Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 757 AM EDT Wed Aug 01 2018 Valid 00Z Thu Aug 02 2018 - 00Z Thu Aug 09 2018 General flow pattern ~~~~~~~~~~~~~~~~~~~~ A deep layer/warm core high to the north of Hawai'i/south of the Aleutians will strengthen this week along 170W (about +2 sigma 500mb heights). A pair of mid of TUTT cells/upper lows will retrograde about 20 degrees to the south of the positive height anomaly moving between the 25th and 30th parallels over the next week in the vicinity of the island chain. Models/ensembles remain stable in this evolution, so a blend of the available guidance should suffice for most of the forecast expectations during the next 7.5 days. Tropical Storm Hector ~~~~~~~~~~~~~~~~~~~~~ In regards to Tropical Storm Hector, it is quite possible that the 06z GFS is too far north/too strong with the system as it tries to approach the Big Island (the usual model bias with systems approaching Hawai'i). For now, advise towards a more 00z ECMWF/00z Canadian compromise solution for this system. Will coordinate with NHC concerning the future track of Hector at 1700 UTC/7 am HDT today. Weather impacts ~~~~~~~~~~~~~~~ Above average moisture persists through Wednesday due to the movement of an easterly wave by the archipelago and the retrogression of TUTT cell #1 past the Papahanaumokuakea Marine National Monument, returning back towards climatological values on Thursday/early Friday in its wake. Another increase is forecast Friday night into Sunday with another surface easterly wave connected to TUTT cell #2. Both periods of enhanced moisture should bring above average chances/coverage of rain to the 50th state. As TUTT cell #2 departs next Monday into Tuesday, precipitable water values should return back towards climatological norms for early August. A third moisture increase is expected north/northwest of Hector and/or its remains as they pass south of the Big Island next Wednesday into next Thursday, which should lead to enhanced rain chances/coverage, though the full impact remains unclear. Stay tuned. Roth