Archive for accumulation
Rain on the way once again
Posted by: | Comments5:15 PM
Another round of moderate to heavy rain is on the way as an area of low pressure over the Tennessee Valley tracks to the Mid Atlantic coast tonight.
Steady rain over the eastern Great Lakes is associated with the warm front that is currently over the Mohawk River Valley and central Hudson Valley. The surface low pressure system is currently over Kentucky and will move towards the Delaware coast overnight. The steady rain over the Ohio Valley will move over the Philadelphia and New York City metropolitan area late tonight through tomorrow morning. The heaviest rainfall will be focused over central/southern New Jersey and the Philadelphia metropolitan area with up to an inch of rain. Lighter rainfall is expected to the north, including the New York City metropolitan area, with a tenth to a half inch of rain expected. The rain will produce minor flash flooding along the Passaic and Raritan Rivers through tomorrow afternoon. As the low pressure system exits, some snow will mix in at the very end over the higher interior. I want to stress that NO accumulation is expected and I doubt any snow will be seen along the coast as dry air will follow rapidly behind the falling temperatures, which will be in the 40′s along the coast.
High pressure will take hold on Friday night and remain in control through Sunday evening with dry conditions and scattered clouds. Temperatures will remain cool with highs struggling in the 30′s and 40′s for highs on Saturday and 40′s and 50′s on Sunday.
Another area of low pressure will bring another round of moderate to heavy rain late Sunday night through Tuesday morning as the low pressure system slowly exits. Another round of heavy rain will bring a continued threat of flash flooding to much of the northern Mid Atlantic but especially for northeastern New Jersey where the Passaic and Raritan Rivers are already near flood stages due to the previous rain events.
The good news is that moderate is on the way with high pressure taking hold by Tuesday night. High pressure will remain in control through the end of next week as a large upper level ridge builds throughout the eastern United States. At first, most locations along the coast will remain cool under a persistent northerly wind with marine influence. However, after Wednesday temperatures will be able to significantly modify with 60′s and 70′s by the end of the week.
-- Weather When Posted --
- Temperature: 60°F;
- Humidity: 51%;
- Heat Index: 60°F;
- Wind Chill: 59°F;
- Pressure: 29.77 in.;
Ocean storm brings rain/snow mix and some coastal flooding today
Posted by: | Comments8:00 AM
The coastal low off the Virginia/North Carolina coastal waters this morning continues to slowly exit to the east-northeast this morning. The coastal low actually has ended up slightly closer to the coast than expected, but is now moving into the Atlantic with diminishing impacts through the rest of the day. However, much of the northern Mid Atlantic has felt the influences of this low pressure system more than most thought, as the precipitation shield expanded further north and west than what has been suggested on guidance, which was warned by me for several days.
The majority of accumulating snowfall has already occurred for many locations west of the Delaware River with on average 2 to 4 inches of snow has accumulated has the precipitation shield expanded north and west last night. Through this morning, snow will continue to taper off to scattered snow showers with little significant impact to travel conditions.
Closer to the coast, a mix of rain and snow is moving through the region with temperatures remain above freezing for most locations. An accumulation of 1 to 4 inches is expected over the Hudson Valley and Connecticut where temperatures will remain at or just below freezing while the immediate New York City metropolitan area through the northern suburbs of Philadelphia will have accumulations of around 1 to 3 inches, mostly on colder surfaces.
Along the coast, a mix of rain and snow will continue, but given that none of the snow is accumulating, the precipitation might as well be rain. Precipitation totals through this afternoon will range from a half an inch to as much as an inch along the immediate coastline. Winds will be sustained at 15 to 30 mph with higher gusts through this afternoon.
The most impressive impact from this storm will be the coastal flooding and strong winds along the coast and over the coastal waters. A coastal flood warning has been issued for all of the New Jersey coast and a coastal flood advisory has been issued for Long Island through tonight. As the low pressure system continues to intensify, gale warnings for sustained wind of 20 to 35 mph and gusts over 40 mph has been issued for all of the New Jersey coastal waters through tonight.
Once this low pressure system exits tonight, the weather pattern will become much more tranquil with a steady moderation in temperatures expected. High pressure will become established over the Tennessee Valley tomorrow through Sunday with dry conditions, scattered clouds, and temperatures averaging near normal with afternoon highs in the upper 30′s to mid 40′s through the period and lows in the upper 20′s to mid 30′s. Temperatures will moderate into the 40′s and lower 50′s by this weekend.
A cold front will move through the northern Mid Atlantic from the Great Lakes on Monday night and Tuesday morning with scattered showers, mostly rain, and slightly cooler temperatures. However, no significant turn to colder weather is expected over the next seven days.
-- Weather When Posted --
- Temperature: 33°F;
- Humidity: 86%;
- Heat Index: 33°F;
- Wind Chill: 23°F;
- Pressure: 29.58 in.;
Light rain and snow tonight leads to minor accumulations
Posted by: | Comments6:36 PM
I have been hinting for some time that the precipitation shield for tonight’s storm was going to be more expansive than what was being forecasted. However, I am not very impressed with the accumulation potential for this storm. The first and foremost is the warm boundary layer temperatures.
Besides the fact that the surface freezing line is located over central New York and central Pennsylvania, the dew points this evening range from the mid to upper 20′s over the interior and lower 30′s along the coast. The problem with these temperatures and dew points is that the wet bulb temperatures are generally above freezing. Further, there is little if any additional cold air advection to this storm, so basically what you have is what you’ll get as far as the state of the atmosphere.
Make no mistake about it, this storm is very dynamic and impressive. In fact, convection is developing throughout the southern Mid Atlantic coast down through Florida with numerous lightning strikes. The precipitation shield is expanding as far west as central Virginia and will like encompass the entire Philadelphia and New York City metropolitan area. The temperatures above 950 MB for most locations is below freezing, suggesting that the precipitation type that will dominate will be snow. The issue, as described above, is that the snow simply will not be able to stick on too many place.
The updated snowfall map is basically for grassy and cold surfaces where the snow will be able to accumulate. Most locations will receive an inch of snow while a few isolated convective bands can push snowfall totals up to 3 inches. Given that the coldest model guidance available had surface temperatures from 32 over northeastern Pennsylvania to 37 degrees along the coast, any accumulation on pavement will be extremely limited.
-- Weather When Posted --
- Temperature: 37°F;
- Humidity: 80%;
- Heat Index: 37°F;
- Wind Chill: 37°F;
- Pressure: 29.85 in.;
Warmer times ahead after glancing blow
Posted by: | Comments7:48 AM
A strong area of low pressure is rapidly developing along the Gulf Coast, however this storm is staying far enough south and east to not have a major impact on the region’s weather.
The “pattern changer” as I like to call it is not over the Gulf Coast however but the West coast as a strong disturbance from the Pacific drives east towards California. This disturbance is dislodging the once powerful ridge over the western United States and causing the entire 500 MB pattern to shift eastward. As a result, the storm track for the storm over the Gulf Coast will have to move east-northeast rather than northeast and therefore stay well south and east of the Philadelphia and New York City metropolitan area.
Clouds will increase through the day with temperatures in the upper 30′s over the interior and lower to mid 40′s along the coast. The once impressive snow pack will continue to shrink under the influence of the modifying air mass in place. The low pressure system along the North Carolina coast this evening will continue to move east-northeast tonight into tomorrow morning. Precipitation will expand as far west as the Delaware River Valley with scattered snow showers overnight and rain/snow showers along the coast. Any accumulation of the snow will be found on the usual colder surfaces like the grass and on car tops, otherwise only wet roads are expected as surface temperatures remain 2 to 4 degrees above freezing throughout the region. Further west over the interior, besides increasing clouds and a slightly strong northeasterly wind, no appreciable impacts will be felt from this storm.
High pressure will dominate thereafter from Wednesday evening on through Monday afternoon. High pressure will position itself over the southern Ohio Valley and northern Tennessee Valley through the period with dry conditions, scattered clouds, and temperatures averaging near normal. For most locations temperatures will remain in the 40′s for highs through the period, with a few shots at the lower 50′s by Sunday and Monday afternoons. A strong cold front will approach the region on Tuesday afternoon with scattered showers and a slightly colder air mass.
-- Weather When Posted --
- Temperature: 30°F;
- Humidity: 80%;
- Heat Index: 30°F;
- Wind Chill: 23°F;
- Pressure: 29.91 in.;
Snow showers hang around for another day
Posted by: | Comments10:42 AM
The upper low from the winter storm a few days ago simply will not quit. I’m about to call this storm, Rocky Balboa as every time you think it is finished, the storm gets back up for another round.
Luckily the next round of this storm will be focused well to the north and east of the northern Mid Atlantic as the upper low currently over eastern Pennsylvania will capture a Sub Tropical disturbance over the Gulf Stream. The Sub Tropical disturbance will intensify into a very nasty winter storm for northern New England and the Canadian Maritimes through tomorrow. The influence of additional Atlantic moisture into the upper level low will aid in keeping widely scattered snow showers in the region through this evening. However, no significant accumulation is expected with these snow showers as surface temperatures rise into the upper 30′s to around 40 degrees for afternoon highs.
The upper low will finally move to the east of the northern Mid Atlantic tonight, bringing about a northwesterly flow and drier conditions to much of the Mid Atlantic for tonight through Tuesday. High pressure will take hold at the surface with temperatures return to near normal levels. High temperatures in the mid 30′s to lower 40′s throughout the region will support a steady melting of the snow pack through the day and a refreeze at night, prompting the threat of black ice each morning, so use caution.
Another winter storm threat is materializing for late Tuesday night into Wednesday morning. At this time, the most significant impacts from this coastal low will remain well south and west of the region. However, some moderate snow accumulations, especially over southern/central New Jersey is possible. This time of year, not only is the track but also the timing of the heaviest precipitation will be key for determining accumulation potential. Due to the higher sun angle and the marginal boundary layer temperatures, snow may fly on Wednesday morning, but the actual accumulation of that snow may be significant limited. Otherwise, this storm is not in any way looking as significant as the storms experienced through much of February.
High pressure returns for Thursday through Saturday with dry conditions and moderating temperatures in the 40′s. Any snow that is left from the previous winter storm will be melting rapidly as a more Pacific air mass influence is felt throughout the nation.
-- Weather When Posted --
- Temperature: 35°F;
- Humidity: 74%;
- Heat Index: 35°F;
- Wind Chill: 29°F;
- Pressure: 29.63 in.;
Snow showers continue as storm slowly exits
Posted by: | Comments10:27 AM
The influences from the winter storm of the past two days simply will not quit. A strong upper low that caused the initial surface low to stall over New York City and then drift through Long Island continues to sit right over the central Hudson Valley. Strong mid level disturbances are rotating around this upper low and producing areas of scattered snow showers. A few of these snow showers are producing heavy snow squalls that can rapidly reduce visibility and hamper travel conditions. Temperatures at 500 MB down through 850 MB are very cold, much colder than the temperatures expected at the surface today. These types of conditions, more normally experienced in the summer, is creating a very unstable atmosphere that will increase in intensity up through the mid afternoon hours as surface temperatures warm. As a result, the intensity and coverage of these snow showers will increase throughout the Philadelphia and New York city metropolitan area. Snowfall amounts for most 
locations will remain under an inch of snow, however in some rare cases accumulations of 1 to 3 inches will be possible and in some extreme cases if snow showers train over a specific location for a long time as what is happening over the central and northern Hudson Valley and Mohawk Valley of New York and developing over central New Jersey and the Philadelphia metropolitan area snowfall amounts of 3 to 6 inches will be possible. However, I stress that would be significantly isolated and most likely will not materialize, but the threat does exist.
The areas high lighted to the left are where the best mid and lower level forcing mechanisms including upper level divergence, low and mid level moisture convergence, weak frontogenessis, and strengthening instability are developing, which will lead to snow showers redeveloping over these locations throughout the day. Therefore minor to moderate accumulation is possible in these location. Elsewhere, snow showers will be widely scattered.
High pressure will slowly take hold tonight through Monday with snow showers becoming more isolated and temperatures moderating back to near normal levels. High temperatures in the afternoon will return to the 40′s along the coast, supporting a slow melt of the snow pack across the region. Of course, temperatures will fall below freezing at night, producing the threat for black ice once again so treatment of pavement for ice potential will be needed.
Another winter storm is possible by Wednesday as a moisture loaded area of low pressure exits the Gulf of Mexico and moves towards the Mid Atlantic. The exact storm track is still in question at this time, however the areas most likely to receive accumulating snowfall from this storm will be over the Philadelphia metropolitan area up through north-central New Jersey and the immediate New York City metropolitan area. Given the development of the 500 MB pattern in this time period, northeastern Pennsylvania through the Hudson Valley, and Connecticut will likely have limited impact from this storm.
High pressure return by Thursday afternoon through Friday with quiet conditions setting in and temperatures falling back to slightly below normal levels with highs in the 30′s throughout the region.
-- Weather When Posted --
- Temperature: 32°F;
- Humidity: 74%;
- Heat Index: 32°F;
- Wind Chill: 22°F;
- Pressure: 29.52 in.;
Philadelphia misses out on steady precipitation
Posted by: | Comments5:35 AM
The coastal low this morning has moved further south than forecasted and as a result the brunt of the light precipitation expected to impact the Philadelphia metropolitan area and southern New Jersey will remain off the coast. While temperatures are cold enough to support a frozen mix of precipitation, the steady precipitation has tracked just off the southern New Jersey coast and is expected to remain off the coast through the morning. Scattered rain and snow showers will move through the Philadelphia metropolitan area and central/southern New Jersey through the early afternoon hours, however no accumulation is expected from these showers. The New York City metropolitan area will remain dry yet with broken cloud cover.
One thing that is not lacking is the ability for the upper level disturbance driving towards the Mid Atlantic coast to produce strong lifting. Cloud tops continue to rapidly cool off the North Carolina and Virginia coast suggesting strong lifting is occurring. The coastal low is rapidly deepening with surface pressures down to 998 MB at the center of this low pressure system.
The low will exit to the east with some breezy conditions through the early afternoon hours. The rest of the day will have clearing skies and temperatures in the 40′s with no significant impacts expected.
Additional updates for the weekend and early next week on the way!
-- Weather When Posted --
- Temperature: 33°F;
- Humidity: 69%;
- Heat Index: 33°F;
- Wind Chill: 27°F;
- Pressure: 29.94 in.;
The cold pattern is coming! The question is when not if!
Posted by: | Comments9:22 AM
Premium Post
This morning I’m looking at an overwhelming amount of data pointing to a returning cold pattern that frankly, I’ve had a hard time piecing together exactly what I’m seeing and what it means for the northern Mid Atlantic and the East coast as a whole. The implications of the developments at the stratospheric level will have long lasting impacts on not only February but also the early Spring months. However, let’s take one step at a time.
-- Weather When Posted --
- Temperature: 35°F;
- Humidity: 69%;
- Heat Index: 35°F;
- Wind Chill: 30°F;
- Pressure: 29.96 in.;
More thoughts on Friday’s threat
Posted by: | Comments8:05 AM
Premium Content
Up to this point, I’ve looked at a wide range of guidance for the event on Friday. This morning I will share my initial thoughts and where I think the best potential for a heavy snowfall is possible.
To continue reading More thoughts on Friday’s threat, you must be a premium member
-- Weather When Posted --
- Temperature: 33°F;
- Humidity: 86%;
- Heat Index: 33°F;
- Wind Chill: 27°F;
- Pressure: 29.94 in.;
Light snow showers through tonight
Posted by: | Comments5:17 PM
Bands of snow showers continue to rotate south and west around the strong coastal storm east of Maine. These snow showers are generally light and will not produce much in the way of accumulation. However, a few bands of snow are producing moderate snowfall.
For example, one band is currently over the Long Island Sound and dropping south. A stronger band is over central New Jersey of Middlesex, Monmouth, northern Ocean, and northern Burlington Counties. These bands of snow are capable of a dusting to an inch of accumulation but can produce an isolated accumulation up to two inches with ocean enhancement. This is especially a possibility over the northern shore of Long Island.
The rest of the evening will be cold and windy. Winds will continue to be from the northwest around 10 to 25 mph with higher gusts. Temperatures are falling through the 20′s and into the 10′s, which supports wind chills in the single digits.
The cold pattern will continue tomorrow without much relief. Another round of scattered snow showers are expected through tomorrow afternoon as well.
-- Weather When Posted --
- Temperature: 21°F;
- Humidity: 62%;
- Heat Index: 21°F;
- Wind Chill: 4°F;
- Pressure: 29.56 in.;
Freehold
57°
Albany
59°
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