10:30 AM | *Mild conditions for Christmas Day…colder pattern to set up as we transition to 2024…updates on MJO, stratospheric warming*
Paul Dorian
Mild conditions should prevail on Monday, Christmas Day, in the Mid-Atlantic region with high temperatures at or above the 50 degree mark in much of the I-95 corridor. Map courtesy NOAA
Overview
The weather stays on the chilly side in the Mid-Atlantic region into the upcoming weekend, but becomes milder by the time we get to early next week with afternoon highs on Monday, Christmas Day, likely at or above the 50 degree mark in much of the I-95 corridor. By the next Tuesday and Wednesday, the mild weather pattern will likely result in more rain for the area as a low pressure system pulls out of the southern US and heads towards the Great Lakes. By the time we get to the end of the next week and following weekend, important upper-air changes across North America will become more evident and they should lead to colder, more winter-like, conditions in the eastern and southern US as the new year gets underway. An update is given in this posting on the teleconnection index known as the Madden-Julian Oscillation (MJO) and a stratospheric warming event that continues to unfold which could impact US temperatures in the month of January.
A colder weather pattern is likely to set up across the eastern and southern US in the days surrounding the transition into 2024 with 00Z EPS 2-meter temperature forecast maps shown here for December 30th (left) and January 3rd (right). Maps courtesy ECMWF, weathermodels.com
Details
Over the next couple of days, an intense upper-level ridge of high pressure over the North Atlantic Ocean will weaken as a new one intensifies over the eastern part of Canada. This new area of high pressure ridging aloft will then tend to retrograde later next week and become centered over west-central Canada in about a week or so on the western side of Hudson Bay. There will also be an extension of this newly placed upper-level ridging from west-central Canada down into the interior sections of the western US.
A colder weather pattern is likely to set up across the eastern and southern states in the days surrounding the transition into 2024 with 00Z EPS 500 mb height anomaly forecast maps shown here for December 30th (left) and January 3rd (right). A change in the overall pattern aloft will result in strong upper-level ridging across west-central Canada by the beginning of the new year and a trough of low pressure across the eastern and southern US. Maps courtesy ECMWF, weathermodels.com
At the same time as the ridge intensifies over west-central Canada, an upper-level trough of low pressure is likely to intensify across the southeastern US with a second one deepening out over the northern Pacific Ocean just to the south of the Aleutian Islands. The combination of these changes to the upper air pattern will be quite important in terms of the overall wind flow across North America by the time we begin 2024. Specifically, this change should be more favorable for cold air masses to make their way from central Canada into the eastern and southern US and an active southern branch of the jet stream should result in increased chances for storms to take a “southern route”.
A teleconnection index known as the Madden-Julian-Oscillation (MJO) that tracks a tropical disturbance rotates into “phases” 8, 1 and 2 in coming days (left plot) and these particular locations usually are correlated with colder-than-normal temperature patterns across the eastern and southern US (right, boxed regions). Maps courtesy NOAA
A look at the teleconnection index known as the Madden-Julian-Oscillation or MJO which tracks a tropical disturbance indicates it will transition in coming days to “phases” or locations which are normally associated with colder conditions across the eastern and southern US this time of year. Another interesting atmospheric phenomenon known as stratospheric warming has begun and indications are that the “polar vortex” will weaken and be disrupted as we head into the new year and this could have ramifications on US temperatures later in the month of January.
A stratospheric warming event continues to unfold with the disruption of the “polar vortex” and these forecast maps of stratospheric temperatures for December 31st (left) and January 2nd (plot) feature an expanding area of warming (red) on one side of the North Pole. There very well may be an impact on US temperatures later in the month of January as a result of this on-going stratospheric warming event. Maps courtesy NOAA, ECMWF, weathermodels.com
Stay tuned…we’ll fine-tune the details in coming days on an impending pattern change that should result in more winter-like conditions for the eastern and southern US.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com
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