Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 725 AM EST Wed Jan 31 2018 Valid 00Z Thu Feb 01 2018 - 00Z Thu Feb 08 2018 An extremely amplified long wave upper trough will be present throughout much of the next week over the central Pacific, from just south of the Aleutians to north and west of the state. Multiple upper-level short waves will round the base of this anomalous feature, which will keep a frontal zone wavering across Hawaii along with moist southwesterly flow. Over the next few days, multiple streams of 1 inch precipitable water values will stretch from south/southwest of the islands through the chain, which should increase showers activity. By the upcoming weekend, this zone of deeper tropical moisture should unified ahead of the cold front and may produce organized rainfall for the northwestern islands or Ni'ihau and Kauai. Then early next week, this entire frontal zone and deep moisture will move through the rest of the islands, as the upper trough over the Pacific begins to advance downstream. This will definitely increase the chances of rain from Oahu to Maui and the Big Island. Some of these rains, over the weekend through next Tuesday, have the potential to be heavy and produce runoff issues. Finally by the middle of next week, this entire frontal zone and moisture will clear the state, basically in the wake of amplified upper trough. The global models do not show a tremendous amount of spread, which adds confidence in the upcoming pattern and details. Musher