textproduct: Gray - Portland

WHAT HAS CHANGED

Patchy fog is likely across much of the area tonight with with potential for locally dense fog to impact the early morning commute.

KEY MESSAGES

1. Low pressure and steady rain exits east this evening. Areas of fog are likely tonight before a cold front crosses that will bring chances for couple of thunderstorms near the CT Valley late this evening.

2. High pressure will build across New England for the first half of this week, bringing mainly dry conditions and cool temperatures. A frontal boundary will bring increased shower chances late in the week.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

Low pressure will continue its trek eastward across southern New England with steady rain along the coastal plain coming to an end this evening. Latest surface analysis shows a cold front through the St Lawrence Valley with showers and thunderstorms developing along the front. These showers and storms will approach the Canadian Border and northern CT Valley after sunset while CAMs suggest upwards of 500 J/kg of MU CAPE will linger until around 10 PM. This instability will bring the potential for a few rumbles of thunder across the north early tonight.

As the low exits, plenty of low level moisture will remain over the area before the cold front pushes offshore Monday morning. This will allow for fog formation overnight with locally dense fog possible. As the front crosses NW winds will increase that will help mix out the fog during the pre dawn hours from NW to SE. These NW winds may not reach the coast until after day break that could lead to fog impacting the morning commute along the coastal plain.

KEY MESSAGE 2 DESCRIPTION...

Surface high pressure will arrive from the west on Monday before cresting over New England Monday night into Tuesday. Gusty northwesterly winds are expected with afternoon mixing on Monday with a few gusts up to around 35 mph. Skies will be mainly sunny south of the mountains with more in the way of cloud cover across the mountains and towards the Canadian border with the upslope flow. High temperatures will be into the 60s to lower 70s, warmest along the coast and in southern NH.

Winds will diminish Monday evening and remain light through the night, which combined with clear skies will allow for strong radiational cooling. As a result, used mostly MOS guidance for forecast lows... which range from the lower to middle 30s in some interior valleys with upper 30s/lower 40s elsewhere. Frost advisories may be needed for some northern zones.

It will remain dry Tuesday into Wednesday as high pressure remains near the region. High temperatures on Tuesday will be mostly into the lower 70s before warming into the middle to upper 70s on Wednesday.

Our next chance for showers will be on Thursday into Friday as a series of weak frontal boundaries cross the region. Temperatures will generally remain near seasonable averages.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Through Monday night...Low cigs will likely continue at least IFR through this evening with low cigs and fog bringing IFR to LIFR tonight. Some improvement is likely late tonight from NW to SE as a front crosses and shifts winds out of the NW. VFR is likely by 12Z Monday morning. NW winds will gust up to 25 kts during the day Monday and will diminish Monday night. VFR is likely Monday night except for HIE and LEB where a period of valley fog may occur.

Outlook:

Tuesday/Tuesday Night: VFR conditions expected.

Wednesday/Wednesday Night: VFR conditions expected.

Thursday/Thursday Night: Restrictions possible in developing SHRA.

Friday/Friday Night: Isolated SHRA may result in possible localized restrictions.

MARINE

Winds and seas will remain below SCA thresholds tonight with SE winds shifting SW ahead of a cold front tonight. The front crosses Monday morning shifting winds out of the NW. These winds will gust around 20 kts with higher gusts closer to the coast as stronger winds over land may push just offshore.

Outlook:

High pressure will keep winds and seas below SCA criteria Monday night through at least mid to late week.

GYX WATCHES/WARNINGS/ADVISORIES

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