Arthur becomes season's first hurricane, expected to reach category 2 intensity

By: wxchaser97 , 4:32 PM GMT on July 03, 2014

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Hurricane Arthur
Arthur has organized nicely since 4:00AM EDT, when I wrote my last blog. Since early this morning, Arthur has built its inner core and closed off its eyewall. The circulation has become even more symmetrical and there are numerous rainbands feeding into the circulation. Radar has also indicated some lightning strikes in the eyewall, which indicates strengthening. Satellite presentation has also become much better. A small eye is now apparent on satellite and upper-level cirrus is improving on the western semicircle. Convection is deeper, more sustained, and more symmetrical than it was several hours ago. Aircraft recon has recorded 80kt surface winds with their SFMR instrument. Satellite estimates from TAFB and SAB are up to T4.5/77kts as well, and the NHC has Arthur at a current intensity of 80kts. The latest NHC advisory info and satellite image can be found below. The NRL site is still having internet issues so loading satellite and microwave images is spotty at best.


11:00 AM EDT Thu Jul 3
Location: 32.4°N 78.5°W
Moving: NNE at 10 mph
Min pressure: 981 mb
Max sustained: 90 mph




Forecast For Arthur
I have to say that I was surprised that Arthur got its act together quickly and strengthened like this, but it wasn't totally unexpected. As I had mentioned earlier, if Arthur had organized its inner core fast enough, then it would be able to strengthen more than what I or the NHC had expected. The HRRR showed this solution and had brought Arthur up to category 2 strength in 15 hours when I last wrote my blog. Well, Arthur has organized it's inner core nicely. The eyewall is almost close to, most of the time, closed and has limited dry air from entraining into the circulation. Arthur is still in a favorable environment for strengthening. SST's are still very warm, currently around 28°C according to a nearby buoy. SST's are expected to stay at or above 26°C for the next 18-24hrs. As Arthur pulls away from NC, SST's begin to drop off dramatically. The cold SST's north of the gulf stream will begin to induce weakening and help with a change to an extratropical cyclone. Wind shear is also running low currently. In fact, anticyclonic flow is looking more organized that when I wrote my previous blog. This is helping to increase the upper-level divergence over Arthur and decrease the shear over the system. Shear should remain low for the next 24 hours before increasing ahead of the incoming mid to upper-level trough. The shear will be destructive to the convection and begin to tear the circulation apart. However, Arthur will be getting into the right-entrance region of this trough soon, which will maximize upper-level divergence over the system. This should help get Arthur even stronger before it turns extratropical. Due to low SST's, high shear, and baroclinic energy getting added to Arthur, an extratropical transition is in store in about 2 days. Arthur will continue to weaken once it becomes an extratropical cyclone and interact with land and a larger extratropical cyclone. My forecast intensity is being pushed upward due to the steady strengthening of Arthur. 90mph was my previous peak, but with Arthur already reaching that it has to be raised. My new forecast peak is 105mph, but it is possible that Arthur could even peak 5 or 10mph stronger.

Arthur has had a general motion off to the north-northeast. There have been some wobbles to the north that have brought Arthur closer to the coast. In fact, the motion over the past hour or so was more northward. Arthur is still expected to turn to the northeast and accelerate ahead of the deep-layer trough advancing from the NW. Model guidance is still tightly clustered in the short-term, but looks to be slightly farther west. With how Arthur still hasn't fully made the NE turn yet, it is likely that Arthur at least makes landfall along the Outer Banks. A landfall would occur in about 18hrs or so as Arthur continues a steady northeast path. The northward motions have brought Arthur closer the the Carolina Coast. If Arthur doesn't make the NE soon, then it is possible that Arthur makes landfall on mainland NC. While most of the guidance doesn't show a mainland NC landfall, I wouldn't rule it out. The 12z GFS brings Arthur very close to Wilmington, NC before turning off to the NE, which is something to keep an eye on. After passing NC, the track of Arthur looks to be fairly certain. As it interacts with the deep-layer trough, it will continue to move off to the NE and accelerate. A landfall in Nova Scotia in just over 48hrs looks on track and then moving into NF after that. My forecast track is moved slightly more westward/northward in the short-term to account for Arthur being farther north than I expected and for the small shift in guidance. My cone does include the Wilmington area and, as mentioned earlier, it is possible for a landfall or very close pass there before moving over the Outer Banks. Rain and gusty winds are already being reported over Eastern SC and Southern NC. More rain and stronger winds should spread into NC as the day progresses, especially if Arthur tacks closer to the coast/makes a mainland landfall. The Outer Banks are still expected to receive the worst weather with Arthur. Strong winds, possibly hurricane-force sustained, moderate to heavy rain, and between 3-6' of storm surge can be expected. Other areas along the Eastern US can receive 1-3' of storm surge and some rain, especially in the far NE as Arthur interacts with the trough.

Forecast Intensity
INIT 03/1630Z 80 KT 90 MPH
12H 04/0000Z 85 KT 100 MPH
24H 04/1200Z 90 KT 105 MPH
36H 05/0000Z 80 KT 90 MPH
48H 05/1200Z 70 KT 80 MPH...POST-TROP/EXTRATROP
72H 06/1200Z 55 KT 65 MPH...POST-TROP/EXTRATROP
96H 07/1200Z 40 KT 45 MPH...POST-TROP/EXTRATROP
120H 08/1200Z 30 KT 35 MPH...POST-TROP/EXTRATROP


Forecast Track



Watches/Warnings/Advisories
A HURRICANE WARNING IS IN EFFECT FOR...
* SURF CITY NORTH CAROLINA TO THE NORTH CAROLINA/VIRGINIA BORDER
* PAMLICO SOUND
* EASTERN ALBEMARLE SOUND

A HURRICANE WATCH IS IN EFFECT FOR...
* LITTLE RIVER INLET TO SOUTH OF SURF CITY

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* SOUTH SANTEE RIVER SOUTH CAROLINA TO SOUTH OF SURF CITY
* THE NORTH CAROLINA/VIRGINIA BORDER TO CAPE CHARLES LIGHT
VIRGINIA...INCLUDING THE MOUTH OF THE CHESAPEAKE BAY
* WESTERN ALBEMARLE SOUND

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA. PREPARATIONS TO PROTECT LIFE
AND PROPERTY SHOULD BE RUSHED TO COMPLETION.

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA. ANY DEVIATION OF THE FORECAST TRACK TO THE
LEFT...OR AN INCREASE IN THE FORECAST SIZE OF ARTHUR WOULD LIKELY
REQUIRE THE ISSUANCE OF HURRICANE WARNINGS FOR ALL OR PART OF THE
HURRICANE WATCH AREA.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA.

INTERESTS ALONG THE UNITED STATES EAST COAST NORTH OF THE WARNING
AREA...PRIMARILY IN SOUTHEASTERN NEW ENGLAND...SHOULD MONITOR THE
PROGRESS OF ARTHUR.

INTERESTS IN NOVA SCOTIA SHOULD MONITOR THE PROGRESS OF ARTHUR.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...INCLUDING POSSIBLE
INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED BY YOUR
LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE.


Have a great Thursday and I'll have another blog late tonight.

*Disclaimer* My forecasts are not official. For making any important decisions, seek the NHC and NWS for all forecasts and statements. Listen to local emergency management when evacuation orders are issued.

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About wxchaser97

I'm in high school and love meteorology and extreme weather. I've been fascinated by weather since I was 5, and I plan on becoming a meteorologist.

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