Now is NOT the time to panic…
As you saw in a previous post, a reliable model – the ECMWF – develops a tropical storm, which would likely be named Danny if it forms, off the Southeast coast early to middle of next week, and brings it very close to the Northeast late in the week or next weekend as a formidable hurricane (ECMWF brings it down to 969mb, which would likely be a Category 2 hurricane given the high pressure nearby). The GFS and other models don’t develop a storm or make it much weaker.
However, don’t panic or get obsessed with the tropical forecast yet. I will explain several reasons why.
1) Any impact would be at least 5-7 days away. In general, preparedness for a hurricane begins about 3 days away (up to 4 or 5 for stronger, larger and slower moving storms or highly vulnerable areas such as New Orleans and Houston). In the Northeast, storms are moving much faster than in lower latitudes most of the time, so the margin of error is greater as well as the number of days out increases. Confidence decreases greatly beyond 3 days and especially beyond 5 days.
2) Most models do not develop the storm. Even though the ECMWF is seen as the most reliable model (we all remember Sandy for one), it has had many misses. Just because it performs best for one storm doesn’t mean it will perform best here. For all we know, the front may not detach and no storm may even form, or shear may be higher and it may barely form into a weak tropical storm or depression.
3) The late July atmosphere is erratic. This is the peak of summer, and troughs tend to be harder to come by, with blocking ridges often resulting in weak steering currents. This is very much unlike the later season when troughs tend to be stronger and faster. Based on the presence of the ridge to the north, it may get driven into the Carolina coast before it even has a chance to affect the Northeast. Also movement would likely be very slow and erratic initially.
There are so many things that could happen over the next 3-5 days, and we will be watching carefully. However, now is definitely not the time to get too concerned. If the trends continue into next week, that may be a different story, so stay tuned.
OVERALL: Confidence in development – Moderate. Confidence in impact to the Northeast – Very Low.
Forecaster Craig Ceecee