5/5 Late-AM Zones Update: Heavy Rain Today, Unsettled Weekend, More Blocking Next Week

Happy Friday! A large, closed low to the southwest, will continue to impact the region today. Rain will continue to be heavy at times, early to mid-afternoon hours, as stronger southerly low-level jet moves across the region. Some embedded thunderstorms are also possible, with weak some instability this afternoon. Rainfall totals of at least 1” to 2” are expected for most areas. But some locally higher totals up 3”or 4” are possible. This could lead some flooding on area roadways and poor drainage areas.

By late this afternoon, a mid-level level slot will be moving into region. This will cause rain to taper off to showers or even come end in some areas, by early this evening. More showers or periods of rain could return later tonight and more jet streak energy and warm front moves across the region, especially parts of Long Island and Connecticut. But this is not expected to be as heavy as rainfall during the day, with lower precipitable water values or less moisture content in the atmosphere.

3km NAM radar loop showing more rain and embedded thunderstorms moving through this afternoon.

3km NAM radar loop showing more rain and embedded thunderstorms moving through this afternoon.

More unsettled weather is still expected to continue this weekend, as an omega blocking keeps a trough or closed low over the Eastern half US into early next week. Skies may clear for sunshine on Saturday, as the warm front will be further north with more southerly winds over the region.. This will support to reach to lower to middle 60s  over much of the region. But a cold front and shortwave will move through region tomorrow afternoon and evening with more scattered showers likely. There might be enough instability for a few isolated thunderstorms as well.

Subsidence behind the cold front and shortwave will likely cause to showers to taper of skies to clear out later Saturday night and Sunday morning . Then more clouds will increase again Sunday afternoon, as another cold front moves through region. Some isolated or scattered showers are possible again during the afternoon, especially northwest of NYC. High temperatures will likely be upper 50s to lower 60s.

Then next week, more blocking from Greenland/Davis Strait retrogrades into the omega block over CONUS. These will keep a closed upper-level low over Northeast US with cold pool aloft and multiple disturbances rounding it . While there will be alot of dry time, some cool and unsettled weather is likely to persist for much of next week.

GEFS showing blocking retrograding from Davis Strait next week

GEFS showing blocking retrograding from Davis Strait next week, keep the closed upper-level low over Northeast for much of next week.

Therefore, after some early morning sunshine, more clouds and some scattered showers are possible, by the afternoon and early evening hours each day. Some snowflakes or graupel may also be mixed across the far northern interior locations. Temperatures will be below normal with daytime highs in mid-upper 50s to lower 60s. Nights will be chiller with lows in the 40s over urban or coastal areas and some 30s possible over the Interior.

No significant rainfall is expected until possibly the end of next week, when some energy with another cut-off low begins ejected out Southwest US. But residual blocking may keep this storm system to the south. So uncertainty is high for more rainfall. Overall, there no signs of any more pleasant, warmer and drier weather, until perhaps late May or early June, when the MJO might headed into more warmer phases. Stay tuned for more zone forecast and premium updates coming on pattern through the weekend.