Thursday, September 2, 2010

Sept 2: Hurricane Earl's Final Forecast

Notes:

- The poll for Earl on whether it will directly affect the NYC area or not has ended, with a total of 26 votes. Here are the results:

14 - Yes (53%)
12 - No (46%)

- While a small update may be posted tomorrow, this is the final full forecast for Hurricane Earl. Some updates will be posted tomorrow, with the next update afterwards to be posted on Saturday, after Earl has left the region, with more details on the weekend and next week.

Hurricane Earl's Final Forecast:

Earl's Current Observations: Hurricane Earl is currently a Category 3 hurricane, with sustained winds near 125 mph and minimum pressure near 943 mb. Earl is moving north at 18 mph. Earl has weakened from earlier today, as it has become less organized, and while it could hold in intensity, Earl has reached its peak, and will continue to generally weaken from this point and on, though the weakening at first should be slow, and Earl may occasionaly show signs of some strengthening.

Earl's Intensity Forecast: Earl is currently more disorganized than it was earlier today, and the latest observations are showing that Earl is weakening. Earl could organize itself more over the next day and slightly strengthen, but it has reached its peak. Earl has maintained its strong intensity quite far north, and is likely one of the strongest storms near the East Coast around its latitude, and with rapid weakening of Earl unlikely for the short term, I delayed the time that Earl weakens to a Category 2 hurricane, but it should still be a Cat 2 hurricane when it passes to the east of the area. Earl will then interact with the trough to its west, and transition into an extra-tropical cyclone.

Earl's Track Forecast: The models are starting to reach a consensus, although there are still some minor differences. Even the NOGAPS, which showed a direct hit for Long Island, has now corrected itself further east, though I am keeping a far eastern Long Island near miss in the westernmost end of the uncertainty cone, even though this solution is very unlikely to happen. However, as we are now in the shorter range, the current observations are more important than the models. Earl has been moving north with some wobbles to the NNW or NNE lately, and these can be expected as hurricanes do not travel in completely straight paths, but these wobbles are only temporary, and Earl will start to move more NNE than N over the next 12 hours.

The cold front and trough are currently over the central United States, where they were expected to be at this time, and continue to move east. There could be slight changes in the timing that could have a slight impact on Earl's short term track, but a significant change in Earl's track is unlikely to happen, unless the trough starts to tilt negatively much sooner than expected, however that is unlikely at this time. Earl will then start to feel the effects of the trough and turn more northeast, interacting with it and starting to turn into an extra-tropical cyclone. At this time, I have my forecast track for Earl very slightly east of yesterday's track, but overall it has the same idea, with a near miss for eastern North Carolina and Cape Cod.

I will likely post a few updates tomorrow morning, which if I do, they will focus on the latest observations and what that may mean on Earl's track. Stay tuned for more details on that.

Earl's Forecast Wind, Rain, Impact Maps

As the models are starting to come into an agreement, with slightly less uncertainty, I decided to post rain and impact maps for tonight. I shifted the impact map slightly east of my previous impact map, however due to uncertainty, it is possible that the western end of the TS conditions area could be shifted slightly east or west, more likely east. The worst of Hurricane Earl will be in Cape Cod and eastern North Carolina, where hurricane conditions are possible, with sustained winds potentially approaching 80-100 mph. Further west, lighter but still strong winds will be observed, between 40 and 70 mph.

For Earl's rain map, I looked at the latest model consensus as well as my thinking of Earl, putting the heaviest rain with over 2 inches for eastern North Carolina and Cape Cod, with lighter rain further west. Note that due to Earl likely having a tight rain gradient, there could be heavier rain than the map shows. This map does not include rainfall from the cold front expected to be in the western parts of the region at that time.

The worst threat from Earl, however, will be its storm surge and large waves, as with Earl close to the East Coast, whether it directly hits the coast or not, there will likely be damage along the coast.

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