaking in the upper 70s to low 80s inland and the low to mid 80s for the rest of the area. The warmest temperature was 84 degrees in JFK Airport, and the coolest high temperature was 78 degrees in Yorktown Heights, NY.



Weekend Outlook: Dry, Mainly Sunny

A high pressure currently building into the region will result in a north wind today and a light southwest wind tomorrow, with mainly sunny skies and temperatures slightly cooler than average. High temperatures today and tomorrow are expected to reach the upper 70s for most with some areas of lower 80s near NYC, with overnight lows falling into the low 50s inland, mid to upper 50s north/west of NYC, in interior Long Island and southern CT, and the low 60s near NYC and the immediate coast.

Next Week: More Humid, Mid-Week Storms

As mentioned over the last few days, an increasingly amplified pattern will develop aloft with a strong ridge in the central US resulting in a widespread heat wave in that region, with the Northeast US under a northwest flow aloft with several shortwave troughs moving through the region during the week. Initially, there was too much uncertainty to narrow down the specific timing and location of these shortwaves, which also carry the potential to trigger strong to possibly severe thunderstorms, although the latest model guidance is emerging on a stronger consensus for Monday and Tuesday that lowers the storm risk for the area, with Monday’s more widespread storms staying to the north, weakening as they shift south into the area on Tuesday. Partly sunny skies are expected for both days with highs on Monday in the low to mid 80s and in the mid to upper 80s on Tuesday, but with increasing humidity as dew points climb back into the 60s.

A more organized low pressure is likely to move through the region on Wednesday, triggering more widespread thunderstorms, but with uncertainty regarding the track of the low pressure and thus the specific impact in the area. The ECM and CMC depict the low well to the north of the area, with the CMC bringing a line of strong thunderstorms through the area and the ECM brushing northern parts of the area with thunderstorms, while the GFS develops the low pressure south of the area with showers and non-severe thunderstorms across the region. The ECM is ultimately more aggressive with developing the low pressure, depicting a closed low over Maine producing heavy rain the following day, while the GFS is flatter and more progressive with the low. I am currently siding with a further south and more progressive low than the ECM shows, with scattered thunderstorms affecting the area on Wednesday with highs again in the mid to possibly upper 80s, although the outlook is subject to some changes.

A high pressure is then likely to build into the region for the late week and the early part of the weekend, bringing drier conditions and temperatures into the low to mid 80s. Beyond Saturday, uncertainty increases regarding the ridge setup, as the GFS shifts ridging slowly into the western US, resulting in a brief surge of heat early next week with another frontal passage and a return of cooler temperatures, while the ECM shifts the ridge east into the region, resulting in a significant heat wave next week. The ECM has had a recurring bias to exaggerate eastward extent and coverage area of heat in its longer range under the current pattern; at this time, preliminary thinking is for a brief surge of heat early-mid next week with another frontal passage, although considering this is more than a week away the outlook is subject to change. Stay tuned for more information on the longer range outlook.

8 thoughts on “Aug 24, 2013: Storms Possible Next Weds

  1. Anonymous Reply

    Is there any chance for more showers today in the area? I heard that there already was a thundershower just south in New Jersey earlier this morning.

    • NYC Area Weather Post authorReply

      No rain is expected across the area both today and tomorrow as a strong high pressure is covering the region. The next risk of rain is likely on Monday night or Tuesday.

  2. Anonymous Reply

    How come there was that thunderstorm down in New Jersey earlier this morning if there is a strong High Pressure covering the region?

    • NYC Area Weather Post authorReply

      Looking through most airport observations and radar estimates in NJ, I haven’t found any thunderstorm report today yet, and if there was one, based on the setup I would assume it would’ve been in southern NJ early in the morning hours when there was still some moisture left in southern areas behind a cold front. Early in the morning, the high pressure was still up in Ontario, but since then a drier air mass has advected into the region as the high pressure continues to sink southeast, and is currently centered over New York state while extending into New Jersey. The high will continue to move south and will be centered over the area tonight and tomorrow, keeping dry conditions in place.

  3. Anonymous Reply

    If you look at archived radar on Wunderground, then you will see a thunderstorm that started off around Long Branch at around 4 AM and then moved south through New Jersey and died out at around 7 AM southwest of Atlantic City.

    • NYC Area Weather Post authorReply

      Yes, now that you mention the archived Wunderground radar I do see a small thunderstorm cell near the eastern coast of New Jersey there which tracked south along the coast. That was an isolated storm cell that was triggered along an area of higher water vapor that moved through the NJ coast early in the day (link to water vapor loop out of PSU e-Wall – link is time sensitive), but this has since moved well offshore, with the high pressure now overhead with sinking air and a cap aloft preventing additional thunderstorm development today and tomorrow, until a more moist air mass advects from the west on Monday.

  4. Anonymous Reply

    What was the cause for the area of high water vapor moving south along the coast in New Jersey early in the day that caused the thunderstorm?

    • NYC Area Weather Post authorReply

      As I noted in my discussion today, a mid level shortwave moved through the region at this time which was also likely the trigger for the storm. For the next few days, several shortwaves will move through the region which will also trigger thunderstorms, possibly strong.

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