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Steven Copertino

FREE Public Analysis: Damp and Dreary Conditions Gives Way to Above-Normal Temps

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Good Afternoon and Happy Friday!

The low pressure that moved just west of our area yesterday has slowly continued on towards the north and east this afternoon, bringing yet another gloomy and day. This low will gradually lift out into eastern Canada by Saturday, but stout northwesterly winds will keep temperatures somewhat below-normal throughout the day. By Sunday, some relief from this cool and gloomy weather should arrive as an area of high pressure builds in from the southwest. As this high locks itself offshore during the beginning of next week, we may see temperatures well-above average for this time of year. The question is, does this warm period last, or is it just a passing tease?

This Afternoon and Evening 

As mentioned, the very energetic area of low pressure that produced heavy rainfall, intense lightning, and even some damaging wind gusts for portions of the New York metro area has lifted into Canada this afternoon, leaving behind much cooler temperatures in its wake. Temperatures have struggled to get out of the mid-upper 40’s this afternoon, which is a good four to six degrees (c) for this time of year. When coupled with wind gusts in the 20-30 mph range, this makes temperatures feel even worse, dropping down into the upper 30’s and low 40’s. These windy conditions are due to the strong area of low pressure exiting to the north east of our area, producing a tight pressure gradient over the region as it presses against a high pressure system currently located over the Mississippi Valley.

Showers have been relatively persistent this afternoon across the area, providing some light rain or drizzle to really put the icing on the miserable conditions of this afternoon. As the last piece of energy associated with Thursday storm swings through, these showers and a weak cold front may bring some more showers towards sunset, with the possibility of a mix of snow and rain in the more inland/elevated locations. These rain or mix showers are expected to be very light in nature and no significant precipitation is expected to fall from these showers as support for their development gradually wanes this afternoon.

Mostly cloudy conditions should persist throughout the rest of the afternoon as the weak front and associated upper level energy wring out the last bit of moisture available in the atmosphere. Once we head into this evening, the remaining showers should die off and skies should gradually clear, leaving temperatures rather cold for this time of year. Most locations should see lows this evening range from the mid 30’s, to low 40’s closer to the coast.

Current surface temperatures, regional radar mosaic, and visible satellite imagery showing relatively cold and damp conditions this afternoon (Courtesy of GREarth)

Current surface temperatures, regional radar mosaic, and visible satellite imagery showing relatively cold and damp conditions this afternoon (Courtesy of GREarth)

Saturday and Sunday

As we work our way into Saturday morning, temperatures should be relatively cool to start off the day with 30’s and low 40’s being commonplace across the area. As high pressure begins to establish itself on Saturday afternoon, winds from the northwest will keep things dry, but also relatively cool. Temperatures should be in the low to upper 50’s across the area under mostly sunny skies, however the pressure gradient that was mentioned earlier will still be lingering over the region, so winds of 15-20 mph may make things feel a bit more chilly than they actually are. Overall, Saturday should be an improvement from the past few days, but will ultimately be a few degrees below normal in the end. Saturday evening should feature clear skies with temperatures in the mid 40’s, with upper 30’s possible to the north and west of New York City.

As the high pressure system begins to move to our south on Sunday morning, winds will begin to shift to the south/southwest with somewhat chilly conditions to start off with. As the morning progresses,  these southwesterly winds will usher in much warmer conditions by Sunday afternoon. Temperatures should have no problem reaching into the 60’s on Sunday afternoon with clear skies and light southerly winds. This will make Sunday the highlight of the weekend, but this is only the beginning of the above-normal temperature regime!

3km NAM showing temperatures reaching at or around 60 degrees areawide on Sunday afternoon (Valid 2pm)

3km NAM showing temperatures reaching at or around 60 degrees areawide on Sunday afternoon (Valid 2pm)

Extended Range (Monday-Friday)

With the area of high pressure centered off of the Mid-Atlantic coast on Monday, warmer temperatures will continue to build throughout the week with increasing, deep southwesterly flow at the surface. This will allow temperatures to reach all the way up into the mid 70’s and possibly even low 80’s for southern locations on Monday and Tuesday. If such temperatures are realized early on in the work week, these would easily be around 12-15 degrees above normal for this time of year, which would be a remarkable contrast to this week’s dreary deluges.

In addition to this period of much warmer weather, conditions should also be much less active for now, as the storm track across the country leads the low pressure track well off to our west.

Temperatures should remain a good 8-15 degrees above normal each day through Thursday afternoon, before a potential disturbance from Canada drops down and brings in a chance at some more unsettled weather and cooler temperatures.

After this period of more calm and dry conditions, the Pacific looks to become much more active once again, so we will have to watch for more stormy conditions on the horizon as multiple systems line up to impact the western US and possibly travel east.

12z GFS upper level winds at 300mb showing a very active potential pattern shaping up over the Pacific, similar to the one that recently provided the severe weather and heavy rains (Valid 8am Thursday)

12z GFS upper level winds at 300mb showing a very active potential pattern shaping up over the Pacific, similar to the one that recently provided the severe weather and heavy rains (Valid 8am Thursday)

With some impressive warmth and a potentially more active pattern returning in the long-range, make sure to stay tuned for updates!

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 weekend!

Steve Copertino

Steven Copertino

Public Analysis: Soaking Rain Today, Very Active Pattern Continues

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Good afternoon and happy Friday!

As promised, today has been a washout so far for much of the area as a large and impressive upper level system located in the Ohio Valley continues to move on east underneath an area of high pressure located to out north east. As this system continues to move east later this afternoon and evening, a low pressure system will form off of the NJ coast and move just south of the south shore of Long Island. This should ensure that dreary conditions last into tomorrow afternoon before finally clearing up tomorrow evening. A very active and energetic Pacific jetstream will provide yet another chance at some more heavy rains as another low pressure system races eastward from the Central US by Tuesday.

Today and This Evening

As of 2pm, the entire NYC metro area was experiencing moderate to heavy rainfall with the heaviest rains currently located over Southeast Pennsylvania. This rain is attributed to the low pressure system that traversed the central US over the past three or so days, dragging up very warm/moist air from the Gulf of Mexico in the process. Despite all of this warmer air being advected into the low pressure system, the high pressure to the north of us in Canada supplied the region with some very stubborn cold air yesterday that refuses to move much at all at the lower levels of the atmosphere.

This colder air at the surface even allowed a few select locations to see some brief mixed precipitation this morning in the form of sleet and freezing rain. Temperatures outside this afternoon, coupled with the heavy rains are really making it feel quite raw outside as temperatures struggle to break out of the upper 30’s and low 40’s.  As the low pressure to our west continues on east, a band of strengthening low level winds at around 5000 feet in the atmosphere, along with an advancing warm front will bring in some more moderate temperatures for central and southern locations. Temperatures may reach the upper 40’s to low 50’s, but the combination of heavy rains and increasing winds will negate any possible comfort from the warmth.

Today’s low pressure is in the perfect position to provide sustained heavy precipitation as the upper level configuration is reminiscent of something that we would look for in the winter to produce a very significant snowstorm for the area. However, the lack of a sustained/fresh cold air source will ensure that the overwhelming majority of this storms precipitation falls as plain rain. This upper level pattern configuration with a closed upper level low being forced east underneath an area of high pressure strongly suggests that a secondary low pressure system will form off of the coast, and this is exactly what will happen late this evening. As this low pressure begins to strengthen late this evening, the aforementioned band of very strong winds just above the surface, or low-level jet, will help to funnel in very moist air from the south. This will increase rain rates for NJ/NY/CT/ and also bring some gusty winds, especially for the LI and CT coasts.

Current look at surface temperatures and the regional radar mosaic which is showing the entire Northeast engulfed in this storm system (Courtesy of GREarth)

Current look at surface temperatures and the regional radar mosaic which is showing the entire Northeast engulfed in this storm system (Courtesy of GREarth)

Tonight Into Tomorrow Afternoon 

As we mentioned on Wednesday, this deep tropical moisture will be quite abnormal for this time of year, so when combined with the impressive low-level jet streak and lift in the atmosphere, rainfall rates of .5″-1″ an hour may be possible in some of the heavier areas of precipitation. All of this rain will make the already saturated ground reach their absorption limit, with flash flood guidance indicating that only 1″ of rain within 6 hours would be needed to cause localized flooding. People should remain aware this evening as some low-lying and poor drainage zones may experience at least minor flooding, with minor to moderate flooding also  possible on roadways. If some of the more intense solutions are realized this evening, limited instability may cause tropical-like downpours with a few rumbles of thunder possible. Please remain vigilant for any possible Flash Flood Watches/Warnings issued by the National Weather Service and be prepared to take action, if necessary. 

As the low pressure develops and begins to mature off of the NJ coastline late this evening and into tomorrow morning, rain should intensify over NENJ/SNY/NYC/CT/LI, with some embedded convection still possible, especially to the east. Winds will also begin to increase once more very early in the morning as gusts of up to 40-50 mph are possible in some of the heaviest downpours, which may cause some damage to trees and localized power outages. Winds will also gust to 40-50 mph along the coast which could cause minor coastal flooding/erosion, especially for portions of Long Island’s south shore.

3km NAM showing intense winds of up to 80 mph just above the surface later this evening. Wind of 40 to 50 mph will be possible in the heaviest downpours (Valid 9pm)

3km NAM showing intense winds of up to 80 mph just above the surface later this evening. Wind of 40 to 50 mph will be possible in the heaviest downpours (Valid 9pm)

As the area of low pressure continues deepen and track offshore, winds will take on a more northerly component later tonight and Saturday morning. This will begin to usher cold air back into region with possibly rain changing to wintry mix of sleet or freezing rain over far northern interior areas late tonight and Saturday morning. But mid-level dry air will cause precipitation begin to tapering off and ending on Saturday morning over much local region. So currently no significant impacts from wintry precipitation are still anticipated even for northern sections of our zones. However, further north over Upstate New York and into Central and Northern New England more significant snowfall is possible. -Miguel Pierre

Tomorrow Afternoon Into Sunday 

As the area of low pressure begins to move to the east, the rain should diminish and end from the west to east tomorrow afternoon. Some clouds and light showers may linger into the afternoon hours for eastern locations, but with clearing skies throughout the day, things should finally begin to dry out with final rainfall totals ranging from 1.5″-3″ in some isolated spots. Temperatures should be able to rise only into the mid-upper 40’s Saturday as northwesterly flow takes over during the afternoon hours. Due to the storm exiting to the east and another area of high pressure moving to our west, a tight pressure gradient should be present over the area, with gusty winds possible into the evening. Lows should range from the low to mid 30’s across the interior, with low to mid 40’s being more common across central and southern zones.

Sunday should be a fairly tranquil day as high pressure takes over our weather for a short period of time. Sunday morning should feature mostly clear skies, with some high-level cirrus clouds indicative of fair weather possible as we progress throughout the day. Temperatures should be a few degrees below-normal Sunday with gusty winds from the north west bringing in windchills in the 30’s to start off the mornings. As the day goes on, temperatures should warm up into the low to mid 50’s across the area and with steady winds from the north, it should feel somewhat bearable when compared to the past few days.

Extended Range  

Drier and more seasonably cool weather should continue through Monday before another storm system rolls through the central US and begins to bring severe weather to the south central US and portions of the Southeast. This system unfortunately appears to have the potential to bring more heavy rainfall late Monday and Tuesday, so with the rains from this weekend’s storm and the possible rain from this event, we may have to watch for more flooding issues.

12z GFS for Monday evening showing another storm system with heavy rain and possible flooding concerns

12z GFS for Monday evening showing another storm system with heavy rain and possible flooding concerns

With the continued active period looking to maintain itself into next week, make sure to check back on the evolving pattern and potential flooding issues!

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 weekend!

Steve Copertino

Steven Copertino

Stormy Pattern Continues With Heavy Rain Possible Friday

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The active storm track that has been running from the Central Plains to the Northeastern states, courtesy of an extremely strong jet streak out in the Pacific, looks to continue into the foreseeable future. Multiple, large cutoff lows are forecast to travel just to the south of fast-moving high pressure systems over southern Canada during the next seven to ten days, and this will lead to numerous chances for moderate to heavy rain chances over the next few days. As mentioned in the last update, this rain will be much-welcomed (for now) as some location in the Northeast are still experiencing moderate to severe drought conditions. However, if this active pattern continue with multiple heavy rain threats affecting the Northeast, we may have to worry about possible flooding later on.

Today and Into This Evening 

After a frontal passage earlier this morning, the mostly-cloudy conditions that have been present over much of the area these past few days have finally been warded off by cooler and dry northwest winds from Canada. While still only slightly above normal, temperatures have been able to rise into the middle to upper 50’s across the entire area with only very isolated clouds noted on visible satellite imagery.

Even though temperatures are still slightly above-normal for this time of year they may “feel” slightly colder as there are some gusty winds of around 25-30 mph being reported across the area. These gusty winds are courtesy of a large area of high pressure over Canada and a low pressure off of the East Coast creating a pressure gradient over the region, which will briefly enhance winds. Despite rather pleasant conditions with mostly sunny skies and temperatures in the 50’s this afternoon, you may still need a jacket when going outside due to gusty winds at times.

As we move into this evening, the aforementioned high pressure in Canada will begin to overspread the region, which should all but end any remaining windy conditions. In addition to eliminating the gusty winds, this high pressure will usher in much cooler temperatures this evening, as lows should fall into the 20’s for inland areas and struggle to remain in the 30’s for the NYC metro as well as areas further to the south.

Latest visible satellite imagery, radar mosiac, and current temperatures for the Northeast showing relatively tranquil conditions (Courtesy of GREarth)

Latest visible satellite imagery, radar mosiac, and current temperatures for the Northeast showing relatively tranquil conditions (Courtesy of GREarth)

Thursday and Thursday Evening 

As we head into Thursday morning, the area of high pressure previously located over Canada should be completely in control of the weather for the Northeast. With mostly sunny skies, light northerly winds, and colder air just above the surface, we’ll more than likely have below-normal temperatures to start off the day. Conditions for the morning commute should be quite chilly with temps in the upper 20’s to the north of New York City, and low to mid 30’s to the south. As the day continues on, temperatures should only be able to rise into the mid to upper 40’s across the entire area, which is still a good 5-10 degrees below normal for this time of year.

Conditions should remain tranquil through the late afternoon and evening hours as the high pressure that was in control begins to move off the coast, with clouds beginning to increase ahead of a massive area of low pressure system that will be centered over the Ohio Valley. These clouds in combination with onshore flow will prevent temperatures dropping all that much, and lows in the low to mid 40’s should be commonplace for the majority of the area tomorrow night.

3km NAM Temperatures at 5000 feet showing cold temperatures just above the surface Thursday morning along with a much warmer airmass just to our south west

3km NAM temperatures at 5000 feet showing cold temperatures just above the surface Thursday morning along with a much warmer airmass just to our south west

Upcoming Friday and Saturday Rainstorm

The storm potential that we have been discussing for over a week now looks to be in relatively good agreement on this afternoon’s model guidance for prolonged moderate to heavy rainfall over portions of the Northeast on Friday and Saturday. A large upper level trough currently positioned over Kansas will continue to head east underneath “confluence”-or a very tight height gradient to the north. As this system continues to head east tomorrow, it will ignite multiple rounds of severe thunderstorms across the Tennessee Valley and sections of the Southeast US. As this system continues to head east, then slightly to the north later in the day tomorrow, it will have a very strong and direct connection to the very warm Gulf of Mexico to its south. Strong low-level winds will take this warm, moist water vapour from the Gulf and begin to transport it to the north as a surface low continues to track through the Ohio Valley on Friday morning. This will lead to highly-anomalous levels of precipitable water in the atmosphere as the moisture connection for this system extends all the way down to Mexico!

As this upper level trough begins to tilt negatively on Friday morning, precipitation should begin to intensify and continue to break out across the Northeast, possibly beginning just before daybreak in western locations of New Jersey. This setup of a blocking mechanism to the north and a trough going negative over the Ohio Valley is something that we would look for in the winter months for widespread significant snowfall, but rain is expected from this setup, with very warm temperatures in the lowest few thousand feet of the atmosphere. As the low pressure tracks over Ohio early Friday afternoon, low level winds in the atmosphere should begin to strengthen quite a bit, leading to more intense precipitation developing across the Mid-Atlantic states, which should head to the north and east. This initial heavy precipitation may be convective in nature due to the strengthening of the low level jet, so very intense rain rates and even a few rumbles of thunder are possible Friday afternoon.

12z GFS Precipitable Water imagery showing a very impressive flow of moisture from the Gulf of Mexico and Bay of Campeche, flowing directly into the gathering storm over the Ohio Valley (Valid 8pm Thursday)

Widespread moderate, to locally heavy rain should continue into Friday evening as the negatively tilted upper level trough begins to encourage the development of a secondary low pressure system off of the New Jersey coast. As this low begins to form off of the coast of New Jersey very late Friday/into Saturday morning, the rich Gulf moisture that the initial low pressure was bringing north will transfer and then become focused over Maryland/Delaware/Eastern Pennsylvania/New Jersey/New York/Connecticut. In conjunction with this abundance of moisture, will be some strong lift in the atmosphere, which could work to locally enhance rainfall in some locations. As the coastal system continues into early Saturday morning, we could see maintained areas of moderate to locally heavy rainfall falling along portions of NY/NJ/CT as the coastal low intensifies and begins to head eastward. The secondary low pressure system should gradually begin to head out to sea Saturday afternoon, finally bringing an end to the precipitation from west to east.

Due to the prolonged nature of this potential system and the increasing potential for heavy localized rainfall amounts, there is an increasing chance of flooding Friday and Saturday in urban/low-lying areas. Also, due to the recent moderate to heavy rainfall over the past few days, the ground is still quite saturated, and this presents a problem for this future storm. Due to high saturation levels of the soil across the area, the amount of rainfall needed within a 6-12 hour period to cause flooding is unusually low, so this is why we are becoming somewhat concerned about possible localized flooding issues this weekend. This is something that will need to be monitored closely over the next few days as more guidance becomes available to us.

“Flash Flood Guidance estimates the average number of inches of rainfall for given durations required to produce flash flooding in the indicated county. These estimates are based on current soil moisture conditions. Note, in urban areas, less rainfall is required to produce flash flooding. “

We still have time for things to change and will be updating you on this potential storm system over the next two to three days, so make sure to check back for future updates!

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

 

Steven Copertino

Public Analysis: Active Pattern Out West Yields Another Damp and Dreary Week

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Good afternoon!

After the brief warmup that some locations saw on Saturday afternoon, we’re back into the same cool and wet pattern that we have been stuck in for nearly a week now. For now, we expect this to continue for at least the rest of this week as a very active Pacific jet streak allows storm after storm to roll through the Central Plains, and then eastward to the Northeast. While the brunt of the weather will be felt out to our west with multiple severe episodes likely, our area should at the very least should see an abundance of rain. Even though this may seem like a pretty abysmal pattern to be stuck in, most of the Northeast does actually need the rain as most of our area and especially portions of Connecticut remain in a moderate to severe drought. So, the more we can chip away at these precipitation departures before the summer months, the better off we’ll be in the long-run.

Earlier this morning we saw multiple rounds of showers roll through with some locally heavy rainfall noted from some weather observation sites. The last batch of steadier showers moved through the NYC metro area at around 930 am, and has since left behind mostly cloudy and cool conditions. As of 3pm, temperatures were quite variable, with southern New York, portions of Connecticut, and far northern New Jersey stuck in the low to mid 40’s. To the south, the NYC metro area is currently near 50 degrees, with warmer temperatures of about 60 degrees common near central/south New Jersey.

A warm front has been lifting to the north through southern NJ this afternoon, which is why we are seeing another stark contrast with temperatures today. Just like this past weekend, this warm front will only be allowed to lift so far north before stalling out. This will cause temperatures to remain generally steady as thicker cloud cover to the north prevents any more significant warming. With moist southwesterly flow overspreading the region, mostly cloudy conditions are expected for the entire region, but some southern locations in NJ and PA may see some less-dense cloud cover, or even a few late peaks of sun.

Latest visible satellite, surface temperatures, and regional radar imagery (Valid 2:20pm)

Latest visible satellite, surface temperatures, and regional radar imagery of the Northeast (Valid 2:20pm)

As we head into the evening, clouds may begin to clear a bit more to partly cloudy conditions with time due to some very brief dry air. This dry air will be located just ahead of another disturbance that will move in during the overnight hours and work to once again enhance the mid to low-level moisture air in the atmosphere just enough so that we may have to worry about some showers. Patchy fog may develop later tonight into tomorrow morning with increasing moisture and very light winds. This fog seems like it will be localized in nature, but motorists may need to exercise caution when proceeding into the morning commute tomorrow.

With the aforementioned warm front stalled to the south of NYC tomorrow morning, another cool and dreary start to the day is expected with another tight temperature gradient likely setting up. Where this gradient sets up will be dependant on where the frontal boundary decides to rest. This will lead to another situation where temperatures to the north of the boundary will be in the 40’s to mid 50’s, and temperatures to the south of the front may rise into the 60’s and even low 70’s in some locations.

This will be a difficult feature to nail down, as yesterday’s models did a poor job with just how much the warm front would lift to the north for today. Regardless, as we go throughout the day tomorrow, an area of low pressure will develop along the stalled frontal system and provide a good chance of some showers, and possibly even a few rumbles of thunder across the area tomorrow afternoon. These showers should continue throughout the afternoon and into Tuesday night just ahead of a cold front. Temperatures should remain relatively mild, with lows in the mid-upper 40’s, to low 50’s for the southernmost locations.

This afternoons 3km NAM showing showers and possibly even a thunderstorm in the southern zones tomorrow evening as an area of low pressure moves through (Courtesy of WxCharts.eu)

This afternoons 3km NAM showing showers and possibly even a thunderstorm in the southern zones tomorrow evening as an area of low pressure moves through (Courtesy of WxCharts.eu)

Finally on Wednesday things seem to calm down for the moment as a cold front associated with the weak area of low pressure moves through the Northeast. This cold front will provide some fresh, cool air for the entire region, so expect highs mainly to be in the mid 50’s to around 60 degrees on Wednesday afternoon with clear skies also likely. As we move into Wednesday night, a large area of high pressure passing to our north in Canada will briefly reinforce this cold air, which will work to drop temperatures into the upper 20’s to mid 30’s across the region—with some frost possible for inland locations.

As the high pressure system up in Canada continues to move quickly to the east on Thursday, another sunny, but below normal day looks to be on tap. Northwesterly flow will limit temperatures to the upper 40’s and low 50’s, and these temperatures will certainly feel below-normal when coupled with some light, but gusty northwest winds.

12z NAM showing a much cooler air mass on Thursday morning with temperatures below freezing for some northern locations (Valid 8am Thursday)

12z NAM showing a much cooler air mass on Thursday morning with temperatures below freezing for some northern locations (Valid 8am Thursday)

Unfortunately, this calmer period seems to be short-lived as a cut-off mid level system works its way east by Friday evening and into Saturday morning. This system will be somewhat slow-moving in nature and will have a hefty moisture feed from the Gulf of Mexico, which may allow for some heavy rainfall across much of the Northeast this weekend. We may have to monitor this system for some potential flooding issues, as warm air and heavy rainfall will quickly erode any residual snowpack in northern New England.

With the extremely active Pacific jet lining up disturbances all the way back to Japan, it seems likely that we should remain in this stormy pattern for at least the next week to ten days, so make sure to stay tuned for the latest updates on any upcoming systems!

12z GFS showing multiple disturbances lined up all the way back to Japan courtesy of a very active upper level jet

12z GFS showing multiple disturbances lined up all the way back to Japan courtesy of a very active upper level jet (Valid Saturday at 2am)

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