SYNOPSIS: Warm conditions expected through Saturday with high temperatures climbing well above normal. Increasingly gusty conditions are expected Saturday afternoon ahead of a disturbance moving through. Cooler conditions are expected Sunday before temperatures rebound early next week. UPDATE: No significant changes were made to the overnight forecast. A band of higher clouds will push through overnight, but cloudy skies are not expected. It is much warmer tonight, with 850mb temperatures running about 10 degrees warmer than last night per the 00Z sounding. Didnt change overnight lows from previous forecast as they already showed a solution much warmer than last nights observed lows. In general, it will be a quiet night with a few passing high clouds, light winds, and mild temperatures.
DISCUSSION through next Thursday: Even as the ridge of high pressure shifts east across the Four Corner states Friday we are looking at our warmest temperatures of 2019 tomorrow. Las Vegas`s official climate station McCarran International Airport took a run at 90 back on April 8. Confidence high 90 will be hit or eclipsed tomorrow as for the past 3 days the GFS/ECMWF ensemble mean temperature guidance has ranged between 90 - 92 degrees.
Closed upper low currently west of San Diego will be kicked inland over southern California tomorrow ahead of strong trough digging southeast out of the northeast Pacific. Moisture is limited but models do develop modest instability along the southern Sierra crest for shower and thunderstorm development. The weaker system will weaken further as it moves inland through Arizona Saturday. By then, showers and thunderstorms will be developing across western and central Nevada ahead of the deeper trough. Those showers and thunderstorms will spread east into Lincoln and northern Mohave Counties Sunday and Monday. Stronger westerly winds across Inyo and San Bernardino Counties Saturday will spread eastward into Clark County Saturday night. Warm temperatures will continue into Saturday before cold front ushers into cooling for Easter Sunday.
High pressure returns next week for day and warm temperatures.
Hawaii Island and State
Synopsis: Moderate to locally breezy trade winds will prevail through much of the week as surface high pressure holds north of the state. Rather stable conditions will remain in place, leading to a typical pattern of mainly windward and mauka showers.
Discussion: A stable, moderate to locally breezy trade wind flow remains in place. The trades are being driven by a 1027 mb high passing about 1,100 miles north-northeast of the state. A mid level ridge is building over the islands from the west, leading to rather stable conditions. Afternoon soundings and recent aircraft data show the inversion settling between 5,000 and 7,000 ft, and precipitable water (PW) across the area is running near to below April normal. A small pocket of moisture in the trade wind flow produced active showers (totals mainly around 1/4 of an inch) over windward Big Island and east Maui this morning. Otherwise, modest rainfall, generally less than 1/10 of an inch, has been recorded at remaining windward gages, while leeward areas have been mostly dry.
Overall, a typical trade wind weather pattern is expected through the upcoming week. The surface high will settle to the northeast of the state, while its associated surface stalls about 300 to 500 miles north of the islands. We could see an uptick in trade winds during the weekend as the ridge briefly strengthens. Stable conditions will dominate through much of the week as the mid level ridge will remain parked overhead. Generally, precipitable water will be near normal, suggesting that showers will be modest and confined to windward slopes. As random pockets of low level moisture move through on the trade wind flow, expect brief and localized increases in showers. Aside from afternoon showers on the Kona slopes of the Big Island, leeward areas will be mostly dry.