June 28, 2012: Peak of Heat Wave Friday, Saturday

Forecast Highlights:

- Heat to peak tomorrow, Saturday; upper 90s west of NYC

- Slow cool down into next week but no major cool down expected

- Storm potential becoming less likely

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Today's Observations:

As the heat blast in the central US continued to spread east, warmer temperatures reached the NYC area as well, with highs reaching the upper 80s inland, upper 80s to lower 90s in the immediate NYC area, and the lower to mid 80s in Long Island/S CT. The forecast verified for the western half of the area but was a bit too warm for Long Island/S CT.

With NE NJ and LaGuardia reaching 90-92 degrees, today marked the first day of the heat wave in these areas, as even hotter temperatures are expected for tomorrow and Saturday, getting as high as the upper 90s west and SW of NYC. The weekend storm potential, however, is becoming less likely, with dry conditions likely for most of, if not the entire time period from Friday through Monday. The heat will gradually weaken going into next week, with temperatures dropping back into the mid-upper 80s range, but no significant cool spell is on the way.


Tomorrow's Outlook:


The warmest 850mb temperatures will move through the region tomorrow, getting up to 21-23C, with partly cloudy skies becoming mostly sunny along with west/WNW winds for most of the area except for eastern parts of Long Island/SE CT. With these conditions in place, tomorrow will challenge June 21 for the hottest day of the year so far. Temperatures will quickly rise in the morning and early afternoon hours, reaching the mid 90s inland, mid to upper 90s in the immediate NYC area, and the upper 80s to lower 90s for most of Long Island/S CT, getting into the mid 90s closer to NYC and the mid 80s further east.

Yesterday it had appeared that there could be thunderstorms tonight, although this became less likely throughout the day, as severe storm development failed to take place further west as modeled 2-3 days ago.There is still the potential for an isolated thunderstorm late tonight into Friday morning, but widespread storm activity is not expected.


Saturday - Next Week: Slow Cool Down, But Still Very Warm


Although the core of the heat will continue to move SE towards the southeastern US, there is no strong cool air mass approaching the region, preventing the heat from quickly collapsing, with a gradual cool down expected instead. Saturday will still be hot, with temperatures in the mid to locally upper 90s from NYC and further west/SW and the upper 80s to lower 90s across the rest of the area, with coastal locations ending up a bit cooler. The latest NAM runs are showing a strong MCS moving through overnight with heavy rain and strong thunderstorms; although the potential is there for storms on Saturday and Sunday in the afternoon/evening hours, it is questionable if any widespread strong thunderstorm development can take place. Temperatures will continue to slightly cool down on Sunday, reaching the lower to mid 90s from NYC and further west, possibly a bit above 95 west/SW of NYC, and the mid 80s to lower 90s in Long Island/S CT.

There is some uncertainty regarding how much cool air comes in by next week. The GFS model is more bullish, showing highs in the 80s, while the ECM still keeps the area close to the northern edge of the heat, with temperatures in the upper 80s to lower 90s away from coastal areas lasting into the middle of next week. At this time, I am siding closer to the ECM but not as warm, with temperatures dropping into the mid to upper 80s range for the immediate NYC area on Monday/Tuesday, possibly warming up a bit across the area around the 4th of July. The models continue to differ with precipitation potential for next week; even though next week does not appear to be very wet, the possibility of some storms cannot be ruled out, although there is not enough confidence at this time to determine exactly which day(s) have a risk of storms. Stay tuned for more information on the outlook for next week, including the 4th of July outlook.