FORECAST DISCUSSION

Synopsis

The inclement weather continues for the Hawaiian Islands this week. The western half of the island chain will have a brief break in the unsettled weather today and Tuesday before another round of weather moves in for the second half of the work week.

Discussion

Some minor adjustments were made to the grids but the philosophy reasoning behind the forecast remains pretty much intact. Basically, a wet and active weather pattern continues for the Hawaiian Islands for this week. Today and Tuesday will be somewhat of a break in the weather for Kauai, Oahu, with a bit more sun as an upper level trough pushes eastward thereby taking and thinning some of the dense layered stratiform mid and high clouds away. The upper trough is slated to head northeast soon, and would not be able to totally clear out these clouds across the eastern part of the island chain. But a bit more sun under a sufficiently unstable air mass, will likely lead to a couple of thunderstorms /ts/ across Maui and the Big Island especially this afternoon. Currently, most of the steady but mainly light precipitation associated with the dense layered clouds lies east of Oahu. The surface trough meanwhile, continues to approach Niihau and Kauai from the west as noted on the weather radar loop. Scattered showers are also present in the convergent southerly flow in the Kauai channel. We expect the surface trough to push past Kauai County by mid morning and usher in a slightly drier more stable airmass. We anticipate the air mass over Oahu to be more stable as well by this afternoon. However, ample day time heating with ample moisture and a sea breeze will result in some scattered showers this afternoon. Although excessive rainfall is not expected at this time for Oahu, we will continue to monitor the situation closely. The surface trough dissipates over Oahu later today while a weak surface high forms north of the islands. With it, weak trades returns briefly to the islands starting this evening and lasting through early Tuesday evening. Thereafter, the southerly winds takes over while the next surface trough shows up just west of Kauai Wednesday morning. It should be noted the ECMWF solution does not show this trough, instead has light trades across the island chain. The GFS goes on to show the surface trough to stall over Kauai and languish there through Thursday before dissipating Thursday night. This surface feature will be aided by another upper level trough that dampens out over the islands Thursday. The models then shows another upper and surface trough combo approaching Kauai Saturday morning, thereby prolonging the inclement weather. More to come.

Aviation

An upper level trough over the central islands will keep conditions unsettled over Maui and the Big Island today, with improving conditions expected tonight as the upper trough weakens. Occasional MVFR cigs/vsbys will be possible in SHRA here, with isolated IFR conditions possible. Over Molokai and Lanai, unsettled conditions and occasional MVFR cigs/vsbys are expected through the morning hours, with improving conditions expected this afternoon. Over Oahu and Kauai, more settled weather is expected, although some afternoon shower development and brief MVFR cigs/vsbys will be possible especially across the interior of the islands. AIRMET Sierra remains in effect for mountain obscuration from Oahu eastward to the Big Island. Conditions are expected to improve over Oahu later this morning. Molokai and Lanai should see improving conditions by this afternoon, and Maui and the Big Island may deal with mountain obscuration through much of the day. AIRMET Tango is in effect for moderate upper level turbulence between 150 and FL350 across all islands. These conditions are expected to improve later this morning. AIRMET Zulu is in effect for icing east of Kauai. These conditions are expected to slowly improve from west to east across the island chain through the day.

Marine

The Hanalei buoy shows a subsiding trend in the seas and northwest swell. The Small Craft Advisory /SCA/ has been extended for another 12 hours to 6 pm HST this afternoon but the area reduced to waters around Kauai. No large swells are expected during the next six days or meaning surf will remain below High Surf Advisory levels.

HFO Watches/Warnings/Advisories

Flash Flood Watch to 6 pm hst this afternoon for Maui and Big Island. Small Craft Advisory until 6 PM HST this afternoon for waters around Kauai.

Footer

DISCUSSION/MARINE...Lau AVIATION...Jelsema

Back to Top