Maria still a monster, Jose chugs on 

Posted: 5:51 am Wednesday, September 20th, 2017

By Kirk Mellish

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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.

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A weak upper level short-wave trough rotating around the backside of Jose brings just a small chance of a shower or thundershower to North Georgia today or tomorrow.

As Maria passes to our north and east it will actually help our weather get nicer by Sunday and next week as subsidence-sinking air motions on its backside cover North Georgia.



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Maria has joined a couple dubious lists:

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The Air Force Hurricane Hunters have been investigating Jose this
morning and found maximum flight-level winds of 78 kt at 5,000 feet
and peak SFMR surface winds of 56 kt. Based on these data, the
initial wind speed is set at 60 kt, which is slightly higher than
the previous estimate. Jose remains a sprawling cyclone, with
tropical storm force winds extending 180 n mi from the center.
Although Jose does not have a purely tropical appearance, it still
has a warm core and well-defined convective bands, especially to the
north of the center.

Jose is moving northeastward at 7 kt toward a mid- to upper-level
trough over eastern Canada. A slightly slower northeastward to
east-northeastward motion is expected through tonight. Thereafter,
the trough is expected to lift out, allowing a mid-level high
pressure system to build to the northwest of Jose. This will likely
cause the storm to reverse its course and drift westward or
west-southwestward. In about 3 days, however, the models suggest
that Jose will be caught in very weak steering currents, and the NHC
official track forecast now shows Jose stationary from 72 to 120

The tropical storm is moving over a tight SST gradient associated
with the north wall of the Gulf Stream current, and it will likely
remain over this gradient for the next several days. These
relatively cool SSTs and dry air should cause a slow weakening
trend, and a gradual transition to a post-tropical cyclone. The NHC
intensity forecast is not too different from the previous one and is
in best agreement with the consensus models.


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Read previous blog posts for more on Maria/Jose and La Nina and winter.

FOLLOW ME on Twitter @MellishMeterWSB