**Post frequency will begin to go up as soon as school gets out. It has been quite hectic for me lately.**
The main story it seems of the past week, has been one of normal early May warmth, all the way to record-breaking May snowstorms. Why is this occurring?
The image above is a chart from the 500 millibar level, which is normally about 5600 meters above the earth's surface. As you can clearly see, there is a large upper level, and nearly stationary low sitting over the Mississippi Valley region. At the same time, you will notice that this same low is producing a band of "retrograding" showers and thunderstorms, which have made very little eastward progress since this morning. In fact, they aren't expected to make ANY eastward progress within the next 48 hours, before dissipating. This means it is very likely that the most rainfall that we see is little more than a trace of precipitation.
Even so.. Conditions will become slightly cooler tomorrow. Temperatures will drop into the upper 60's and lower 70's.
For the next 10 days or so, expect rather tranquil and pleasant weather conditions, with temperatures hovering in the low to mid 70's. Late next week, the possibility of thunderstorms arrives again as a series of weak shortwaves approach the area from the NW.
And then.. The model differences come into play. The GFS is forecasting the continuation of a relatively warm pattern, and in fact, shows the first potential "heat" wave of the season coming for the Midwest by May 15. While I doubt it will get warmer than the middle to upper 80's, this is definitely something to watch.
On the otherhand, the ECMWF forecasts that a deeper trough could come into play in Southeast Canada, which could lead to a series of "backdoor" cold fronts which bring periods of relatively cooler weather (highs in the 60's). In fact, it forecasts that we could have a few additional frosts before mid-month, according to the model.
At this point, it is unreasonable to make any kind of long-range predictions based upon models. What I CAN do is make predictions based upon current observations.
1.) The MJO, which is the main driving force behind the "nature" (speed, curvature, and the wave number) of the Pacific jet stream will become very active, and head into phases 4, 5 and 6 by mid-May. This would allow for a zonal Pacific pattern, but with an active jet stream, which will not allow for the development of any significant troughs or ridges, leading to a warmer pattern.
2.) The continuing weak La Nina/Neutral ENSO points against a cooler May/Summer period.
3.) The drought in the West.
Why should I say the drought in the West? Specifically because whenever the core of the heat across North America focuses in the Rocky Mountain region, it almost always is pushed eastward by an active Pacific jet, which is why I believe there will be several periods of warmth, with increasing frequency into June. And that is when we will see our first heat waves much like last year. But the thing about this season is that it will be much wetter, with a much higher frequency of storm complexes and severe thunderstorms.
More details will be coming in a few weeks, when I create my official summer outlook.
The main story it seems of the past week, has been one of normal early May warmth, all the way to record-breaking May snowstorms. Why is this occurring?
The image above is a chart from the 500 millibar level, which is normally about 5600 meters above the earth's surface. As you can clearly see, there is a large upper level, and nearly stationary low sitting over the Mississippi Valley region. At the same time, you will notice that this same low is producing a band of "retrograding" showers and thunderstorms, which have made very little eastward progress since this morning. In fact, they aren't expected to make ANY eastward progress within the next 48 hours, before dissipating. This means it is very likely that the most rainfall that we see is little more than a trace of precipitation.
Even so.. Conditions will become slightly cooler tomorrow. Temperatures will drop into the upper 60's and lower 70's.
For the next 10 days or so, expect rather tranquil and pleasant weather conditions, with temperatures hovering in the low to mid 70's. Late next week, the possibility of thunderstorms arrives again as a series of weak shortwaves approach the area from the NW.
And then.. The model differences come into play. The GFS is forecasting the continuation of a relatively warm pattern, and in fact, shows the first potential "heat" wave of the season coming for the Midwest by May 15. While I doubt it will get warmer than the middle to upper 80's, this is definitely something to watch.
On the otherhand, the ECMWF forecasts that a deeper trough could come into play in Southeast Canada, which could lead to a series of "backdoor" cold fronts which bring periods of relatively cooler weather (highs in the 60's). In fact, it forecasts that we could have a few additional frosts before mid-month, according to the model.
At this point, it is unreasonable to make any kind of long-range predictions based upon models. What I CAN do is make predictions based upon current observations.
1.) The MJO, which is the main driving force behind the "nature" (speed, curvature, and the wave number) of the Pacific jet stream will become very active, and head into phases 4, 5 and 6 by mid-May. This would allow for a zonal Pacific pattern, but with an active jet stream, which will not allow for the development of any significant troughs or ridges, leading to a warmer pattern.
2.) The continuing weak La Nina/Neutral ENSO points against a cooler May/Summer period.
3.) The drought in the West.
Why should I say the drought in the West? Specifically because whenever the core of the heat across North America focuses in the Rocky Mountain region, it almost always is pushed eastward by an active Pacific jet, which is why I believe there will be several periods of warmth, with increasing frequency into June. And that is when we will see our first heat waves much like last year. But the thing about this season is that it will be much wetter, with a much higher frequency of storm complexes and severe thunderstorms.
More details will be coming in a few weeks, when I create my official summer outlook.
No comments:
Post a Comment