Monday, November 25, 2013

Wrong time for Much Needed Moisture. Detailed Storm Blog

Well, we need rain in a bad way but unfortunately Mother Nature has decided to dispense it and a lot of it on arguably the busiest travel days of the year in the United States. Add to that the potential for strong to damaging wind gusts and we have a recipe for a potential traveling disaster.

The Arctic Front passage late Saturday and Sunday will be a distant memory by Wednesday morning as many in Southern New England will spike to or exceed 60°  as a strong broad low pressure system to our south/southwest takes hold and intensifies with a very active south/southeast wind ahead of it right into our area. Enough cold air will be stubborn and in place at the onset late Tuesday that some wintry precipitation could fall across far western SNE before all levels of the atmosphere warm as the storm approaches closer to our area.
 High clouds ahead of approaching coastal low are already on the increase and will continue to increase and lower through the daytime hours on Tuesday. We may actually see some wintry precipitation (light) break out in scattered form for central and especially western SNE early on Tuesday before we warm all levels. Just be aware of this and also be aware that it is very likely to not last long. The main batch of precipitation will start to enter south coastal Southern New England most likely after 5pm, advancing from southwest to north/northeast as the day progresses and reaching the eastern SNE shorelines by approximately 7-8pm . A few sleet pellets cant be ruled out briefly but will quickly transition to plain rain. A wind driven heavy rain event will commence over all of SNE Tuesday eve and last right into  mid afternoon Wednesday. Though I am not a member of  the “TSA”, I can certainly see some flight delays or even cancellations, so do be prepared and have some patience if you are traveling out of one of the East Coast hubs. Overnight Wednesday into the wee hours of Thursday morning as low pressure moves off to the north of our area cold air on the back side will snap back into SNE and could bring an end to the precipitation with a few flakes flying around. Very dynamic storm with northern energy, southern Gulf of Mexico moisture and rich Atlantic tropical moisture.  This is not your typical “coastal storm”, though to many folks its effects will seem much like that of a Nor'easter, the fact is the winds will never go to the northeast until the low reaches the US/Canada border. Another aspect that prevents this system from being a Nor'easter is the lack of a present cold high pressure system to the north of SNE. Nor'easters thrive off  Low pressure development moving into cold high pressures to the north and the tight pressure gradient created by it and a low pressure working into it, and that simply is not there this go around.  In fact , this storm system will be working off pressure gradient as well but from a west to east perspective, not south to north. This also means the that system is rather progressive with nothing to hold it at bay. All the flow from all directions around the periphery of low pressure takes this thing quickly up the coast and off into southeast Canada before it “bombs out" into a very formidable storm .
Below is the expected rainfall through the entire event from Tuesday pm -late Wednesday. It appears as though with all guidance in agreement that most of SNE is in for a widespread 2-4” of rain. This would be the single most in a storm since June ! Again, much need at the worst time. Funny how Mother Nature sticks it to us at times. The precipitation shield will move from SSW-NNE and with that trajectory its relentless rains over the same areas. Training of heavy downpours are likely and we surely could see street flooding along with big puddles. It would be a good idea to clear storm drains of leaves and waste while you can early on Tuesday. Also try to get up on the roof and get those leaves out of those gutters! It will help, trust me. We will be on the eastern side of the storm so there will be a rich Atlantic moisture feed/transport along with some nasty churning winds at mid and high levels which will be transported to the surface in heavy downpours and thunderstorms….Yes, thunderstorms! Only 48 hours removed from arctic air. Welcome to November in Southern New England. So below is my thinking on rainfall expectations. There certainly could be isolated higher amounts but just too difficult at this time to pinpoint exactly where they line up.

Wind will be the other issue and on the increase again after seeing damaging winds Sunday as early as Tuesday eve with sustained winds of 20-30 mph creeping in from south to north. Sustained winds will increase to 20-40 mph east of Worcester , Ma up and down SNE. Widespread wind gusts will go to 40-50 mph with max gust of  60-65 mph over southeast MA early to mid day Wednesday. Winds of this magnitude are certainly capable for damage to power line and tree’s and loose property objects.

 Coastal flooding not a huge deal as this is not a Nor’easter but there could be minor splash over near the shores. Waves *will* be impressive though, especially southeast facing shores. Possibly as high as 10-15’ with some offshore SNE swell reaching 18’ ! The storm is out of here by Thanksgiving though leaving cold in its wake with high temperature back into in the upper 20’s and 30’s for highs with a gusty NW wind. 

Sunday, November 17, 2013

The Pattern Ahead And Some Winter Thoughts

Overall it has been a very quiet Autumn thus far in Southern New England, temperatures have been up and down just like we are accustomed to this time of year. Many locations saw their first flakes and also their first minor snowfall accumulation and it came right around the average date that it should do so. We have seen some strong cold front passages this season , but they have come with little fanfare in the precipitation department. So, as we now are just past mid month November, where do we stand compared to the mean average of years past in both temps and precip?..The graph below shows the numbers of each. (Click all images to enlarge and please do not redistribute)
So now the big question, how does it look moving forward as we head towards late Autumn and approach the beginning of Winter? I am seeing signals of a pattern change starting as early as mid to late week upcoming. The pattern as of late has been a northern branch dominant one, again not uncommon for this time of year. As we approach December those northern storm tracks tend to shift further south leading to increasing opportunities for the northern energenic branch to phase with the moist southern branch of the jetstream leading to the increase in storm development over the south and south central United States. Step one is to first get a pattern that becomes conducive for storm development in locations that typically are the breeding grounds for storms to then approach the East Coast then either make the ride all the way up to the US /Canada border or depart the coastlines father south at some point. Its that time of year where we need to start watching for these potentials.
In recent years those that are "snowlovers" have almost come to expect a snowstorm in November and even October. Not the case this year, at least so far. Changes start next week and energenic disturbances to the north will start to descend further to the southern United States allowing for a more amplified pattern to take shape. There currently are no strong signals that this leads to any type of storm just yet but surely is an indication of a pattern becoming more conducive for development. That is apparent in the graphic below which shows the 500mb Ensemble  Mean 
 and "spaghetti plots"  as we approach mid to late next week. Showing amplified trough and northern (blue) and southern(red) streams getting closer to interaction.
Again, none of this indicates a set in stone storm or that one will develop, but they can and should start to as early as the upcoming weekend. One other graphic to show you is the favorable teleconnections starting to point in that direction as well. 1st is the North Atlantic Oscillation (NAO)..Which represents Upstream Greenland Blocking in a negative phase. Also conducive for storm development hovering around Neutral. Next is the Pacific/North American Pattern (PNA) which in a positive or trending positive phase develops a ridge across the western US which tends to lead to a trough over the east. Lastly is the Arctic Oscillation (AO) which is just as the name suggests , provides arctic air and a negative or trending negative phase usually does the trick. So, nothing set in stone yet, but its the conduciveness that has me keeping an eye on model as we approach December. 

All signals I have gone over and all that I continue to see as the days pass continue to point to a "traditional" winter over the Northeast. This means the snowiest periods should occur in December, especially mid to late month into 1st half of January . Appears a very cold February is in the cards along with a major storm threat early to mid month. Normal snowfall and temperatures should be the rule through March into April. As of now I feel near normal to slightly above normal snowfall is in the cards for the Northeast this winter season. Thank you for reading !   ~Anthony 

Strong Cold Front Approaching...It's effects.

Sunday, November 10, 2013

   Its been a long time since I have composed a blog and apologize for that. It is very tough during my work season to do such though will most definitely have more time moving forward and once again look forward to that, so lets get into it...
   I provided much talk about the *potential* of an East Coast storm in the works for the middle to latter half of next week. Its nothing more than I offer at any other potential that arrises. I had offered up two different scenarios at which potentially things could iron out and would issue a forecast the moment I felt one had validity over the other. That day came yesterday.
   All signals in recent days have been pointing to the arrival of an anomalously strong 1040mb Arctic High diving south and east from central Canada. This will push a storm off to the north of SNE with a strong trailing cold front approaching Monday. That 1040 high will be positioned off to our west and building during that time. A High Pressure system of that magnitude and strength will now be enough to squash or suppress the southern jet to allow for any moisture that would try to ride up the East Coast and phase with the northern energetic jet to phase well offshore of Southern New England to bring minimal to zero effect from that. That is not to say that this upper level pattern and setup will leave us uneventful.  As we approach Monday night into Tuesday as that huge High builds behind the cold front, the air will be so cold that a line of snow showers and squalls will break out *behind* the cold front along with gusty winds on the order of 25-35 mph. Travel for some across the Northeast will become a bit rough late Monday as squalls will reduce visibility at times. The potential is there for dustings to coatings and even a couple inches for areas hit the hardest. These squalls are often like thunderstorms and very hard to predict timing, location and intensity so watching radar and nowcasting becomes a necessity into Monday eve. Below is a graphic showing the setup and my thoughts as to the areas that may be impacted the greatest. 
One aspect of the forecast that has remained is the surge of cold air that will come down on the eastern side of High Pressure. Temperatures will continue to fall progressively until they bottom out Wednesday am. Many locations east of The Rockies will see their temperatures fall to 10-25° below their average for this time of year and the coldest 2nd week of November since 2003 for some in Southern New England. Get some fresh wood cut ready to throw in that fireplace and get ready for spiked heating bills. The good news is the pattern is fairly quick to swing right back towards moderating warmth as a trough begins to build out west with a ridge developing into the eastern US.
   In other news many in New England saw their first accumulating snows of the season this week, surely nothing to write home about for some but for others that 1st snow is just the time to write home......Always exciting ! My thoughts and prayers continue to be with the Philippines as they were devastated by Super Typhoon Haiyan, one of the worst cyclones to ever make landfall anywhere across the globe in history.   ~Anthony