4/02 All Zones PM Update: Two Heavy Rainfall Events Likely This Week

Good evening, everyone! Just an quick update on forecast for this upcoming week. More pleasant weather is store for tonight and tomorrow with high pressure still in control. But more inclement and potentially hazardous weather is on the way by late  Monday night! Skies likely clear to partly cloudy tonight with some high clouds streaming into region form the northwest. Overnight low low temperatures will be mid-upper 30s in many of the suburbs to lower 40s in NYC and other urban areas. Some of Interior valley and Pine barrens may radiate well tonight, dropping into upper 20s to lower 30s.

High pressure will be slide offshore tomorrow. This will for more clouds to increase by afternoon hours. It may turn mostly cloudy by the end of the day. But it will remain dry with temperatures still reaching the mid-upper 50s to lower 60s. Some light southeast winds may keep shore locations a little cooler and temperatures may drop a few degrees with more cloud cover during the late the afternoon.

As discuss in the update this morning, low pressure will track into the Great Lakes with warm front lift northward through the region. This will cause rain to break during the late evening and overnight hours.  Then a strengthening southerly low-level jet will cause rain to become heavy at times late Monday night and will continue into Tuesday morning. Some isolated thunderstorms are possible and heavy rainfall lead to localized flash flooding. In fact, the National Weather has issued flash flood watch for much New Jersey and Lower Hudson Valley for late Monday night and through Tuesday evening.

3km NAM composite simulated radar showing heavy rainfall moving through region early Tuesday morning

3km NAM composite simulated radar showing heavy rainfall moving through region early Tuesday morning

 

The warm front lifts farther north by Tuesday afternoon, cause much of the rain to shift into NewEngland. The 12km NAM, GFS and ECMWF models suggest clouds break for sunshine and temperatures rising well into 60s and 70s into Northern NJ and NYC. But the 3km NAM suggests morning rainfall enhance a marine airmass, which cause keep warm front further south over Central New Jersey Tuesday afternoon. This will keep areas to north cooler with more cloud cover. Nevertheless, more scattered showers and thunderstorms are possible later in the afternoon as cold front and vigorous shortwave energy moves through region. A few thunderstorms could also become strong in more unstable airmass near and south of the warm front.

Some more pleasant weather returns briefly on Wednesday before the next storm system approaches for Thursday. Northern stream and southern Pacific energy will be phasing large, deep closed low over Great Lakes/Ohio Valley region Thursday. Deep southerly flow Atlantic, Gulf of Mexico and subtropical moisture will streaming northward up the East coast. There is potential for very heavy rainfall and localized flooding in the region on Thursday. Also the some instability and strong shear may lead to some severe weather over Mid-Atlantic region which could extend into our southern zones, particularly south of NYC.

ECMWF model with a large 500mb closed low over the Great Lakes with firehose of rainfall along into local region on Thursday

ECMWF model with a large 500mb closed low over the Great Lakes with firehose of rainfall along into local region on Thursday

We will to monitor this storm, have more updates on this system once we get passed the Tuesday. More flooding around rivers and streams will gradually become a bigger concern with pattern staying more active over next couple week.  Stay tuned more zone forecast updates for this week on both storm system. Have a great night!