Feb 26: Coastal Storm Detected

Jonathan Carr
By Jonathan Carr February 26, 2018 19:59

Feb 26: Coastal Storm Detected

Discussion: I’ve been watching this tremendous blocking pattern evolve and unfold for a while now. There is no doubt it’s coming. As a quick refresher, blocking is represented by a negative-phased state of the North Atlantic Oscillation (NAO). It means a strong higher heights block over Greenland which prevents a low from progressively passing out to sea to the NE. Typically when a low pressure system tracks like a typical miller-A or miller-B, there is NE movement of the low from the S US or SE US. If this were the case with this Thursday PM-Saturday AM, the low would stall and possibly become stationary. This would be very bad for coastal flooding interests.

The March 1-3 low is expected to come from the W/NW however due to an unfavorable W US/E Pacific pattern. We will likely not have a W US ridge (+PNA). Instead we should have a trough over the W US and a ridge over the C US. This sort of takes the low up, over (to the E) and down…around the C US ridge. That’s why the low is coming in from that W/NW angle instead of from the SW. Therefore, even though the block is significant, the low can maintain momentum from W/NW to E/SE…down and around the bottom of the greater W/N Atlantic block. Either way, once it hits that wall it will not be able to move NE.

The latest trend in model guidance is for the primary low to track a little further to the E. This would mean a track towards the E Great Lakes rather than the C Great Lakes. The low is then expected to transfer to the Atlantic Ocean. A further E primary track would mean a further E transfer out-to-sea. This would be great for the coast. It would mean a run-of-mill coastal storm rather than something more serious. We are still not there yet on how this will exactly play out. Tomorrow, the pieces of energy involved will be much better sampled and we can begin to estimate low tracks with higher precision.

For now, expect a coastal storm to form and impact NJ between Thursday PM (March 1) and early Saturday AM (March 3) with the meat and potatoes of impact occurring Friday (March 2). Obviously coastal areas would see the higher impacts while those inland would likely just see gray, breezy/windy and rainy contitions. The jury is still out on rain changing to snow. NW areas of NJ would have the best shot if precipitation rates can reach high levels. We will likely have a marginal temperature profile at the low-mid levels which would fight the idea of snowfall accumulation for NJ. This is also something that will become apparent as we closer approach. A paste job is not out of the question with this kind of setup. Eventually winds should switch to the N. The sooner the better for the coast. Then the entire state will be subject to higher N winds heading into the weekend.

In English: Impacts from a coastal storm are expected between Thursday PM and Saturday AM. This could include moderate-to-heavy rainfall, gusty winds, coastal flooding and beach erosion. Snow is currently a lesser concern with this system but possible especially after winds switch from onshore to northerly. I’m also monitoring a storm signal in the ~March 6-7 time period but we’re going to have to get through this Thursday PM-Saturday AM system first. The exact intensity of the coastal storm will be ironed out over the next few days as well as precipitation type. It currently looks like a warmer storm for winter. For now, plan on some level of impact in that Thursday PM-Saturday AM period. Timing will also narrow as we further approach. Have a great night and please be safe! JC

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Jonathan Carr
By Jonathan Carr February 26, 2018 19:59

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