MikeC
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6 AM EDT Update 7 August 2017
Tropical storm Franklin has a small chance to become a hurricane before landfall in the Yucatan, and the government of Mexico has put up a hurricane watch to reflect this. Landfall for the Yucatan is around midnight tonight (CDT), once back over the open water it has a second chance to strengthen.
Invest 99L is in a bad spot for development right now, it likely won't develop before passing north of the Caribbean. However it should be watched as long as it could potentially develop later.
Flhurricane Radar recording of Belize Radar for Franklin's approach
Webcams:
Mahahual / Costa Maya Webcam Recording
Xel Ha Webcam Recording
10:45PM EDT Update 6 August 2017
Ptnl SEVEN has become Tropical Storm Franklin, the sixth named storm, and seventh tropical cyclone of the 2017 Atlantic Hurricane Season. Only four other years have had six Named Storms by this date in the Atlantic basin: 1936, 1959, 2005 and 2012. (Cr. Philip Klotzbach)
-Ciel
3:30PM EDT Update 6 August 2017
Invest 90L is very close to meeting the qualifications to be considered a tropical cyclone, and advisories are likely to be issued soon on SEVEN. Interests in the western Caribbean should prepare for tropical storm conditions early next week. A hurricane prior to crossing into the Bay of Campche is also not out of the question. The next name on the list is Franklin. Not to be confused with the former forecaster.
Elsewhere, 99L in the central Tropical Atlantic appears to be succumbing to dry air and shear, but could pull out of that region later in the new week and still needs to be monitored.
- Ciel
Original Entry
August beings the ramp up in earnest into the peak of the Atlantic Hurricane Season toward the climatological peak, which is the second half of August and most of September. This is the time of year where we watch all areas in the tropics and the most surprises tend to happen. It's also the time when conditions tend to be the best for development, and this year is no exception to that.
In the far east Atlantic, a wave has emerged from Africa in a very good position to develop, and because of this the National Hurricane Center requested an investigation area be put on it almost immediately. This system, tagged as 99L now has a 50% chance for development and multiple model support for it, so it's likely by the weekend we'll have a depression or named storm to track across the Atlantic. This does not guarantee a system will make it across, but history tells us that everything this time of year should be monitored closely.
If it were to develop and maintain itself it would likely be closest to the Caribbean in the middle of next week, and closer to the US late next week. See the forecast lounge for long range discussion and speculation on the system. There are factors that could keep it weak and hamper development, so out this far its impossible to say where or how strong it could be.
There may be other areas to track next week as well, watch for a potential area near the Yucatan / Bay of Campeche.
Flhurricane Radar recording of Belize Radar for Franklin's approach
Webcams:
Mahahual / Costa Maya Webcam Recording
Xel Ha Webcam Recording
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MikeC
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60% chance for development now, this system will likely be an interesting one to keep track of over the next two weeks. Euro ensembles have it at about a 70% chance for development, the has 60%. Long range discussion in the lounge.
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MikeC
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Added
Flhurricane Radar recording of Belize Radar for Franklin's approach
Webcams:
Mahahual / Costa Maya Webcam Recording
Xel Ha Webcam Recording
Summary of all franklin related recordings: here
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MikeC
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GOES 16 high res visible sat loop of Franklin http://rammb.cira.colostate.edu/ramsdis/...oop_speed_ms=80 (Note takes a bit to load)
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MikeC
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Recon just left and is on the way to Franklin.
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MikeC
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Franklin, as feared it may, seems to be rapidly intensifying, recon is there now, which is amazingly good timing, no good readings yet but we will know shortly.
source http://rammb-slider.cira.colostate.edu/?...;s=rammb-slider
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cieldumort
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Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 7th day of the month at 17:49Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5304
Storm Number & Year: 07 in 2017
Storm Name: Franklin (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 07
A. Time of Center Fix: 7th day of the month at 17:20:10Z
B. Center Fix Coordinates: 17°59'N 85°12'W (17.9833N 85.2W)
B. Center Fix Location: 200 statute miles (322 km) to the E (80°) from Belize City, Belize.
C. Minimum Height at Standard Level: 1,405m (4,610ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 48kts (~ 55.2mph)
E. Location of the Estimated Maximum Surface Wind Inbound: 58 nautical miles (67 statute miles) to the NNE (25°) of center fix
F. Maximum Flight Level Wind Inbound: From 121° at 46kts (From the ESE at ~ 52.9mph)
G. Location of Maximum Flight Level Wind Inbound: 21 nautical miles (24 statute miles) to the NNE (24°) of center fix
H. Minimum Sea Level Pressure: 999mb (29.50 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 1,530m (5,020ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 19°C (66°F) at a pressure alt. of 1,521m (4,990ft)
K. Dewpoint Temp & Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Open in the northwest, NW
M. Eye Shape & Diameter: Circular with a diameter of 16 nautical miles (18 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigational Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 3 nautical miles
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SouthGAwx
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Certainly not rapidly intensifying. What appears at first glance to be an eye feature is a bit of dry air intrusion that has been wrapped up into the circulation. This is evident in water vapor and IR imagery. Overall, cloud tops have warmed significantly since this morning, and Franklin has a more ragged appearance. As of yet, the recon aircraft has found no data to support the current 50 kt initial intensity -- and I expect that is a bit too generous.
(Also note that the recon fix has been to the south of what is mistaken for an eye. Conclusive evidence that this is indeed not an eye, since it is not co-located with the center of circulation.)
Take care,
-C.
Edited by SouthGAwx (Mon Aug 07 2017 03:12 PM)
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Hawkeyewx
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Yes, Franklin has a nice general structure and a well-defined circulation, but the core is kinda wimpy. Only slow strengthening is to be expected until deeper convection fills in over the center. Landfall is only several hours away, so cane status may have to wait until the Bay of Campeche.
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cieldumort
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Interesting debate going on among knowledgeable people, and I come down on the side of the lowest minimum pressure being found inside an incipient eye (which is also confirmed by Recon). Recon has also found winds that support a maximum intensity at or above 55 MPH, which operationally is reasonable to round to 60, as it is likely the strongest winds inside Franklin have not been sampled.
As per the first Vortex messageQuote:
D. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 48kts (~ 55.2mph)
M. Eye Shape & Diameter: Circular with a diameter of 16 nautical miles (18 statute miles)
The time of this, the first (inbound) center fix, was 17:20:10Z and located the surface center at 17.9833N 85.2W. Rounding the center location to 18N 85.2W plots the verified lowest surface pressure center at the time of the fix well within the south side of the alleged developing eye.
It does look like some dry air has been entrained, and that may limit Franklin's initial attempts at a more robust period of intensification, but based on recon data it seems plausible that the suspected developing eye is mostly exactly that, and not a 'sucker hole.'
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SouthGAwx
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Latest center fix comes with more reliable SFMR data which could barely support an initial intensity of 50 kts... but the overall satellite appearance is such that I would set the initial intensity at a more conservative 45 kts. Especially since the last fix at 17:45 was 3.0/45 kts, and cloud tops have continually warmed/convection near the center has been disrupted by some dry air entrainment as noted above.
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MikeC
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Agreed, glad for recon on this one.
Mark Sudduth doing a livecast for Franklin
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MikeC
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Recon is finding lower pressure each pass, now down to 996.
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SouthGAwx
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SFMR data also showing some stronger winds in the northeast quadrant -- which is interesting given the continued degradation in IR presentation. Even in the last hour, convective tops near the center have warmed further. With the exception of a band well to the east of the center, Franklin is completely void of any cloud tops less than -65 degrees Celsius.
Interesting indeed!
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cieldumort
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Wish there could have been some more fly-ins after 22:30 yesterday. A combination of Franklin improving internally during the hours before landfall (with each progressive recon penetration finding lower pressures and stronger winds, despite the markedly warming cloud tops and subsequent lowering of CI numbers that would otherwise suggest), increased overnight humidity, and friction, may have led Franklin to briefly attain near-hurricane or even hurricane status around completion of landfall. Something for those who do reanalysis to have tons of fun with ;-)
You will seldom read a more unbalanced-looking paragraph from the (but then Franklin has also been quite the enigma)Quote:
Tropical Storm Franklin Discussion Number 7
NWS National Hurricane Center Miami FL AL072017
400 AM CDT Tue Aug 08 2017
The Belize Doppler weather radar indicates that Franklin's inner-core circulation has tightened up considerably since the previous advisory, likely due to frictional convergence, and that a 10-15-nmi-diameter closed eye has developed. Radar reflectivity values have been steadily increasing in the eyewall, and this development trend is supported by infrared satellite imagery, which shows deep convection with cloud tops of -75C to -80C now completely covering the radar eye. The initial intensity is lowered to 45 kt for this advisory based on a typical decay rate for landfalling tropical cyclones.
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MikeC
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Added a Veracruz cam of the city center http://flhurricane.com/imageanimator.php?261
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