Midday Zones Update: Cool Weather Through Friday, Weekend Coastal Storm Threat Increases

Happy Tuesday afternoon! Some sunshine will continue for rest of today. But we will continue be under the influence of a large, anomalous cold upper-level low or trough over the Northeast US. This will lead to more cumulus clouds developing, instability increases with more daytime heating.  A few isolated showers could also pop up, but these will be over more Connecticut or New England today. Temperatures will rise in the upper 50s to lower 60s.

Some clouds could linger into evening hours. But then skies may clear later tonight more confluent flow develops over the region. More clearing and calmer winds will support more radiational cooling overnight. Temperatures will likely fall into lower to middle 40s again NYC and urban areas. But many of the suburbs may will likely fall into upper 30s. Some pockets of patchy frost are possible over interior valleys and Pine Barrens, where temperatures may fall into low to middle 30s.

High-latitude blocking retrograding over the Davis Strait and Hudson Bay will keep the upper-level low, from moving out of the New England region during Wednesday and Thursday. Some more clouds and isolated showers can’t be ruled out, especially with multiple disturbance rotating around the upper-level low. But more pleasant, cool and dry weather is expected overall with a more northerly flow, on the backside of this low. High temperatures each day will be in the upper 50s to lower 60s over much of the region. Temperatures on Wednesday night will likely be in mid-upper 30s in the suburbs and lower to middle 40s over urban areas, again.

Thursday night and Friday, the blocking over Davis Strait/Hudson Bay region will begin to weaken. This will allow upper-level low to slowly move out into the Atlantic. However, this may also lead more onshore winds or a backdoor cold front to move through during the period.  Some mid-level warm-air advection ahead of low pressure trough approaching southwest, may lead more isentropic lift could lead more cloud cover, scattered showers and drizzle over the region. As a result, temperatures may struggle to get out the lower to middle 50s during the day on Friday.

The weather will just get worse over much of the weekend. More details on extent of rainfall, winds and other impacts over the local region, remain highly uncertain now. But latest indications are that northern and southern energy will likely phasing along trough going negative. This will result in a coastal storm intensifying into Nor’easter and moving northward near New Jersey or Delaware coasts on Saturday and Saturday night. Rain is likely, and it could be heavy at times with some strong, gusty east-northeast winds. This could lead some flooding in poor drainage and low-lying areas. Also with a persistent, strong onshore flow, some coastal flooding possible during high tides.

Afterwards, the coastal storm may begin to occlude, as the low becomes more vertically stacked with some mid-level dry air intrusion. But unfornately, more periods of rain and gusty winds could still continue into Mother’s Day Sunday, as the storm will only moving slowly offshore.  Temperatures this entire weekend, will likely remain several degrees cooler than normal with mostly cloudy skies, onshore winds and more rainfall.

Some unsettled weather is possible into early next week, as the storm weakens and slow move further out into the Atlantic. Then some improving weather and moderating temperatures may follow for rest of next week, as more ridging over the Central United States begins to build further east. But some residual high-latitude blocking and troughiness over Southeast Canada may still mitigate major warmth over the Northeast.

So if you are hoping, for more summer-type warmth and beach weather before Memorial Day weekend, that is still looking not too likely at this time. But there some indications the overall cool, unsettled pattern may change afterwards. Stay tuned for zone forecast and premium articles and video updates on the coastal storm this weekend and pattern over next few weeks!