textproduct: Gray - Portland

WHAT HAS CHANGED

No major changes were needed at this time, tranquil weather still expected this weekend. Increased shower probabilities tonight as guidance continues to look more bullish on at least a couple scattered showers over the region late tonight.

KEY MESSAGES

1. Above normal temperatures are expected through the remainder of the weekend. Outdoor recreation is bound to be in high demand and area inland and ocean waters remain very cold.

2. Above normal temperatures continue into early to mid week which should feature the warmest days of the year so far. With the heat also come the chance for scattered showers and thunderstorms on Tuesday and Wednesday.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

A tranquil weekend is expected, with warm temperatures expected and mostly clear skies. A decaying cold front will move through the region tonight, bringing some chances to see some showers across the area late in the evening. Skies clear early in the morning tomorrow. Another warm and tranquil Sunday is on tap, with high temperatures in the upper 70s and lower 80s.

With the abundantly warm weather today and tomorrow, it is crucial to recognize that lake and ocean water temperatures have not warmed up. Ocean sea-surface temperatures are still in the lower to mid- 40s, with lake temperatures only at most a few degrees warmer. Lake and ocean temperatures this cold pose a significant hazard to swimmers, boaters and beachgoers. Hypothermia and cold shock can occur in these water temperatures.

KEY MESSAGE 2 DESCRIPTION...

Ridging noses into the region Monday as surface winds turn onshore. This should lead to a stable, uneventful day of weather, but it will keep coastal and some inland portions a couple degrees cooler. Daytime highs run up into the mid to upper 60s along the coast, while interior and western portions of the forecast area continue warming into the mid to upper 70s.

Amid a very large warm sector, areawide temperatures continue higher Tuesday and Wednesday. 850mb temps come within reach of climo maxes this period, and it should lead to surface temps in the 80s areawide. Low 90s appear possible for southern portions of the CWA, with more uncertainty to the north and west. This mainly has to do with how close frontal lift to the north is, generating more in the way of clouds and precipitation.

As mentioned in previous forecast, there is the potential for a strong thunderstorm environment Tuesday and Wednesday. The question for Tuesday will be how near a continuous forcing mechanism will be (largely still displaced to the north and west). Present forecast soundings depict weak to moderate instability by the afternoon hours in the 1000 to 1500 J/kg range depending on the parcel trace, but also have a cap of stable air above the mixed layer. This would need to be overcome for a greater storm threat.

For Wednesday, cold front is prog'd to be moving through the forecast area which will indeed supply lift for storms should it remain on this timeline. The questions here will be where is its exact positioning, and how much time ahead of the front exists for daytime instability to increase. Should the front bisect the forecast area come Wednesday, its possible only the eastern half would see the greater chance for general/strong storms.

With the passage of the front, cooler temperatures look to arrive for late week with lingering showers moving out of the area by Thursday morning. With very little NBM spread, this cool down is a fairly high confidence forecast.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Tranquil weather this evening will allow for VFR conditions to prevail this afternoon and into the evening. A couple isolated showers late tonight may allow for a very brief period of MVFR between 00Z and 06Z Sunday (tonight). VFR is expected to continue through the day on Sunday and even into Monday morning. However, westerly wind gusts of 20 to 30 kt are expected Sunday.

Outlook:

Monday: VFR Expected.

Tuesday: AM VFR, PM MVFR possible due to showers/thunderstorms.

Wednesday: AM VFR, PM MVFR possible due to showers/thunderstorms.

Thursday: VFR Likely.

MARINE

Southerly SCA-level winds will subside this evening. Light and variable winds are expected tonight and will continue through Tuesday morning. Southerly winds build up to near SCA levels during the day Tuesday, but slowly start weakening Tuesday night and into Wednesday. Below-SCA level winds and seas will continue through the remainder of next week.

Seas of 4-7ft are expected this evening, and weaken to 2-4ft by Sunday afternoon. Seas of 2-5ft are expected through the end of next week.

GYX WATCHES/WARNINGS/ADVISORIES

ME...Beach Hazards Statement until 8 PM EDT this evening for MEZ023>028. NH...Beach Hazards Statement until 8 PM EDT this evening for NHZ014. MARINE...Small Craft Advisory until 5 AM EDT Sunday for ANZ150-152-154.