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Eastern Pacific Tropical Cyclone Outlook # 4 for July 28th, 2019

The National Hurricane Center (NHC) continues to monitor 2 disturbances in the East Pacific basin:

- Tropical Storm Erick: currently 1,650 miles ESE of Hilo & moving to the west at 17 mph.

- Tropical Depression Seven-E (Soon to be Tropical Storm Flossie): currently 3,000 miles ESE of Hilo & moving westward at 21 mph.

Based on the latest models, Tropical Storm Erick is expected to past to the south of the Island of Hawaii around Friday morning to Saturday. Wet Weather Associated with Erick is expected to come onshore Thursday night going into the weekend.

For Seven-E (Soon to Flossie): it's still too early to determine the exact track of Seven-E and it impacts to Hawaii Island, we will have a better idea of the projected forecast around Friday and Saturday at the earliest as it expected to cross into the Central Pacific basin on Saturday.

Currently, No Watches or Warnings are in effect at this time related to these disturbances.

The HIRSC team will continue to follow these disturbances and will be providing 2 daily updates (11am & 11pm Daily) on both disturbances.

Update on Tropical Storm Erick (As of 11am HST):

Tropical Storm Erick Discussion Number 6 NWS National Hurricane Center Miami FL EP062019 1100 AM HST Sun Jul 28 2019 Although Erick's upper-level outflow has continued to improve, the overall convective pattern hasn't changed much. The earlier increase in central convection has been waning somewhat in recent satellite imagery, and the low-level center remains displaced just north of the central convection. However, passive microwave imagery indicates that the center has made a slight west-southwestward jog, possibly due to reformation closer to the strongest convection. The initial intensity has been increased to 40 kt based on a blend of Dvorak satellite intensity estimates of T2.5/35 kt from TAFB and T3.0/45 kt from SAB. An 1807Z partial ASCAT-A scatterometer pass indicated a 36-kt vector in the northeastern quadrant, and allowing for some undersampling also supports the 40-kt initial intensity. The initial motion estimate is 270/15 kt. It is possible that the initial position could be too far north, and a southward shift may be required on the next advisory. However, the general trend in the model guidance remains a westward motion for the next 24 hours or so, followed by a gradual turn toward the west-northwest as Erick moves into a slight weakness in the subtropical ridge. By 72 hours and beyond, the weakness is forecast to fill with the narrow ridge building westward across the Hawaiian Islands. This is expected to force Erick on a general westward to west-northwestward track through the remainder of the forecast period. On the forecast track, Erick is expected to cross into the Central Pacific basin Tuesday morning. The new NHC forecast track has again been shifted south of the previous advisory track, mainly due to the more southerly initial position, and lies down the center of the tightly packed guidance envelope and is close to a blend of the consensus track models HCCA, FSSE, and TVCN. The aforementioned ASCAT-A pass indicated that Erick has maintained a small radius of maximum winds (RMW) of about 20 nmi. The small RMW, low vertical wind shear, and SSTs near 28 deg C continue to support at least steady strengthening for the next few days, and Erick is forecast to become a hurricane in 36 hours. Although rapid intensification (RI) remains a possibility owing to the small RMW and low shear, the recent pronounced dry mid-level intrusion into the inner-core region, along with mid-level shear undercutting the other favorable outflow pattern, is expected to hinder any RI for at least the next 24 hours. By 72 hours, strong westerly vertical wind shear is forecast to affect the cyclone, inducing a steady weakening trend through the 120-h period. The latest Navy COAMPS model has backed off slightly and is now forecasting Erick to become a high-end category-3 hurricane in about 72 hours. However, this scenario has again been disregarded due to the abundance of dry mid-level air expected to affect the cyclone. The official intensity forecast is similar to the previous NHC advisory, and closely follows the HCCA corrected consensus model. FORECAST POSITIONS AND MAX WINDS INIT 28/2100Z 12.0N 131.3W 40 KT 45 MPH 12H 29/0600Z 12.3N 133.5W 45 KT 50 MPH 24H 29/1800Z 12.8N 136.4W 55 KT 65 MPH 36H 30/0600Z 13.5N 139.1W 65 KT 75 MPH 48H 30/1800Z 14.1N 142.0W 75 KT 85 MPH 72H 31/1800Z 15.3N 146.4W 85 KT 100 MPH 96H 01/1800Z 16.2N 150.9W 60 KT 70 MPH 120H 02/1800Z 16.8N 155.9W 40 KT 45 MPH

Update on Seven-E as of 3pm MDT Sunday Afternoon:

Tropical Depression Seven-E Discussion Number 2 NWS National Hurricane Center Miami FL EP072019 300 PM MDT Sun Jul 28 2019 The depression has not changed much in organization since the previous advisory. The system has a broad circulation, with the low-level center located near the southeastern edge of a long convective band. Dvorak classifications are now a consensus T2.0 from TAFB and SAB, which supports maintaining an initial intensity of 30 kt. This is also in good agreement with just-received ASCAT-C data. Various objective analyses suggest that the shear over the system is light, but that doesn't appear to be the case based on high-level cloud motions seen on visible satellite imagery. Even with the depression's fast forward speed, the center is chasing the convection out ahead of it. Given the cyclone's current structure, only slow strengthening is anticipated during the next 24 hours while the depression continues to become better organized. Once an inner core forms, faster strengthening is likely due to low shear and warm waters, and the cyclone is forecast to become a hurricane just after 48 hours. In fact, SHIPS Rapid Intensification indices indicate that there is about a 40 percent chance that the cyclone's winds will increase by at least 65 kt during the next 3 days. Therefore, the NHC intensity forecast has been raised from the previous one, especially after 48 hours, and most closely follows the HWRF and the European version of the SHIPS model, which lie above the intensity consensus and near the upper bound of the guidance envelope. The initial motion is still fast--285/17 kt--due to the strength of the mid-level high to the north. Ridging is expected to keep the cyclone on a westward or west-northwestward heading for the entire 5-day forecast period, with some decrease in forward speed as it moves south of a weakness in the ridge. The track models are still tightly clustered, and the NHC track forecast is very close to HCCA and the other multi-model consensus aids, which also ends up being very close to the previous official forecast. FORECAST POSITIONS AND MAX WINDS INIT 28/2100Z 11.5N 109.1W 30 KT 35 MPH 12H 29/0600Z 11.9N 111.9W 35 KT 40 MPH 24H 29/1800Z 12.1N 115.0W 40 KT 45 MPH 36H 30/0600Z 12.1N 117.9W 50 KT 60 MPH 48H 30/1800Z 12.1N 120.5W 60 KT 70 MPH 72H 31/1800Z 12.8N 125.6W 85 KT 100 MPH 96H 01/1800Z 14.0N 131.0W 90 KT 105 MPH 120H 02/1800Z 15.5N 136.5W 90 KT 105 MPH

Next HIRSC Update will be made at 23:00 Hours Sunday Night (July 28th).

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