Oct 30, 2013: Rain, Wind Friday, Then Cold Weekend

Forecast Highlights:

A strong cold front will nam-hires_namer_042_sim_reflectivityaffect the region on Friday, bringing the most significant rain event in nearly a month with as much as 1/2 inch of rain possible, while high temperatures surge well into the 60s and the low 70s along with strong wind gusts in the 35-50 mph range. A brief yet strong cool down is expected over the weekend with widespread lows in the 20s, followed by another significant warm up next week with highs approaching the upper 60s again.



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Tuesday, October 29 Observations:

10.29.13A strong cold air mass entered the northeast US, with widespread cold temperatures, as the boundary between colder temperatures and near average temperatures set up over the area. Temperatures peaked in the upper 40s-mid 50s in the northern half of the area, and the mid 50s to near 60 degrees in the southern half. The highest temperature was 60 degrees in Somerset, NJ, and the coolest high temperature was 48 degrees in Yorktown Heights, NY, marking the first sub-50 high temperature in the area this fall.

 


 

Tonight – Friday: Rain, Wind, Warmer

Forecast Analysis: A strong upper level low is currently exiting the western US, with a low pressure developing in the central US producing widespread rain and severe weather. Ahead of this upper level low, ridging is amplifying over the region, with a strong southwesterly flow advecting a mild air mass into the region, with 850mb temperatures warming up to the 10-14C range. The central US shortwave will then interact with another trough entering the western US and a strong upper level low in Canada, and will rapidly track to the northeast while becoming negatively tilted and quickly intensifying, with the surface low pressure deepening from about 996 mb to about 972 mb in just 12 hours as it tracks through Michigan and into Canada. The low level jet will strengthen, with 925mb winds near 60-70 knots, supporting strong wind gusts across the region. Most of the rain will remain inland closer to the low pressure, however, with clearing skies and decreasing winds expected on Friday afternoon and evening after the frontal passage.

Forecast for NYC Area: Mostly cloudy skies will continue into Halloween, with a breezy south wind at 8-15 mph, gusting up to 20-30 mph, with generally dry conditions aside from scattered showers north and west of NYC around 11 AM-2 PM. Highs are expected to reach the low to mid 60s across the area. Temperatures will struggle to drop overnight, briefly doing so early on before rising towards the morning, as rain gradually develops west of NYC and winds increase. The peak of the storm is expected on Friday morning with a strong south wind at 15-30 mph, gusting to/over 40 mph, especially east of NYC, along with occasional showers across the area. Rain is expected to end around 11 AM-1 PM west of NYC and 2-4 PM east of NYC, with rain totals generally around 1/4 to 1/2 inch, locally below 1/4 inch south/east of NYC and above 1/2 inch for interior northwest areas. With most of the rain falling after 12 AM Friday, however, October will still be on track for a top 10 driest month on record, with the only notable rain event this month having occurred on the 7th. Clearing skies are then expected for the rest of the day with decreasing winds along with unseasonably warm highs, peaking in the mid 60s to low 70s across the area.

 

Saturday – Next Week: Briefly Cold, Then Warm Again

A brief yet strong cold air mass will enter the region for the weekend, with temperatures slowly cooling down. Saturday will still be mild, with highs in the low to mid 60s across the area, approaching the upper 60s near NYC, with a west wind and partly sunny skies. Sunday will continue the cool down, with highs in the upper 40s-low 50s inland and low-mid 50s elsewhere with a breezy NW wind, gusting up to 30 mph, and mostly to partly sunny skies. The coldest temperatures are expected on Sunday night, with lows in the 20s across most of the area away from NYC and the coast, which are expected to reach the low to mid 30s, with temperatures as cold as the low 20s possible in interior northwest areas and interior Long Island. Monday will be mostly sunny and cool as well, with highs in the upper 40s to low 50s for most of the area.

The strong high pressure that will provide the region with cold temperatures will quickly shift to the east, where it will settle as an anomalously strong ridge builds over the eastern US, with 500 millibar heights as high as 588 decameters, to possibly even 594 decameters which is unusually high for this time of the year. Temperatures will end up above to well above average, but with the duration of the warmth the main uncertainty, as the high pressure will still be positioned north on Tuesday and Wednesday, with a south/SE flow limiting how warm temperatures get on Tuesday and Wednesday. Temperatures on Thursday and possibly Wednesday, however, are expected to be unseasonably warm, likely returning into the mid to upper 60s; in the warmer case scenario, temperatures in parts of the region may return into the low 70s.

A broad trough will cover the western half of the US in this time frame, slowly shifting east. A low pressure is expected to develop well to the west of the area on Wednesday and Thursday, gradually shifting east. While there is still some uncertainty with the development of this system, with the GFS the most progressive model and the ECM failing to develop a well organized low pressure, which were biases observed with this week’s storm as well, this storm may bring the next widespread rain event for the area around the end of next week, with rain totals uncertain but with the heaviest rain likely to remain north/west of the area. Another cool down is then likely towards next weekend with temperatures returning closer to average.

2 thoughts on “Oct 30, 2013: Rain, Wind Friday, Then Cold Weekend

  1. Anonymous Reply

    My there be any evening squall with a line of thunderstorms with the actual cold front?

    • NYC Area Weather Post authorReply

      The front itself is expected to move through NYC during the afternoon, with the front and basically the whole rain event limited to a relatively short period of rain in the morning for most of the area, except for NW NJ and SE NY where occasional showers will continue tonight. A weak squall line is possible along the frontal passage, however. The front will then stall near NYC/Long Island in the evening and night before making a final push offshore, with heavy rain expected to develop offshore; some of it may clip parts of Long Island especially further east but with minimal rain amounts, if any expected.

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