December 8th 2024.

 

A look at the week ahead and a bit on the long range.

Today is much warmer than it has been, we also have partly to mostly cloudy skies overhead.

 

Moisture from the Gulf is going to stream northward and interact with a Clipper in the northern stream. Widespread rain will push into the region Monday.

Starting late overnight early morning, widespread rain moves into Southwest Pennsylvania. Rain will be moving into the Finger Lakes mid-morning, and then Central New York State late morning. By Midday into early afternoon rain and a mix snow/sleet, freezing rain will be pushing into the Adirondacks, Rain will also be pushing into the Central Hudson Valley around the same time. Rain will be working into Southeast Pennsylvania and the Northern Middle Atlantic very late morning into the afternoon. Rain/mix will be working into New England during the afternoon into Evening.  A mix and snow showers will move into Maine Monday evening into Monday night.

As the rain pushes north and east there will be period of steady rain that could be heavy at times. The widespread rain should last for a few hours, before starting to taper off. General rainfall amounts of 0.25 to 0.50 inches but there could be locally higher amounts.

Tuesday and Wednesday will see breezy southwest winds drive in mild temperatures. Tuesday will see drying conditions, with just a few lingering showers; but then another system will be approaching on Tuesday.  

Midweek Storm

This system is much stronger than the first. This will work through on Wednesday into Thursday. With the warm conditions, this is going to be mainly a rain event for the entire region, but there could be some mixing in the higher elevations, especially over northern parts of the region. Gusty winds ahead of the arctic front will be 10-30 mph with higher gust. Rain amounts of 1-3 inches will be possible.  Behind the system much colder air will move in, changing rain over to snow. A flash freeze will also be an issue, freezing any standing water and uncleared snow. Significant snow could fall across interior parts of Pennsylvania, New York State and Northern and Central New England.  There is a chance this storm bombs out, becoming a major nor’easter. It would be possible for snow even for the I-95 Corridor.  But if it stays weak, snow amounts would be much lower, with no snow closer to the Coast.  Everything will depend on the track and how quickly this ends up strengthening.  

Longer Range:

There is a chance the Polar Vortex could stretch or even break away, due to a Sudden Stratospheric warming (SSW) event. Depending on how this unfolds and were the vortex disruption takes place, there is a chance we could end up with a cold pattern in the next 2-3 weeks. We will just have to wait and see how this unfolds.

The ENSO is still neutral. So, it’s not playing a major role in the global pattern. Right now, the MJO is sitting in the driver’s seat for tropical atmospheric forcing.

 The MJO appears to be heading for a weak to moderate phase 7. If this is what happens, it supports the idea of a colder pattern setting up with the southeast ridge being suppressed.

 As I said on Friday, there are signs, that we could see a Sudden Stratospheric Warming (SSW), which would stretch and elongate the Polar Vortex (PV). This would hint for a colder pattern, setting up due to the disruption of the PV.

This SSW and disruption could happen around mid-month

Mean zonal wind at 10 hPa chart is showing currently the PV is strong. But when we look at the chart, we can see the model is showing a trend that the PV could become weaker.

 

The QBO is currently positive. The QBO deals with the strength of the PV

Here is a look at the GDAC-CPC Zonal Zonal Wind Anomaly Time Series

Neutral to negative AO and Weak negative NAO once we get into January. So some high latitude blocking is possible. 

 

For the rest of December we should expect an active but transient pattern with shots of cold and shots of warm. Then when we get into January, the pattern could become much colder, with continued chances for snow.