Sept 21, 2012: Chilly Pattern Continues


Forecast Highlights:

– Scattered storms, some strong, Saturday evening N/W of NYC
– Another cool down for Sun-Tues; highs in 60s, lows in 40s
– Rain event possible mid-late next week
– Chilly pattern continues through end of month


Saturday – Tuesday: Storms, Then Chilly Again

The next cold front will move through the region on Saturday evening through the overnight hours as a strong trough drops into the north central US, bringing another surge of colder than average temperatures into the north central and NE US with a trough locked over the region as a result of the current pattern. Temperatures on Saturday are expected to warm up into the mid to upper 70s across the area, with parts of the immediate NYC area reaching and/or slightly exceeding 80 degrees. Marginal instability and shear are expected, although unlike Tuesday’s cold front, there is no strong low level jet present in this set up, and mid level lapse rates are unfavorable as well. The timing of the day is also less supportive with the storms mostly moving into the area towards the evening and early overnight hours. Scattered thunderstorms are expected, especially north/west of NYC, with some of these storms strong with gusty winds the main risk, although no widespread severe weather outbreak is expected. Dry conditions will return by early Sunday morning.

Winter weather is associated with the strong trough entering the north central US; snow has been reported tonight in Minnesota, including Duluth, with some snow expected in the Great Lakes region on Saturday and possibly even in the high elevations of the Northeast on Monday. The cool air mass will spread into the Northeast, with 850mb temperatures expected to drop to near 2-4 degrees Celsius, the coldest observed so far.

Temperatures on Sunday will peak in the upper 60s to lower 70s across the area with mostly sunny skies. The coldest temperatures are expected for Sunday and Monday nights; with mainly clear skies, temperatures will drop into the upper 30s to low 40s for interior areas and the mid to upper 40s across the rest of the area except for NYC, in the low 50s. The coolest high temperatures are expected for Monday with highs only in the low to mid 60s inland and the mid to locally upper 60s across the rest of the area, with Tuesday’s temperatures slightly warming into the upper 60s to lower 70s across most of the area.


Wednesday – Beyond: More Showers, Then Colder Again

A pattern change that unfolded early this week sent the US into a warm west and chilly central/east pattern, with persistent ridging near the western US/western Canada and near the Davis Strait and east of Atlantic Canada keeping a trough locked over the central US and parts of the NE US. The pattern is expected to generally continue through the rest of the month, with additional cool spells expected. The next cold front to move through the region will be on Wednesday with additional showers likely. Cooler temperatures will return for Thursday through Saturday with highs likely returning into the mid 60s to low 70s range along with lows again in the 40s for most of the area away from NYC. While temperatures are likely to warm up into early next week, at this time there does not appear to be any significant warm spell on the way.

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