Winter Storm Watch Issued for Hawaii as Ice, 50 mph Winds, Snow, and Flash Flooding Approach: 'Impossible' Travel
Hawaii is bracing for another punishing round of weather this week, and for a state that just endured some of the most destructive flooding in its history, the timing couldn't be worse.
The entire state is under flood watches as powerful bands of heavy rain are expected to sweep across the islands beginning Wednesday and lasting through Friday. At the same time, a winter storm watch has been issued for the Big Island's highest summits, where snow, ice and dangerous winds are forecast to make travel nearly impossible by midweek.
More Flooding Coming to Hawaii
According to The Weather Channel, rainfall totals are expected to be highest across the Big Island and Kauai, where up to 8 inches of rain is possible, and even more at higher elevations. The threat is compounded by what's already happened. Honolulu has seen over a foot of rainfall since March 1, which is about six times its average. Kahului has seen over 20 inches in the same period, running about a foot and a half above normal. The ground across the state is saturated, meaning rivers and streams will rise faster than usual and it will take far less rain to trigger flooding than it normally would.
This follows back-to-back Kona lows in March that caused an estimated $1 billion in damage across the state — some of the worst flooding Hawaii has seen in 20 years.
Winter Storm Watch in Hawaii
At the highest elevations, the concern shifts from flooding to winter weather. The summits of Mauna Kea and Mauna Loa above 12,500 feet are under a winter storm watch through Friday afternoon. Up to 3 inches of snow and ice accumulation up to a quarter inch are possible, with wind gusts between 40 and 55 mph. Those conditions are expected to make summit road travel very difficult to impossible, with rangers likely to close roads as conditions deteriorate. Anyone planning travel to the summits this week should postpone until conditions improve.
@weatherchannel Hawaii is going to see yet another round of very heavy rainfall this week. The entire state is under flood watches as rounds of powerful bands of rain are expected beginning Wednesday and lasting until Friday. This comes after the state just saw powerful rainfall that caused devastating flooding in March.
♬ original sound - The Weather Channel
What is Causing the Extreme Weather in Hawaii?
The Weather Channel reports that a cold front approaching from the northwest is the primary driver, with a surface trough developing ahead of it and causing winds to blow in from the southwest. An upper-air trough moving over the area will pull a powerful surge of moisture from the southwest across the state. A surface low pressure system will eventually develop west of the islands and enhance that moisture surge further.
While this system is meeting some of the criteria of a Kona Low — the type of storm system that caused March's devastating flooding — forecasters say it is not a classic Kona Low setup. That distinction doesn't change the impact. Whether it's technically a Kona Low or not, days of heavy rainfall are coming to an already waterlogged state, and the flood threat is very real.
Winter Storm Watch vs. Winter Storm Warning: What the Difference Means
A winter storm watch means conditions are favorable for a winter storm but its exact track, timing or intensity remains uncertain. Watches are typically issued 24 to 48 hours in advance when forecasters believe heavy snow, sleet or ice is possible.
A winter storm warning means a storm is imminent or already occurring and confidence is high that hazardous winter weather will impact the area. Warnings are usually issued within 24 hours of the event and signal dangerous travel conditions and disruptions are expected.
The NWS advises anyone planning travel to the Big Island summits to monitor forecast updates closely and consider postponing trips until conditions improve. For the latest information visit weather.gov.