Puna Weather
Wednesday 19th August 2026
Today moderate easterly trade winds with widely scattered showers.
Thursday humid with scattered showers and light winds. VOG is possible.
Friday and Saturday humid with scattered showers and moderate easterly trade winds.
Sunday and Monday very humid with periods of heavy rain and moderate to breezy easterly trade winds.
High pressure to our northeast maintains easterly trade winds over us today. As the remnants of ex-Hernan pass by Thursday they interrupt our trades for the risk of VOG. The moisture associated with Hernan's remnants takes an extra day to clear the area keeping us warm and humid into Friday.
Saturday might be less humid. Persistent easterly trades keep showers in the forecast.
Sunday and Monday we are likely to see tropical moisture from Invest 90E overspread our island. As the low passes by to our south the pressure gradient over our island tightens for a bump in trade winds. The onshore winds and tropical moisture combine for the risk of persistent heavy rain for the windward side of our island.
For a while last night the GFS over amplified activity associated with 90E showing an unrealistic path northwest and towards our island. It should be noted that the lower resolution emsemble model solutions did not have this problem and maintained a path to our south.
The hyperactive GFS showed us that a stronger storm takes a more northerly path being steered by winds higher in the atmosphere and also from a more pronounced beta drift... stronger tropical storms have a northward tendency in the northern hemisphere.
Yesterday's GFS showed an upper level trough imparting strong shear on 90E as it moved west-northwest. The last two runs of the GFS no longer show this trough or shear. That means, in the off chance that 90E consolidates earlier, it could see a relatively low shear environment up to our coast. I'd give this scenario a less than 10% chance at this point.
We won't really know what's going on with the storm until it actually forms a center of circulation, which took Lala a couple of days to accomplish.
Long story made short... 90E is much more likely to bring high humidity and heavy rain, but has a small (<10%) chance of being a repeat of Lala.
At this moment the storm is a broad area of disturbed weather with very heavy convection. There is no low level center but there is diverging flow aloft providing outflow in all quadrants (water vapor loop). It is also over very warm waters, and waters are warm all the way from the tropics to our island. Given the excellent ventilation and warm sea surface tempertures the low could overcome the modest shear that is currently over it, and strengthen to a tropical storm in the next day or two.
