Archive for Mississippi Valley
Another excellent day of weather expected, rain on the way for tomorrow
Posted by: | Comments07/31/10 11:40 AM
High pressure over the eastern Great Lakes and southern Mid Atlantic will continue to produce excellent weather conditions through this evening. With the exception of increasing clouds for this evening, the weather conditions for today will pretty much mirror the same as yesterday with highs in the lower 80′s and low humidity.
However, the pleasant conditions will not last for tomorrow. A low pressure system, currently over the mid Mississippi Valley this morning will track towards Delaware by tomorrow afternoon. The combination of high pressure over New England by tomorrow morning with this approaching low pressure system will lead to the establishment of an easterly to northeasterly wind over much of the Northern Mid Atlantic. This easterly wind will push a marine air mass into the coast, thus stabilizing the atmosphere. In short, this means the threat for thunderstorms, or at least strong to severe thunderstorm is very small to nonexistent. If anything, a strong thunderstorm slipping north from Maryland may impact southeastern Pennsylvania and extreme southern New Jersey, but that about it. Even in that case the thunderstorm will rapidly become elevated and lead to just a heavy downpour with some thunder. Overall, scattered showers can be expect with variable cloud cover. Temperatures will rise into the 70′s and lower 80′s for highs, making tomorrow the coolest of the entire seven day forecast.
The low pressure system will exit by Monday morning with a few lingering showers and then clearing skies. High pressure will take hold by Monday afternoon and remain in control through Tuesday with light winds and slowly modifying temperatures back into the 80′s to lower 90′s. The high pressure system will become established off the Mid Atlantic coast where a strong Western Atlantic Ridge will become established in the upper levels. As a result, the southwesterly flow will return at all levels of the atmosphere from the surface to 500 MB. With this southwesterly flow will come the return of moderate to high humidity, high temperatures in the upper 80′s to mid 90′s, lows around 70 degrees, and a constant threat of strong to severe thunderstorms in the afternoon for Wednesday into next weekend.
For details for your location, visit the NY NJ PA Weather Local Seven Day Forecast!
-- Weather When Posted --
- Temperature: 75°F;
- Humidity: 50%;
- Heat Index: 78°F;
- Wind Chill: 75°F;
- Pressure: 30 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.;
Departing upper low leads to major warm up
Posted by: | Comments05/24/10 4:10 PM
The upper low over the western Atlantic will have a variety of interesting impacts going forward for the rest of the week.
On the tropical potential side of this disturbance, there is some concern that this upper low will gain some tropical characteristics over the next several days. However, this influence will remain well out into the Atlantic and will have no direct impact on the northern Mid Atlantic.
Another more interesting development is the sinking air that is developing over the Mississippi Valley and Tennessee Valley this afternoon. This sinking air is a direct result of the rising air to the east, and the influence of this sinking air is causing temperatures this afternoon in those locations to rise into the 80′s and 90′s. A similar set up will take place over the northern Mid Atlantic, especially over eastern Pennsylvania and the Delaware River Valley, on Wednesday and Thursday with the potential for temperatures to rise into the mid to upper 80′s for many locations.
So, for tonight, low clouds will continue to linger over the northern Mid Atlantic with some areas of fog developing along the coast and in valley locations. The fog may be locally dense along the coast where dew points will be enhanced due to the easterly flow.
By tomorrow, the upper low begins to drift further east into the Atlantic with drier air working southwest from the Great Lakes into the Hudson Valley and Connecticut first and then points south and east through the afternoon. Clouds will break up by evening with dry conditions thereafter.
With clear skies, sinking air, and a warm 850 MB temperature regime; high temperatures on Wednesday and Thursday will spike into the 80′s and potentially lower 90′s throughout the region. Dew points are expected to be in the upper 50′s to mid 60′s, supporting humid conditions as well. Both of these days will be excellent for rushing to the beach!
A cold front will follow on Friday with the threat for showers and thunderstorms. The bulk of the upper level dynamics with this cold front will be over New England, so I’m not expecting much of a severe threat. However, a strong thunderstorm is possible.
A cooler, Polar enhanced Marine air mass will take hold for next weekend with variable cloud cover yet dry conditions. Temperatures will return to near normal levels, in the 70′s for highs.
-- Weather When Posted --
- Temperature: 64°F;
- Humidity: 77%;
- Heat Index: 64°F;
- Wind Chill: 64°F;
- Pressure: 30.3 in.;
A windy Mother’s Day in store
Posted by: | Comments05/09/10 9:40 AM
In case you didn’t notice it’s pretty windy out there. Branches are down all over my neighborhood and believe me, driving over a branch at night is not fun. So what’s causing all this wind?
Well, let’s take a look at this morning’s surface map. Note the lines that are tightly packed over the northern Mid Atlantic. These lines represent pressure and the tighter they are packed together like this, the faster air is moving from a high point (high pressure over the Ohio Valley) to the lower point (low pressure over the Canadian Maritimes). So basically, the wind is simply the air trying to rush towards the low pressure, trying to fill the void of air being lifted over the Canadian Maritimes. Conservation of Mass is a wonderful thing!
So how long will this last? Well, the low pressure system over the Canadian Maritimes will continue to slowly lift northeast to around 50N/50 W, which will set up our new west based negative NAO pattern. High pressure over the Ohio Valley will settle over the Philadelphia metropolitan area by tomorrow morning with clear skies and diminishing winds by tomorrow morning. High pressure will continue to slide to the east on Monday night and Tuesday with clouds increase by Tuesday evening.
Now, remember that negative NAO pattern I mentioned above? Well, the same low that is giving the region a very windy Mother’s Day will be the same low that is going to set up a rather unsettled pattern for the region for the middle and end of next week. A ridge will begin to build over the Mississippi Valley and Southeast, which will cause a warm front from these locations to drive northeast towards the Mid Atlantic. If the large upper low that will set up over the Canadian Maritimes was a bit further east (that would be an east-based negative NAO pattern), then the warm front would move through just fine and a very warm end of the week would be on tap. However, this pattern features a west-based negative NAO, which is going to block the warm front from moving north. Naturally, that warm front will stall right over the Philadelphia metropolitan area, which will lead to a clash of air masses right over all of the northern Mid Atlantic Wednesday through Friday. As a result, the middle and end of the week will not only remain cool with highs in the 60′s but also unsettled with a risk of showers each day. Depending on the exact position of the warm front, an easterly wind may set up for several days leading to minor coastal flooding, overcast skies, and just plain raw conditions. Not pretty at all!
For more details for your location, check out the seven day forecast!
-- Weather When Posted --
- Temperature: 60°F;
- Humidity: 72%;
- Heat Index: 60°F;
- Wind Chill: 58°F;
- Pressure: 29.63 in.;
Summer heat returns for the weekend
Posted by: | Comments04/30/10 3:49 PM
High pressure has now set up off the Southeast coast, providing a southwesterly flow and pushing temperatures into the mid 70′s along the coast to upper 70′s to lower 80′s over parts of the Delaware River Valley.
Clear skies centered over the Ohio Valley will remain in place through this weekend. As the southwesterly winds strength from the surface to the upper levels tonight, warm and moist air advection can be expected with a notable rise in dew points into the 50′s by tomorrow morning. With plenty of clear skies and strong mechanical mixing, I expect temperatures to drive into the 80′s for most locations with the exception of the south shore of Long Island where the influence from the Atlantic will temper highs in the 70′s. On the other side of the range, there is a good chance for locations within the Delaware River Valley, which including all of the Philadelphia metropolitan area along with central and northeastern New Jersey to reach highs in the lower 90′s. The combination of highs in the 80′s and 90′s along with dew points in the 60′s will make temperatures feel like the lower to upper 90′s, so use caution outside as these conditions can cause some health issues.
Similar conditions can be expected on Sunday however a cold front currently producing severe weather over the northern Mississippi Valley and western Great Lakes, will approach the northern Mid Atlantic with increasing clouds. An isolated shower or thunderstorm is possible, especially over eastern Pennsylvania, but not likely.
The cold front will finally move through the region on Monday with showers and thunderstorms through the afternoon hours, however the cold front will be weakening in this time period, with the majority of the showers becoming widely scattered. A few thunderstorms may be strong enough to produce severe weather such as frequent lightning, heavy downpours, strong wind gusts, and hail. The most likely threat from the thunderstorms will be the heavy downpours and strong wind gusts given the high moisture content up to 700 MB and the strong LLJ at 850 MB ahead of the cold front.
High pressure will return for Tuesday and Wednesday with tranquil conditions and temperatures remaining above normal in the 70′s. Another cold front will attempt to move through the region, but will not make much of a dent on the hold of high pressure off the East coast. However, a few isolated thunderstorms will be possible in the afternoon. High pressure will produce clear skies and very warm temperatures with potentially another repeat of highs in the 80′s and 90′s once again.
For a detailed look at the next seven days, go here!
-- Weather When Posted --
- Temperature: 78°F;
- Humidity: 24%;
- Heat Index: 78°F;
- Wind Chill: 78°F;
- Pressure: 29.8 in.;
As storm exits, a new pattern emerges
Posted by: | Comments04/27/10 7:07 AM
The upper low responsible for the bouts of heavy rain and overcast conditions the past two days is finally exiting into the Atlantic. Note the strong disturbance on the water vapor over the Mississippi Valley. That disturbance is called a “kicker” in the meteorology world because that disturbance will kick the coastal low east of New Jersey into the Atlantic.
So after a few lingering showers this morning and overcast skies, dry air will work in from the west, which will lead to clearing skies by this afternoon. The disturbance over the Mississippi Valley will remain well south of the northern Mid Atlantic tonight, exiting into the Atlantic. However, as the “kicker” disturbance moves into the Atlantic tomorrow morning, the coastal low (that’s exiting off the New Jersey coast this morning) will interact with the “kicker” disturbance and intensify. As the coastal low intensifies, the pressure gradient over New England and the northern Mid Atlantic will increase, leading to rather windy conditions through the day on Wednesday. Winds will be sustained from the northwest around 10 to 20 mph with gusts to 25 to 30 mph at times. While no precipitation is expected, the windy conditions will make high temperatures in the 60′s feel like the 50′s.
As the coastal storm finally pulls into the Canadian Maritimes on Thursday afternoon, a significant change in the pattern will take place! Over the past several weeks, a strong upper low has been sitting to the east of Maine, leading to a persistent influence of marine air masses, slow moving low pressure systems, and temperatures averaging near to slightly below normal. By the end of this week, that upper low (which is associated with the negative NAO pattern) will shift north and east, and that change is extremely important.
Note the 500 MB map to the right via the 00Z GFS. Because the upper low over the Canadian Maritimes is further north, the ridge is able to build into the St. Lawrence River Valley. This leads to a southwesterly flow aloft and at the surface, which means much warmer times ahead for the northern Mid Atlantic as a while. This type of pattern also leads to cold fronts attempting to run right into the ridge and weaken as they do so, which leads to widely scattered but at times very impressive strong to severe thunderstorms in the afternoon and evening hours.
So after Thursday, expect a significant moderation in the high temperatures for Friday through Monday with highs in the 70′s and 80′s for much of the northern Mid Atlantic. Each afternoon and evening will feature a threat for thunderstorms, but not a wash out as most of the region will remain dry, warm, and humid! Welcome to a taste of summer!
For a detailed seven day forecast, go here!
-- Weather When Posted --
- Temperature: 46°F;
- Humidity: 87%;
- Heat Index: 46°F;
- Wind Chill: 43°F;
- Pressure: 29.3 in.;
Clear and dry mark the end of the week
Posted by: | Comments04/23/10 6:55 AM
No rain today! I can promise that has high pressure will basically sit right over the northern Mid Atlantic today.
The water vapor satellite picture shows plenty of sinking air over the northern Mid Atlantic, which is shown via the blacks and reds. The sinking air will prevent any showers or thunderstorms from forming this afternoon despite the overall unstable air mass in place.
The key feature though is over the Plains as strong to severe thunderstorms drive east towards the Mississippi Valley. The upper low responsible for driving the severe thunderstorms will be a key rain maker from Sunday on through Tuesday as the warm front, currently just south of the Tennessee Valley this morning. I should note that the back door cold front I’ve been discussing the past few days is now well south and west of the region, but will be a non-factor as the cold front washes out and becomes overwhelmed by the stronger warm front.
Now, note the intense yet small storm well to the east of New England. This upper level feature will enhance the convergence and confluence over New England over the next five days, which is going to be very important. Convergence and confluence produces sinking air and enhance the surface high pressure, giving the Philadelphia and New York City metropolitan area excellent weather conditions today and tomorrow. However, this same high pressure system will shift towards northern New England and the Canadian Maritimes, which will cause the approaching warm front to stall just south or over southern New Jersey on Sunday.
The combination of strong warm air advection from the southwest and a stubborn marine air mass from the Atlantic at the surface will lead to an environment favorable for periods of moderate to heavy rain with otherwise overcast skies and drizzle. Similar conditions can be expected on Monday as the warm front remains stalled south of Philadelphia and cutting across southern New Jersey. A persistent easterly wind can be expected as a result, which may create some minor coastal flooding issues.
The low pressure system over the Plains will eventually redevelop east of the Delaware Bay on Monday night and exit into the Atlantic on Tuesday with additional moderate to heavy rain through at least the early afternoon hours on Tuesday. Total rainfall amounts from this storm will be over an inch throughout the northern Mid Atlantic and may exceed two inches in some locations, especially over northeastern Pennsylvania, northern/central New Jersey, much of southeastern New York including New York City, and the southern half of Connecticut.
High pressure will take hold along with a northwesterly flow on Wednesday with still an isolated shower or thunderstorm possible due to the unstable nature of the air mass. However, much warmer times will be ahead going forward as a new pattern begins to take hold.
For a detailed seven day forecast, go here!
-- Weather When Posted --
- Temperature: 41°F;
- Humidity: 60%;
- Heat Index: 41°F;
- Wind Chill: 37°F;
- Pressure: 29.86 in.;
Weak disturbance clips the northern Mid Atlantic
Posted by: | Comments04/21/10 7:03 AM
High pressure over the past few days have provided excellent conditions with low humidity, highs in the 60′s, above all else dry conditions. However, a weak disturbance is on the way that will interrupt the pleasant weather for a short time.
The water vapor satellite this morning is showing two significant disturbances over the United States. The first disturbance is heading towards the Mid Atlantic coast. This disturbance is being sheared by the northwesterly flow from the Polar jet stream and as a result is weakening rapidly. However, the disturbance will still be strong enough to produce a few scattered showers throughout the northern Mid Atlantic this afternoon and evening.
High pressure will quickly become reestablished by tomorrow morning with dry conditions and near normal temperatures Thursday afternoon through Saturday.
The next disturbance is a developing storm that will have a significant impact on the Philadelphia and New York City metropolitan area. The Pacific disturbance will move through the Rockies and into the Mississippi Valley by this weekend. As the upper disturbance moves into the Plains and Mississippi Valley on Saturday, an upper low is expected to intensify. Meanwhile, a back door cold front, a lovely gift from the negative NAO pattern over the Atlantic, will drop south and west through the New York City metropolitan area on Saturday night with increasing clouds. Now, here is where this pattern gets interesting!
The back door cold front will stall over or just south of the Philadelphia metropolitan area on Sunday morning while impulses or mid level disturbances from the upper low will race along the stationary boundary, that will gradually transition into a warm front, which will produce waves of moderate to potentially heavy rain from Sunday through Monday. I don’t expect continuous rainfall with these disturbances, but overall Sunday and Monday will not be pleasant outdoors.
The upper low opens up on Monday night and slides towards the coast while a Polar disturbance dives south towards the New England coast, which give birth to a developing coastal low on Monday night into Tuesday with periods of moderate to heavy rain once again. Overall, not a pleasant start to next week.
For a detailed seven day forecast, go here!
-- Weather When Posted --
- Temperature: 46°F;
- Humidity: 75%;
- Heat Index: 46°F;
- Wind Chill: 45°F;
- Pressure: 29.88 in.;
Comfortable and cool this evening, rain on the way
Posted by: | Comments04/20/10 4:00 PM
Another excellent afternoon as high pressure produced tranquil conditions with highs in the mid to upper 60′s, and even a few isolated lower 70′s throughout the Philadelphia and New York City metropolitan area.
However, the great weather conditions will take a pause starting tomorrow afternoon. A disturbance over the Ohio Valley this afternoon will slowly push east towards the Mid Atlantic tonight through tomorrow. Clouds will increase through the day with the risk of widely scattered showers throughout the northern Mid Atlantic. These showers are expected to be weak without much of a significant impact except perhaps on some baseball games and other evening out door activities.
The disturbance will leave rather quickly though with improving weather conditions by Thursday afternoon and tranquil conditions on Friday. Temperatures through this week will average near normal with highs in the 60′s and low’s in the 40′s.
The next significant weather event is going to gear up on Saturday night and continue on through early next week. A back door cold front will slide south on Saturday evening with increasing clouds and a few scattered showers. However, the main influence on the Philadelphia and New York City metropolitan area will come from the Mississippi Valley. As a strong upper low approaches slowly from the west, a series of disturbances will move along the stalling back door cold front leading to periods of moderate to even heavy rain over the Philadelphia and New York City metropolitan area on Sunday, Monday, Tuesday, and possibly extending into Wednesday. While I don’t expect continuous rainfall throughout this period, there will be a constant threat of showers and a northeasterly wind that will keep conditions cool, overcast, and raw.
A detailed seven day forecast can be found here!
-- Weather When Posted --
- Temperature: 62°F;
- Humidity: 36%;
- Heat Index: 62°F;
- Wind Chill: 61°F;
- Pressure: 29.92 in.;
Variable clouds, but mostly dry
Posted by: | Comments04/18/10 8:30 AM
This morning’s water vapor satellite picture is like a thousand words to me, well maybe two thousand!
An upper level low over northern Maine will continue to rotate weak disturbance from the eastern Great Lakes to the northern Mid Atlantic with periods of widely scattered showers. However, much better conditions are on the way. Note the blacks and reds over the Tennessee River Valley, which signifies sinking air on the satellite image. This sinking air will support the development of high pressure which will build into the entire Philadelphia and New York City metropolitan area tonight through Wednesday with excellent weather conditions. Temperatures through the week will slowly moderate with highs pushing into the 70′s by Wednesday.
Another weak disturbance will move to the south of the Philadelphia metropolitan area on Thursday with a few widely scattered showers, however this disturbance is not expected to produce any significant rainfall. High pressure will take hold once again on Friday, setting up a very interesting pattern for next weekend.
The high pressure system, which will set up over Maine, will drive a back door cold front through the region on Friday night. This cold front will stall over the Philadelphia and New York City metropolitan area on Saturday morning and rebound northward as a very slow moving warm front as a strong area of low pressure approaches from the Mississippi Valley. With warm air surging north and cool, moist air locked in from the Atlantic Maritimes, the potential for widespread and persistent heavy rain is high.
For a detailed seven day forecast, go here!
-- Weather When Posted --
- Temperature: 42°F;
- Humidity: 56%;
- Heat Index: 42°F;
- Wind Chill: 35°F;
- Pressure: 29.92 in.;
Freehold
57°
Philadelphia
62°
Albany
59°
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