1. Shower activity has increased this morning in association with a
tropical wave located about 1100 miles southwest of the southern
tip of the Baja California peninsula. This system is expected to
move west-northwestward, and some development is possible late this
weekend and early next week before it moves into less favorable
environmental conditions.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...medium...50 percent.
WTPN21 PHNC 190630
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
175 NM EITHER SIDE OF A LINE FROM 14.1N 123.9W TO 19.3N 132.5W
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS
IN THE AREA ARE ESTIMATED TO BE 20 TO 25 KNOTS. METSAT IMAGERY AT
190600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 14.5N
124.5W. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 11 KNOTS.
2. REMARKS: AN AREA OF CONVECTION (INVEST 99E) HAS PERSISTED NEAR
14.5N 124.5W, APPROXIMATELY 1165 NM SOUTH-SOUTHWEST OF SAN DIEGO,
CA. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 190247Z SSMIS
91GHZ MICROWAVE IMAGE DEPICT A CONSOLIDATING LOW LEVEL CIRCULATION
(LLC) WITH FORMATIVE CONVECTIVE BANDING WRAPPING INTO THE CENTER OF
THE DISTURBANCE. UPPER-LEVEL ANALYSIS INDICATES THE DISTURBANCE IS
LOCATED IN AN AREA FAVORABLE FOR DEVELOPMENT WITH LOW VWS (< 15KTS),
STRONG POLEWARD OUTFLOW, AND WARM SST (28-29C). GLOBAL
DYNAMIC MODELS INDICATE SLIGHT INTENSIFICATION OVER THE NEXT 24-36
HOURS AS THE SYSTEM TRACKS WEST-NORTHWESTWARD. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
200630Z.//
NNNN
1. A tropical wave accompanied by a surface low pressure system is
located about 1100 miles southwest of the southern tip of the Baja
California peninsula. Shower and thunderstorm activity has become
better organized over the past several hours, and environmental
conditions are conducive for a tropical depression to form during
the next day or so while the system moves west-northwestward.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...medium...60 percent.
Tropical Depression Seven-E Discussion Number 1
NWS National Hurricane Center Miami FL EP072020
1100 PM HST Sun Jul 19 2020
The small low pressure are that the National Hurricane Center has
been tracking for the past couple of days has finally developed
enough persistent organized deep convection for the system to
classified as Tropical Depression Seven-E. An earlier burst of
strong convection with cloud tops colder than -80C helped to spin up
the low-level wind field and cause the center to become better
defined based on a 0529 UTC ASCAT-A overpass. The aforementioned
scatterometer data showed surface winds of 29-30 kt in the western
semicircle, which is the basis for the 30-kt initial intensity. This
intensity is also supported by 06Z Dvorak satellite intensity
estimates of T2.0/30 kt from both TAFB and SAB.
The initial motion estimate is 310/10 kt based on conventional,
microwave, and scatterometer satellite fix data over the past 12
hours. The small cyclone is expected to be steered northwestward to
west-northwestward at about the same forward speed for the next day
or so due to a strong subtropical ridge situated to the north of the
depression. By 24-36 h, the system is forecast to degenerate into a
shallow remnant low and be steered westward through 48-60 h,
followed by a turn toward the southwest before dissipating by 96 h.
The NHC official forecast track lies close to the tightly packed
simple consensus models, which is consistent with the NOAA
corrected-consensus model, HCCA.
Although the vertical wind shear is expected to remain low at less
than 5 kt for the next 24 h or so, the small cyclone is already
moving over sub-26 deg C sea-surface temperatures (SST), with
slightly cooler water ahead of the system. The ingestion of cooler
and drier air, along with the cool SSTs, is expected to weaken the
system below depression status by 24 h. Although it is possible that
the system could hold on to tropical cyclone status a little longer
than currently indicated, especially when the system moves
southwestward toward warmer water, moderate to strong southwesterly
vertical wind shear should cause the small cyclone to dissipate by
96 h. The official intensity forecast closely follows the IVCN
intensity consensus model.
Post-Tropical Cyclone Seven-E Discussion Number 6
NWS National Hurricane Center Miami FL EP072020
800 AM PDT Tue Jul 21 2020
The cyclone has decayed to a remnant low, and is now comprised of
a swirl of low- to mid-level clouds with organized convection
unlikely to re-develop. The remnant low is forecast to degenerate
to a trough between 24-36 h, and the global models suggest this
could happen earlier than forecast.
The initial motion is 270/11. The remnant low is expected to turn
west-southwestward in the low-level trade winds before it
dissipates.
This is the last advisory issued by the National Hurricane Center
on this system. For additional information on the remnant low
please see High Seas Forecasts issued by the National Weather
Service, under AWIPS header NFDHSFEPI, WMO header FZPN02 KWBC, and
on the web at ocean.weather.gov/shtml/NFDHSFEPI.php
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