MONTHLY PRECIPITATION SUMMARY State of Hawaii portion of Honolulu HSA MONTH: September 1998 PREPARED October 4, 1998 State: No significant flash flooding was reported. For Hawaii, September was a month of contrast with many of the windward sections of the islands receiving slightly above normal rainfall whereas leeward areas continue to be drier than normal. Only Oahu reported below normal rainfall amounts for nearly all reporting sites. A high pressure system remained entrenched north of the islands throughout the month with trade showers the main producer of rain. However, there were 5 days with heavier than normal shower activity on the Big Island primarily due to afternoon heating. Island of Kauai: Windward sections received near normal rainfall for the month but leeward sections were generally around half of normal. Rainfall extremes ranged from 7.43 inches or 122 percent of average at Wainiha to .46 of an inch or 33 percent of normal at Hanapepe. The wettest days recorded were the second and third days of the month. Island of Oahu: Oahu remained drier than normal for the month with few exceptions. Nui Valley reached normal rainfall with 1.60 inches and Ahuimanu with 4.55 inches was 103% of normal. All other reporting sites recorded below normal amounts. The driest site was the airport followed by the leeward sections of the Waianae range which all reported a tenth of an inch or less. Maui County: Rainfall extremes occurred in Maui county this month with Kihei and Mahinahina both reporting no rainfall again this month. Windward sections of Maui fared better with above normal rainfall. Kahakuloa reported 2.77 inches or 198 percent of normal. However, Hana received only 3.01 inches or 56 percent of normal. Kaunakakai on Molokai reported 0.52 of an inch but this was 260 percent of normal for that site. The second was the wettest overall day for Maui county. Hawaii County: The windward sections of the Big Island all received more than normal rainfall for the month -- a welcomed event. Leeward sections remained below normal again this month. Rainfall extremes ranged from 11.24 inches at Honokaa or 401 percent of normal to 0.08 of an inch at Kamakoa which is 20 percent of normal. The most rainfall reported this month was 13.59 inches at Waikea Uka. Much of the rainfall on the windward side fell between the 20th and 23rd. On the leeward side, more convective events occurred on the 4th, 10th and 19th. BELOW ARE RAINFALL STATISTICS FOR SELECTED LOCATIONS FROM AROUND THE STATE. THE FIRST COLUMN IS THE RAINFALL FOR SEPTEMBER. THE SECOND COLUMN HAS THE 30 YEAR AVERAGE FOR THAT LOCATION, WITH THE THIRD COLUMN THE PERCENT OF AVERAGE RAINFALL FOR THE MONTH OF SEPTEMBER. KAUAI SEP 98 AVE PCT AVE LIHUE 1.33 2.40 55 HANALEI 5.75 4.70 122 HANAPEPE .46 1.40 33 OAHU HONOLULU 0.05 0.80 6 MANOA ARBOR. 9.35 10.50 89 HAWAII KAI 0.39 0.90 43 AHUIMANU 4.55 4.40 103 WAIANAE 0.10 0.70 14 WAIALUA 0.53 1.10 48 MOLOKAI KAUNAKAKAI 0.52 0.20 260 LANAI LANAI CITY 1.66 2.20 75 MAUI KAHULUI 0.42 0.40 105 HANA 3.01 5.40 56 KIHEI 0.00 0.20 00 LAHAINALUNA 0.11 0.60 18 WAILUKU 0.96 0.60 160 HAWAII HILO 10.76 8.50 127 PAHALA 1.14 3.40 335 HONAUNAU 5.32 7.20 74 KAMUELA (UPPER) 5.55 2.30 241 KAMUELA 4.65 2.20 211 LAUPAHOEHOE 10.59 6.90 153 Data Sources: First order climate network weather observations stations of the National Weather Service at Lihue, HI; Honolulu, HI; Kahalui, HI; Hilo, HI. Additional data were taken from the HYDRONET state network of automated rain gages. Data collected in the automated gages are not certified and information used above should be used for information purposes only. Alan Olson, Assistant Focal Point National Weather Service Forecast Office Honolulu, Hawaii