NY NJ PA Weather Forecasts

Isolated showers and thunderstorms are developing over the forecast area this evening as expected, but I want to bring everyone’s attention to the developing area of showers and thunderstorms over western New York.  

This area of showers and thunderstorms is under a strong area of divergence and difluence at 500 MB currently over the eastern Great Lakes.  Meanwhile, at 300 MB, the overall wind flow is from northwest to southeast, towards the forecast area.  

A weak 850 MB and 950 MB low level jet will feed the complex of showers and thunderstorms with moisture and latent heat energy as the complex moves to the south and east.  The showers and thunderstorms will reach the forecast area by early tomorrow morning and will be a significant impact to morning rush hour traffic.

I’ve been noticing that an old winter friend has returned to the weather scene over the past few model runs and just want to touch on the potential influence of the return of the Caspian Ridge influence on the weather pattern in the Northeast and throughout the CONUS.  

Naturally, the ridge, which forms over the Caspian Sea in northern Russia, can develop at any time.  However, the influence the ridge has on North America begins to increase from August on through early April.  The development of the Caspian ridge means that the coldest air over the North Pole is focused towards North America instead of Asia.  It is a key indicator that colder air will be on this side of the pole, and also gives meteorologist a better idea on the potential magnitude of the trough over North America.  In most cases, the presence of the ridge leads to a trough in the Eastern United States, but not always.

In this case, the development of the ridge, which appears rather strong on both the GFS and ECMWF, reaching close to 36 decameters above normal, would suggest that the trough that is expected to remain over the East through August 15th if not longer will likely support temperatures running below normal.  August looks to be setting up as a very cool month indeed.

Should this pattern keep up through the fall, I’m thinking a lot of winter lovers are going to start getting very excited.

The bulk of the severe weather will be concentrated around the Mid West, Ohio Valley, eastern Great Lakes, and eventually the Mid Atlantic.  

A trough will continue to dig into the eastern United States with a series of strong mid level disturbances moving through the areas described above.  The strong disturbances will enhance the thunderstorms located along the cold front over the Mid West and the stationary front over the Southeast.  The warm front will move north while the cold front moves east over the next 24 hours, leading to a clash of air masses.  The combination of strong upper level and mid level winds and divergence aloft will lead to significant vertical directional and speed shear over the region, which will support the potential for an isolated tornado, wind gusts over 60 mph, and large hail.  The thunderstorms will also be capable of frequent cloud to ground lightning and heavy downpours.  Localized flooding will be possible in these thunderstorms.

As the thunderstorms move east into the Mid Atlantic, they are expected to weaken below severe levels, but remain a threat as the thunderstorm form into a line over night.  Although the majority of the severe threat will diminish, the thunderstorms will still be capable of producing strong wind gusts to 55 mph, hail, heavy downpours, and frequent lightning.

Meanwhile, isolated tornadoes will be possible over the northeastern coast of Texas and southwestern Louisiana as Tropical Storm Edouard makes landfall later this morning.  The main threat from Edouard will be the heavy rain and sustained winds of 65 mph with gusts to 80 mph.  However, an isolated tornado can develop as bands of thunderstorms move on shore and wind shear increases from the surface to 850 MB.  

Finally, a mid level disturbance will interact with up sloping winds over eastern Wyoming, western Nebraska, and northeastern Colorado to produce strong to severe thunderstorms.  The thunderstorms will be capable of very heavy rainfall, frequent lightning, and wind gusts over 65 mph.

The local forecast update is done and now I’ll be writing the technical forecast discussion.  Just a brief overview of my thoughts.

1.  Although I’m expected unsettled conditions through next week, that does not mean we can expect a total wash out or even above normal precipitation for the entire area.

2.  This trough digging into the East part of the nation will bring fall like low temperatures to the interior.  

3.  The presence of the trough over the Northeast will continue to say much of the Mid Atlantic on northward from any tropical threat.

Tropical Storm Edouard continues to move to the west-northwest around 12 mph and is currently 38 miles southwest of Port Arthur, Texas at this time.  Edouard will likely remain a strong tropical storm with winds around 65 mph sustained.  The main threat from Edouard over the next 24 hours will be the very heavy rains with 3 to 5 inches expected widespread and up to 10 inches of rain locally.  Further, a few isolated tornadoes may develop in the bands of the tropical storm this morning, which will add to the chaos in the region. 

Edouard will continue to move in land towards central Texas over the next 24 hours under a very strong heat ridge over the central Plains.  The majority of the moisture will be trapped over much of Texas producing a very much needed heavy rainfall over the region, which should at least help cool the state down from the very hot conditions over the past few weeks.  The moisture from the remnants of Edouard will eventually become entrained in a cold front by the end of the week, however no direct nor indirect influence is expected from Edouard on the Mid Atlantic on northward.

For additional information go to the Tropical Weather page.