Hurricane Arthur

[phil882]

SFMR was 82, BL mean is not surface, and not all altitudes are reduced at the same %age.  The level at which those 100+ KT readings were taking are better reduced at around 80% which is borderline at best.  Combine that with the degrading presentation of Arthur, and I would be highly, highly surprised if it is upgraded at 5 PM unless the NHC just feels the need to err on the side of extreme caution.

 

We'll see... its not really worth arguing over 5 knot changes in intensity to the degree that we are. Based on my previous experience though, I've seen NHC upgrade a TC based on a surface reading from a dropsonde. That doesn't mean they will in this case, but I've seen precedence for it before. I agree with tony that its a poor assumption to say degradation of the radar reflectivity indicates a less organized TC. Just because some areas around the edge of the eyewall are not precipitating doesn't mean there is dry air intruding into the circulation. There is a lot of misinformation going on in this thread (including some provided by me earlier) but lets state some facts.

 

The storm in the last 24 hours has increased 30 knots in intensity... all while it was in the process of mixing out dry air from the circulation center. Its clear that these occasionally blips from a perfect radar presentation are not preventing the storm from intensifying, and indeed the presentation continues to improve on satellite imagery. 

[wxwilmington]

_{BRB!!! got the ok...}

[PSUBlizzicane2007]

Weird...I'm at Carolina Beach and it isn't as you've described...windy and rain, but not hearing transformers blowing and we still have power here! Good luck!

 

Generally transformers don't blow in 40 MPH winds unless they are extremely poorly constructed or very, very old.

[Weathergun]

I'm honestly not sure what radar you are looking at.  The western eyewall is not "notably intensifying"...latest returns show a reduction in reflectivity.  There is also clearly dry air on the SW side of the eye.

 

Composite radar looks better. Latest extrap pressure is 975.9mb

[heavy_wx]

Another thing to keep in mind is that if it ends up riding the coast, the friction of the land may cause it to further tighten while it would still have a sufficient latent heating source from the water.

Yes though it may also have a better source of low-level dry air. Dew points are currently in the upper 60s and lower 70s in SC where there may be some fetch into the sw quadrant. However, the convective bands wrapping around the storm will likely prevent the drier air from getting too deep into the circulation, at least in the near term.

[PSUBlizzicane2007]

Up to 80 KT FL on the SE side on this pass... looks like the extrap is going to come in ~1.5 MB lower than the last pass.  Basically continued ever-so-slight strengthening, but nothing significant yet.  SFMR not really that impressive in that quadrant, but that's not terribly surprising.

[BuffaloWeather]

Wind gust to 82 MPH on platform off coast according to TWC.

[downeastnc]

Wind gust to 82 MPH on platform off coast according to TWC.

 

That would most likely be this

 

http://www.fptower.com/

[toxictwister00]

We'll see... its not really worth arguing over 5 knot changes in intensity to the degree that we are. Based on my previous experience though, I've seen NHC upgrade a TC based on a surface reading from a dropsonde. That doesn't mean they will in this case, but I've seen precedence for it before. I agree with tony that its a poor assumption to say degradation of the radar reflectivity indicates a less organized TC. Just because some areas around the edge of the eyewall are not precipitating doesn't mean there is dry air intruding into the circulation. There is a lot of misinformation going on in this thread (including some provided by me earlier) but lets state some facts.

 

The storm in the last 24 hours has increased 30 knots in intensity... all while it was in the process of mixing out dry air from the circulation center. Its clear that these occasionally blips from a perfect radar presentation are not preventing the storm from intensifying, and indeed the presentation continues to improve on satellite imagery. 

 

I'm not arguing against this because I agree it does, but isn't it possible that can be a bit deceiving in determining whether a hurricane is intensifying or not? 

[PSUBlizzicane2007]

I'm not arguing against this because I agree it does, but isn't it possible that can be a bit deceiving in determining whether a hurricane is intensifying or not? 

 

Absolutely.  There have been many cases of storms looking gorgeous on satellite imagery, only to have recon find it to be not nearly as impressive as expected.

 

Never judge a tropical cyclone by its satellite imagery...unless that's the only thing you have.

[Weathergun]

NOAA plane just a made pass. Reported a 974.3mb extrap pressure.

203130 3322N 07801W 7506 02291 9744 +168 +138 017006 009 015 002 00203200 3321N 07759W 7505 02288 9743 +168 +135 134003 004 014 002 03203230 3321N 07756W 7508 02287 9746 +165 +133 163009 012 019 001 00

[griteater]

I will just say that this is a heck of a satellite signature for a category 1 storm

 

[PSUBlizzicane2007]

 

NOAA plane just a made pass. Reported a 974.3mb extrap pressure.

203130 3322N 07801W 7506 02291 9744 +168 +138 017006 009 015 002 00203200 3321N 07759W 7505 02288 9743 +168 +135 134003 004 014 002 03203230 3321N 07756W 7508 02287 9746 +165 +133 163009 012 019 001 00

 

 

This makes sense.  The NOAA plane will likely have a lower extrap since it is flying at a higher altitude than the USAF plane.

[dan88]

This makes sense.  The NOAA plane will likely have a lower extrap since it is flying at a higher altitude than the USAF plane.

 

 

NOAA is flying at 750mb, USAF is flying at 700mb

[HKY_WX]

i think there's def a little bit more organization going on over the last few hours. This will be fun to watch tonight.

[klw]

past two hours on radar

[jbenedet]

I took a break from this for a few hours and at some point Arthur clearly took a nice jog east, but over the past hour he definitely looks to be back heading due north or ever so slightly east of due north.

 

http://radar.weather.gov/radar.php?rid=LTX&product=NCR&overlay=11101111&loop=yes

[phil882]

NHC stayed with 80 knots at 5pm. Still forecasting 85 knots max intensity.

[Weathergun]

From 5pm Advisory:

A TROPICAL STORM WARNING HAS BEEN ISSUED FOR NANTUCKET ISLANDAND FOR CAPE COD FROM PROVINCETOWN TO CHATHAM.

[TropicalAnalystwx13]

 

 

HURRICANE ARTHUR DISCUSSION NUMBER  12

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012014

500 PM EDT THU JUL 03 2014

The eye of Arthur has become more distinct in visible satellite

imagery this afternoon, although the overall radar presentation has

changed very little. The latest flight-level and SFMR wind

observations are 84 kt and 82 kt respectively.  These data support

maintaining the 80-kt initial intensity. Environmental conditions

are expected to remain conducive for strengthening during the next

12 to 18 hours and Arthur is still forecast to reach category two

intensity as it nears the North Carolina coast.  Vertical shear is

forecast to increase significantly by Friday night and weakening

should commence by that time.  Arthur is expected to interact with

an approaching deep-layer trough and should become a post-tropical

cyclone within 48 hours. Steady weakening is anticipated after

Arthur becomes post-tropical.

Aircraft and radar fixes indicate that the initial motion is 020

degrees at 11 kt, a little faster than before.  Arthur is expected

to turn northeastward and accelerate ahead of a deep-layer trough

that will move into the eastern United States during the next day

or so.  Although the models still remain in good agreement on the

track of Arthur during the next couple of days, there has been a

westward shift this cycle.  The new NHC track has been shifted

westward and lies between the GFS and ECMWF models through 36

hours.  The updated track now shows landfall in eastern North

Carolina or the Outer Banks later tonight.   Beyond 36 hours, the

NHC track has been adjusted about a degree westward, but it is not

as far west as the GFS and ECMWF model trackers.

While in most cases this westward shift in the track will be

immaterial to impacts, it does mean that the hurricane's strongest

winds are now more likely to be experienced along the Outer Banks,

rather than remain offshore.

NHC public advisories will be issued every two hours beginning at 7

pm EDT this evening and Tropical Cyclone Updates will be issued

on the hour between each Public Advisory to provide hourly position

updates.

The new experimental potential storm surge flooding map is

available at: www.nhc.noaa.gov/graphics_at1.shtml?inundation

FORECAST POSITIONS AND MAX WINDS

INIT  03/2100Z 33.4N  77.9W   80 KT  90 MPH

12H  04/0600Z 35.3N  76.1W   85 KT 100 MPH

24H  04/1800Z 38.2N  72.6W   85 KT 100 MPH

36H  05/0600Z 41.9N  68.0W   75 KT  85 MPH

48H  05/1800Z 45.2N  64.2W   60 KT  70 MPH...POST-TROP/EXTRATROP

72H  06/1800Z 50.4N  56.2W   40 KT  45 MPH...POST-TROP/EXTRATROP

96H  07/1800Z 56.5N  47.5W   35 KT  40 MPH...POST-TROP/EXTRATROP

120H  08/1800Z 60.0N  37.5W   30 KT  35 MPH...POST-TROP/EXTRATROP

$$

Forecaster Brown

[Max]

The advisory has 979mb for the central pressure yet the last VDM had 977mb. I am confused by this. No mention of the higher pressure being reported by the aircraft in the discussion.

[PSUBlizzicane2007]

Good decision by the NHC at 5 PM intensity-wise, but I think I would have extended the hurricane warning south a little bit just to be on the safe side.  At least include the city of Wilmington.

[PSUBlizzicane2007]

The advisory has 979mb for the central pressure yet the last VDM had 977mb. I am confused by this. No mention of the higher pressure being reported by the aircraft in the discussion.

 

The VDM pressure was extrapolated, and the dropsonde measured pressures have been running a little bit higher than those.

[icebreaker5221]

While the southward outflow channel has been impressive for some time now, the northward channel has lagged behind a bit.  That should change over the next 12 hrs or so as the trough to the north lowers the static stability, requiring the storm to do less work to expel mass northward.  In other words, there should be some dynamical strengthening even as the thermodynamics gradually become less favorable. 

[David Reimer]

Product: NOAA Vortex Message (URNT12 KWBC)
Transmitted: 3rd day of the month at 20:56Z
Aircraft: Lockheed WP-3D Orion (Reg. Num. N43RF)
Storm Number & Year: 01L in 2014
Storm Name: Arthur (flight in the North Atlantic basin)
Mission Number: 13
Observation Number: 03
A. Time of Center Fix: 3rd day of the month at 20:31:48Z
B. Center Fix Coordinates: 33°21'N 77°59'W (33.35N 77.9833W)
B. Center Fix Location: 57 miles (92 km) to the ESE (115°) from Myrtle Beach, SC, USA.
C. Minimum Height at Standard Level: Not Available
D. Estimated (by SFMR or visually) Maximum Surface Wind: 61kts (~ 70.2mph)
E. Location of the Estimated Maximum Surface Wind: 23 nautical miles (26 statute miles) to the W (272°) of center fix
F. Maximum Flight Level Wind Inbound: From 1° at 67kts (From the N at ~ 77.1mph)
G. Location of Maximum Flight Level Wind Inbound: 26 nautical miles (30 statute miles) to the W (271°) of center fix
H. Minimum Sea Level Pressure: 977mb (28.85 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 13°C (55°F) at a pressure alt. of 2,461m (8,074ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 17°C (63°F) at a pressure alt. of 2,462m (8,077ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 14°C (57°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Open in the southwest
M. Eye Shape & Diameter: Ci 
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: Other - Not surface, 1500ft, 925mb, 850mb, 700mb, 500mb, 400mb, 300mb or 200mb
O. Navigational Fix Accuracy: 1 nautical mile
O. Meteorological Accuracy: 3 nautical miles
Remarks Section:
Maximum Flight Level Outbound and Flight Level Wind: 85kts (~ 97.8mph) which was observed 22 nautical miles (25 statute miles) to the E (97°) from the flight level center at 20:37:16Z
Maximum Flight Level Temp: 17°C (63°F) which was observed 7 nautical miles to the W (272°) from the flight level center
Dropsonde Wind at Center: From 125° at 5kts (From the SE at 6mph)

[PSUBlizzicane2007]

While the southward outflow channel has been impressive for some time now, the northward channel has lagged behind a bit.  That should change over the next 12 hrs or so as the trough to the north lowers the static stability, requiring the storm to do less work to expel mass northward.  In other words, there should be some dynamical strengthening even as the thermodynamics gradually become less favorable. 

 

I agree on this, although I am most concerned with just how far inland Arthur gets at this point.

[phil882]

Good decision by the NHC at 5 PM intensity-wise, but I think I would have extended the hurricane warning south a little bit just to be on the safe side.  At least include the city of Wilmington.

 

Yea that is a little strange... especially given this wind swath. They are playing a bit of catch up with the last two or three advisories having to shift the track westward.

 

[dan88]

The advisory has 979mb for the central pressure yet the last VDM had 977mb. I am confused by this. No mention of the higher pressure being reported by the aircraft in the discussion.

Just a mistake, the text of the public advisory has the correct pressure of 977mb from the drop shortly before the advisory time

 

THE LATEST MINIMUM CENTRAL PRESSURE MEASURED BY AN AIR FORCERESERVE RECONNAISSANCE AIRCRAFT WAS 977 MB...28.85 INCHES.

[blueheronNC]

Cape Fear's about to get the eyewall of a 90-mph hurricane and not be covered by a hurricane warning.  Crazy stuff.

[theredball]

Cape Fear's about to get the eyewall of a 90-mph hurricane and not be covered by a hurricane warning.  Crazy stuff.

 can't scare away the tourists