A strong cold front swept across Kauai County Tuesday night and Oahu and Maui County on Wednesday, before stalling and weakening near Hawaii County Wednesday night. Southerly winds and heavy rain developed ahead of the front, with thunderstorms bringing even gustier winds and rain closer to the front. The first reports of flash flooding occurred on the Big Island Tuesday evening when Highway 11 was closed near Kawa Flats. On Wednesday, Piilani Highway was unpassable between mile markers 29 and 31 due to flood waters. Wind damage was greatest on Oahu Tuesday night, associated with convection near the cold front, with reports of uprooted trees and widespread power outages.

The image on the right is from the Multi-Radar/Multi-Sensor (MRMS) quantitative precipitation estimates (QPE) for the 48 hour period ending at 8 am HST, Thursday, April 20. The color scale is on the right, in inches of rainfall. The highest QPE is located across southeast slopes of Maui and Hawaii Islands.

The following are peak wind gusts from April 18 to 19, 2023. Wind gusts are in miles per hour (MPH).

Location                     Speed     Time/Date

...Kauai...
Nawiliwili                   40 MPH    0448 PM 04/18
Lihue Airport                40 MPH    0453 PM 04/18
Moloaa Dairy                 33 MPH    0645 AM 04/18
Barking Sands                33 MPH    0218 PM 04/18

...Oahu...
Honolulu Harbor              50 MPH    0145 AM 04/19
Kalaeloa Airport             48 MPH    0144 AM 04/19
Honolulu Airport             47 MPH    0147 AM 04/19
Makapuu Beach                47 MPH    0301 AM 04/19
Kaneohe Mcas                 46 MPH    0210 AM 04/19
Schofield East               43 MPH    1158 PM 04/18
Kuaokala                     39 MPH    1236 PM 04/18
Mokuleia                     39 MPH    0303 AM 04/19
Kaneohe                      37 MPH    0230 AM 04/19
Pearl City                   37 MPH    0205 AM 04/19
Laniakea                     37 MPH    1249 PM 04/18
Wheeler Air Force Base       36 MPH    0239 AM 04/19
Schofield Barracks           35 MPH    1157 PM 04/18
Makua Range                  34 MPH    1258 PM 04/18
Oahu Forest NWR (USFWS)      34 MPH    0936 AM 04/18
Laie                         30 MPH    0128 AM 04/19

...Maui County...
Makapulapai                  57 MPH    0315 AM 04/19
Kihei                        47 MPH    0600 AM 04/19
Kahului Airport              46 MPH    0226 AM 04/19
KULA                         43 MPH    0345 AM 04/19
Molokai Airport              39 MPH    0136 AM 04/19
AH6GR Maui                   37 MPH    0321 AM 04/19
Kanaha WF                    37 MPH    0312 AM 04/19
Lanai Airport                35 MPH    0456 AM 04/19
Kealia Pond (USFWS)          31 MPH    0620 AM 04/19

...Big Island...
Kailua Kona Airport          39 MPH    0151 PM 04/19
Kaloko-Honokohau             31 MPH    0615 AM 04/19
Hilo                         31 MPH    0120 PM 04/19

The following are notable rainfall totals for the 48-hr period ending at 8 AM HST, April 20. All amounts are in inches. These totals are considered preliminary for information purposes only.

Location                             48-hr total

...Kauai...
Mount Waialeale (USGS)                   5.00
North Wailua Ditch (USGS)                4.58
Waiahi Rain Gage (USGS)                  3.78

...Oahu...
Poamoho                                  4.72
Waiawa Correction Facility               4.46
Luluku                                   3.37
Maunawili                                3.35

...Maui...
Kepuni (USGS)                            5.43
Ulupalakua Ranch                         4.40
Puu Kukui (USGS)                         4.37

...Big Island...
Pali 2                                  15.29
Pahala                                   4.44
Lower Kahuku                             4.20
Kapapala Ranch                           3.13