ScreenHunter_296 Mar. 22 13.22

Public Analysis: The Wild Ride of Two Seasons Continues On

The wild roller coaster ride of temperatures that we are currently experiencing has taken another deep plunge-as promised. Though, this wild ride will continue as we make our way back up the tracks to much warmer temperatures by this weekend. The question is, will there be another rapid drop back down to winter-like temperatures? Find out below!

The brief warmer weather we saw earlier this week where temps made it into the 50’s just yesterday, was violently replaced with a fresh injection of Arctic air this morning. This Arctic airmass was ushered in by a strong cold front associated with a large and impressive high pressure system centered over Great Lakes region as of this afternoon. This has caused temps to plummet to the upper 20’s to mid 30’s across much of the area, with some locations in Southern New Jersey in the low 40’s. For the northern sections of the area, this is a good 20-25 degrees colder than it was yesterday. Things become even colder when you factor in the current wind chills across the area, which are ranging from the low 20’s, teens, and even single digits across some of the northern sections!

The aforementioned large area of high pressure and a deepening low pressure system over the Canadian maritimes and Nova Scotia are working together to create a tight pressure gradient over the Northeast-which is making for a very gusty afternoon. These gusts have been responsible for numerous reports of downed tree limbs, localized power outages, and even some delays at Newark and La Guardia airports. We anticipate wind gusts to remain in the 40-50 mph range for the rest of the afternoon, with some isolated gusts of up to 60 mph possible (especially along the shores of Long Island and Connecticut where tree and roof damage has been reported)  There is currently a Wind Advisory from the NWS in effect for the NYC Metro area until 6pm for the potential for downed tree limbs, some trees, and power lines.

As we continue through the afternoon, only streams of high clouds are expected as the atmosphere remains extremely dry, with the only source of moisture for clouds/precipitation being the Great Lakes. As we get closer to sunset, the winds will begin to settle down as the high pressure system starts to envelope the area. The combination of light winds, very cold upper levels of the atmosphere, and clear skies will lead to near-perfect conditions for what is called “radiational cooling”. Since the water vapor in clouds tend to trap heat quite efficiently, when we remove the clouds and wind, we allow the temperatures to “radiate” back into space since there is no longer a barrier holding them in. This means that tonight is going to be a very cold night for the entire area, with temperatures dropping into the teens and single-digits.

One thing to mention is that those who still have snow cover need to be extremely cautious of black ice tomorrow morning as any water from melted snow will quickly freeze this evening and potentially cause very slippery conditions tomorrow.

Latest surface observation, radar, visible satellite, and frontal positions over the Northeast this afternoon (Courtesy of Simuawips.com)

Latest surface observation, radar, visible satellite, and frontal positions over the Northeast this afternoon (Courtesy of Simuawips.com)

As we move into tomorrow, high pressure will be in control of the weather once again. Relatively clear skies and light winds will be likely across the entire area for yet another day. Thursday shouldn’t be as cold as it was today as we should see highs in the upper 30’s and lower 40’s across most of the area just ahead of a building upper-level ridge. Later in the day and into tomorrow evening, some high clouds should begin to move in ahead of a warm front that will be situated over the Ohio Valley. Lows should still be cool Thursday night, with temperatures hanging into the mid to upper 30’s across most of the area.

As the ridging that we mentioned earlier begins to build in on Friday, the high pressure that has been in control for today and tomorrow will begin to exit off to the east. Once off the Mid Atlantic coast, this will allow winds from the southwest to move in and usher in a warmer and more moist airmass. Just ahead of this airmass will be a weak warm front that has the potential to bring some light precipitation to the area in the morning hours. There is the possibility that some of the northern locations and higher elevations may possibly see a mix of wintry precipitation in the form of freezing rain and sleet. Otherwise, Friday should be a more seasonable end to the work week as we clear out, and temperatures reach the upper 40’s to mid 50’s by the afternoon hours.

12z NAM 2-meter temperature anomaly showing much more seasonable temperatures across the area by Friday afternoon with warmer air on the way (Valid 8pm Friday)

12z NAM 2-meter temperature anomaly showing much more seasonable temperatures across the area by Friday afternoon with warmer air on the way (Valid 8pm Friday)

By Saturday much warmer conditions are expected as the warm front begins to lift across our region, with winds from the southwest reinforcing the warm air from the much colder temperatures just to the north. With just a few clouds likely and light winds across the area, highs should have no problem getting into the upper 50’s and middle 60’s-with some locations in Southern and Central NJ possibly seeing temperatures rise into the 70’s! By this time, most locations could see temperatures as much as 12 degrees above normal, which will be an amazing contrast to today (Wednesday) 

Back on Monday we mentioned the potential for some wintry weather across the area this weekend as a complex situation involving a cutoff low in the Central US, a large upper-level ridge over the East, and another upper-level system in Canada. I mentioned how the upper level system in Canada would have to be able to “press” down hard enough on the ridge over the east coast to create “confluence” that would block the storm system in the Plains from cutting to our west. As of this afternoon, it appears that the upper level system in Canada will not be able to force the confluence far enough south to keep the storm system from cutting to our west through the Ohio Valley on Sunday/Monday. When this low passes to the west of the area, warm air from the mid levels of the atmosphere will surge north and prevent any snow from falling, but with colder air in the lower levels, it is *possible* that some locations in Pennsylvania, Southeast NY, Northern NJ, and New England see some sleet or freezing rain at some point. For now, New York City and points south look to remain all rain. Again, there is still some uncertainty here, so make sure to check back for updates!

12z GFS 500mb map showing the different pieces that have to come together for a very light wintry event for portions of the Northeast (confluence marked by the wavy line)

12z GFS 500mb map showing the different pieces that have to come together for a very light wintry event for portions of the Northeast (confluence marked by the wavy line)

This system will exit the region with more clearing expected by Monday night. Temperatures may warm up again later next week if ridging builds into the Northeast US as some models indicate. However an active pacific jet could keep weather conditions more unsettled over the entire region, with the possibility of one or two more cool shots.

We will continue to monitor this system throughout the rest of this week, so make sure to stay tuned for future updates. Again at this time, we do not feel there is support for significant wintry precipitation this weekend, especially closer to the coast.

For more information and posts like this one, make sure you sign up for Zone Forecasts — where multiple detailed articles, videos, and interactives are posted each day. Also, come interact with our staff and many other weather enthusiasts at 33andrain.com!

Have a great day!

 

Steve Copertino

ScreenHunter_294 Mar. 20 14.51

Public Analysis: A Tale of Two Seasons This Week

Astronomical Spring has finally arrived even though meteorological Spring has been here since March 1st. The only difference between the two is that meteorological Spring is based on the division of our calendar into four separate seasons, each having three months in each season. This makes it easier for observations and the ability to compare things like seasonal statistics. Astronomical Spring (or the Vernal equinox) is determined by the 23.5 degree tilt of the Earth’s rotational axis in relation to the Earth’s orbit around the sun.

Regardless, today has been mostly sunny across the entire New York Metro area with a few high clouds noted on the latest visible satellite imagery. Temperatures have been able to rise in the high 40’s and lower 50’s across much of the area, which is right around normal for this time of the year-if not a few degrees below normal. Winds are generally calm across the area, but portions of NJ, NYC, and Long Island are seeing some winds in the 10-15 mph range with higher gusts, which are bringing wind-chills into the low 40’s in some locations, so we’re not feeling the Spring weather just yet. As we move on throughout the rest of the day, predominantly clear skies will be commonplace over the area as we await the arrival of a weak frontal system that it currently situated over the Ohio Valley.

Current visible satellite, surface observations, and regional radar composite for the Northeast US (Courtesy of Simuawips.com)

Current visible satellite, surface observations, and regional radar composite for the Northeast US (Courtesy of Simuawips.com)

This weak frontal system is currently over Indiana, producing some strong showers and thunderstorms which have dropped hail up to 2″ in diameter as they track to the south-east. This area of showers, in conjunction with a very weak mid-level system located southeastern Canada will work towards our area later this evening. While the main area of stronger thunderstorms will die-off quite quickly as they move into a stable airmass, the associated showers and cloudy weather will begin to take over during the overnight hours.

With increasing cloud cover, temperatures will likely struggle to get lower than the mid 30’s to low 40’s for this evening’s low temperatures across the area. This afternoon’s computer model guidance has the bulk of the shower activity from these systems remaining to the south west of the NYC area as a very weak area of low pressure forms along the frontal system that will push through the region tomorrow morning.

After some limited light showers and clouds initially, Tuesday afternoon should clear up quite nicely as winds from the northwest (moving over deep snowpack in NY and PA) usher in drier air. Temperatures should be able to rebound quite quickly tomorrow into the lower to middle 50’s across much of the area by late afternoon, which will be a few degrees above normal.

This above-normal air mass will be very short-lived as a stronger cold front associated with a large area of high pressure centered in Canada will slowly make its way towards the Northeast. By Wednesday morning this cold front will be situated right to the north west of the metro area, with winds from the NW steadily increasing. Once the front passes, temperatures will likely struggle to push out of the 30’s across the entire area, with gusty winds making it feel like its even colder in most locations.

3km NAM model showing the strong cold front and its associated winds and temperatures at 850mb or 5,000 feet in the atmosphere.

3km NAM model showing the strong cold front and its associated winds and temperatures at 850mb or 5,000 feet in the atmosphere.

Temperatures should remain 10-15 degrees below normal until at least Thursday, before a large ridge begins to build over the central part of the country and begins to head east. This ridge could possibly bring temperatures back to normal or even back to above-normal conditions by this weekend. However, we are monitoring the *potential* for some possible wintry precipitation across the northern sections of the area this weekend as a very delicate and complicated pattern takes shape.

The models at least agree on a cutoff low pressure system developing over the US Plains states by Friday afternoon with a large ridge of high pressure situated over the Southeastern states. With another upper-level system in Canada pressing down on the upper level ridge to its south, this setup would create “confluence” to our north, which would essentially limit the storm system in the Plains from cutting through the Great Lakes like these types of systems usually tend to do. Instead, with a large and cold high to the north, the storm would have the potential to stay underneath that high pressure and track more eastward. While it is getting very late in the season, this setup does have the potential to produce a redeveloping low pressure system off the Mid-Atlantic coast as the initial cutoff low transfers its energy.

500mb map from the GFS showing a very complex situation developing for this weekend regarding any chance for wintry precipitation

500mb map from the GFS showing a very complex situation developing for this weekend regarding any chance for wintry precipitation

We will continue to monitor this system throughout this week, so make sure to stay tuned for future updates. However at this time, we do not feel there is a lot of support for significant wintry precipitation this weekend, especially closer to the coast.

For more information and posts like this one, make sure you sign up for Zone Forecasts — where multiple detailed articles, videos, and interactives are posted each day. Also, come interact with our staff and many other weather enthusiasts at 33andrain.com!

Have a great evening!

 

Steve Copertino

ScreenHunter_293 Mar. 17 17.56

Public Analysis: Snow Possible Saturday, Quiet Week Ahead

Today has been a beautiful day in contrast with the previous few days across the entire area as temperatures have climbed into the mid-upper 40’s the afternoon underneath mostly sunny skies. While it does feel more comfortable outside, these temperatures are still below-normal for this time of year. Some gusty winds were noted this afternoon as a large area of high pressure situated to our south and a quick-moving low in Canada create a pressure gradient over the Northeast. As we head into the evening, the winds should subside a bit, but as the aforementioned low pressure in Canada begins to move to the south east, some broken high clouds should begin to take over. This is part of a frontal system associated with the low in Canada that could bring the threat of some light rain or snow to western areas of NJ and eastern Pennsylvania.

While precipitation should remain quite light for those who do happen to experience any rain/snow this evening, no significant accumulations are expected at this time as the frontal system begins to slow its approach towards the New York City metro area until tomorrow. Temperatures will vary quite significantly this evening, with lower 30’s possible around coastal areas and close to the city, but locations that are more inland should see temps drop into the 20’s for an overnight low.

Latest visible satellite imagery with temperatures for the entire area (Credit: GREarth)

Latest visible satellite imagery with temperatures for the entire area-note the white on the image is actually snowcover and not clouds  (Credit: GREarth)

As we move into tomorrow, there is potential for some snow starting very early Saturday morning as the low pressure in Canada begins to move into the Great Lakes region, which will act to push the stationary front towards the area. Clouds should increase in earnest tomorrow morning with an early threat of some light rain or snow, but mainly a mix of rain and snow is expected for New York City, Central New New Jersey, Long Island, as well as locations to the south. Since we are getting further into March, ground temperatures will be an issue-as is the case with tomorrow’s initial batch of precipitation. Since the rain/snow mix will be quite light in nature along with warmer surface temperatures, very little to no accumulations are expected for these aforementioned regions. Since thermal profiles will be more supportive of an all-snow scenario to the North and West, some light accumulations can be expected-especially on grassy surfaces. Even though accumulations should be relatively minor with this first batch of precip, they may create slick driving conditions even if they are in the form of plain rain, so please use caution.

3km NAM simulated radar valid at 9am tomorrow morning showing a very light mix of rain and snow over the area (Credit: Tomas Burg UAlbany)

3km NAM simulated radar valid at 9am tomorrow morning showing a very light mix of rain and snow over the area (Credit: Tomas Burg UAlbany)

The associated upper level energy with system at about 500mb (or 18,000 feet) is very potent with this system. As it dives down from Canada, it will cause the main low pressure system in the Great Lakes to slowly die and subsequently fill-in. As the upper level energy continues east, it will also trigger the development of a secondary-low pressure system that will form off the Mid-Atlantic coast Saturday afternoon or early evening. This is what is called a Miller-B type storm development with a primary transferring all of its energy to the coast so that a secondary low can take over and drop more significant precipitation.  As the low begins to form off the coast, colder air from the North/North East will begin to wrap into the low pressure system from which should help to turn any precipitation over the area into mostly snow by evening. As we talked about, the upper level trough associated with this system is quite impressive and as it moves east, energy will rotate underneath the base of this trough and work to strengthen the low at the surface while it continues to the east.

This advection (or movement) of energy will allow steadier precipitation to break out across the area as the atmosphere becomes much more conducive for snow during the evening. As we have mentioned a few times this winter, “lift” is very important if you want to see heavier snow rates, especially since these areas of heavier snow can also work to cool the local environment (which would help accumulations). As of this afternoon’s computer model runs, we have noticed a trend where the higher resolution models are hinting at the potential for such lift to exist over Long Island, Connecticut, and even portions of Northeast New Jersey. As we get later into the Winter season, it is a bit tougher to get accumulating snow in a marginal setup like this with no fresh cold air supply. So to counter that, you need the snow to fall more quickly than it can melt at the surface. This is achieved through these favorable dynamics mentioned above, and coupled with cooling from the strengthening surface low which should allow snow to accumulate at a more steady pace across the area on most/if not all surfaces through Saturday night.

12km NAM showing very favorable lift (in yellow, orange, and red) for heavier snow on Saturday evening

12km NAM showing very favorable lift (in yellow, orange, and red) for heavier snow on Saturday evening

At this time, with the high uncertainty, we are still maintaining our snowfall total forecast for light accumulations. But will be likely be reevaluating our forecast later this evening, as new model data comes in. Nevertheless, there will still be huge bust potential on either the high or low side, with snowfall totals, if model guidance is poor in handling where the heaviest snow and amount of cooling that will take place. The storm should move far enough offshore to for more clearing by Sunday evening.

Overall, next week is looking relatively seasonable with some cool nights in store as a few frontal systems move through the area with a chance of some light rain. Later in the week, a ridge of high pressure should begin to build over the area, which would allow for more continued quiet weather with potentially warmer weather in the longer range.

For more information and posts like this one, make sure you sign up for Zone Forecasts — where multiple detailed articles, videos, and interactives are posted each day. Also, come interact with our staff and many other weather enthusiasts at 33andrain.com!

 

Have a great evening!

 

Steve Copertino

Screen Shot 2017-03-15 at 10.33.26 AM

Where did New York City’s blizzard go?

Let’s cut straight to the point here: Our forecast snowfall amounts in and around New York City were too high. Our snowfall forecast, which by the night before the storm had settled into the 15-18″ range for the metro area, ended up too high by 8-10″, which as you may assume is a much larger spread than we are comfortable with. While the forecast did verify very nicely in many other areas, the I-95 corridor was an area where verification was specifically poor.

Before starting an organized mob with pitchforks and torches to storm your local meteorological office, we’re going to attempt to provide some perspective today. The reality of it is, these kinds of blown forecasts are difficult for us all. The general public — and our clients — planned ahead based on our forecast amounts, and frustration was very high when they didn’t work out. Accordingly, our team worked tirelessly to get the forecast right, spending countless hours pouring over data and pinpointing intricate processes, and getting it wrong was a frustrating and humbling experience.

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