Hurricane Maria went through a phase of explosive intensification, dropping over 20mb pressure in a few hours, shortly before making landfall on Dominica as a compact but intense category 5 hurricane. The size and structure of the storm at landfall was very similar to Hurricane Andrew at landfall in South Florida in 1992, although at least officialy Maria was not quite as intense. We may never know precisely how intense the inner eyewall was at landfall since, like Andrew, it was an exceptionally tight feature.
The storm’s structure was somewhat disrupted by the moderately high mountains on the island and it declined to category 4 at it crossed and emerged into the Caribbean. However, it has quickly recovered and as of the 8 am intermediate advisory Maria is once again a category 5 hurricane with sustained winds of 160 mph and a minimum central pressure of 933mb.
Some variation in intensity is likely over the next couple of days. The official forecast is that Maria will be an upper end category 4 as it passes near or over the US Virgin Islands and Puerto Rico. But it could just as easily be a strong category 5. We simply don’t have the skill to forecast intensity with any great precision.
Reports out of Dominica are sparse, but it appears there has been the kind of devastating damage one would expect from such an intense storm. Search and rescue operations are underway. I will update this diary with any significant news regarding damage, injury or possible loss of life.
The neighboring islands of Guadeloupe and Martinique did see tropical storm force winds, but I have not seen any reliable reports of sustained hurricane force. This is due to the very compact nature of Maria as it passed through the island chain.
Model guidance is very tightly clustered in taking Maria over or very near St. Croix in the US Virgin Islands and then Puerto Rico. This is an emergency situation for these islands. The nearest thing in relatively recent history would be Hurricane Hugo in 1989, which was a devastating blow to those islands. But Maria will in all likelihood be significantly worse. The Virgin Islands suffered a major blow from Hurricane Irma and are only in the early stages of recovery from that. A storm like this coming when buildings and infrastructure are already damaged and piles of debris are everywhere has more than the usual potential to be deadly.
Puerto Rico did not see a direct impact from Irma but nonetheless suffered significant damage to infrastructure, particularly the power grid. That makes them even more vulnerable than usual to damage from a direct impact of a major hurricane.
Beyond Puerto Rico, the Dominican Republic is likely to see a major rain/flooding event in its eastern districts but probably not a direct impact. The Turks and Caicos islands, which were directly hit by Irma, will likely receive another direct hit from Maria. After that the model consensus is gradually converging on a recurve scenario, keeping Maria offshore from the US east coast. This is however highly dependent on what happens with the remnants of Hurricane Jose and also on the timing of a trough approaching through the continental US. While a recurve out to sea now appears to be the most likely result, one cannot yet rule out a US impact, particularly from the Carolinas northward. Hopefully we will have confidence in this forecast within the next couple of days.
I will update this diary when the 11 am advisory comes out and during the day as new information comes in. My thoughts are with the people of Dominica and of the US Virgin Islands and Puerto Rico.
Tuesday, Sep 19, 2017 · 2:53:06 PM +00:00 · jrooth
11 AM advisory:
11:00 AM AST Tue Sep 19
Location: 16.3°N 63.1°W
Moving: WNW at 10 mph
Min pressure: 927 mb
Max sustained: 160 mph
Reports from an Air Force Reserve Hurricane Hunter Aircraft indicate
that Maria regained category 5 status shortly after the last
advisory, and that it is currently maintaining an intensity near 140
kt with a central pressure near 927 mb. The aircraft data suggests
an outer wind maximum that could be the start of an eyewall
replacement cycle, but this feature does not yet have a good
signature in radar data or microwave imagery.
The eye of Maria has been wobbling quite a bit, but a smoother
long-term motion is 300/9. There is little change to the track
forecast reasoning or the forecast track since the previous
advisory. A weak ridge situated over the western Atlantic is
expected to steer Maria west-northwestward through 48 hours, and on
this track the center of the hurricane is forecast to pass near or
over the Virgin Islands and Puerto Rico on Wednesday. After that
time, the western portion of the ridge is forecast to weaken,
partially due to the influence of the large circulation of Hurricane
Jose off the U.S. east coast. This pattern should cause Maria to
turn northwestward and then north-northwestward by days 4-5. The
track guidance is tightly clustered through 72 h and fairly well
clustered at 120 h, and the new track is to the left of center of
the cluster mainly between the GFS and ECMWF models.
Maria should remain in a generally favorable environment through 48
h, and based on this and the latest guidance the new intensity
forecast keeps Maria at 135-140 kt up to the time of landfall in
Puerto Rico. After crossing Puerto Rico, the upper-level winds are
expected to become less favorable, and the intensity forecast shows
a slow weakening that follows the upper edge of the guidance. A
complication to the intensity forecast is that there will likely be
fluctuations caused by eyewall replacement cycles superimposed on
top of the general trends shown in the official forecast.
Tuesday, Sep 19, 2017 · 3:41:37 PM +00:00 · jrooth
Some HAM radio reports from Dominica:
As “potentially catastrophic Hurricane Maria” is headed for the Virgin Islands and Puerto Rico. Frans van Santbrink, J69DS, on St. Lucia checked into the VoIP Hurricane Net to relay damage reports he gathered via repeater conversations with hams on Dominica, which was hit by Category 5 Hurricane Maria.
He recounted a damage report from Kerry Fevrier, J69YH, in Roseau, Dominica. “Trees down, river has flooded half the village, cars are all over, most houses have lost their roofs or are destroyed, the area between his house and the church is just flattened…in his words, ‘devastation is total,’” van Santbrink told the net.
He also heard from J73CI, who has lost his roof; J73WA on the northern end of the island, who lost his tower and was uncertain how he was going to weather the back end of the storm, and J73MH, who also lost his roof and was “just hunkering down and hoping for the best.”
Tuesday, Sep 19, 2017 · 6:12:37 PM +00:00 · jrooth
2 pm advisory:
2:00 PM AST Tue Sep 19
Location: 16.6°N 63.6°W
Moving: WNW at 10 mph
Min pressure: 927 mb
Max sustained: 160 mph
This advisory was presumably issued before recon got to the center, because they found substantially lower pressure than that. More like 920 mb.
Tuesday, Sep 19, 2017 · 6:32:18 PM +00:00 · jrooth
Special NHC update 2:15 pm
...HURRICANE HUNTER AIRCRAFT FINDS THAT MARIA HAS STRENGTHENED...
Recent reports from an Air Force Reserve Hurricane Hunter aircraft
indicate that Maria has strengthened above the intensity in the
2 PM AST advisory, with estimated maximum sustained winds of 165 mph
(265 km/h).
SUMMARY OF 215PM AST...1815 UTC...INFORMATION
---------------------------------------------------
LOCATION...16.6N 63.6W
ABOUT 110 MI...175 KM SE OF ST. CROIX
ABOUT 140 MI...225 KM W OF GUADELOUPE
MAXIMUM SUSTAINED WINDS...165 MPH...265 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...920 MB...27.17 INCHES
Tuesday, Sep 19, 2017 · 8:54:31 PM +00:00 · jrooth
NHC 5 pm advisory:
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5:00 PM AST Tue Sep 19
Location: 16.8°N 64.0°W
Moving: WNW at 10 mph
Min pressure: 916 mb
Max sustained: 165 mph
Maria has continued to strengthen this afternoon, with surface and
flight-level winds from an Air Force Reserve Hurricane Hunter
aircraft supporting an intensity of 145 kt, and the central
pressure inside the 5 n mi wide eye falling to 916 mb. The
aircraft data also indicates that an outer wind maximum is present
about 20-30 n mi from the center, but this has not yet developed
into enough of an outer eyewall to stop the intensification in the
inner eyewall.
The initial motion remains 300/9. The forecast track philosophy
remains the same, with the eye of Maria expected to move near the
U. S. Virgin Islands tonight and across Puerto Rico on Wednesday,
followed by a motion just north of the eastern Dominican Republic
Wednesday night and Thursday. Subsequently, a break in the
subtropical ridge caused in part by Hurricane Jose should allow
Maria to turn north-northwestward and northward by the end of the
forecast period. Only minor changes have occurred in the track
guidance since the last advisory, and the new track has only minor
adjustments from the previous track.
Some additional strengthening is possible this evening before the
outer eyewall becomes better defined or the cyclone reaches its
maximum potential intensity. It now appears likely that Maria will
be at category 5 intensity when it moves over the U. S. Virgin
Islands and Puerto Rico, although there is a chance that the start
of the eyewall replacement cycle might reduce the intensity a little
bit. The hurricane should weaken as it crosses Puerto Rico, and
after that proximity to Hispaniola and less favorable upper-level
winds are likely to lead to continued slow weakening. The new
intensity forecast remains at the upper edge of the intensity
guidance.
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