Forecast Highlights: Following a cold front on Wednesday which produced light rain in parts of the area, temperatures have started to slowly trend cooler, with today’s highs peaking in the mid 50s to low 60s. …
This post is a general overview of recent anomalous late October events and a brief update on the upcoming storm. For the latest technical analysis of the upcoming weekend storm and its potential impact in …
Forecast Highlights: A warm front passed through the region early on Wednesday, having brought a brief taste of early fall as temperatures surged into the 70s away from the coast. The warmth was only short …
This post is a general overview of recent anomalous late October events and a brief update on the upcoming storm. For the latest technical analysis of the upcoming weekend storm and its potential impact in the region, please refer to yesterday’s post. Images in this post are from the PSU e-Wall NARR.
Anomalous Late October Events – A Brief Review of Recent Events
Late October is typically highlighted by Halloween on the last day of the month. It also represents the impending onset of winter, as hours of daylight continue to decrease with each day and clocks turn back an hour on November 2nd, marking the ending of daylight saving time. During the last few years, this time of the year has also featured several highly anomalous weather events over the United States, ranging from hurricanes and anomalously deep low pressures to snow and cold. Tonight’s post briefly reviews some of the recent late October events and their impact on the United States and the New York City area.
A warm front passed through the region early on Wednesday, having brought a brief taste of early fall as temperatures surged into the 70s away from the coast. The warmth was only short lasting, however, as a cold front will move through on Wednesday with a few showers. A gradual cool down will continue through Friday and Saturday, when a strong cold air mass will enter the region, accompanied by a developing coastal low off the coast which may produce light snow for parts of the region, potentially including the area.
The coastal low pressure which affected the area over the last week has finally moved out, but with another cold front having passed through last night resulting in a breezy northwesterly wind today as high temperatures peak in the upper 50s to low 60s. A brief warm up is expected early this week with highs in the 70s possible before a gradual cool down begins on Wednesday, peaking next weekend as a strong upper level trough may bring significantly colder temperatures and the possibility of snow in parts of the region.
The coastal low which has affected the region with clouds, rain and wind throughout the week will slowly depart on Friday, allowing for clearing skies with temperatures slowly warming back into the low 60s, but with a breezy northwesterly wind persisting through Sunday as another cold front passes through the area on Saturday night. A significant warm up is expected early next week with temperatures rising into the 70s for parts of the area before a cold front produces scattered showers next Wednesday (image credit: PSU e-Wall).
Tonight’s forecast discussion is an update from yesterday’s discussion. The next full analysis will be posted on Thursday evening.
From left to right, the latest available surface analysis and radar composite from the NWS Weather Prediction Center (WPC), and the initialized GFS 500 hPa heights and vorticity from NCEP Model Analyses & Guidance; both are valid at 1800 UTC Wednesday (2:00 PM Wednesday EDT).
Since yesterday’s update, the upper level trough has cut off with a closed upper level low, while the surface low pressure redeveloped offshore and deepened to near 1003 hPa southeast of New Jersey. As the low developed last night, heavy thunderstorms persisted over northeast NJ, coastal NYC and western Long Island, where rain totals locally exceeded 1 inch with flash flooding and localized hail yesterday evening. A more organized band of heavy rain developed this morning over eastern New Jersey, shifting offshore throughout most of the day before reorganizing and retrograding west throughout the evening and early overnight hours as the surface low deepened along with increased upper level forcing over the area. The latest regional radar imagery from the Pennsylvania State University e-Wall, posted to the left, depicts the moderate rain bands covering the majority of the area; the latest radar estimates depict storm total rainfall since yesterday morning around 1/2 to 1 inch for most location, locally up to 2 inches over the same locations which observed heavy thunderstorms yesterday evening.
Occasional rain bands will continue to rotate through the area tonight with another 1/4 to 1/2 inch of rain expected, locally higher, before gradually decreasing in intensity and coverage area on Thursday as the low pressure occludes and the stronger forcing and low level jet shift northeast towards New England and Maine. Isolated showers will continue through Thursday afternoon and Friday with otherwise mainly cloudy skies and temperatures slowly rising into the low to mid 50s on Thursday and the upper 50s to low 60s on Friday. The windy conditions will continue, however, with the wind shifting to the northwest and continuing through Saturday, when a mostly dry frontal passage will usher in a brief cool down on Sunday followed by a quick warming trend next week. Tomorrow’s forecast discussion will analyze the longer range in more detail.
A developing coastal low off the coast will deepen before stalling off the coast of Long Island by Thursday, providing the area with a stretch of cloudy skies, breezy northerly winds and occasional showers through Friday with rain totals generally amounting to 3/4 to 1.5 inch. Cloud cover will begin to decrease by Saturday, but with a secondary frontal passage on Saturday night briefly reinforcing the cloud cover and wind before a brief warm up early next week.
Tonight’s forecast discussion is an update from yesterday’s discussion. The next full analysis will be posted on Tuesday evening.
From left to right, the latest available surface analysis and radar composite from the NWS Weather Prediction Center (WPC), and the initialized GFS 500 hPa heights and vorticity from NCEP Model Analyses & Guidance; both are valid at 1800 UTC Monday (2:00 PM Monday EDT).
Since yesterday’s update, the shortwave trough over the Midwest has progressed into Indiana, continuing to amplify due to strong ridging to its west. Analyzing the last 4-8 model runs, the most noticeable change in the model guidance has been to correct for a stronger, sharper and farther south shortwave trough than previously forecast, which results in stronger forcing tonight into Wednesday and would lead to a more widespread coverage area of scattered showers over Pennsylvania and New York state than initially expected. The outlook remains unchanged for the area through Wednesday evening, with scattered showers late tonight and into Wednesday amounting to less than 1/4 inch.
There has been relatively little change in the forecast positioning of the low as it becomes cut off on Wednesday and Thursday, with a period of light to moderate rain expected to affect the area on Tuesday night into Wednesday. The main change since yesterday’s update has been to include more rain over the area on Thursday as rain bands over New England wrap around to the west of the low, but with otherwise no significant changes in the forecast to note. The latest outlook is slightly wetter than yesterday’s forecast, with rain totals between 1/2 and 1 inch in northern NJ, and 1 to 2 inches over NYC, Long Island, southern CT and southeast NY. A more detailed analysis will be posted with Tuesday’s update.
A much colder air mass is currently positioned over the region, with temperatures having only peaked in the low to mid 50s this afternoon across most of the area. Areas of frost are possible tonight as temperatures fall into the 30s outside of NYC, but with increasing cloud cover and wind as a coastal low pressure stalls off the coast, with occasional showers expected between Thursday and Friday generally amounting to 1/2 to 1 inch.