Archive for Virgina
Active Start To The Week
Posted by: | Comments6:47 AM
Welcome to another start of the week! Well for some of us, MLK Day means that many will be off today while others get prepared for Inaugreation Day tomorrow, however the weather never takes a day off, so off I go!
The active pattern for the forecast area will continue today. A few scattered snow showers will move through the forecast area this afternoon, but otherwise I’m not expecting much from these snow showers put a few flurries. The main show is latter this evening.
An energetic yet fast moving disturbance currently over West Virgina will spawn an area of low pressure over northern Virginia this afternoon. Rapidly cooling cloud tops over northern Virginia and southwestern Pennsylvania signal that lifting is beginning to intensify and a low should be formed by this afternoon. This disturbance and the low pressure associated with it at the surface will move fast and is generally moisture starved. Given the dynamics this morning at 700 MB, I don’t foresee measureable precipitation north of New York City or even Trenton, New Jersey from this disturbance. In fact, I think the main focus of precipitation will be over the Philadelphia metro to the New Jersey coast.
In fact, I’d keep an eye on this low off the New Jersey coast again. I am seeing in the data once again the potential for a rapidly developing band of moderate snow right along the New Jersey coast this evening that may surprise some people. I don’t expect much in the way of accumulation, but the band may add an additional inch or two compared to everyone else in the forecast area.
Descripition:
Brown: I’m only expecting a few flurries for most locations north of Philadelphia and northwest of New York City including all of Connecticut. A dusting is possible over the northern half of Long Island and New York City, but not much more.
Light Blue: A weak yet organized area of light snow will move over this region with accumulations of a dusting to 2 inches expected over these locations including southern Long Island and much of the Philadelphia metro.
Blue: Overall most locations will see a dusting to two inches of snow like the rest of the Philadelphia metro. However, there is a higher chance of some short lived banding of precipitation and a moderate snow band may develop some where between central/eastern Monmouth County down through Cape May County. Accumulations would increase to 2 to 4 inches in this band, where ever the band sets up. Otherwise, a dusting to 2 inches is expected.
-- Weather When Posted --
- Temperature: 24°F;
- Humidity: 85%;
- Heat Index: 24°F;
- Wind Chill: 20°F;
- Pressure: 29.69 in.;
Coastal Low Starting To Organize
Posted by: | Comments7:47 PM
A coastal low is beginning to develop off the Mid Atlantic coast betwen the New Jersey coastal waters and the North Carolina coastal waters. Why the range? Well, I’ve checked several different sources that are very reliable, the E-wall from Penn State, the Plymouth State Website, and RAP-UCAR all with slightly different positions of this coastal low. What is clear is that pressure is clearly falling at a constant rate off the coast and the change in pressure field can be seen with the wind direction as the entire forecast area has switched to a north to northwest wind, clearly suggesting the position of the primary low is now along the coast.
All focus is back to the DELMARVA Peninsula where the back end of the precipitation has slowed and precipitation has moved back into the southwestern part of the Penninsula. Is this a trend or a temporary straight area of precipitation? I’ll keep an eye for further development.
Meanwhile, the upper disturbance that was suppose to miss the chance to interact with the coastal low and the moisture is now racing through West Virgina and western Pennsylvania. Light precipitation from this disturbance is forming over central Pennsylvania. We’ll see in the next two hours if this disturbance was too late or right on time. If there is interaction, look for that precipiation over central Pennsylvania to expand eastward, and in a hurry. Also, cloud tops continue to cool rapidly along the coast on the IR and water vapor images.
-- Weather When Posted --
- Temperature: 30°F;
- Humidity: 86%;
- Heat Index: 30°F;
- Wind Chill: 25°F;
- Pressure: 29.78 in.;
Virga Building, Carefully Monitoring
Posted by: | Comments2:50 PM
If you are wondering why I am not shooting out rapid updates, it is because I am trying to be very careful in what I am seeing this afternoon.
Personally, the issue at hand is I don’t want to go off screaming snow storm developing and then it does. That would kill my credibility of my skills and this site. On the other hand, virga is developing all over the forecast area, when it shouldn’t. The satellite images are showing rising air throughout the coastal plain from the mouth of the Hudson Valley down to the Carolina’s. It is clear that a disturbance is starting to support cyclogenesis off the southern Mid Atlantic and Southeast coast. It is also clear that the primary low over the Great Lakes is weakening and thus so is the warm air advection over the region. This precipiation and virga is forming due to the interaction of PVA and the developing theramal gradient from the surface to 700 MB over the East coast.
As far as temperature trends, notice that temperatures have stopped rising over southern New Jersey. Virga over these locations are blunting the warm air advection. In fact, some locastions over east-central PA are observing temperatures falling AHEAD of the cold front.
So here is the question that is running in my head. If virga is developing along the coastal plain and there seems to be a developing thermal gradient setting up along the coast, then would this mean that precipitation is more likely along the coast. My instincts say yes, but I don’t want to jump the gun yet. If that precipitation over eastern North Carlina starts to back build and move into northeastern Virgina and the DELMARVA Peninsula, then we are looking a potentially HUGE bust in guidance. I’m not ready to make that announcement yet, but if the trends continue, I will have to.
In the meantime, the virga developing over the forecast area will continue to cool temperatures this afternoon and eventually snow and rain depending on locastion will fall. At this point, the precipitation is going to be light, so don’t expect a quick and significant accumulation. However, like I said, the trends are troubling for those that thought the forecast area would see nothing but partly cloudy skies and generally dry conditions.
-- Weather When Posted --
- Temperature: 35°F;
- Humidity: 43%;
- Heat Index: 35°F;
- Wind Chill: 35°F;
- Pressure: 29.82 in.;
Heavy Icing To Start Over Eastern Pennsylvania
Posted by: | Comments8:30 PM
Very heavy precipitation is quickly moving from southwestern Pennsylvania, West Virginia, Maryland, and Virgina towards eastern Pennsylvania this hour. With temperatures in the 20′s for much of eastern Pennsylvania, significant sleet and freezing rain is expected with accumulations of 0.25″ to 0.50″ of ice possible with this band of freezing rain and sleet.
Philadelphia and Trenton, New Jersey are currently hovering between 30 and 33, which means those locations as well have the opportunity to have significant icing over night. In fact, the threat at this hours extends eastward towards many locations over interior New Jersey like interior Monmouth, Burlington, Mercer, and Middlesex Counties.
More to come!
-- Weather When Posted --
- Temperature: 32°F;
- Humidity: 86%;
- Heat Index: 32°F;
- Wind Chill: 24°F;
- Pressure: 29.89 in.;
Tropical Storm Cristobal Churns Off The North Carolina Coast
Posted by: | Comments
The main story this morning is the development of Tropical Storm Cristobal. Yesterday, Cristobal was still unnamed tropical depression, ironically Cristobal looked more impressive as a tropical depression than as a tropical storm. Weak shear and dry air is suppressing the ability for showers and thunderstorms to develop around the well formed low level circulation. The current radar images shows this current development very well with scattered showers and thunderstorms around the center of circulation and then more organized thunderstorms to the south and east of the circulation. There have been some signs of redevelopment of thunderstorms near the center of circulation, however convection has yet to wrap around the center this morning.
This afternoon and evening, upper level winds will weaken and the environment will become more favorable for some brief strengthening. However, by tomorrow morning the upper trough over the Great Lakes will begin to influence Tropical Storm Cristobal via strong southwesterly shear and forcing Cristobal to increase in speed to the northeast away from the East coast. Other than slowing the cold front down over the Northeast, Cristobal’s impacts will be limited to eastern North Carolina with tropical storm force winds up to 45 to 50 mph and heavy rainfall at times. By Tuesday afternoon, Cristobal will become to become absorbed by the 500 MB trough and will no longer be a threat to the western Atlantic.
Freehold
77°
Philadelphia
81°
Sussex
73°
Allentown
77°
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