Dense Fog Advisory issued February 24 at 4:12AM EST expiring February 24 at 9:00AM EST in effect for: Adams, Columbia, Cumberland, Dauphin, Franklin, Juniata, Lancaster, Lebanon, Lycoming, Montour, Northumberland, Perry, Schuylkill, Snyder, Sullivan, Union, York
Areal Flood Watch issued February 23 at 9:34PM EST expiring February 25 at 7:00PM EST in effect for: Adams, Bedford, Blair, Cambria, Cameron, Centre, Clearfield, Clinton, Columbia, Cumberland, Dauphin, Elk, Franklin, Fulton, Huntingdon, Juniata, Lancaster, Lebanon, Lycoming, McKean, Mifflin, Montour, Northumberland, Perry, Potter, Schuylkill, Snyder, Somerset, Sullivan, Tioga, Union, Warren, York
Areal Flood Watch issued February 23 at 10:27AM EST expiring February 25 at 7:00PM EST in effect for: Adams, Columbia, Cumberland, Dauphin, Franklin, Juniata, Lancaster, Lebanon, Lycoming, Mifflin, Montour, Northumberland, Perry, Schuylkill, Snyder, Sullivan, Tioga, Union, York
The fact we will get warm next week does not bode well for the many who want the snow and cold! Look, I get it; I really do get it! When it's winter it's supposed to be cold and snowy. When it's summer it's suppose to be hot and sunny! The winter so far has been a let down for many. BWI has officially recorded 1" of snow so far (4"+ outside the city). So far we are at and slightly above the levels for 2011 which means we can only go higher from here!
So what is next? A series of things are beginning to unfold in the atmosphere. I will do my best to explain it as broad and simplistic as possible. 1. The MJO is switching to a cold phase. 2. A stratospheric warming event is underway. 3. The EPO and NAO are switching Negative supporting a MAJOR cold outbreak. Should all three come together.. WATCH out! Things will get a. Brutally cold b. Historically cold in parts of the country and C. We increase our chance for snow by 50X the level we were at.
What in the heck do you mean Stratospheric Warming? Look, the stratosphere is a layer of the atmosphere the sits just above the troposphere (which is the layer we are most concerned with when it comes to weather). The stratosphere is 6 miles above our head at the 10-1 MB level. Generally speaking when our stratosphere is running on the chilly side or in a cold phase the response is warming in the troposphere. When the stratosphere warms suddenly we witness a reversal in westerly winds to either a massive slow down or a full reversal towards the easterly direction. Instead of getting into the "details" I will sum it up as this.
A SUDDEN STRATOSPHERIC WARMING EVENT will break apart the main polar vortex sending it either down into the United States or on the oppose side of the world. In some cases we see the MAIN polar vortex split in all directions sending "daughter" vortices (mini polar vortex) all over the place pushing cold air due south.
IMAGE shows the warming event underway.
MJO shifts to COLD PHASE 7,8, & 1
The MJO short for Madden_Julian Oscillation. The MJO affects the entire tropical troposphere but is most evident in the Indian and western Pacific Oceans. The MJO involves variations in wind, sea surface temperature (SST), cloudiness, and rainfall. Because most tropical rainfall is convective, and convective cloud tops are very cold (emitting little longwave radiation), the MJO is most obvious in the variation of outgoing longwave radiation (OLR), as measured by an infrared sensor on a satellite.
Essentially what you need to know is that MJO is a wave that moves across the globe affecting weather patterns across the United States and the globe.
The image shows the various phases we see with the MJO which ranges from 1 - 8. This image shows how the temperatures respond to each phase. Ideally in the winter we would like to see PHASE 1,2,3, and 8 for COLD and stormy while phase 5, 6, 7, and 5 support warmth and lack of storms.
The MJO is currently in Phase 4 however, will stay fairly progressive going into phase 7 before potentially dying. Now you'd say OK Mike Phase 7 is warm.. I would say you are right. However, indications are it will progress towards phase 8 which is ideal to cold and snow in the east. Another theory of mine is the fact the MJO may die a quick death and could potentially play a small if non existent role in our weather. The best thing I see right now is it does NOT stay in what's called the "Circle of Death" which is sits in one phase (the warmer phase) keeping storms away and warmth around!
The EPO, NAO, AO
These are three variables we watch in winter that both run in negative and positive phases. The EPO stands for Eastern Pacific Oscillation - The NAO stands for North Atlantic Oscillation - The AO stands for Arctic Oscillation. When all three are in a negative phase WATCH OUT, major cold is on the way.
The European and GFS models both show the three coming together to deliver a cross polar flow across the USA. Cross polar flow is when you pump the true arctic air from Siberia around the ridge and down the back of it into the USA. Note the HUGE ridge over the Gulf of Alaska (negative EPO) combined with the huge ridge forming over Greenland ( Negative NAO). These ridges with set a block on top forcing the air mass over northern Canada to come rushing south!