July 27, 2013: Some Storms This Week

Forecast Highlights:

northeast3A high pressure briefly returned into the region late yesterday and today, bringing seasonable temperatures and more sunshine along with it. Showers and storms will briefly return for Sunday afternoon and evening until another cold front moves through, with seasonable conditions returning for the early-mid week again until additional scattered storms return for Thursday and possibly next weekend.




Friday, July 26 Observations:

7.26.13 - CopyA coastal low developed offshore early in the day, tracking north into New England, carrying the unseasonably cool and rainy conditions to the northeast of the area; showers continued through the morning hours in Long Island/CT, where at least 1/4 to 1/2 inch of rain, locally higher up to 1-2 inches further east, were observed. More sunshine was observed as well especially west of NYC, with high temperatures reaching the low to mid 80s from NYC and further north/west and the mid to upper 70s east of NYC. The highest temperature was 85 degrees in Newark and Teterboro, NJ.

Tonight – Sunday Night: Some Storms Expected

The current set up consists of an abnormally strong upper level low in the Midwest region, bringing fall-like temperatures to that region. The ULL will slowly track to the northeast, then north, pulling the cold air mass into the Great Lakes and then back into Canada, while dragging a weak surface cold front into the region. The front will be slow moving as well, with scattered thunderstorms developing across Pennsylvania and New York during the afternoon and evening hours. Severe weather is not anticipated with widespread cloud cover, limited instability/bulk shear and unfavorable mid level lapse rates, although given high moisture content, storms will be capable of producing heavy rainfall and localized flash flooding. During the day through the evening hours, most storms will be focused in interior western regions (northwest NJ, interior SE NY), and north/west of the area with highs in the upper 70s-low 80s, while locations further east observe scattered late afternoon storms and highs in the low-mid 80s. Storms will gradually spread east into NYC and western LI/CT in the evening and early overnight hours while weakening and eventually collapsing.

Next Week: Seasonable Start, Stormy Ending

The strong upper level low will retreat back north into Canada as previously mentioned, pulling the unseasonably cold air mass back north as well. As a result, troughing will flatten over the region as a southwest flow sets up at the surface, with seasonable temperatures expected for Monday through Wednesday as highs reach the low to mid 80s across most of the area with overnight lows ranging from the upper 50s inland to the mid-upper 60s near NYC.

The pattern across the northern US near the Canadian border will remain cooler than average as a longwave trough settles over south central-eastern Canada, which will keep the mean trough in the US positioned over the eastern US and preventing heat from reaching the region for at least the next 10-14 days. Several shortwave troughs are expected to track through the region, triggering several rounds of showers and thunderstorms, the first of these rounds likely on Thursday with scattered thunderstorms expected; at this time, models indicate unfavorable parameters for severe weather, although as this is still a few days away, this aspect of the forecast is subject to change. Dry conditions are likely to briefly return for Friday before the next wave of low pressure moves through the region, likely producing additional scattered storms into next weekend. Depending on the exact setup, a brief surge of heat is possible on Saturday, although the sustained heat will remain suppressed well to the south. Stay tuned for more information on the outlook for late next week and next weekend.

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