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WxWatcher007

Tropical Storm Arthur

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Alright, it's time to shake off the rust and get back to tracking. 

Invest 90L is slowly organizing off the Florida coast, with recon making its first flight of the year. If we get a name, it would be Arthur, and it would be the sixth consecutive year we've seen a named storm prior to June 1 in the Atlantic Basin. 

Recon is finding a weak and broad low, but the system has organized gradually since yesterday. 

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Guidance is in good agreement that 90L takes an NNE track until the system reaches the coast of NC on Monday. From there, there is a split in the guidance, with the GFS and its ensembles most notably taking the system northward into the Mid-Atlantic/NE region. This has been the case the last two runs. 

The rest of the guidance takes the low more eastward and OTS. I think we're going to need to wait until we have a better defined low to get a sense of how it interacts with the dropping CONUS upper level low to be sure of the eventual track,  but at any rate, heavy rainfall and rough seas are the biggest threats. 

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First VDM of the year. Looks like there's at least a weak center. 

 

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 16th day of the month at 15:59Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5303
Mission Purpose: Investigate first suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 10 ( See all messages of this type for this mission. )

A. Time of Center Fix: 16th day of the month at 15:17:10Z
B. Center Fix Coordinates: 27.65N 79.11W
B. Center Fix Location: 88 statute miles (141 km) to the NE (42°) from West Palm Beach, FL, USA.
C. Minimum Height at Standard Level: Not Available
D. Minimum Sea Level Pressure: 1009mb (29.80 inHg) - Extrapolated
E. Dropsonde Surface Wind at Center (Undecoded): NA
F. Eye Character: Not Available
G. Eye Shape: Not Available
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 31kts (35.7mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 28 nautical miles (32 statute miles) to the N (3°) of center fix at 14:57:00Z
J. Maximum Flight Level Wind Inbound: From 82° at 29kts (From the E at 33.4mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 38 nautical miles (44 statute miles) to the NNE (30°) of center fix at 14:52:30Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 34kts (39.1mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 28 nautical miles (32 statute miles) to the N (359°) of center fix at 15:56:00Z
N. Maximum Flight Level Wind Outbound: From 34° at 22kts (From between the NNE and NE at 25.3mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 5 nautical miles to the WNW (296°) of center fix at 15:18:30Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 21°C (70°F) at a pressure alt. of 217m (712ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 305m (1,001ft)
R. Dewpoint Temp & Sea Surface Temp: Not Available
S. Fix Determined By: Penetration, Wind and Pressure
S. Fix Level: 1,500 feet
T. Navigational Fix Accuracy: 0.02 nautical miles
T. Meteorological Accuracy: 6 nautical miles

Remarks Section:
 

Maximum Flight Level Wind: 29kts (~ 33.4mph) which was observed 38 nautical miles (44 statute miles) to the NNE (30°) from the flight level center at 14:52:30Z
Sea Level Pressure Extrapolation From: Below 1500 feet
Maximum Flight Level Temp: 23°C (73°F) which was observed 14 nautical miles (16 statute miles) to the S (190°) from the flight level center
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Second VDM

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 16th day of the month at 17:42Z
Agency: United States Air Force 
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5303 
Mission Purpose: Investigate first suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 13 ( See all messages of this type for this mission. )

A. Time of Center Fix: 16th day of the month at 17:12:10Z
B. Center Fix Coordinates: 27.98N 78.75W
B. Center Fix Location: 115 statute miles (185 km) to the E (95°) from Melbourne, FL, USA.
C. Minimum Height at Standard Level: Not Available
D. Minimum Sea Level Pressure: 1008mb (29.77 inHg) - Extrapolated
E. Dropsonde Surface Wind at Center (Undecoded): NA
F. Eye Character: Not Available
G. Eye Shape: Not Available
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 34kts (39.1mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 10 nautical miles (12 statute miles) to the ENE (62°) of center fix at 17:08:30Z
J. Maximum Flight Level Wind Inbound: From 54° at 30kts (From the NE at 34.5mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 12 nautical miles (14 statute miles) to the NNW (336°) of center fix at 16:59:30Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 33kts (38.0mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 7 nautical miles to the W (276°) of center fix at 17:14:30Z
N. Maximum Flight Level Wind Outbound: From 338° at 12kts (From the NNW at 13.8mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 7 nautical miles to the W (276°) of center fix at 17:14:30Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 22°C (72°F) at a pressure alt. of 187m (614ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 192m (630ft)
R. Dewpoint Temp & Sea Surface Temp: Not Available
S. Fix Determined By: Penetration, Wind, Pressure and Temperature
S. Fix Level: 1,500 feet
T. Navigational Fix Accuracy: 0.02 nautical miles
T. Meteorological Accuracy: 6 nautical miles

Remarks Section:
 

Maximum Flight Level Wind: 30kts (~ 34.5mph) which was observed 12 nautical miles (14 statute miles) to the NNW (336°) from the flight level center at 16:59:30Z
Sea Level Pressure Extrapolation From: Below 1500 feet

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Special Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Sat May 16 2020

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Special Tropical Weather Outlook issued to discuss the potential 
for tropical or subtropical development off the east coast of 
Florida. 

Data from the Air Force Hurricane Hunters and satellite images 
indicate that the low pressure system located just off the coast of 
east-central Florida has become better defined today.  In addition, 
the associated showers and thunderstorms continue to gradually 
organize. If these trends continues, advisories will likely be 
initiated on this system as a tropical or subtropical depression 
later today. Later in the weekend and early next week, the system 
is expected to move generally northeastward over the western 
Atlantic near or east of the Carolinas.

The system will continue to bring gusty winds and locally heavy 
rains across portions of east-central Florida through tonight.  
Interests near the North Carolina coast should closely monitor the 
progress of this system, as it could produce gusty winds and heavy 
rains there on Monday, and a tropical storm watch will likely be
issued for that area later today.  In addition, hazardous marine 
conditions will spread northward during the next few days, likely 
causing dangerous surf and rip currents along much of the southeast 
and mid-Atlantic coasts of the U.S. See products from your local 
National Weather Service office for more details. Another Air Force 
Reserve Hurricane Hunter aircraft is scheduled to investigate the 
system this evening. The next Special Tropical Weather Outlook on 
this system will be issued by 9 PM EDT today, or earlier if needed.
* Formation chance through 48 hours...high...near 100 percent.
* Formation chance through 5 days...high...near 100 percent.

$$
Forecaster Cangialosi

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2 hours ago, WxWatcher007 said:
Special Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Sat May 16 2020

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Special Tropical Weather Outlook issued to discuss the potential 
for tropical or subtropical development off the east coast of 
Florida. 

Data from the Air Force Hurricane Hunters and satellite images 
indicate that the low pressure system located just off the coast of 
east-central Florida has become better defined today.  In addition, 
the associated showers and thunderstorms continue to gradually 
organize. If these trends continues, advisories will likely be 
initiated on this system as a tropical or subtropical depression 
later today. Later in the weekend and early next week, the system 
is expected to move generally northeastward over the western 
Atlantic near or east of the Carolinas.

The system will continue to bring gusty winds and locally heavy 
rains across portions of east-central Florida through tonight.  
Interests near the North Carolina coast should closely monitor the 
progress of this system, as it could produce gusty winds and heavy 
rains there on Monday, and a tropical storm watch will likely be
issued for that area later today.  In addition, hazardous marine 
conditions will spread northward during the next few days, likely 
causing dangerous surf and rip currents along much of the southeast 
and mid-Atlantic coasts of the U.S. See products from your local 
National Weather Service office for more details. Another Air Force 
Reserve Hurricane Hunter aircraft is scheduled to investigate the 
system this evening. The next Special Tropical Weather Outlook on 
this system will be issued by 9 PM EDT today, or earlier if needed.
* Formation chance through 48 hours...high...near 100 percent.
* Formation chance through 5 days...high...near 100 percent.

$$
Forecaster Cangialosi

Advisories going up at 5pm per NHC

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FORECAST VALID 19/0600Z 37.1N 72.3W MAX WIND 50 KT...GUSTS 60 KT. 50 KT... 40NE 30SE 0SW 0NW. 34 KT...120NE 100SE 70SW 90NW.

NHC is expecting a 50 knot peak for future Arthur.

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BULLETIN
Tropical Depression One Advisory Number   1
NWS National Hurricane Center Miami FL       AL012020
500 PM EDT Sat May 16 2020

...TROPICAL DEPRESSION FORMS OFF THE COAST OF EAST-CENTRAL
FLORIDA...
...TROPICAL STORM WATCH ISSUED FOR A PORTION OF THE NORTH CAROLINA
COAST...


SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...28.4N 78.6W
ABOUT 125 MI...200 KM E OF MELBOURNE FLORIDA
ABOUT 505 MI...810 KM SSW OF CAPE HATTERAS NORTH CAROLINA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NNE OR 20 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

A Tropical Storm Watch has been issued for the North Carolina coast
from north of Surf City to Duck, including Pamlico and
Albemarle Sounds.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Watch is in effect for...
* New River Inlet to Duck NC
* Pamlico and Albemarle Sounds

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.

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.


DISCUSSION AND OUTLOOK
----------------------
At 500 PM EDT (2100 UTC), the center of Tropical Depression One 
was located near latitude 28.4 North, longitude 78.6 West. The
depression is moving toward the north-northeast near 13 mph (20
km/h) and this motion should continue during the next day or so.  
After that time, a faster northeastward motion is expected.  On 
the forecast track, the depression is expected to move offshore, 
but parallel to, the coast of Florida tonight, and then move near 
or east of the coast of North Carolina on Monday.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Gradual strengthening is forecast, and the depression is expected 
to become a tropical storm on Sunday.

The estimated minimum central pressure based on surface observations 
and earlier aircraft reconnaissance data is 1008 mb (29.77 inches).

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Still looks like towards June should be another time frame to keep an eye on as a KW possibly moves into the GOM along with the MJO starting to strenghten in P8 by the Euro towards the end of the month,just my hunch and no forecast

AccuWeather_com®_Professional_Forecast_Models (1).png

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Not quite on topic, but we aren't in storm mode yet...

I just wanted to point out how nice it is to have this message board at a time when Wunderground is less and less science/community friendly for severe and tropical weather. Their tropical page is complete garbage. Satellite imagery is no longer loopable. Their image for Arthur is off the coast of Asia. WTF? I'll go there for my daily forecast, but this is the best source (or aggregate of sources) when the big stuff happens. Let's all have a safe and educational tropical season!

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Turns into a bizarre zonal frontal wave in 48hrs.  

Also doesn't look like much of Aurthur's moisture gets into the ULL that will undoubtedly cause flooding in the Carolinas and VA

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It's May. Fun to track. Probably will cause some coastal winds and flooding per typical coastal low, but Arthur does looks anemic. We'll see if any convective forcing could tighten up its gradient tonight, but that's probably asking a bit much at this point. I think coastal Carolinians will handle poor Arthur without much of a hiccup.

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12 minutes ago, Windspeed said:

It's May. Fun to track. Probably will cause some coastal winds and flooding per typical coastal low, but Arthur does looks anemic. We'll see if any convective forcing could tighten up its gradient tonight, but that's probably asking a bit much at this point. I think coastal Carolinians will handle poor Arthur without much of a hiccup.

Yeah,odds of getting a TC this time off year are rare anyways

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pretty pathetic right now,but some convection is showing up east of the circulation

Tropical Storm Arthur Discussion Number   6
NWS National Hurricane Center Miami FL       AL012020
1100 PM EDT Sun May 17 2020

Arthur's appearance in radar and satellite imagery has degraded
significantly since the previous advisory with very little
convective banding features present now. However, an Air Force
Reserve reconnaissance aircraft investigating the cyclone late this
afternoon and early has found maximum 850-mb flight-level winds of
46 kt in the eastern quadrant along with reliable SFMR surface wind
speeds of 36-38 kt, plus a central pressure of 1003 mb. Based on
these data, the initial intensity has been held at 40 kt for this
advisory since higher wind speeds could be present within areas of
convection north of the center that were not sampled.

Aircraft and satellite fixes indicate that Arthur has continued to
move north-northeastward or 020/09 kt. The cyclone is forecast to
accelerate northeastward on Monday ahead of an approaching shortwave
trough and frontal system, and remain just offshore of the North
Carolina Outer Banks. By Tuesday night, Arthur will be entering the
strong mid-latitude Westerlies, which will steer cyclone eastward
and also induce extratropical transition when the cyclone merges
with the aforementioned frontal system. The new NHC track guidance
is tightly clustered about the previous forecast track, so no
significant cross-track changes were required. However, some slight
changes to the forward were required on days 2 and 3, and the new
NHC track forecast now shows Arthur moving a little faster to the
east and southeast on those days.

Arthur is currently moving over the warmest waters in the Gulfstream
where ocean temperatures are 26-26.5 deg C. However, some mid-level
shear undercutting the otherwise upper-level outflow pattern,
coupled with the entrainment of dry mid-level air has disrupted the
overall convective pattern. These unfavorable conditions should
continue for the next coupe of days, with only intermittent bursts
of deep convection occuring near the center until Arthur passes
northeast of the Outer Banks by late Monday. Thereafter, baroclinic
effects along with extratropical transition are expected to cause
some further strengthening before weakening begins late Tuesday and
on Wednesday. The official intensity forecast follows a blend of the
intensity consensus model IVCN, and the GFS and ECMWF model
forecasts.

 

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