Arthur Slowly Meandering off Florida

Tropical Storm Arthur has slowly intensified over the last 24 hours and is forecast to continue to do so over the next 48. As of 11am Wednesday, here is the latest information:

Location: 260 miles SSE of Charleston, SC
Winds: 60 mph
Movement: N @ 7 mph
Pressure: 997 mb

NEW WITH THIS ADVISORY:
A tropical storm WARNING has been issued from Little River Inlet, nc to the NC/VA border
Tropical Storm watch previously in effect for the east coast of Florida is discontinued.

A hurricane watch remains in effect from Bogue Inlet to Oregon Inlet, NC as well as the Pamlico Sound.

12Z 2014-07-02 Spaghetti Models TS Arthur

12Z 2014-07-02 Spaghetti Models TS Arthur

As seen by the spaghetti models, as well as from my post yesterday, the forecast track is fairly confident. The center of Arthur will pass on or close to the NC Outer Banks Thursday to Friday morning, then exit northeast. MOST places along the coast north of the Outer Banks won’t really see much from Arthur at all – but more from a cold front that will help to push Arthur out to sea. The primary effects of Arthur will be felt very close to the coast up to the Outer Banks. Arthur is expected to be a category 1 hurricane when it does come close to NC.

Arthur Becomes 1st Named Storm of 2014 Season

The first month of the season has gone under our belt with no named storms, but July has changed that right away! Tropical Storm Arthur formed this morning off Florida’s coast and will most likely dampen part of this weekend’s holiday plans for the east coast.

Before you fret, it won’t be an entire weekend washout across the eastern seaboard. Arthur will be gone and out of the way later Saturday. The farther south you are on the coast, the earlier you will be done with impacts from the storm.

Here’s the current information on Arthur as of 2pm Tuesday:

Location: 80 miles ESE of Cape Canaveral, FL
Winds: 40 mph
Movement: NW @ 5 mph
Pressure: 1007 millibars

Spaghetti Models for Arthur's future track. 12Z Tuesday 2014-07-01

Spaghetti Models for Arthur’s future track. 12Z Tuesday 2014-07-01

As you see in the above “spaghetti models” for Arthur’s future track, the forecast is fairly certain. Arthur has begun to move a little more this afternoon towards the NW, but with an approaching frontal boundary, will be steered northward and eventually up the coast. It will be close to, or just over the North Carolina Outer Banks on Friday morning, then accelerate up the Gulf Stream and out to see with the front, and by Sunday – will be off the coast of Nova Scotia.

As for the intensity forecast, that’s a little less certain. Until this morning, Arthur wasn’t all that organized, with very little convection on the northern side of the circulation. Since then, the outflow around the cyclone has gotten better organized and a NOAA hurricane hunter plane is investigating this storm this afternoon. Arthur will be in an area of favorable atmosphere to intensify over the next few days and could become a hurricane by the time it gets near the Outer Banks.

Regardless of what happens over the next couple days, this will not be an inland threat, but rip currents, heavy rain, and gusty winds will be the main impacts along the immediate coasts.

TD 7 Becomes Gabrielle

Tropical Depression Seven didn’t waste much time strengthening tonight into the season’s seventh named storm. As of 11pm, here is the latest on Tropical Storm Gabrielle:

70 miles S of Ponce, Puerto Rico
Winds: 40 mph
Moving: NW @ 8mph
Pressure: 1008 millibars

Nothing has really changed in the forecast philosophy over the last 6 hours. Gabrielle is expected to move through the Caribbean islands of Hispaniola and Puerto Rico, dumping potentially life-threatening flooding rains through the area. Thereafter, the ridge over the Atlantic will steer it north, then a trough over the US should kick it northeastward and out to sea. Most computer models agree with this scenario, as is evident by the spaghetti model output that I have attached to the post. For right now, we can continue to disregard those outliers that keep Gabrielle westward. That is an unlikely scenario.

00Z Gabrielle spaghetti models

00Z Gabrielle spaghetti models

Seventh Depression Forms; Caribbean Heavy Rain Threat

The season’s seventh tropical depression has just formed this afternoon in the northeastern Caribbean Sea, south of Puerto Rico.

Here’s the latest information on the depression as of 5pm:

Location: 130 miles S of San Juan, PR
Winds: 35 mph
Movement: NW @ 9 mph
Minimum pressure: 1009 millibars

The depression will continue to move towards the west and northwest over the next couple days, slowly. This means that heavy rain will be a problem for the islands of Hispaniola and Puerto Rico. The mountainous terrain of Hispaniola will aid in the potential of flooding and mudslides.

The computer models generally take the depression northwestward then getting picked up by a high pressure system off the US East coast by this weekend, and steering it off back into the Atlantic. If the depression stays relatively weak, then it could miss this boost out and stay on a more westerly course, but that seems highly unlikely at this point. You can see that as an outlier on the “spaghetti forecasts” but the general consensus is the ‘curve out to sea’ option.

As for intensity, while the storm will be interacting with land over the next couple days, only slow intensification is expected. It doesn’t look like this will become the season’s first hurricane at this time. However, when the depression becomes a tropical storm (should happen the next 12 to 24 hours), it will get the name Gabrielle.

07L_tracks_latest

 

#Dorian Staying Healthy… for now

Tropical Storm Dorian has been able to keep up with dry air and less-than-ideal water temperatures over the last 24 hours as it chugs west-northwestward through the Atlantic.

As of 5pm this afternoon, Dorian had winds of 60 mph and was located 1670 miles east of the Leeward Islands. While still currently well away from impacting any land areas, Dorian is moving at a good clip west-northwestward, at 20 mph.

Dorian is expected to maintain its west to west-northwestward track over the next 5 days. In fact, as I said yesterday, almost all dynamical models are consistent with this scenario. A look at this afternoon’s spaghetti models reinforces this thought.

Thursday afternoon's spaghetti models for the future track of Dorian.

Thursday afternoon’s spaghetti models for the future track of Dorian.

As you can see, there are a few outliers, but the general track is to keep Dorian north of the Caribbean islands, and that is also the official forecast. However, it is still too early to determine exact track – especially 3-5 days out. There are other factors that will influence the track of Dorian after 5 days, and it is just better for those of you with interests in the southeast US to keep checking back on how the next few days evolve out.

As for the intensity forecast, that also is dependent on a few variables. As I stated earlier, Dorian has survived a somewhat unfavorable environment over the last day. It will be again traversing a relatively favorable envirornmentn over the next couple days, so it may strengthen as it travels the Atlantic. Some models bring Dorian to a hurricane, while others actually weaken the storm. The official forecast calls for Dorian to steadily strengthen to just below hurricane strength by 5 days.

The name of the game right now is to just track Dorian while it’s out over the open waters. Check back for later updates.

#Dorian Continues Across the Open Atlantic

Dorian continues to rapidly fly across the eastern Atlantic Ocean this afternoon.

Inside the center, winds are estimated to be near 50 mph as the forward progression continues towards the west-northwest at 20 mph. This information is as of 5pm Eastern time from the National Hurricane Center.

Everything remains as I posted earlier today about the track of the storm. With a large subtropical ridge over Dorian, a general west to west-northwestward path is expected.

Also as I mentioned earlier, there are a few factors against the rapid strengthening of Dorian. In fact, Dorian will probably weaken a bit over the next few days as it battles dry air and wind shear. The near future Dorian may slightly strengthen, but that will be short lived.

There has already been a little bit of attention about Dorian on a US level, and while that’s good to keep paying attention to the forecast, any impacts won’t be for at least 6 days. There are a lot of variables that can come into play between now and the end of the weekend/early next week. Just keep updated on the latest information as it becomes available.

Here’s a look at those famous spaghetti models for Dorian as of late this afternoon:

Possible tracks of Dorian, should the storm survive the hostile Atlantic ahead of it.

Possible tracks of Dorian, should the storm survive the hostile Atlantic ahead of it.

Dorian Forms in East Atlantic; No Immediate Threat

It’s a little early to be talking about Cape Verde storms, but that’s what we have this late July morning as tropical storm Dorian has formed over the far eastern Atlantic.

As of 11am, Dorian was located 410 miles west-southwest of the Cape Verde Islands with winds of 50 mph. Dorian is moving at a good clip, 21 mph, to the west-northwest. Dorian is expected to continue to the west-northwest over the next 24 to 36 hours before turning a little more due-west.

There is a very good model consensus as to the future track of Dorian. Surprisingly good consensus too, I may add. The “spaghetti models” seem to have a good handle on the path, so I won’t deviate from them as of now. Currently there is a very large ridge of high pressure located over the Atlantic, which you can see on the graphic below. This will be what keeps Dorian to the west-northwest and west – with not much opportunity to recurve out to sea.

This morning's upper level analysis of the Atlantic shows a large subtropical ridge, which will keep Dorian on a general WNW to W track over the next 3-5 days.

This morning’s upper level analysis of the Atlantic shows a large subtropical ridge, which will keep Dorian on a general WNW to W track over the next 3-5 days.

Here’s the famous spaghetti models forecast path, and with the exception of a few outliers (we’ll throw those out), shows the general track for Dorian through the next 120-168 hours.

al032013

The intensity forecast is a little tricky, because there are a few obstacles that will be in Dorian’s way. Dorian is currently over an area of relatively warm sea surface temperatures, as well as low shear, which has allowed it to strengthen this morning. However, the future doesn’t look quite so bright for this little guy. This morning’s analysis shows that drier air and more shear (which would prevent the storm from growing vertically in the atmosphere – hence that would not let it strengthen) ahead of Dorian in a day or so.

This morning's shear tendency map shows that as Dorian moves westward, it will encounter a more hostile environment for strengthening.

This morning’s shear tendency map shows that as Dorian moves westward, it will encounter a more hostile environment for strengthening.

This map shows how the moisture content in the Atlantic decreases towards the west of Dorian.

This map shows how the moisture content in the Atlantic decreases towards the west of Dorian.

Thus with these inhibiting factors, Dorian may only slightly strengthen the next day or so before leveling off or even weakening a little bit thereafter. The official forecast from the National Hurricane Center this morning has Dorian peaking at 60mph over the next 24 hours, then gradually leveling off to around 45 mph through 5 days.

Right now with Dorian well out in the Atlantic, we have plenty of time to monitor its progress – so that it what we will do. Check back for updates throughout the week.

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