[notice]Blog Note: A post-storm analysis of the Sunday-Monday event will be posted late today.[/notice]
January-like conditions continue across the region with an anomalously cold air mass, with temperatures falling to 13 degrees in NYC and the single digits away from the immediate NYC area and the coast, as low as -4 degrees in Montgomery, NY. A gradual warming trend is expected this week as high temperatures rebound into the 30s and later the 40s, along with a slight risk of precipitation on Thursday night and Saturday night but with no significant precipitation event expected over the next 7 days.
Today – Friday: Moderating Cold, Possible Light Precipitation Thursday Night
Posted above from left to right are the latest available surface analysis and radar composite from WPC, and the initialized GFS 500 millibar heights and vorticity from NCEP MAG; both are valid at 6z (1am). The polar vortex, which was responsible for preventing Monday’s snow event from materializing as forecast in the area, is currently east of Canada, over the Davis Strait, and will continue to depart North America. Otherwise, there is little activity ongoing besides some snow over Wisconsin and rain over southern Texas. As of this morning, much colder than average temperatures continued across the region, with highs today only forecast to peak in the mid to upper 20s. Increasing clouds are expected tonight with lows mostly in the 10s, with highs on Wednesday warming up into the mid to possibly upper 30s. Thursday’s outlook is more uncertain as a strong high pressure builds into New England, setting up for a northeasterly surface wind, with overnight lows likely to fall into the 10s inland and low-mid 20s near the coast, while daytime highs on Thursday are likely to be similar to those of Wednesday, if not slightly cooler.
The next time frame to monitor is Thursday into Friday, as a weak shortwave trough currently over California will amplify as it tracks ESE towards the Gulf of Mexico coast, where a low pressure is expected to develop and track NE up the southeastern US coast, producing heavy precipitation. As this event is mostly driven by the southern stream with a lack of interaction with the north stream and cold air mass to the north, most of the precipitation is expected to fall as rain. The main uncertainty is how far north precipitation expands; due to the initial high pressure over the region, the lack of interaction with the north stream, and the trough taking too long to become neutrally or negatively tilted, most of the precipitation is expected to remain south of the area, but with the possibility remaining for at least isolated precipitation reaching the area. At this time, a slight risk of rain/snow showers was added for coastal locations, although at this time this does not appear to be a major precipitation event for the area.