Hurricane Maria underwent an eyewall replacement cycle last night as it’s core passed just barely south of St. Croix in the US Virgin Islands. That reduced Maria’s maximum sustained winds from 175 mph to 155 mph and raised its minimum central pressure from 909mb to 917mb. Maria made landfall this morning on the southeast coast of Puerto Rico as a top-end category 4 hurricane. That is the (very small) silver lining in what is an ongoing natural disaster of devastating proportion.
As noted, the core of Maria passed just south of St. Croix so that island most likely saw “only” category 3 conditions as the newly forming outer eyewall passed over. I have not had time this morning to find any post-storm reports that may exist from St. Croix but it’s without doubt that the damage is extensive.
It appears the northeastern core of Maria crossed the western tip of the island of Vieques. Again, I have yet to see any post-storm reports from there but we can expect very substantial damage.
Currently Maria is moving northwest across the eastern half of Puerto Rico.
8:00 AM AST Wed Sep 20
Location: 18.2°N 66.1°W
Moving: NW at 10 mph
Min pressure: 921 mb
Max sustained: 150 mph
The eye has filled in somewhat with land interaction and the intensity has dropped slightly, but Maria is still a very dangerous category 4 hurricane. The eye will likely pass just southwest of San Juan, bringing the intense winds of the northeast eyewall near or over that city.
Beyond Puerto Rico, Maria will bring heavy rains and tropical storm force winds to the eastern and northern coast of the Dominican Republic. This has the potential to be a deadly flooding event.
Maria should recover its structure after leaving Puerto Rico and will likely strike the Turks and Caicos as a category 3 or possibly a category 4. After that the storm is forecast to turn more northward and weaken in the face of increasing shear, most likely remaining slightly east of the Bahamas but near enough for them to experience heavy rains and tropical storm force winds. In the long term, the highest probability is for Maria to remain offshore from the US east coast, but a landfall anywhere from the Carolinas northward as a category 1 or 2 cannot be ruled out.
Here are the ECMWF ensembles from the overnight run:
and from the overnight run of the GFS:
I apologize for the brief nature of this diary. The power finally came on in my mother’s house last night and I need to take her down there, clean up and get her settled in. I will try to update this diary as I can, but I may not be online much to do it.
Wednesday, Sep 20, 2017 · 2:47:54 PM +00:00 · jrooth
NHC 11 am advisory:
11:00 AM AST Wed Sep 20
Location: 18.4°N 66.5°W
Moving: NW at 12 mph
Min pressure: 930 mb
Max sustained: 140 mph
The last radar image from the San Juan WSR-88D was received at 0950
UTC when Maria's eye was located only about 5 n mi off the
southeastern coast of Puerto Rico. Subsequent 1-minute imagery from
the GOES-16 satellite, as well as surface observations, indicate
that the eye made landfall a little south of Yabucoa Harbor, Puerto
Rico, around 1015 UTC. Now that the center is moving over the
mountainous terrain of the island, the eye has become cloud filled,
and the infrared satellite presentation has degraded. Without radar
velocity data, the initial intensity is incredibly uncertain, but my
best guess is 120 kt based on a typical inland decay rate. Maria's
center is expected to move off the northern coast of Puerto Rico
soon, and an Air Force Reserve reconnaissance aircraft is scheduled
to intercept the center early this afternoon and provide a better
estimate of how much Maria has weakened.
The initial motion is northwestward, or 305/10 kt. This
northwestward motion is forecast to continue for the next 48 hours,
followed by a turn toward the north by days 4 and 5, while Maria
moves between a mid-level high centered southeast of Bermuda and a
broad trough extending from Tropical Storm Jose southwestward into
the Gulf of Mexico. The track guidance is tightly clustered this
cycle, and there were no significant changes made to the NHC
forecast track.
Once Maria moves off the coast of Puerto Rico, it will take some
time for the structure to reorganize over the warm waters of the
Atlantic Ocean. However, the shear is expected to be less than 10
kt for the next 24-36 hours, and Maria has an opportunity to
restrengthen a bit over that time period. After 36 hours, a gradual
increase in shear is likely to lead to a commensurate gradual
decrease in the hurricane's intensity through the end of the
forecast period. Since the SHIPS model, in particular, responds to
the favorable conditions for intensification, the NHC intensity
forecast lies just above the intensity consensus through much of the
forecast period.
Since we don't have radar imagery from San Juan, and the eye has
become cloud filled in satellite imagery, the hourly position
updates are being discontinued.
Wednesday, Sep 20, 2017 · 9:47:32 PM +00:00 · jrooth
5pm advisory and discussion:
5:00 PM AST Wed Sep 20
Location: 18.8°N 67.3°W
Moving: NW at 12 mph
Min pressure: 957 mb
Max sustained: 110 mph
An Air Force Reserve reconnaissance aircraft found that Maria's
center moved off the northwestern coast of Puerto Rico just before
1800 UTC, but the hurricane appears to have taken quite a hit from
the high mountains of the island. The aircraft measured a maximum
flight-level wind of 106 kt to the east of the center and SFMR
surface winds as high as 91 kt. The initial intensity is therefore
set to 95 kt. The central pressure has also risen considerably, and
the latest report from the airplane is 957 mb.
Maria may have taken a temporary jog west-northwestward across
Puerto Rico, likely due to topographic effects, but the longer-term
motion remains northwestward, or 305/10 kt. Maria should maintain
a northwestward motion for the next 36 hours while it remains on
the southwestern periphery of a mid-level high over the western
Atlantic. After 36 hours, Maria is expected to turn northward
between the high and a broad trough extending from Tropical Storm
Jose southwestward into the Gulf of Mexico. The updated track
guidance remains in excellent agreement on this scenario, and the
overall guidance envelope has shifted a bit eastward on this cycle.
The new NHC forecast is therefore nudged a little east of the
previous forecast toward the various consensus aids.
It may take some time for Maria's structure to reorganize itself
now that it is back over water. Although the intensity models are
not all that enthusiastic about strengthening, the environment
looks conducive for intensification, and the NHC forecast lies at
the upper bound of the guidance, closest to the HWRF solution. It
would not be surprising, however, if Maria eventually strengthens
more than shown here. Some weakening is expected by days 4 and 5
due to increased shear, as well as Maria possibly moving over the
cold wake of Tropical Storm Jose to the east of the Carolinas.
We would like to thank the crew of the latest Air Force Reserve
mission for their incredible service today. After beginning their
mission this morning before the center first moved onshore, the crew
went above and beyond, returning to Curacao to refuel, and then
heading back to Puerto Rico to catch Maria's center when it first
moved back off the coast. The data collected by the crew was
incredibly important for us to analyze Maria's intensity and
structure after moving across the island, and we are grateful for
their effort.