NY NJ PA Weather Forecasts

This Evening:  Tonight, I discuss the influence of the cold front over the eastern Great Lakes and what the trough is doing to Tropical Storm Fay.  Plus, a discussion on where Fay is going and what it means for the forecast area!

Monday August 18th, 2008

Tropical Storm Fay is really starting to get it’s act together over the eastern Florida keys.  The center of circulation is clearly seen on the latest radar images and the majority of the convection is starting to wrap around the middle of the circulation. 

The 12Z model guidance from the GFS to the ECMWF and even the various hurricane models have started to come into strong agree on the track of Tropical Storm Fay, which is a huge improvement on this morning.  Here is the basic idea of how this tropical storm or possibly hurricane will track over the next several days.

Tonight through tomorrow afternoon, Fay will be under the steering influence of the trough that is moving through the eastern third of the nation.  In terms of strength, the trough is generally weak for the Southeast, but strong enough to influence the direct of Fay and move the tropical storm over the Florida peninsula.  

By Tuesday night, a ridge will begin to build and intensify over the Northeast from the surface to 500 MB.  In previous model runs, the ridge axis was off the East coast and thus allowed Fay or the remnants of Fay to move up the coast.  However, the latest trend has the ridge axis right over the Mid Atlantic, which will act like a road block for Fay.  With Fay not able to move much further north than the coastal waters of Georgia, Fay will be forced to move back to the west either into the Southeast or across Florida into the northeastern waters of the Gulf of Mexico.  At this time, I am not sure which.  

There is significant potential for Fay to intensify rapidly off the waters of western Florida and will have to be monitored hourly.  The one factor against significant intensification though is the southwesterly shear, which thus far has prevented convection to wrap around the center of Fay completely and therefore limiting intensification.

There are two main areas of focus for severe weather today.

The first area is over northern New England and much of northern and western New York.  A trough will begin to move from the eastern Great Lakes through the Northeast with strong divergence aloft, strong PVA, and developing vertical wind shear.  As a result, thunderstorms that develop in these locations will be capable of strong wind gusts over 60 mph, frequent light, large hail, and heavy downpours.  An isolated tornado is possible, but not likely.  

The second area is naturally over southern Florida where Tropical Storm Fay has and will continue to impact locations over southern Florida.  When tropical systems move on to land, the wind shear can lead to isolated tornadoes.  The individual rain bands will also be capable of very heavy rainfall and tropical storm wind gusts.

My best advice for the forecast of Tropical Storm Fay is to through the models out for now.  Why?  Well, let’s look at the facts this morning.  Fact one, a trough that will be lifting to the north and east over the East coast is currently producing strong southwesterly shear over Fay.  Fact two, the position of Fay is much further to the east than originally forecasted.  Fay is currently moving through central Cuba and directly to the south of Florida on a north-northwesterly direction.  At this point, I am leaning heavily of the forecast guidance furtherest to the west, which would take Fay towards the eastern Florida Keys and directly over the Florida peninsula.  How strong can Fay get?  Well, first lets assume that Fay will weaken a bit over the next 12 hours.  The circulation is ragged and most of the convection to to the east of the low level circulation.  The combination of upper level wind shear and the disruption of the low level circulation due to the Cuban topography is having a significant impact on Fay this morning.  The center is also elongated and I wouldn’t be surprised if Fay weakens to a weak tropical storm by the 11 AM update from the National Hurricane Center.  

So what can we expect from Fay once the tropical storm exits Cuba?  I think we will see some strengthening, but the limited time over the waters of the Florida Keys will cut short the potential for strengthening.  At this point, I just don’t see Fay having the ability to reach hurricane strength let alone major hurricane strength, over the next 48 hours.  

After Tuesday evening, I honestly am not sure what to do with Fay.  The GFS just has Fay wonder around the Southeast coastal waters and then back into the Gulf of Mexico.  The ECMWF family sends Fay eventually into the Mid West as the tropical system is drawn into a slowly advancing trough.  Considering that global model guidance has been very shaky with forecasting the position of the ridge along the East coast for the end of the week, I’m taking a wait and see approach with this situation.

The local forecast discussion is updated!

This forecast is getting tricker by the hour.  While only a weak cold front is expected to impact the forecast area over the next 48 hours, Tropical Storm Fay will likely keep many forecasters on their toes over the next few days!  Where will Fay go?  That’s the big question for everyone who is forecasting for any location from Alabama to Maine.  Here are the thoughts I’ll cover in the technical forecast discussion.

1. Clear skies today, stormy weather tomorrow.

2. Road block to the north!

3.  Where will Fay go?