Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 825 AM EDT Thu May 02 2019 Valid 00Z Fri May 03 2019 - 00Z Fri May 10 2019 A sharp trough to the northwest of the area will deepen into an extremely anomalously deep closed upper low tonight and continue dropping southeastward to near 30N/160W by 12Z Saturday. 500mb height anomalies will be near 6 sigma below average (below observed values in recent decades for this time of year). It will then turn to the east-southeast to a position near 25N/151W by 12Z Monday before lifting eastward then northeastward next Tue-Wed. An associated cold front is forecast to pass through the state from northwest to southeast late Friday night though Sunday. Though this front will move through fairly quickly, models show the potential for some deeper tropical moisture to be pulled northward into the system (PWs 1.50-2 inches). This would result in the potential for heavy rainfall Sat into Sun for the islands from O`ahu east to Hawai`i, but the models do focus most of the rainfall to the northeast of the region. ECMWF ensemble probabilities have lowered the chance of heavier rainfall (>1") but the potential remains due to the strong dynamics associated with the system. In addition to the rainfall potential, 20-30 kt and gusty southerly to then northwesterly winds should develop ahead of (then behind) the front starting on Saturday across the state. Drier air on northerly flow is forecast for next week with lighter winds overall as the surface low lingers to the north-northeast of the state. Trades will start to re-establish themselves by next Wednesday or Thursday as an area of high pressure slides eastward along 35N. Ensembles were in good agreement overall next week with the ECMWF ensemble mean a bit more defined than the GEFS mean. Fracasso