2021 Spring outlook update

 

Here is a update to my earlier Spring Outlook for 2021

The Spring Outlook can be found here.

 

Teleconnections:

Images from WeatherBell

Looking at Sea Surface Temperatures (SST) in the Pacific, it’s clear we’re still in a weak La Nina. But as I’ve been saying, we should see the La Nina conditions strengthen again as we head toward Summer. We also have those cool SSTs off the Southwest Coast. These extend north along the West Coast into the Gulf of Alaska.  These two teleconnections will play a big role in the trough and ridge pattern across North America this Spring. Add to that the severe drought conditions across the Southwest CONUS, means we have an interesting and possibly quite dangerous Spring ahead of us.

 

 

The North Atlantic Oscillation (NAO) has been strongly positive, but now it looks to go negative.

 

 

The Eastern Pacific Oscillation (EPO) is also turning negative

 

Currently the Madden Julian Oscillation (MJO) is currently active over the western Indian Ocean. The MJO will continue to move across the Indian Ocean, currently Phases 2 and 3 (cold phases for this time of year), then Into Phases 3 and 4 where it intensifies.  This means that our warm weather of late, is coming to an end.  MJO phase 2 and 3 are showery and cold here in The Northeast.   As we move toward April the MJO is in phase 4 and 5, which are still cold phases but they are also dryer here in the Northeast and Middle Atlantic Region. As we get into April the MJO looks to move into Phase 6 and then Phase 7.  Phase 6 is Warm and Dry in April, but phase 7 is a cool and wet phase. If it gets into Phase 8 that is slightly a warmer phase but it does tend to be a little dry.  

 

 Spring Temperatures:

 

The MJO is indicating that the warmth of the last couple of weeks could be a false spring. Meaning that we’re still not out of the woods as far as cold intrusions and possible snow events.  I do think the Pacific will tend to stay in the driver’s seat. So, as we get closer to late-April, the threat of real cold and snow should be over. The setup in the Pacific is a strong indicator that the predominate pattern during the second half of Spring heading into Summer, will feature a lot of ridging over the East. So, my earlier thoughts for overall temperatures to be above average for the Northeast into Middle Atlantic Region is spring are still looking right. But April could see real cold invade around mid month.

Generally, the March, April, and May time period look to see overall temperature anomalies to be +1.0°F to +3.0°F above average.

Spring Precipitation:

 

 

Here is a look at the current drought conditions from the Climate Prediction Center. The Map shows, some areas in across the Northeast into the Middle Atlantic are currently experiencing dry conditions and, in some cases, a moderate drought.

Below is a look at the latest Soil Moisture Anomaly for the CONUS.

 

We’ve had yet another week of below-normal precipitation across our region. As a result, Moderate drought has expanded in western Vermont and northern New York, while abnormal dryness expanded in western Maine, northeastern Massachusetts, and western and northern New York. Conditions remained unchanged elsewhere in the region. The U.S. Drought Monitor released on March 25 showed 8% of the Northeast DEWS region in a moderate drought and 39% as abnormally dry compared to 7% and 33%, respectively, last week.

The Standardized Precipitation Index (SPI) is a simple measure of drought (absolute, departure from normal, maximum, and minimum) and is based solely on the accumulated precipitation for a given time period. For this map is show precipitation departure over the last 60 days, compared with the long-term average.

The pattern that is looking to setup, would indicate that Spring 2021 will end up with overall above average precipitation. the pattern does support the idea that conditions across the Mid Atlantic, Pennsylvania, New York State into western New England, could end up with above average precipitation over the Spring. Maine looks to see average to below average precipitation. 

Snowfall: For the Middle Atlantic into Pennsylvania your chances for accumulating snow is very low, so you’ve most likely seen the last of the white stuff. But some accumulating snow is still a real possibility across the northern tier of Pennsylvania, New York State, and New England.  The odds of significant snowstorms are over in my opinion.

 

 Springtime Severe Weather:

In the 2021 Spring Outlook part 2, I talked about how the widespread severe to exceptional drought across the Southwest CONUS into the Central Rockies, and how it would play a big role in the Spring severe pattern.  Between that and the cooler than normal Pacific explains why the severe season is starting out a little earlier than average.   Typically, during years like this the tornado season starts around 4 weeks earlier and tends to be more active than average.

In the first part of the Spring Outlook; I also talked about how the tropical Pacific are similar to the infamous year 2011. Remember, back in April 2011 there was a very extreme with deadly historic tornado outbreak.

From January into March, we saw a slow start of the storm season. By March 1^st there were only 24 reported tornadoes across CONUS.  But the severe weather activity has started to trend upward.  La Nina years do see to start earlier than usual. Also, when the Pacific is cool Dixie Alley, often experiences significant tornado outbreaks.  And with pattern the weather models seem to be indicating, this year’s tornado season could again be an above-average this spring.

 

 

2011, also had a slow start, that too was due to the cooler Pacific waters. But those cool Pacific SST led to a vigorous and stronger Jet Stream.  So, with a similar SST and atmospheric pattern this year could also be very active. In last than a week, the month of March has seen to severe tornado outbreaks, both of which had the Storm Prediction Center raised rare High Risk severe chances. Currently the tornado count stands a 163, which means we’re almost to the yearly mean for this time of year.

 With these same conditions looking likely for April, and the idea that recent Aprils have been active. Surely means the chances for more significant severe outbreaks are possible for April and beyond. the typical northward shift of the jet stream will occur. But the winds will likely remain stronger than normal, so the tornado season will probably continue as above-average during the peak season. With the gradual northward retreat of the upper-level jet stream the severe season will move north with it.  So, May and June, will probably continue as above-average during the peak season.

 The same setup that looks to bring the Northeast into Midwest seeing maybe a soggy spring. The Ohio Valley, Maryland, Delaware, Much of Pennsylvania, and Western New York State will most likely experience enhanced severe activity this Spring. For the rest of New York State, far eastern Pennsylvania, New Jersey and New England, severe chances look to be around average for spring 2021. 

Well that is it, Just a reminder, my 2nd part of the Atlantic Hurricane Outlook, will be released in a couple of weeks.