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Tropical Storm Julio Discussion Number 3
NWS National Hurricane Center Miami FL EP152020
300 AM MDT Sun Sep 06 2020
Julio is a compact and well-defined tropical storm as indicated by
recent satellite-derived wind data and microwave imagery, with the
center located underneath the eastern portion of the deep
convection. A recent ASCAT overpass showed maximum winds of 39 kt,
and based on this data the initial intensity has been increased to
40 kt.
Julio has accelerated and is now moving west-northwestward at 18 kt
around the southwestern periphery of a mid-level ridge. This motion
should continue for the next day or so, with a gradual decrease in
forward speed. A turn to west is anticipated by Monday as the
cyclone begins to weaken and becomes steered by the low-level flow.
The latest forecast is similar to the previous one through 24 h, but
was shifted southward thereafter in response to a southerly shift in
the guidance.
The intensity forecast for Julio is low confidence, as the global
models have struggled to resolve the small size of the cyclone,
resulting in a large spread in the intensity guidance. The SHIPS
guidance suggests that the moderate easterly shear currently
impacting Julio will decrease in 12-24 h, while the system is still
over warm waters and in a moist atmospheric environment. Therefore,
this guidance indicates that some slight strengthening is expected
over the next couple of days. Despite the generally favorable
conditions shown in the SHIPS guidance, the global models show no
further intensification and weaken the cyclone almost immediately.
Due to the resilience of Julio up until this point, the latest NHC
intensity forecast leans towards the higher SHIPS guidance over the
next day or so, then trends toward the lower global model forecasts
later on in the forecast period. All of the global models suggest
Julio will dissipate in a few days, and this is still being
indicated in the NHC forecast.
FORECAST POSITIONS AND MAX WINDS
INIT 06/0900Z 17.6N 106.0W 40 KT 45 MPH
12H 06/1800Z 18.6N 108.2W 45 KT 50 MPH
24H 07/0600Z 19.5N 110.5W 45 KT 50 MPH
36H 07/1800Z 19.9N 112.0W 40 KT 45 MPH
48H 08/0600Z 20.1N 113.3W 35 KT 40 MPH
60H 08/1800Z 20.2N 114.3W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 09/0600Z...DISSIPATED
$$
Forecaster Latto
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