Archive for mid level moisture
A great day to be outdoors
Posted by: | Comments11:10 AM 08/07/10
Can the weather conditions today be any better than what we have right now?!
High pressure will produce clear skies and comfortable weather conditions today through tomorrow. Winds will be light and variable with high temperatures in the lower 80′s for this afternoon. Humidity will be very low making for a very refreshing feel to the air mass in place!
The excellent conditions will continue through this evening and into tomorrow as high pressure drifts across the Northern Mid Atlantic with no impacts from any precipitation at all. The tranquil conditions will continue into Monday morning as well.
Sadly, the strength of days of low humidity and comfortable high and low temperatures will come to a halt by Monday afternoon. High pressure will move off the Mid Atlantic coast on Monday morning with a developing southwesterly wind from the surface up to 850 MB, which means the return of low and mid level moisture into the Northern Mid Atlantic once again. High humidity will be felt throughout the Philadelphia and New York City metropolitan areas by Monday afternoon.
By Tuesday, a hot and humid pattern will become established for all of the Northern Mid Atlantic. High temperatures will return to the mid 80′s over the far interior to lower 90′s over the Delaware River Valley with increasingly high levels of humidity. The three hated words of the summer will be back; hazy, hot, and humid.
While temperatures and humidity return to uncomfortable levels, so will the threat for strong to severe thunderstorms as disturbances from Ontario, Canada attempt to move through the Northern Mid Atlantic. While the cold fronts will collapse and remain north of the region, the ability for the thunderstorms to move through the region will not be impeded, leading to a threat for showers and strong to severe thunderstorms each day through next week.
The latest guidance and development of teleconnections suggest that this pattern is not going away any time soon with hot and humid conditions continuing on through next weekend.
For details for your location, visit the NY NJ PA Weather Local Seven Day Forecast!
-- Weather When Posted --
- Temperature: 78°F;
- Humidity: 47%;
- Heat Index: 79°F;
- Wind Chill: 78°F;
- Pressure: 30 in.;
Premium Discussion Overview for July 31, 2010
Posted by: | CommentsThe last day of July is here! Is it me or did this month go really fast? I heard this has to do with getting older, so for this birthday (August 3rd, by the way!), I have decided to become 29 rather than 31 because I need more time in the day. Anyway, today I discuss the impacts from an approaching area of low pressure for tomorrow and also the developments in the Tropical Atlantic! Are you a Premium Member? Get the details on Premium Membership here!
To continue reading Premium Discussion Overview for July 31, 2010, you must be a premium member
-- Weather When Posted --
- Temperature: 75°F;
- Humidity: 50%;
- Heat Index: 78°F;
- Wind Chill: 75°F;
- Pressure: 30 in.;
Heat and humidity returns today, heavy rain threat tomorrow
Posted by: | Comments9:40 AM 07/28/10
The break in the humid weather conditions ended last night and this morning a far muggier air mass has taken hold. You can feel the increase in moisture in the air mass already and current dew points in the mid to upper 60′s over the New York City metropolitan area and upper 60′s to mid 70′s throughout the Philadelphia metropolitan area certainly support the claim that the hot and humid weather conditions are back!
The water vapor satellite this morning shows that plenty of mid level moisture is sitting over the Southeast. A warm front over the southern Mid Atlantic is driving north and northeast ahead of a cold front over the Great Lakes, which will support the mid level moisture over the Southeast to build northward as well.
So clearly hot and humid weather conditions are back, but what about the thunderstorms?
The lifting needed to support the development of thunderstorms is clearly lacking in the atmosphere. The main deterrent against thunderstorms this afternoon is timing as the warm front is not expected to reach the Northern Mid Atlantic in any form until late this afternoon, after the peak period of instability in the atmosphere. While a strong 850 MB low level jet streak will lead to some lifting, only a few isolated thunderstorms are expected. The main threat from these thunderstorms this afternoon will be heavy downpours and strong wind gusts. Otherwise, I expect scattered clouds with temperatures rising into the upper 80′s to lower 90′s for most locations. A few isolated urban locations like Newark or Philadelphia may even touch 95 degrees this afternoon, pushing the heat index towards 100 degrees.
The cold front over the Great Lakes is the next threat for widespread showers and thunderstorms. This cold front will move faster over the Great Lakes and New England than over the Ohio Valley, leading to a cold front passage that sinks south and southeast over the Northern Mid Atlantic by tomorrow morning. Once again, the timing of the cold front producing clouds, showers, and thunderstorms in the late morning hours tomorrow limits the potential for the air mass to become significantly unstable. Further, the high level of moisture up 500 MB suggest a high heavy rain threat rather than a severe thunderstorm threat. Also, the fact that the cold front will move faster over New England points to a stronger upper level support (upper level jet streak located over New England) and therefore better upper level dynamics away from the most potentially unstable air mass. All of these factors argue against widespread severe weather. However, there is a threat for widespread heavy rain, which may lead to localized flash flooding. The fact the cold front slows down over the Philadelphia and New York City metropolitan area between 10 AM and 5 PM tomorrow means that showers and strong thunderstorms will train or redevelop and move over the same location, through the day tomorrow. This type of development can lead to heavy rainfall amounts with a half an inch to an inch of rain or more can fall in a short period of time.
The cold front will exit by the late afternoon to early evening hours with rapid clearing from northwest to southeast. The dew points will crash leading to a far less humid conditions by tomorrow evening and continuing into Friday. High pressure will produce excellent weather conditions for Friday and Saturday with clear skies, low humidity, and high temperatures in the 80′s. An easterly wind will develop on Saturday, leading to slightly cooler conditions along the immediate coast compared to locations further inland.
A strong disturbance is now expected to move through the Northern Mid Atlantic on Sunday with showers. This disturbance will be aided by the easterly wind, transporting more Atlantic moisture into the region. As a result, periods of showers can be expected with temperatures in the lower 80′s for many locations.
High pressure takes hold once again but now will drop south from New England towards the southern Mid Atlantic coast, which will mean the southwesterly flow will return. Hot and humid conditions will return for Monday and Tuesday with high temperatures in the upper 80′s to lower 90′s, lows in the mid 60′s to mid 70′s, and dew points around 70 for the start of next week.
For details on your location, visit the NY NJ PA Weather Local Seven Day Forecast!
-- Weather When Posted --
- Temperature: 77°F;
- Humidity: 65%;
- Heat Index: 79°F;
- Wind Chill: 77°F;
- Pressure: 30.08 in.;
Another hot and humid day, but some slight relief on the way
Posted by: | Comments07/07/10 7:35 AM
Yesterday, another day of record highs were recorded throughout the northern Mid Atlantic. Conditions today won’t be much better, however there is some good news going forward as high temperatures will be closer to 90 rather than 100 through the rest of this week.
A weakness in the atmosphere or a weak area of low pressure will hover around the New Jersey coast today, which will lead to a slightly better chance for thunderstorms this afternoon. Otherwise, another hot and humid day is expected with temperatures, already in the mid 80′s in some locations, rising rapidly into the mid 90′s to lower 100′s once again. Dew points will continue to increase as more low and mid level moisture builds into the region, leading to a heat index well into the 100′s once again. Use caution in these dangerous conditions and be sure to drink plenty of water.
As for the thunderstorms, the weak area of low pressure along the coast will enhance the sea breeze front, which will create lifting along the New Jersey coast and New York city metropolitan area. These thunderstorms are likely to move very slowly if they develop, which would lead to very heavy rainfall. Flash flooding, occasional lightning, and wind gusts over 45 mph can be expected in these thunderstorms.
Through the rest of the week into this weekend, a slight change will take place over the northern Mid Atlantic. Over the past few days, 850 MB have ranged from 20 to 24 degrees Celsius which supports the high temperatures that have been observed. However, those hot 850 MB temperatures will reposition further to the south, which means that 850 MB temperatures will fall off slightly into the 16 to 20 degree Celsius range for tomorrow through Sunday, which will put high temperatures ranging from the upper 80′s to lower 90′s. However, dew points will not be decreasing at all. In fact, with temperatures in the lower 90′s and dew points remaining in the 60′s to lower 70′s, humidity in the atmosphere will actually increase. So those hoping from a break from the heat and humidity will be disappointed. On the some what positive side, the decrease in temperatures at 850 MB will allow for a higher potential for isolated to scattered thunderstorms each afternoon, which could provide a nice yet rainy break from the heat and humidity.
For more details on your location, visit the NY NJ PA Weather Local Seven Day Forecast!
-- Weather When Posted --
- Temperature: 80°F;
- Humidity: 61%;
- Heat Index: 82°F;
- Wind Chill: 80°F;
- Pressure: 30.03 in.;
Premium Membership Overview for Monday July 5, 2010
Posted by: | CommentsThe heat and humidity is here as advertised, but is there more to be concerned about with this pattern than the heat and humidity? I discuss these threats in the Premium Membership Discussion. Are you a Premium Member? Get the details on Premium Membership here!
-- Weather When Posted --
- Temperature: 78°F;
- Humidity: 54%;
- Heat Index: 79°F;
- Wind Chill: 78°F;
- Pressure: 30.02 in.;
Ridge begins to build as models start to catch on
Posted by: | Comments06/15/10 8:50 AM
Today is likely to be the most comfortable day for the next 15 days if not more as the new summer pattern becomes established over much of the eastern United States.
The water vapor satellite picture this morning really tells the story behind this developing pattern. There is a saying that a picture tells a thousand words, but I’m going to add a few more. Note the trough over New England this morning. This trough is associated with the negative NAO pattern that is shift to the east for the next several days if not weeks. Right now, that same trough is producing a northwesterly flow at the upper levels and supporting a cool northerly flow at the surface, all of which is keeping relatively dry air over the region. While clouds will slowly increase through the day, temperatures and dew points will remain very comfortable with highs in the 70′s and 80′s and dew points in the 40′s and 50′s. A perfect June day!
However, note how mid level moisture (the white and blue colors) have started to move north and northeast from the Ohio and Tennessee Valleys into the northern Mid Atlantic and eastern Great Lakes. As the trough becomes established over the Canadian Maritimes and another trough sets up over the Mississippi Valley and Plains, an impressive ridge is starting to develop over the Southeast. This ridge will continue to build over the next several days, and force the stationary front over Virginia this morning to the north through the northern Mid Atlantic. This newly enforced warm front will bring showers to the region by tomorrow morning through tomorrow evening, but the important detail is that this warm front will move north of much of the northern Mid Atlantic with the exception of portions of northern Connecticut and the Hudson Valley. Behind this warm front is a building tropical air mass from the Gulf of Mexico that will support high temperatures in the 80′s and 90′s along with dew points in the 60′s and 70′s, in other words hazy, hot, and humid air is on the way!
Let me take a step back here and explain why this evolution is important. For several weeks I’ve been putting out the call to all Premium Members that a hot, humid, and active pattern is going to become established over much of the East, and that this pattern will evolve in June and become established through much of the summer. The details of this evolution can be found in the Long Range Thoughts Page, where the major change in the pattern is that the ENSO El Nino pattern has collapsed and the ENSO LA NINA pattern is now quickly becoming established. This pattern supports a ridge building in the East. Further, the higher latitude blocking is not expected to weaken due to certain stratospheric influences, which will keep the negative NAO pattern in place over the Atlantic. All of this points to a western Atlantic ridge becoming established, which has been advertised in the teleconnections, but not the models for several weeks now. The question was not if, but when the hot and humid weather pattern would set up.
However, with hot and humid weather conditions will also come thunderstorms from Thursday on through next week. The fact that a trough will be over the Canadian Maritimes and at times over northern New England means that mid level disturbances will drive through the northern Mid Atlantic, which will lead to an out break of strong to severe thunderstorms ahead and along these mid level disturbances. The forecasting of the track, intensity, and influence of these disturbances will have to be monitored on a day by day to even hour by hour basis.
So basically from Thursday on expect a regime of temperatures in the 80′s and 90′s for highs, mid 60′s to lower 70′s for lows with plenty of humidity in the air. There will be a risk of thunderstorms, sometimes rather severe, each afternoon especially away from the coast.
For details on the next seven days for your location, visit the NY NJ PA Weather Seven Day Forecast!
-- Weather When Posted --
- Temperature: 69°F;
- Humidity: 60%;
- Heat Index: 69°F;
- Wind Chill: 69°F;
- Pressure: 30.04 in.;
End of hot conditions will go out with a bang
Posted by: | Comments05/27/10 7:45 AM
How warm is the weather outside this morning? Current temperatures in the lower to mid 70′s throughout the Philadelphia and earlier New York City metropolitan area are the normal highs for this time of year! Not to be out done, dew points are in the lower to mid 60′s throughout the New York City and Philadelphia metropolitan area as well. So what gives?
An area of low pressure just along the New Jersey coast and a back door cold front positioned along the immediate New Jersey coast up through the Hudson Valley is moving very slowly to the east. Ahead of this back door cold front, is the air mass that gave much of the northern Mid Atlantic record breaking high temperatures and heat index values in the 90′s to lower 100′s! Well, this air mass is being forced to the south and west as a marine air mass over New England moves south.
Locations to the west of the back door cold front this morning though are in for a rough afternoon. The air mass over eastern Pennsylvania and western New Jersey is very unstable with loaded with plenty of low level and mid level moisture. The forecasted sounding for Philadelphia strongly supports the potential for severe weather, and further to the west over Allentown and Scranton, Pennsylvania the soundings are even more impressive! The air mass at 600 to 500 MB is also significantly colder and drier, leading to several severe threats including large hail and down draft wind bursts. There is also some potential for vertical wind shear, thus leading to the isolated threat of a tornado, however I have not been impressed with the soundings to support such a threat. Still, the potential for these thunderstorms to become very intense is a real threat for any location along and west of the Delaware River including Philadelphia, Pennsylvania and Trenton, New Jersey.
Further to the east, strong thunderstorms will still be possible for any location to the west of the back door cold front including much of northern New Jersey and locations away from the coast over central and southern New Jersey. Your severe weather threat will be at an end however when your location’s winds veer to the east. Then the more stable marine air mass will follow with broken clouds and a risk of showers. So for example, all of Connecticut, the Hudson Valley, Long Island, the New York City metropolitan area, and coastal New Jersey from Belmar to Cape May are pretty much out of the severe threat.
High pressure will take hold from New England by tonight and slide off the New England coast on Friday with dry conditions and scattered clouds. Temperatures will be significantly cooler in the 60′s and 70′s for highs. Another weak disturbance will clip the Philadelphia and New York City metropolitan area on Saturday with an isolated shower, however most locations will remain dry, especially along the coast.
High pressure will regain control by Saturday night and remain in place through Monday with clear skies, dry conditions, and temperatures rebounding to above normal levels in the upper 70′s to upper 80′s. Humidity will increase each day.
The next threat for severe weather will be on Tuesday as a strong cold front will plow through the northern Mid Atlantic with showers and thunderstorms in the afternoon. Another Polar air mass will take hold by Wednesday with clear skies, lower humidity, and temperatures in the 70′s and 80′s!
For more details on your location, go to the NY NJ PA Weather Seven Day Forecast!
-- Weather When Posted --
- Temperature: 69°F;
- Humidity: 68%;
- Heat Index: 69°F;
- Wind Chill: 69°F;
- Pressure: 29.81 in.;
One more day of summer-like conditions
Posted by: | Comments04/08/10 6:55 AM
The brief pre-view of the summer will be coming to an end by tonight, however at least through this afternoon; warm and relatively humid conditions will continue for the Philadelphia and New York City metropolitan area.
A strong southwesterly jet stream is developing from the Gulf Coast to the Mid Atlantic with plenty of low and mid level moisture racing into the northern Mid Atlantic this morning. High pressure will slowly drift to the east into the Atlantic through this afternoon with clouds increasing through the day. The increasing clouds will keep most locations cooler than the historically warm conditions experienced yesterday with highs expected to remain in the 80′s rather than push into the lower 90′s.
A strong cold front will approach from the Ohio Valley tonight with showers and thunderstorms after mid night. These thunderstorms will be enhanced by a strong 850 MB Low Level Jet Stream (LLJ) that will enhance lifting and transport deep tropical moisture into the region. As a result, the thunderstorms will have the potential to produce heavy downpours, wind gusts over 40 mph, small hail, and frequent lightning along with flash flooding, minor wind damage, and rapidly reduced visibility. The showers and thunderstorms will move through the Philadelphia and New York City metropolitan area at the height of the morning rush hour tomorrow morning, but will exit Long Island and Connecticut by noon.
A much cooler, and overall dry regime will take hold by Friday night with clear skies, falling humidity, and temperatures near normal. Tranquil and comfortable conditions can be expected on Saturday as well with highs in the 50′s and 60′s.
A northwesterly flow at 500 MB will become established over much of the Northeast and Mid Atlantic Sunday through next Thursday with weak disturbances dropping southwest from the Great Lakes creating a threat of isolated to scattered showers and thunderstorms each day. Otherwise dry and cool conditions can be expected with low humidity and rather comfortable weather conditions in the afternoon.
-- Weather When Posted --
- Temperature: 64°F;
- Humidity: 34%;
- Heat Index: 64°F;
- Wind Chill: 63°F;
- Pressure: 30.24 in.;
A few linger showers, then a well deserved break
Posted by: | Comments03/31/10 6:30 AM
The low pressure system that has produced at least 2 inches of rain throughout the northern Mid Atlantic and as much as 7 inches of rain over Long Island and parts of Connecticut is finally exiting into the Atlantic this morning.
Showers still are lingering over the Philadelphia and New York City metropolitan area, however the showers are widely scattered and relatively weak. Although the rain is over, the threat of flooding will remain through today as rivers crest by this afternoon. The good news is that rivers will be declining by this evening with rapidly improving conditions through tonight. Most flooding will peak at a moderate stage before falling.
As for weather conditions, overcast conditions will linger through the day as plenty of low and mid level moisture will linger over the region, as we can see with the water vapor satellite picture to the left. However, clearing conditions will be on the way by this afternoon with the chance of some breaks of sun shine at times.
High pressure will take hold by tonight and remain in control through this weekend. The only way to describe the weather conditions through this weekend is perfect! Absolutely wonderful and perfect with clear skies and high temperatures in the 60′s along the immediate coast due to some minor Atlantic influences and lower to mid 70′s for the rest of the region. In fact, there is even the potential for temperatures in the upper 70′s in some locations, especially over the Delaware River Valley.
The excellent conditions will continue for the opening day for baseball (by the way, for Premium Members the baseball weather conditions forecast will start on Sunday) with clear skies and continued warm conditions.
A cold front will slip south from the St. Lawrence River Valley on Tuesday morning with increasing clouds and an isolated shower. Temperatures will be cooler, especially along the coast as a marine air mass builds into the region. However, the cold front will quickly rebound north into New England on Tuesday night with returning warm conditions for Wednesday.
The next significant threat for rainfall will be next Thursday with a cold front with the threat of showers and thunderstorms.
-- Weather When Posted --
- Temperature: 44°F;
- Humidity: 81%;
- Heat Index: 44°F;
- Wind Chill: 38°F;
- Pressure: 29.62 in.;
Wet rush hour marks the start of soaked weekend
Posted by: | Comments3:50 PM
The rain is here and it is not going to be stopping any time soon through this weekend, which will be a perfect time to catch up on some movies, a good book, or perhaps finally conquer a very difficult video game. What ever you do this weekend, it likely will not be done outdoors.
Light to moderate rain continues to develop and expand north and west over much of the Philadelphia and New York City metropolitan area. This rainfall is not directly connected to what will be an impressive coastal storm tomorrow morning, but is a result of the developing moisture advection at the mid levels off the Atlantic and a stationary front positioned along the New Jersey coast. The isentropic lifting produced by this frontal boundary is supporting the development of this rainfall, which will have breaks in the steady rain from time to time. However, for this rush hour, steady rain and increasing winds from 15 to 20 mph with gusts over 25 mph can be expected for the New York City metropolitan area down through the northern Philadelphia metropolitan area. More scattered rainfall can be expected further south and west, over the Hudson Valley, and Connecticut.
The upper level dynamics for this storm, namely the 500 MB low over the Mississippi Valley is developing as expected. Note the spreading out of the moisture off the Southeast coast. This is a calling card for divergence aloft and means that lifting will continue to intensify as the evening continues. This fanning out of the moisture plume from the Sub Tropical jet stream has been expanding north and west through the day in response to the Polar jet stream and upper low interacting with the Sub Tropical jet stream and tilting the long wave trough axis into a negative position. Currently, the two jet streams and associated disturbances remain separate, as we can see with the area of dry, sinking air between the two areas of lifting (moisture). However, the development of mid level moisture and weak lifting over central and eastern South and North Carolina means that the phase of the two jet streams is on the way.
When the phase occurs this evening, the primary low over the Tennessee Valley will weaken rapidly and the coastal low over North Carolina will become the new primary low pressure system. Strong upper level divergence at 500 MB on up to 200 MB will support strong lifting throughout the Mid Atlantic and allow the surface low to deepen into a strong coastal storm by tomorrow morning. With the trough tilting into a negative position, the upper, mid, and low level jet streams will all set up in an orientation from southeast to northwest, which will drive plenty of Atlantic moisture right into the northern Mid Atlantic and support a prolonged heavy rainfall event. The final piece of the puzzle is the high pressure system over Quebec (note the dry air seen in black over Maine) that will enhance the pressure gradient and support a strong easterly wind sustained at 20 to 40 mph throughout the region with gusts over 60 mph possible along the coast and over the coastal waters.
Because the upper low captures the surface low on Saturday evening and causes the storm to become vertically stacked, the low pressure system will be slow to exit, which will keep rain in the forecast through at least Monday afternoon. However, the worst conditions are expected on Saturday afternoon through early Sunday morning where very heavy rain will develop and sustained winds will be at their peak.
The rainfall map to the left includes today’s rainfall on through Monday morning, which will be rather impressive for many locations. The potential for over 4 inches of rain is very real and given the mesoscale forcing that will develop due to the stationary front just off the coast, the threat needs to be addressed.
This storm will be capable of flash flooding of rivers, streams, and urban locations throughout the region, thus the Flash Flood Watch that has been issued for the region. Due to the persistent easterly wind, a Coastal Flood Warning, as has been warned about by me for several days, has also been issued for much of the New Jersey coast. High Wind and Gale Warnings have also been issued to address the strong winds that are expected. Those that may be boating in these conditions should also take head of the Small Craft Advisory for this weekend that has been issued as well.
The good news is that after this storm, the weather pattern improves significantly with high pressure dominating the northern Mid Atlantic from Tuesday on through next weekend with dry conditions, clear skies, and temperatures in the 50′s and possibly even 60′s for the Delaware River Valley.
So my advise for this weekend is stay home or at least indoors. Hey, at least it’s not snow!
-- Weather When Posted --
- Temperature: 41°F;
- Humidity: 86%;
- Heat Index: 41°F;
- Wind Chill: 32°F;
- Pressure: 30.03 in.;
Freehold
57°
Philadelphia
62°
Albany
59°
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