textproduct: Gray - Portland

WHAT HAS CHANGED

Minor update to the Aviation section for the 00Z TAFs.

KEY MESSAGES

1. High astronomical tides combined with some surge may bring total water levels to near minor flood stage during tonight's high tide cycle. Locally dense fog is also possible, especially across the coastal plain.

2. Widespread rainfall is expected on Sunday with some snow possible late in the day across the mountains and near the Canadian Border.

3. A cooler and unsettled pattern gradually moderates through the week.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

The combination of high astronomical tides combined with surge of up to around 1/2 foot will bring total water levels to near minor flood stage during tonight's high tide cycle. The greatest threat will be from Portland and points south, where a coastal flood statement has been issued.

A deck of low ceilings and fog will continue to advance northward through this evening from the Gulf of ME, leading to a cloudy and foggy night. Locally dense fog is possible, especially across the coastal plain. There will also be an increasing chance for showers to develop towards dawn on Sunday as low pressure tracks northeastward over southeastern New England. Low temperatures will primarily be into the lower to middle 40s.

KEY MESSAGE 2 DESCRIPTION...

Low pressure will track across the Gulf of ME on Sunday before exiting to our northeast over the Canadian Maritimes Sunday evening. This area of low pressure combined with a passing cold front will bring widespread rainfall to the region with generally between 0.25- 0.75" of QPF expected. Locally higher amounts are possible across the mountains. A non-diurnal temperature trend is expected on Sunday as the front crosses with temperatures initially into the 40s before falling into the middle and upper 30s from northwest to southeast.

This may allow for some snow to mix in across portions of western NH and extending into the Lakes Regions of NH/ME and points northward. Given warm ground temperatures, marginal air temperatures, and the high late April sun angle, little to no accumulation is expected outside of the higher terrain and near the Canadian Border. A slushy 1-3" is possible across those locations, highest above 4k ft. Rain will end by sunset in most locations but it may linger another few hours from roughly Augusta and points east. Low temperatures will be into the 20s across the interior with lower 30s along the coast and in the urban corridors.

KEY MESSAGE 3 DESCRIPTION...

The week starts off on a cool note behind the cold front. After lows in the 20s and 30s Monday morning, highs range from the mid 30s across the north to near 50 along the coast. A weak trough swings through during the daytime, bringing the chance for some scattered rain or snow showers in the afternoon. A fresh cold airmass follows as high pressure continues to build in, with lows ranging from the mid teens across the north to mid 20s along the coast Monday night.

High pressure crosses through the Northeast on Tuesday, bringing a mainly sunny day with lighter winds. It also marks the start of a moderating trend through the remainder on the week. Lows over the following nights won't be as cool, with mid 20s across the north and mid 30s along the coast generally expected.

A warm front brings the next chance some showers to the area on Wednesday, with a cold front following later in the day. However, a warmer airmass moves in from the west behind the front, with highs likely to make a return to the 60s for Thursday and Friday. The next front likely approaches the area on Friday and into the weekend, bringing the next chance for some showers.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Ceilings will continue to lower over next couple of hours with drizzle at times at PWM. Fog and low cigs will bring IFR/LIFR across all sites by 03Z except LEB and HIE where MVFR may persist until 06Z and then lower to IFR. RA will begin from west to east on Sunday morning between 10-14Z (latest at KAUG and KRKD) with RA persisting through 21-00Z Monday along with FG. Light and variable winds during the morning will become NW with gusts up 20 kts by early afternoon. Conditions will gradually improve Sunday night but some restrictions will likely linger through 12Z Monday.

Outlook...

Monday: Mainly VFR conditions with NW winds at 10-15 kts during the daytime before becoming light and variable at night. MVFR or lower possible at HIE.

Tuesday: VFR conditions with light winds. Lowering ceilings possible at night.

Wednesday: Showers and MVFR are possible, otherwise VFR conditions continue.

Thursday - Friday: Mainly VFR expected.

MARINE

NW wind gusts may approach 25 kts behind a cold front on Sunday evening with 2-5 ft seas across the near-shore coastal waters. Otherwise, winds and seas will generally remain below SCA criteria through period. Marine fog is likely tonight into Sunday.

Winds and seas stay below SCA levels as high pressure builds across the waters through Tuesday. SCA conditions in southwesterly flow are then possible ahead of a cold front Tuesday night and Wednesday. Broad high pressure follows the front for the end of the week.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...None.