Heavy Rain, Honolulu
- When
- February 7, 1:14 PM HST to 4:09 PM HST
- Where
- Honolulu County, 0.78 mi W of Makaha Valley to 0.76 mi NE of Makakilo City
- Reported by
- Official NWS Observations
- Coordinates
- 21.479, -158.212
Heavy Rain in Hawaii, February 7, 2009
Convective conditions prevailed over Oahu, and heavy showers developed over western parts of the isle. Even small hail was reported by a pilot and several residents near Nanakuli.
Where it happened
Every event with a place to put it. Tap one for its entry below.
- Tornadoes
- Tropical storms and surge
- Floods
- Wind
- Hail
- Winter weather
- Heat and drought
- Cold
- Fire, smoke and dust
- Marine and coastal
- Other
The toll
- Deaths
- 0
- Injuries
- 0
- Property damage
- None recorded
- Crop damage
- None recorded
- Events
- 1
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
What happened
The episode as NWS HFO wrote it up.
Convective conditions prevailed over Oahu, and heavy showers developed over western parts of the isle. Even small hail was reported by a pilot and several residents near Nanakuli. There was ponding on roadways, and small stream and drainage ditch flooding. However, no significant injuries or property damage were reported.
What forecasters said that day
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Honolulu, HI wrote its last area forecast discussion before the first event at Feb 7, 12:10 PM HST, 1 hour 4 minutes earlier.
Area forecast discussion, Feb 7, 12:10 PM HST, 1 hour 4 minutes before
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 1210 PM HST SAT FEB 7 2009 .UPDATE... UPDATED FORECASTS TO ACCOUNT FOR THE EXPIRATION OF THE HIGH SURF ADVISORY FOR NORTH AND WEST FACING SHORES. ALSO UPDATED TO REFLECT A SEA BREEZE PATTERN IN THE POP...SKY AND WEATHER FORECAST OVER THE ISLANDS THIS AFTERNOON. && .SYNOPSIS... LIGHT TRADE WINDS WILL ALLOW AFTERNOON SEA BREEZES AND A FEW INTERIOR CLOUDS TO DEVELOP THIS AFTERNOON...WITH A SLIGHT CHANCE OF THUNDERSTORMS OVER THE BIG ISLAND SLOPES. WHILE TRADE WINDS WILL STRENGTHEN SLIGHTLY TONIGHT AND SUNDAY...THEY WILL WEAKEN ONCE AGAIN MONDAY AND TUESDAY. THE TRADE WINDS WILL DELIVER A FEW CLOUDS AND SHOWERS TO WINDWARD AREAS DURING NIGHTS AND MORNINGS...WHILE INTERIOR AND LEEWARD AREAS CAN EXPECT AFTERNOON CLOUDS AND ISOLATED SHOWERS. && .DISCUSSION... CURRENTLY A COMPLEX PATTERN ALOFT EXISTS OVER THE ISLANDS...WITH A HIGH-LEVEL TROUGH AXIS JUST EAST OF THE BIG ISLAND...AND A LINGERING MID-LEVEL TROUGH OVER THE ISLANDS. LAYERED CLOUDS ASSOCIATED WITH THE UPPER TROUGH COVER A GOOD PORTION OF THE CENTRAL NORTH PACIFIC... MAINLY TO THE NORTH AND EAST OF THE ISLANDS...WITH MOST OF THESE CLOUDS CURRENTLY CLEARED OUT OF ISLAND SKIES. MORNING SOUNDINGS REVEAL UNUSUALLY COLD AIR IN THE MID-LEVELS...WITH 500 MB TEMPERATURES NEAR -14 DEGREES CELSIUS. WHILE THE ATMOSPHERE IS STABLY STRATIFIED BETWEEN 6 AND 9 THOUSAND FEET WITH THE TYPICAL SUBSIDENCE INVERSION...THE AIR MASS ABOVE IS QUITE UNSTABLE DUE TO THESE COLD MID-LEVEL TEMPS. MEANWHILE AT THE SURFACE...A 1036 MB HIGH IS CENTERED ABOUT 1100 MILES NORTH-NORTHWEST OF KAUAI...WITH A 1034 MB HIGH CENTERED ABOUT 1350 MILES NORTHEAST OF THE BIG ISLAND. NORMALLY THESE HIGHS WOULD SUPPORT MODERATELY STRONG TRADE WINDS AT OUR LATITUDES...BUT LAND- BASED OBSERVATIONS REVEAL A LIGHT WIND PATTERN OVER THE ISLANDS THIS MORNING...WHILE NEARBY BUOYS ARE SHOWING GENTLE TO MODERATE EAST WINDS. A DISSIPATING FRONTAL BOUNDARY TO THE NORTH OF THE ISLANDS...IN COMBINATION WITH THE TROUGH ALOFT NEAR THE ISLANDS... HAVE LOOSENED THE PRESSURE GRADIENT SUFFICIENTLY TO KEEP WINDS LIGHT THIS MORNING. RADAR AND SATELLITE SHOW LITTLE IN THE WAY OF SHOWERY LOW CLOUDS OVER THE ISLANDS AND NEAR SHORE WATERS...WITH CLUSTERS OF THUNDERSTORMS DEVELOPING 125 TO 250 MILES NORTH OF KAUAI...ALONG 160W. FORECAST PROBLEMS OF THE DAY INCLUDE 1/ WHETHER OR NOT SURFACE-BASED AIR PARCELS WILL BE ABLE TO TAP INTO THE HIGH-LEVEL INSTABILITY BY PUNCHING THROUGH THE STABLE LOW-LEVEL LAYER AND...2/ THE SURFACE WIND FORECAST. CURRENTLY WE ARE FORECASTING A SLIGHT CHANCE OF THUNDERSTORMS TO DEVELOP OVER INTERIOR BIG ISLAND THIS AFTERNOON... WHERE DAYTIME HEATING OF THE SLOPES CAN MORE EASILY TAP INTO THE ELEVATED INSTABILITY. THIS CONTINUES TO BE A REASONABLE EXPECTATION...AND ASIDE FROM AN ISOLATED THUNDERSTORM DEVELOPING IN ISLAND PLUMES OVER WATERS TO THE LEE OF THE ISLANDS TONIGHT...IT LOOKS AS IF THE INSTABILITY ALOFT WILL NOT BE REALIZED. ON THE LARGE SCALE...EAST TO SOUTHEAST LOW LEVEL WINDS ARE EXPECTED TO CONTINUE INTO TONIGHT...AFTER WHICH THE REMNANT FRONTAL BOUNDARY TO OUR NORTH WILL BEGIN TO DISSIPATE FURTHER...ALLOWING THE PRESSURE GRADIENT OVER THE ISLANDS TO TIGHTEN. WITH THE ESE WIND DIRECTION... THE SMALLER ISLANDS ARE IN THE WIND SHADOW OF THE BIG ISLAND...WHICH WILL ALLOW SEA BREEZES AND THEIR ASSOCIATED CLOUDS TO DEVELOP OVER THE ISLANDS THIS AFTERNOON. MODERATE TRADE WINDS WILL PREVAIL ON SUNDAY...BUT THERE ARE SOME MODEL INDICATIONS THAT A TROUGH WILL PASS BETWEEN THE ISLANDS AND THE TRADE-WIND SUPPLYING RIDGE ON MONDAY AND TUESDAY...LOOSENING THE PRESSURE GRADIENT AGAIN...WITH LARGE-SCALE ESE WINDS ALLOWING ISLAND SCALE CIRCULATIONS TO DEVELOP AGAIN...ESPECIALLY IN AREAS SHELTERED FROM THE PREVAILING FLOW. THE LIGHTER THAN NORMAL TRADES AROUND MID-WEEK ARE CURRENTLY FORECAST TO BECOME QUITE STRONG AS WE HEAD INTO NEXT WEEKEND...BUT CONFIDENCE REMAINS LOW AS MODEL GUIDANCE HAS NOT BEEN CONSISTENT FROM RUN TO RUN. THE MID-LEVEL TROUGH CURRENTLY NEAR THE ISLANDS IS FORECAST TO WEAKEN AND MOVE NORTHEAST TODAY...WHILE A NEW MID LEVEL TROUGH DIGS IN FROM THE NORTHWEST. THIS WILL KEEP MID-LEVELS COOLER AND MORE UNSTABLE THAN NORMAL...BUT AS MENTIONED ABOVE...THIS INSTABILITY IS NOT EXPECTED TO BE REALIZED IN THE FORM OF HEAVY SHOWER OR THUNDERSTORM DEVELOPMENT /OUTSIDE THE KONA SLOPE THREAT/ AS THE LOW-LEVEL RIDGE WILL CAP SURFACE PARCELS BELOW 6 TO 7 THOUSAND FEET. && .MARINE... A SCA MAY NEED TO BE ISSUED FOR AREAS WHERE WINDS ARE CHANNELED AROUND THE BIG ISLAND AS THE TRADES BUILD SLIGHTLY LATER TODAY AND TONIGHT. && .HFO WATCHES/WARNINGS/ADVISORIES... NONE. && BIRCHARD
The radar
The national radar mosaic for the moment the first event began.
Event by event
1 heavy rain. Local standard time, as filed.
What these are
- Heavy Rain
- Rainfall totals unusual for the place and season that did not produce a flood.
After NWS Directive 10-1605, the rules offices file Storm Data by.
The same day elsewhere
More
Every storm in Hawaii in 2009Every state in 2009This day in weather historyWarnings in Hawaii, February 2009
Sources
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 149415.