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TROPICAL STORM NEWTON DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL EP152016
900 AM MDT MON SEP 05 2016
Newton's cloud pattern is characterized by a large mass of very
cold-topped convection, with the center located underneath this
formative central dense overcast on the north side. A ship earlier
reported 50 kt, and although the ship had somewhat of a high bias,
the 12z sounding from Manzanillo reported an 850 mb wind of 65 kt.
A typical wind reduction over the water would suggest about 50 kt
at the surface, and since the sounding supports the ship
observation, the initial intensity is set to 50 kt.
The center location of Newton has been difficult to determine, and
hence the initial motion estimate is an uncertain 330/11. Newton
is currently being steered northwestward on the southwest side of a
mid-level ridge over the United States Lower Mississippi Valley.
The cyclone should be drawn north-northwestward and then northward
in 36 to 48 hours between this feature and a trough of low pressure
gradually lifting out over the western United States. The official
NHC track forecast is somewhat faster and slightly to the left of
the previous one and near the multi-model consensus. It lies on
the western side of the guidance, but with only the ECMWF and UKMET
models to the left.
Newton is expected to remain in a very moist environment with
generally light northeasterly shear during the next 24 hours.
These factors, along with the cyclone's passage over sea surface
temperatures above 29 deg C, should allow for steady
intensification until the center reaches the coast. The only
obvious obstacle to strengthening is Newton's broad structure, but
indications are that the cyclone may be in the process of
consolidating. It should be noted that the SHIPS RI Index
indicates a 60-70 percent chance of an intensity increase of around
25 kt during the next 24 hours. The NHC intensity forecast now
calls for Newton to become a hurricane prior to landfall, which is
a little above the multi-model consensus. Weakening is likely when
Newton moves across the Baja California peninsula, but little
change in strength is expected as southwesterly shear begins to
increase over the Gulf of California in 36 to 48 hours.
Newton is expected to be a large hurricane at landfall, and hazards
are likely to affect a large portion of Baja California and
northwestern Mexico. In addition, moisture associated with the
remnants of Newton could cause heavy rains and localized flash
flooding over parts of Arizona and New Mexico.
Based on the new intensity and track forecasts, the government of
Mexico has made a variety of changes to the watches and warnings.
FORECAST POSITIONS AND MAX WINDS
INIT 05/1500Z 19.1N 107.0W 50 KT 60 MPH
12H 06/0000Z 20.6N 108.4W 60 KT 70 MPH
24H 06/1200Z 22.8N 110.0W 70 KT 80 MPH
36H 07/0000Z 25.3N 111.3W 60 KT 70 MPH
48H 07/1200Z 28.1N 111.6W 50 KT 60 MPH...INLAND
72H 08/1200Z 33.5N 110.6W 25 KT 30 MPH...POST-TROP/REMNT LOW