Snow in the burbs tonight? I have to think so
The much hyped “April Fool’s Day Storm of 2011″ is now forming, but just in the last model run the major suite of models that meteorologists rely upon pulled an early April’s fool on the forecasters by trending the storm weaker and further east in its track up the east coast. That could have major implications for a number of locations, including the philly NW burbs and New England. First for New England, I’m having a hard time believing the winter storm warnings all over upstate NY and portions of Northern VT verify if this weaker and further off the coast solution is right. That rationale may also apply in the PA Poconos, though the Poconos should still get a decent dump of snow on the order of 6 or 8 inches. The implications for the Philly NW burbs are more suttle, but with a further eastward track to the storm, and a majority of the storm occuring at night, I have to think that places like Quakertown, Springtown, and even down to Doylestown, Souderton and Lahaska don’t end up with accumulating snow overnight.
In fact, looking at the radar even at this hour, the indications of banding and the stratiform nature of the radar echos indicates that snow is falling aloft and its making it pretty darn far down into the atmosphere, nearly to the surface! The only thing preventing snow right now in Doylestown and Quakertown is the strong late March sun which warmed the boundary layer abit today (upper 30s). The Boundary layer is the layer of air near the surface. The other critical signal I am seeing is if you look at the winter radar on Intellicast.com, it is already showing areas of pink shading (mixed snow and rain) in upper bucks county, chester county and the lehigh valley. These “pockets” of heavier precipitation which will fall as snow should increase overnight and their location will be unpredictable.. Once the intensity of the preciptation lightens, the preceip will likely go back to rain or drizzle. All of this makes for a really interesting night of weather.
The other interesting thing will be just how far south the pockets of snow get? Could it snow all the way down to PHL and the nearby suburbs? I have a feeling it will not snow here in Marlton, NJ, but who knows. IF the storm can intensify quickly enough and dynamically cool the boundary layer, things can get interesting. In order for snow to be a real possiblity as far south as PHL we would need both the further east track (which we now seem to have) but also a very intense storm (latest models are trending weaker and flatter with the trough and associated low pressure system).
I still think Maine takes the brunt of this thing. It should really unload some serious precip in the form of snow there.
Spring snow chances…
The forecast high for tomorrow is near or above 70F, which is going to make for a beautiful day! I’m noticing budding of the trees already here in Marlton, and daffodils have already bloomed in a few areas. It seems to me that its abit early for daffodils seeing how it is still March. I remember early April as a more likely time for daffodils, but then again I can’t remember exactly. In any event, its been a beautiful stretch of weather lately, but I had a feeling that things had to change after the type of winter we have had, and they may very well change after we have already moved into official Spring next week!
What seems like it may unfold is a relatively tranquil weekend, though not nearly as warm as tomorrow. There may also be some showers around. Then, early next week should remain very mild with some rain and a front moving through. This front means business and has some seriously cold air north of it. Temperatures in eastern Canada will struggle to get into the teens next week with below zero temps at night, which confirms that yes, there still is alot of cold, dry air around. One of the reasons for the big relaxation of temps around here is the postive phase of the NAO which emerged around mid-February. There have been signals that the NAO would go at least slightly negative in later March, and the models had been hinting at a storm around March 24-25th for awhile now.
The lastest runs of the models indicate that another storm will develop along the tremendous temperature gradient which will set up along the front from the Monday/Tuesday storm. The GFS would have that front south of PA/NJ and would place us in the cross-hairs of potential accumulating snow and much colder temperatures. The Euro is about 150 miles north of the GFS and would bring snow to the PA/NY border area as opposed to PHL. As of right now its too hard to tell where that front will set up and where the storm will track. The GFS has been very consistent saying the storm goes across VA and MD. In fact, a few runs of the GFS have shown significant precipitation amounts in the cold sector of this storm, which could be a real surprise after the weather we have been having lately.
The other thing that seems to be getting more clear is for some much colder air to be around later next week and into next weekend. This time of year it gets more complicated to get a snow storm, but there does appear to be some credibility to the GFS solution given the NAO is going negative and there is alot of cold air moving through eastern Canada. So, enjoy the warmth now, its going to be beautiful. It should be much colder this time next week and maybe even snowy! I’ll have updates as this all plays out. Its 7 days out, so my confidence is not tremendously high yet, but it should increase over the next few days.
Big change in 12Z models for Thursday/Friday storm… Stay Tuned…
Quick recap, last nights storm was a nice little storm dumping around 5-6″ of snow here in the Marlton Area. Following last nights storm is a cold, crisp, blue sky day now, and tonight should prove cold with the new snowpack and clear skies. Not to mention the dewpoints are down in the low single digits right now. All eyes are now turning to a bigger, more moisture laden storm which will be heading toward the PHL region later this week on Thursday and Friday. The models had been pointing towards a warmer solution with the storm tracking just northwest or even right over top of PHL. The models seemed to be indicating mostly rain for PHL and the nearby suburbs. However, the 12Z run of the NAM and even more so the GFS now divide the storm into 2 parts, which is critical to what may play out later this week, and end up with a much colder, snowier solution for the PHL area and on north and west.
The key result of the storm breaking into 2 parts is that the first part is very weak and slides out to sea without much moisture on a track basically over PHL. Anything that falls from the first storm would likely be very light rain or drizzle as it will be milder before the 1st storm. However, the second part of the storm is expected to be very moisture laden and it is now looking like it may track further south following the first part of the storm. The other key element of this second storm being delayed and tracking further south is that colder air will be able to seep southward following the first part of the storm setting the stage for what could be a heavy snow event in the northwest suburbs of PHL and maybe even in the city itself. This is a major change, and more model runs need to be monitored to see if the models continue to trend in this direction. However, as of right now, the potential for a major snow event does now exist further south into the PHL region than I would have thought a day or two ago. It also doesn’t hurt that we have a snowpack again which will tend to force a storm further south in its track.
I will post more on this potential situation later today and tomorrow. As I said, this is just one model cycle, but the possibliity of the storm breaking into 2 parts, and the 2nd part being stronger and with more cold air to work with is starting to seem like a logical possiblity. The next few model runs will help clarify the possibilities. Stay Tuned to Robs Weather Blog for updates!!!
Busy week coming up, alot to talk about…
3 potential events are on the table for this week and each has the potential to be a major story.
1) Complex storm system Monday/Tuesday timeframe
2) Possible nor’easter snowstorm Thursday/Friday
3) Coldest air of the winter so far coming down from the arctic this upcoming weekend
First, the storm on Monday/Tuesday is complex in several respects. The models have been all over the map with this storm and have had trouble figuring out whether the storm heading to the great lakes would remain the strongest low and would cause a warmup in the northeast or whether a coastal low will take over and the great lakes low will weaken. What the models do agree upon at this point is that this is unlikely to be an “all-snow” event given some warming that takes place ahead of and during the storm, however the models have trended much colder with this storm in recent runs. So what does this all mean?
Right now it looks like the coastal storm will be the dominant storm. The great lakes low simply won’t be strong enough long enough to cause a real warmup. However, a weak warmfront will be in the vicinity of the PHL region and there will be some warming that takes place aloft well up in the atmosphere. The models are starting to catch onto the fact that with a weak great lakes low, and with all the snow on the ground and the very cold air mass in place ahead of this storm, it will be hard to warm up the surface. So, the potential for ice does exist with this storm. How I see the storm playing out is that it will have the potential to drop a few inches of snow in a heavy burst late Monday and into the morning Tuesday. The storm should then transition to a mixture of snow, sleet and then potentially a period of freezing rain. The severity of this storm will in large measure depend on how long the freezing rain period lasts in any given location. The storm should eventually change to plain rain for a time in most locations, but the rain amounts do not appear to be substantial. The storm would then end as rain/snow showers late Tuesday/early Wednesday. This storm really needs to be monitored to see if the models continue to trend colder, which would mean more in the way of snow and ice.
Following the Monday/Tuesday storm, colder air will build back into the region for the mid-week period. Then, later in the week the Euro is calling for a major northeast snowstorm in the Thursday/Friday timeframe. Its too early to really talk about this storm, but I just wanted to highlight the potential for another storm to follow the early week storm.
The models are very consistent in showing brutally cold arctic air making its way into the northeast this upcoming weekend. This air will be the coldest air of the winter thus far, with sub -20c air at 850mb. Depending on clouds and winds, that sort of air could translate to nighttime temperatures near or even below zero. Indications are that a healthy snowpack will remain or even be increased by next weekend, which will only aid in maintaining the brutal cold characteristics of this airmass as it moves into the area.
So, all in all it is a busy week and depending on how things play out, it could be awfully wintry around here as we move through the upcoming week and into the weekend. The storm early in the week will be a key player. I will post more on that storm as it approaches, it will be interesting to see if the models trend colder or warmer with that storm. For now, it looks like a real mess with snow, ice, and rain.
Major east coast winter storm on the way…
The ingredients are now coming together for another major east coast winter storm. A surface low is beginning to form off the SC coast near a strong jet stream over FL and a temperature gradient, meanwhile an upper level system is moving through the midwest and great lakes. These two players will work together to “bomb” a coastal system near and just south of our latitude and then moving northeast just inside or right over the 70 longitude/40 latitude benchmark. The storm will not be quite as intense or deep as the December 26th storm, but it will have a subtropical moisture feed and explosive intensification. Thundersnow is not out of the question during this storm, more so northeast of the PHL region.
My post from a few days ago called for 4 – 8″ from this storm in the PHL region and that still looks good from my perspective. The biggest question in my mind is if this storm can slow down slightly while it undergoes explosive intensification at our latitude and whether meso-scale banding can set up. If either of those occur, this could be a “footer” type storm for PHL. The temperatures during the snow will also play a big role in the snow/water ratios. 10/1 or 15/1 or even 20/1 can have a big difference on final accumulations. Right now, I would place the big snows in the NYC area into CT and RI and up to MA and coastal ME. Either way, its a plowable, potentially very disruptive snow in the PHL region. This is a volatile storm, so its development and track today will in great measure tell the story of who gets what and whether my prediction needs to be increased, or even decreased. For now I am sticking to my guns with a general 4 – 8″ snow in PHL, with locations well west of the Delaware in the lower end of that range. Areas north and east abit higher.
It will turn windy during the storm and the winds will increase even more after the storm departs tomorrow mid-morning. There should be significant blowing and drifting as this should be a rather powdery snow. It will also remain quite cold with temperatures not exceeding freezing until the weekend at the earliest. Another arctic outbreak is forecast next week, and there are some storms on the map.
Tuesday/Wednesday Storm looks intriguing…
The models seem to be moving toward concensus of a potentially significant east coast winter storm starting Tuesday afternoon through early Wednesday. The models have had some waffling on the track, with the Euro and Nam being pretty consistent on a close to the coast storm. The deterministic run of the GFS has been showing a weak and southern solution which would avoid much snow, and would lead to a very minor event. However, the GFS ensemble mean the past few days has shown a much closer to the coast solution and a much more significant storm.
Looking at the most recent run today at 12Z of the GFS now has come closer to the coast and more significant. The NAM shows an all-out major nor’easter for PHL on north and eastward. The general setup would seem to favor areas near NYC and northeast for the heavier snows, but I think PHL does get a good dump of snow from this system. Of course, its still around 2 days off, and things can surely change. The 12Z NAM does look impressive for this storm, so it bears watching. The key for this storm will be how quickly the northern and southern branch energy can phase and intensify off the coast. Right now, I like the idea of a substantial snow event, in the neighborhood of 4 – 8″. I’m not ready to talk about higher totals, but if the NAM idea plays out and the storm intensifies quickly and hugs the coast, we could easily talk a foot or more from this sort of synoptic setup. That sort of scenario may also bring the possibility of mixed preciptiation to the coastal areas near ACY. However, for now, I see an all snow event even at the coast.
One thing we do know is it will be cold tonight and tomorrow. It should also be very cold after the tues/wed storm, including the liklihood of some of the coldest nights of the entire winter on Thursday and Friday nights. With the expectation that we will have a fresh snowpack by then, it will likely get down into the single digits on one or both nights in parts of the area. Climatologically we are entering the coldest time of year, so this seems fitting. It should remain close to or below freezing for the next 6 – 7 days.
More on the potential storm tomorrow…
3 part storm!?
My last post discussed the potential for a 2 part storm from the period starting late Thursday night through later Friday and maybe into Saturday. The idea was that a clipper system would hit us on Friday and then a Coastal low would develop later Friday and Saturday. However, the models subsequently caught on to the fact that in reality neither of the 2 parts discussed above would likely impact our region, instead a third, and pretty rare feature will impact us. The 3rd part of the storm is referred to as a “Norlun Trough.” A Norlun Trough is a feature that develops between an upper level low pressure system over the Great Lakes or somewhere inland of the coast and a surface low out over the ocean. The 2 storms are far enough apart that they do not fully phase with each other to form a major nor’easter, but yet close enough that a low pressure trough develops between the two storms. This can lead to a narrow (50-100 mile wide), but very intense band of precipitation with a typical orientation of southeast to north west. These troughs would often setup over coastal Maine during my time there, but they seem to be much more rare in the mid-atlantic. They are also extremely difficult to forecast as a slight shift in their position can mean a big difference in snow amounts.
Latest indications are that such a trough will develop tomorrow and that it may be very dynamic, i.e. it may have strong upward motion and good moisture flow from the ocean and could create 8 or even 9 inches of snow where the band sets up the longest and is the strongest. Most models indicate the PHL region gets some snow from an initial clipper type system, and maybe even some snow from the southern side of the Norlun Trough as it shifts northeast ward. However, this positioning of the trough would mean PHL would not bear the brunt of this situation, and areas around NYC and northeast would stand to really get hit by this trough. Of course, given the volatile nature of this sort of a trough, it has to be watched very carefully to see where it ends up positioning itself.
Regardless of what happens tomorrow, whether it is a dusting, 1″ or 4″ in the PHL region, it will be cold and remain cold through at least the next 7 days. Not to mention there has been a very interesting storm hinted at by the models for next Tuesday/Wednesday. That storm needs to be watched as it appears to have the potential to be a Type A east coast winter storm… More on that in the coming days. For now, should be fun to monitor this unusual norlun trough development tomorrow.
2 Part Storm Potential – Jan. 6th through 8th timeframe
We got several hours of unexpected sun ahead of the front yesterday, and that certainly boosted temperatures into the 50s across inland areas. In fact, I drove through the Pine Barrens yesterday on my way to LBI (I’ve never been to the beach in January, and it was alot of fun!), and the car thermometer read 54 degrees in the pines. Then, to our surprise, the temp plummeted to 39 as we approach the island and it was very cold out there.
I have to say, the volume of snow from Manahawkin out onto the island was staggering. It was odd as the snow piles would make you think you were at a ski resort in the mountains, yet we were at the Jersey shore. I can only imagine how that island looked immediately after the storm prior to any melting. I hope to post some of our photos on my blog soon, it was incredible. Also of note, there were big ice bergs floating in the bay and large portions of the bay were frozen. Really a sight to behold down at LBI yesterday.
The front basically behaved as expected, except for the sun yesterday which boosted temps and the negligible drop in temps last night with the clouds and southerly flow. Even today, temps are more hestitant to drop than I expected, but you can see the dewpoints dropping back with a 34 degree dewpoint at PHL at this hour. An area of precipitation is developing to our southwest, and it is moving northeast. I note on the 12Z GFS some indication that additional precip could develop from this feature at a time when the 0 degree 850 mb line will have moved south. Not sure whether this means anything, but maybe a snowflake or two could mix in with any rain showers later this evening with this feature. especially over NJ.
Seasonably cold this week, and I still expect temps to be mostly in the upper 30′s by day and 20′s by night. Storm potential for the weekend remains, but as usual, the models are all over the place in handling northern and southern energy and how those streams may interact and whether a storm can develop quick enough to be a big snow producer. It does look cold enough at that time frame to talk snow, rather than precipitation type issues.
I’m not ready to make any predictions on this storm, though it does appear to be in 2 parts. The first part will be similar to a clipper system coming through from the north. The clipper itself won’t have tremendous amounts of precip with it, but it could produce some 1 – 3″ type snows on the 6th-7th. Then, when that storm hits the coast, and interacts with southern energy, a storm should develop, and become pretty strong around the 8th. At this point, that storm would appear to be more of a threat to New England, but then again, the models often change their tune closer to an event, and I wouldn’t let your guard down in the PHL region just yet.
Indications are for some pretty cold air to follow the weekend. Should be an interesting week to see how this all unfolds.
In a change, I’ll highlight weather in the South, around Nashville, for some of my new readers. Today, the front which will cross the Northeast later tonight and early Sunday is already most of the way through the mid-State of TN today. Light showers accompanied the front in TN with a few embedded elevated convective elements. No severe weather with this feature however. Behind the front, expect temps to fall from the low to mid 50′s back into the 40′s as the day wears on and temps tonight should bottom out in the mid 20′s. The remainder of the week looks generally dry and breezy with highs in the mid to upper 40′s and lows in the upper 20′s. Watch out in TN around the middle of January for a significant arctic outbreak, colder than those experienced in December and a potential return to snowy weather in that same timeframe in the mid-state.
Ok, enough on TN weather for now, back to my main focus of Northeastern weather. So far, my feelings on today’s frontal passage hold true. After the front passes, tomorrow will remain mild with the cold air advection holding back over western PA and the downsloping flow creating compressional heating of the airmass coming over the mountains. Next week looks dry and seasonably chilly with highs in the upper 30′s in general, lows in the 20′s.
With regard to the potential storm on the 7th, the 12Z Euro run made things interesting spinning up a vigorous east coast nor’easter. However, the 0Z backed off and the GFS really has never had such a storm yet. However, the GFS does have the various players needed for a big storm hanging around in the January 7th timeframe. The GFS is dreadful at this time range, so I’m not worried that it doesn’t have the storm yet. This time frame is worth monitoring this week though.
Also, moving beyond the 7th and into the middle of the month, La Nina seems like it will step aside once again to the incredibly negative NAO and Arctic Osillation and we will once again see major blocking over Greenland and Northeastern Canada, with a potentially major arctic outbreak affecting the Midwest and spreading to the Northeast around the middle of the month. This cold outbreak could match or potentially exceed the cold outbreaks in December. However, with the -20 850 mb line not expected to get to PA, I do not see excessive cold, but this will have to be watched. A few days with temps not out of the teens and single digits at night seems possible, depending of course on the extent of the snowpack, if any, at that time.
Happy New Year to all and best wishes for a wonderful 2011!!
Week recap and looking ahead
Well, we did see some very cold nights this past week, we dropped to 11 here in Marlton Wednesday night and we haven’t seen very much snow melt thus far. So far today some snowmelt is evident, but with the dewpoint remaining in the 20′s and the long nights, the melt will be very controlled and slow, and a majority of the snow should make it well into the weekend, if not beyond. It will really depend on how high the temp/dewpoint gets this weekend prior to the frontal passage on Sunday.
As a matter of comparison, last December we received 28″ of snow on December 18th here in Marlton, we then had a tremendous warmup and heavy rains on December 26th throuth 28th. High temps of 56 and 52 occured with a low of only 42 during that period. In addition, we received nearly 2″ of rainfall. That period melted most all of the 28″ of snow, aside from the huge piles. It was an impressive melt of such a deep snow.
In contrast, this year, we had around 12″ of snow from the recent blizzard, and highs this weekend are expected to remain in the upper 40′s with dewpoints into the upper 30s. The other key difference is we are only expecting from a tenth to a quarter inch of rain as the front is very extended and weak at our latitude with the parent low tracking way west through the upper midwest and towards James Bay in Canada. A track that far west doesn’t have the ability to produce a strong southerly flow here nor do fronts of that type usually produce much by way of rain here. In fact, with remaining snow cover, its possible cold air damming could set up in portions of the northeastern US with this storm. I do not see any cold air damming in our local region, but I do think temps stay in the 40′s and likely do not take a run at 50′s (unless we get more sun than expected tomorrow).
WIth all of that said, I do not see the tremendous snowmelting potential with the front this weekend and wouldn’t be surprised to see a good deal of snow survive to next week. It will be interesting to monitor the snowmelt. So, all in all the storm for this weekend is unfolding exactly as I thought it would a few days ago with my last post.
Following the front, the -10 850mb line will be getting close to SE PA, and if you check the NWS forecast for monday through wedesday of next week for this area it includes some awfully optimistic temperatures in the low 40′s. With that -10 850 mb line nearby and good cold air advection, I think the nws is shooting too high and temps will more likely be in the 34 – 38 range early next week.
Beyond that, some have been talking about a storm for January 7th timeframe, i can see how a storm would be conceivable for that period, but for now I’m not overly excited. Looks to me like a southern stream storm passes out to sea and development is too late in the game to affect the eastern seaboard. Of course, we are heading in to early January, and things can get interesting quickly. I’ll be keeping an eye on things for sure.
