Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 721 AM EST Tue Nov 27 2018 Valid 00Z Wed Nov 28 2018 - 00Z Wed Dec 05 2018 Strong upper-level ridging (500mb heights about +2.5 standard deviations) will weaken across Hawai'i over the next couple of days, with models showing good agreement that an anomalous trough will amplify across the central Pacific by early Thursday. The trough or perhaps upper low (500mb heights about -2 to -3 standard deviations) is expected to remain just north of the region as it progresses eastward, but its attendant surface cold front will work into the area Friday. Ensembles show a brief surge in precipitable water values to about 1.50-1.75 inches along and just ahead of the front, which should be sufficient to produce at least isolated locally heavy rains (possible embedded convection given the cold mid-levels) through Saturday (from NW to SE) as the front should clear the Big Island as soon as early Sunday or possibly Monday. Timing differences remain among the guidance but a middle ground solution is preferred for now given uncertainties in the upstream Pacific flow. Trades will veer to southeasterly then southerly ahead of the front before becoming northwesterly post-FROPA. After Saturday, heights are expected to build with trades resuming and veering back to east-northeasterly next Mon/Tue but rather breezy. Fracasso