MONTHLY PRECIPITATION SUMMARY State of Hawaii portion of Honolulu HSA MONTH: July 1999 PREPARED: 2 August 1999 State: No flash flood warnings were required or issued during July. Trade winds once again continued unabated throughout July at mainly moderate to fresh intensities. A brief period of strong trades occurred during 26 to 27 July, though this did not appear to have a significant impact on rainfall statewide. July largely turned out to be a repeat of June's rainfall pattern of persistent trade wind showers over the islands of Kauai and Oahu, and drier conditions over the islands of Hawaii and Maui. The remnant circulation of Hurricane Beatriz managed to pass over the island chain late on 19 July. However, most of the enhanced shower activity passed to the north of the state with the islands of Hawaii and Maui getting mainly unpleasant humidity and little drought relief from the moist tropical airmass. Island of Kauai: As was the case in June, the month of July saw consistent, mainly light rainfall produced by the trades over Kauai. For example, the gage at Hanalei recorded measurable rain every day, but amounts were mostly light leaving the July total at 7.99 inches or 93 percent of normal. For this site, the median daily total was 0.16 inches and only one day had an inch or more rainfall (1.08 inches on 20 July). Three other gages (Wailua, Lihue V. S., and Omao) recorded measurable rain on 30 out of 31 days. Five sites reported above normal totals with the gage at Kapahi showing both the largest total (9.69 inches) and the largest positive anomaly (176 percent of normal). Island of Oahu Oahu was quite wet during the month of July with 19 out of 29 Hydronet sites reporting totals at or above normal. Central Oahu gages at Waipio (1.95 inches), Waiawa C.F. (8.59 inches), Mililani (3.74 inches), and Wheeler A.A.F. (5.20 inches) showed the highest positive anomalies at 195, 172, 178, and 200 percent of normal, respectively. For all four sites, the monthly totals represent the highest rainfall amounts in July since Hydronet rainfall records were started in 1991. As is usually the case, the Manoa Lyon Arboretum gage reported the highest rainfall total for the island. Its 16.68 inches for the month ranks as the highest July total since 1993 and is 126 percent of normal (13.20 inches). Daily rain totals at all Oahu sites were not particularly high as there were no 24-hour amounts greater than two inches. As was the case in Kauai, it was the persistence of rainfall that elevated the monthly totals. Maui County Drought-stricken areas in Upcountry Maui continued to have dry conditions throughout July. Gages at Pukalani and Kula saw less than 20 percent of normal rainfall for the month. The Ulupalakua area did see some drought relief during the passage of Hurricane Beatriz's remnants with our gage recording 0.21 inches on 19 July. This rainfall helped bring the Ulupalakua total to 0.60 inches, or 37 percent of normal. The Kihei gage reported no rainfall for the second consecutive month, and the gage at Waikapu C. C. has recorded only 0.01 inches in the last two months. Windward areas experienced the most rainfall as a result of its exposure to the persistent trade wind showers. Amounts received at Hana and Haiku on the slopes of Haleakala volcano were 64 and 86 percent of normal, respectively. The gage at Kahakuloa saw 2.34 inches, which was 156 percent of normal. The two gages on the island of Molokai and the lone gage on the island of Lanai reported less than one inch for the month of July. However, these sites are normally quite dry and the 0.28 inches observed at Kaunakakai Mauka was actually 140 percent of normal. Island of Hawaii: Another dry month for the island of Hawaii with 15 out of 19 sites reporting less than 50 percent of normal rainfall. The Kau and Waikoloa areas have been especially dry this summer. Three- month (May-July) totals at Pahala, Kapapala Ranch, and Kamakoa are only 10, 12, and 16 percent of normal. The Kamakoa gage in leeward Kohala has received only 1.60 inches all year (15 percent of normal) within an area characterized as being under extreme wildfire risk. For the Hamakua and Hilo districts, 1999 started out with very wet trades. However, conditions reversed in mid-April and these areas have been relatively dry since. The five gages in both districts show three-month totals for the period from May through July to be in the 20 to 40 percent of normal range. As a result, year-to-date totals have now dropped below normal. The three gages covering the Puna area have also seen less rainfall recently, but year-to-date totals remain at or above normal. The gage at Kamuela Upper stands out as the lone positive anomaly with 5.49 inches during July, or 125 percent of normal. THE FOLLOWING LIST CONTAINS RAINFALL STATISTICS FOR SELECTED LOCATIONS FROM AROUND THE STATE. THE FIRST COLUMN IS THE OBSERVED RAINFALL FOR JULY. THE SECOND COLUMN IS THE 30-YEAR AVERAGE FOR THAT LOCATION WHILE THE THIRD COLUMN LISTS THE PERCENT OF AVERAGE RAINFALL FOR THE MONTH OF JULY. THE FOURTH AND FIFTH COLUMNS ARE THE YEAR-TO-DATE TOTAL AND THE PERCENT OF AVERAGE, RESPECTIVELY. YTD KAUAI JULY AVG %AVG YTD %AVG LIHUE AIRPORT 2.74 2.1 130 18.49 78 HANALEI 7.99 8.6 93 45.41 65 HANAPEPE 1.60 1.3 123 12.67 74 OAHU HONOLULU AIRPORT 0.57 0.6 97 6.50 56 MANOA ARBORETUM 16.6 13.2 126 89.07 101 NIU VALLEY 2.6 2.0 131 16.38 71 WAIHEE PUMP 4.0 7.8 52 33.25 53 LUALUALEI 1.05 0.7 150 8.65 60 WAIALUA 1.33 1.3 102 10.44 52 MOLOKAI KAUNAKAKAI 0.28 0.2 140 4.23 41 LANAI LANAI CITY 0.83 2.0 42 9.27 39 MAUI KAHULUI AIRPORT 0.03 0.4 8 6.58 51 HANA 3.61 5.6 64 N/A N/A HAIKU 4.23 4.9 86 N/A N/A KIHEI 0.00 0.1 0 2.13 21 LAHAINALUNA 0.01 0.3 3 4.12 33 WAILUKU 0.26 0.6 43 7.39 42 HAWAII HILO AIRPORT 3.53 9.7 36 72.03 96 PAHALA 0.04 2.1 2 12.38 37 HONAUNAU 2.41 7.3 33 13.71 35 KAMUELA (UPPER) 5.49 4.4 125 36.63 101 GLENWOOD 5.84 9.9 59 128.03 129 LAUPAHOEHOE 2.52 10.0 25 64.63 69 Data Sources: First order climate network weather observation stations of the National Weather Service at Lihue, Honolulu, Kahului, and 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. Kevin R. Kodama, Senior Service Hydrologist National Weather Service Forecast Office Honolulu, Hawaii