DROUGHT WATCH IN EFFECT FOR NEW JERSEY

The local forecast discussion is updated.

While great conditions will continue through the first part of the week, it is becoming clear that a coastal storm will have a significant impact on the forecast area.

The following themes are covered in the technical forecast discussion.

1. High pressure providing great fall-like conditions.

2. Strong pressure gradient developing.

3.  Many parts for many roles in potential storm.

While high pressure will remain in control over the forecast area on Wednesday, the weakness to the south and east of the region that has been festering for several days will begin to show signs of development.  The contrast between the cool, dry air over the Northeast and Mid Atlantic and the warm, moist air over the Gulf Stream will produce a stationary front and an area for prime development of low pressure systems.  By Wednesday evening, a low pressure system will develop off the Southeast coast at the surface while a trough and later an upper level low will form over the coastal waters of the Carolina’s.  

This morning, I’ve been examining water vapor images of the short wave disturbance that will help to carve out a new trough in the East by next weekend and the week to follow.  The speed and strength of this disturbance over the north Pacific right now will dive towards the northern Plains by Thursday evening, however stay far enough north to only pull the developing upper low off the Southeast coast towards the forecast area.  Meanwhile, a strong upper low over north Atlantic, which is producing an impressive negative NAO structure, will prevent the surface low along the coast to exit east.  Thus, by Friday evening through Saturday, a strong coastal storm will approach the forecast area.  The strong thermal gradient coupled with the strong divergence aloft will allow this low pressure system to strengthen and produce a significant rain and wind event along the coast on Saturday and possibly into Sunday morning.  

The model guidance for this storm is still in a state of change, however the trend of all model guidance is clearly towards a storm along the coast next weekend.  How strong and the exact time frame is still debatable.  

The local forecast discussion is updated!

Sure, the weather outside is wonderful!  However, trouble is brewing off the East coast and an interesting twist from the tropics may cause even more trouble.  In the meantime, cool and dry conditions can be expected over the next three days.  The low pressure system that will cause trouble will impact the forecast area by next weekend.

The following themes are covered in the technical forecast discussion.

1. Cool conditions continue.

2. Developing low pressure system along the coast by next weekend.

3. Models are confused.

This is exactly why no one should ever follow any model and take it to be 100% gospel.  After almost all model guidance sent next weekend’s storm threat out into the Atlantic, the new 12Z data brings the storm back to the west and impacts the coastal plain.

The models are wavering back and forth due to the uncertainty of the disturbances currently in the Pacific.  However, I am standing firm that there is a real and significant threat for a Nor’ Easter next weekend.  Due to the current developments of contrasting air masses along the coast and over the coastal waters, a well developed weakness in the atmosphere off the coast will be a spawning ground for areas of low pressure.  As the week progresses, I expect the area of weakness at the surface and mid levels to support the development of an upper low off the coast, which in turn will enhance the surface low pressure over the coastal waters.  How much rain or how strong this low will get is still unknown.  However, the atmospheric pattern is supportive of cyclogenesis off the East coast and with the Polar Jet initially well to the north, the speed in which this low pressure moves will be rather slow.  So once the storm begins to impact the forecast area, the potential is there for the unsettled conditions to last for a few days.  

I expect the model guidance to waver back and forth through the week until we can get a better read on the disturbances diving out of Northwestern Canada.  Should the disturbance on Wednesday turns out to be strong, then the Polar Jet will dig much faster into the Great Lakes and force the disturbance off the coast out into the Atlantic.  However, if the disturbance is slightly weaker like I believe it will be based on the latest water vapor images and the latest 12Z guidance, then game on for a very wet weekend next week.