11:00am Update. Tropical Storm Calvin has intensified slightly to 50mph maximum winds
Tropical Storm Calvin Advisory Number 29 NWS Central Pacific Hurricane Center Honolulu HI EP032023 1100 AM HST Tue Jul 18 2023 ...TROPICAL STORM CALVIN SLIGHTLY STRONGER THIS MORNING... ...IMPACTS IN HAWAII COUNTY STARTING THIS EVENING... SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION ----------------------------------------------- LOCATION...17.8N 151.9W ABOUT 245 MI...395 KM ESE OF HILO HAWAII ABOUT 460 MI...740 KM ESE OF HONOLULU HAWAII MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H PRESENT MOVEMENT...W OR 280 DEGREES AT 22 MPH...35 KM/H MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY... None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT... A Tropical Storm Warning is in effect for... * Hawaii County A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area. Interests elsewhere in Hawaii should monitor the progress of Calvin. For storm information specific to your area, please monitor products issued by the National Weather Service office in Honolulu Hawaii. DISCUSSION AND OUTLOOK ---------------------- At 1100 AM HST (2100 UTC), the center of Tropical Storm Calvin was located near latitude 17.8 North, longitude 151.9 West. Calvin is moving toward the west near 22 mph (35 km/h), and this general motion is expected to continue over the next few days. On the forecast track, tropical storm conditions will likely begin spreading over Hawaii County starting this evening. Maximum sustained winds are near 50 mph (85 km/h) with higher gusts. Calvin is expected to remain a tropical storm over the next 36 hours, and then will weaken quickly afterward. Tropical-storm-force winds extend outward up to 115 miles (185 km) from the center. The estimated minimum central pressure is 1002 mb (29.59 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Calvin can be found in the Tropical Cyclone Discussion under AWIPS header TCDCP1 and WMO header WTPA41 PHFO. and on the web at hurricanes.gov/text/HFOTCDCP1.shtml WIND: Tropical storm conditions are expected within the warning area starting this evening. Persons in Hawaii County should complete preparations for tropical storm force wind impacts during daylight hours prior to the onset of tropical storm conditions. RAINFALL: From later today into Thursday, storm total rainfall amounts of 4-8 inches, with maximum amounts of 10 inches are possible, mainly along the windward and southeast flank of the Big Island of Hawaii. Storm total rainfall amounts of 3-6 inches are expected on the windward areas of Maui, and 2-4 inches elsewhere in the state. This rainfall could lead to localized flash flooding and mudslides. SURF: Swells generated by Calvin are expected to begin spreading across the main Hawaiian Islands later today and tonight. This will lead to a rapid increase in surf along east facing shores, with high surf continuing into Wednesday. This elevated surf will likely cause life-threatening conditions along exposed shorelines. Please consult products from your local weather office for details.
A large area of deep convection developed overnight in the northern
semicircle of Calvin’s circulation. This convection has persisted
through this morning and has obscured the low level circulation
center that was so clearly visible yesterday. Fortunately, the US
Air Force Reserve has a WC-130J flying a mission into the system
today that has helped better identify the system’s center and
surrounding wind field. SFMR data indicated 46 kt in the NE
quadrant and a large area of winds at or above 34 kt. As a result,
the initial intensity for this advisory has been increased slightly
to 45 kt. The 34 kt radius in the NE quadrant has also been
increased as well.
The initial motion for this advisory is 280/19 kt as Calvin
continues to move south of a subtropical ridge. No significant
changes in this steering is expected over the next several days.
The main objective aids have the center of Calvin passing south of
the Big Island tonight. The track forecast is essentially the same
as the previous advisory and is on the northern side of the
guidance envelope, but still south of the Big Island.
The overall environment around Calvin remains dry and stable. Calvin
is currently passing over SSTs of 25-26C. Along the forecast track,
SSTs will be gradually increasing and will be 26-27C as Calvin
passes the Big Island. Vertical shear affecting the tropical cyclone
is expected to be moderate through tonight. The lack of strong
vertical shear, and the warmer SSTs should allow Calvin to maintain
winds at tropical storm intensities through Wednesday. Shear levels
should significantly increase Wednesday night onward, and should
result in a weakening to post-tropical/remnant low status on
Thursday.
KEY MESSAGES:
1. Calvin is forecast to pass very close to Hawaii County tonight,
bringing a period of heavy rain, high surf and locally strong winds.
Calvin is expected to weaken as it moves westward to the south of
the other Hawaiian Islands Wednesday and Wednesday night, bringing
the potential for some peripheral impacts.
2. It is important to not focus on the exact forecast track and
intensity when preparing for Calvin. Persons in Hawaii County
should prepare during daylight hours for impacts prior to the
onset of tropical storm conditions, which are expected to start
this evening. These impacts could include flash flooding, damaging
winds, and large and dangerous surf.
FORECAST POSITIONS AND MAX WINDS
INIT 18/2100Z 17.8N 151.9W 45 KT 50 MPH
12H 19/0600Z 18.2N 154.3W 45 KT 50 MPH
24H 19/1800Z 18.8N 158.1W 40 KT 45 MPH
36H 20/0600Z 19.2N 161.8W 35 KT 40 MPH
48H 20/1800Z 19.5N 165.6W 30 KT 35 MPH
60H 21/0600Z 19.8N 169.3W 25 KT 30 MPH…POST-TROP/REMNT LOW
72H 21/1800Z…DISSIPATED
