textproduct: Gray - Portland

WHAT HAS CHANGED

Have increased ice coverage tonight into Friday morning and have issued a Winter Weather Advisory for much of interior western Maine and central to northern NH for light icing into the Friday morning commute.

KEY MESSAGES

1. Low pressure lifts a warm front into the region tonight bringing widespread light precipitation. Mixed precipitation looks more widespread than previous events but it should be light. Some slippery travel is possible tonight and Friday morning, but the light amounts should keep impacts minimal.

2 Temperatures remain above normal over the weekend with rain likely from Saturday night into Sunday night. A return to drier weather is then likely into the middle of next week with near to a little below normal temperatures.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION... A stalled frontal boundary will provide a focus for mainly a cold rain across southern NH and far SW through mid morning. High pressure to the north will keep the rest of the area dry and will press south allowing for southern NH to see a break in the rain this afternoon. Skies will be partly cloudy across the north with mostly cloudy to overcast skies holding over the southern third of the area. Cloud cover will keep southern areas cooler with highs around 40F while areas to the north that see some sun will climb into the mid 40s, except for the far north where highs will be in the upper 30s.

Low pressure will deepen over the Midwest today and then track northeastward into SE Canada tonight. This low will lift the stalled boundary back to the north as a warm front bringing increasing chances for precipitation overnight. Models are in decent agreement that high pressure to the north will allow surface temperatures to drop below freezing across the interior late this evening before precipitation onset. Warm air advection aloft combined with sub freezing surface temperatures will bring a light wintry mix across the the interior with a transition to freezing rain during the pre dawn hours Friday morning. Overall precipitation and icing amounts will be light, but have issued a Winter Weather Advisory for much of interior locations to account for light icing bringing the potential for slick travel into the Friday morning commute. Will have to watch trends for portions of southwest NH where icing looks to be confined to the higher terrain and have not included these zones yet into the Advisory.

The warm front will press northward Friday with temperatures climbing above freezing across all of the area by late morning. This will transition any wintry precipitation to rain showers with showers tapering off SW to NE during the afternoon.

KEY MESSAGE 2 DESCRIPTION... Drier conditions will then return Friday night into Saturday as an H5 s/wv ridge axis moves across the forecast area. Low temperatures Friday night will be mild into the 40s/50s with high temperatures on Saturday into the 50s and 60s once again in most locations south of the mountains.

Precipitation chances will then increase again Saturday night as stacked low pressure exits the upper Great Lakes towards Quebec and in doing so sends a sfc warm front northward. This will result in overrunning precipitation to develop from south to north overnight, mainly in the form of rain. Depending on sfc temperatures, some freezing rain cannot be ruled out across some interior valleys though. Widespread rainfall is then likely on Sunday until a trailing cold front crosses late in the day. Ahead of this front, temperatures will be mild into the 50s and 60s.

Other than some upslope rain/snow showers across the mtns and towards the Canadian Border, dry conditions will return Sunday night into the middle of next week with temperatures trending near to a little below average.

AVIATION /06Z THURSDAY THROUGH MONDAY/

Through Friday...VFR conditions are expected today. However late day MVFR conditions may creep into southern NH terminals late in the afternoon.

Conditions deteriorate quickly as widespread light precipitation moves back into the region tonight. This has a higher chance of featuring a wintry mix and bringing about IFR conditions.

IFR likely to persist into Friday morning, but improvement to MVFR is likely as precipitation comes to an end. Conditions possibly improve to VFR Friday afternoon.

Outlook...

Friday night: IFR to MVFR ceilings possible. Visibility restrictions also possible with patchy fog.

Saturday: Mainly VFR conditions but some MVFR Ceilings along with -SHRA is possible late day across NH TAF sites.

Saturday night-Sunday night: Widespread precipitation (mostly rain), fog and flight restrictions are likely. Conditions may start to improve late Sunday night behind a cold front.

Monday: MVFR ceilings and rain or snow showers possible at HIE. Otherwise, VFR.

MARINE

Low pressure moving over the waters is keeping wave heights elevated, and it looks like this will continue through this afternoon. Winds will generally be northeasterly through this period as high pressure moves into the Canadian Maritimes. Winds then shift through the day Friday, ending up southerly by Friday afternoon, as another system moves into the region.

Friday night-Wednesday...A cold front crosses the waters Friday evening into Friday night, with southwest winds out ahead of it gusting to around 25 kt. Winds switch W/NW behind the front but then quickly turn north to east on Saturday with high pressure to the north and east of the waters. These may also contain gusts to SCA levels. Flow turns more southerly on Sunday as a cold front approaches from the west with SCA gusts likely, but gales are possible. SCA conditions continue through at least Sunday night behind the cold front and possible into Monday as winds become W/WNW. High pressure builds in from the west Tuesday into Wednesday.

GYX WATCHES/WARNINGS/ADVISORIES

ME...Winter Weather Advisory from 11 PM this evening to noon EDT Friday for MEZ007>009. Winter Weather Advisory from 11 PM this evening to 10 AM EDT Friday for MEZ012>014-020>022-033. NH...Winter Weather Advisory from 8 PM this evening to 10 AM EDT Friday for NHZ001>006. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ150- 152-154.