Cape Elizabeth ME to Merrimack River MA Marine Forecast
|Rest Of Today...Ne Winds 10 To 15 Kt, Becoming E 5 To 15 Kt This Afternoon. Seas Around 2 Ft.|
|Tonight...Se Winds 5 To 10 Kt. Seas Around 2 Ft.|
|Thu...Se Winds 10 To 20 Kt With Gusts Up To 25 Kt, Increasing To 20 To 25 Kt With Gusts Up To 35 Kt In The Afternoon. Seas 2 To 4 Ft, Building To 6 To 9 Ft In The Afternoon. A Chance Of Rain In The Morning, Then Rain In The Afternoon With Vsby 1 To 3 Nm.|
|Thu Night...W Winds 20 To 30 Kt With Gusts Up To 40 Kt. Seas 6 To 9 Ft. Rain In The Evening With Vsby 1 To 3 Nm.|
|Fri...W Winds 20 To 25 Kt With Gusts Up To 40 Kt. Seas 5 To 8 Ft, Subsiding To 3 To 5 Ft In The Afternoon.|
|Fri Night...W Winds 15 To 25 Kt With Gusts Up To 30 Kt. Seas 2 To 4 Ft.|
|Sat...W Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft.|
|Sat Night...W Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 1 Foot Or Less.|
|Sun...Sw Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas Around 2 Ft.|
|Sun Night...S Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 2 To 3 Ft. A Chance Of Showers.|
Area Forecast Discussion|
...UPDATED National Weather Service Gray ME
1058am EDT Wednesday April 8 2020
High pressure builds into the region on Wednesday before the weather turns significantly more active on Thursday as low pressure develops over the Gulf of Maine with rain and mountain snow expected. High pressure returns on Friday into Saturday with temperatures a bit below normal for this time of year.
Near Term - Until 6pm This Evening
1050 AM Light radar echoes are moving across southern NH and far SW ME this morning, but nothing is reaching the ground. Temperatures and other near term parameters like sky cover and dew points were adjusted for minor differences from the forecast. Otherwise forecast is on track with the last quiet day before the rain and snow arrive Thursday.
Update...Minor changes to reflect latest observational trends.
Previous discussion...The warm front never quite made it into the forecast area...with convection remaining well to our S. Some warm air advection over the top of it however has brought a few very light showers to parts of Srn NH this early morning. These will move SE thru the remainder of the morning...leaving us with a dry and seasonable day. The proverbial calm before the storm.
Short Term - 6pm This Evening Through Thursday Night
***SIGNIFICANT LATE SEASON SNOWFALL POSSIBLE THURSDAY***
Rapid cyclogensis is forecast to take place over New England...as a jet streak in excess of 150 knots moves off the Mid Atlantic coast. The left exit region will reside overhead and within the diffluent region of the upper trough. Lift will be maximized...with mid level low centers quickly consolidating in the vicinity of the Wrn ME coastline.
This set up is primed for heavy precipitation over the local forecast area. It will move quickly into the area over the first part of Thu...as more of a warm air advection forced band. This will transition to a deformation band of precipitation as mid level lows become stacked by late afternoon. Beneath the heaviest precipitation evaporational and melt cooling will help to drive surface temps down towards freezing. There remains a great deal of uncertainty as to just how close to the coast that process will occur...depending on track of the low. Given the rates of precipitation this makes the forecast a tough call...because even an hour or two of near freezing temps could be several inches of snow. Forecast models do show 925 and 950 mb temps falling back towards 0C over a large chunk of Wrn ME. This suggests that much of that area could see some snowfall. The best combination of forcing...temps...and Quantitative Precipitation Forecast will be over the Wrn ME mtns and foothills...possibly even spilling into parts of Kennebec County. Guidance is showing an excellent signal for banded precipitation on the NW side of the developing low. Significant snowfall is possible in the mtns...and 6 inches or more thru the foothills. Another complicating factor will be late season injection of higher theta-e air...and dry slot racing Nwd. This will be a system will plenty of convection...and that includes most of the local area whether it is snowing or not. Convectively enhanced snowfall rates add additional uncertainty to snowfall forecast.
I have decided to expand the watch into Northern Coos County at this time...as enough snowfall occurs at valley location to justify a 50 percent risk of 6 inches or more.
Long Term - Friday Through Tuesday
Overview: Rain and snow showers linger and gusty northwest winds develop on Friday as low pressure moves off to the northeast. Northwest flow dominates over the first half of the weekend and high pressure briefly nudges into the region on Sunday. The beginning of next week currently looks wet and unsettled as a large low pressure system develops over the Midwest and slowly moves northeast.
Impacts: Winds gusting to 30-40 mph Friday afternoon in parts of central and southern NH.
Forecast Details: Light rain or snow showers continue on Friday as a low pressure system quickly moves away to the northeast. Northwest winds will pick up as the morning progresses, and that direction is ideal for downsloping which could enhance the winds. Have gusts to 30-40 mph for much of east central and southern NH Friday afternoon and evening and it is possible that gusts above 40 mph will occur. A wind advisory may be needed for those areas, but will let that decision be made by future shifts. The northwest winds continue through Saturday but should be weaker and much less gusty; Saturday otherwise looks dry though clouds will linger most of the day. High temperatures on Friday and Saturday will range from the mid 30s to the upper 40s.
High pressure nudges into New England early Saturday night and warm southerly flow begins to develop over our region. Sunday looks dry for our region at the moment with warmer temperatures than previous days, but developing low pressure over the Midwest looks to bring another round of precipitation to our region for the early part of next week. This system will slowly move north through the rest of the long term period with secondary lows developing and move northeast toward New England simultaneously. The global deterministic models are not in great agreement, but the general consensus amongst their latest runs is for rain on Monday that begins to diminish on Tuesday.
Quiet over the waters today...but conditions will be deteriorating quickly into Thu. Gale watch remains in effect for rapidly developing coastal storm. At this time gale force wind gusts look fairly likely...but depending on exact low location there is a low chance of some storm force gusts over parts of the waters. This would be most likely N of Port Clyde.
Long Term...Seas will begin to diminish on Friday as the coastal storm pulls away to the northeast though winds will be gusty out of the northwest. A gale watch is up through Friday afternoon and SCA (Small Craft Advisory) conditions will likely continue through Friday night. Seas pick up again early next week as southerly flow develops over the waters.
A period of heavy rain is likely along the Maine coast Thursday evening...transitioning to snow over the interior. Given snow in the mountains and a mix into the foothills...do not expect significant river flood issues. May have some short-fused issues along the coast especially with water levels rising towards the ~1AM Friday high tide which may prevent efficient surface water drainage along the coast.
Tides / Coastal Flooding
An extended coastal flood advisory is in effect for high tides continuing through early Friday. Astronomical tides are near minor flood levels without wind impacts already...and with surge levels expected to increase ahead of Thursday's storm...minor impacts are likely. There is some potential that the Thursday night high tide could see moderate /warning level/ impacts depending on exact timing/location of storm development and how long winds remain onshore. Forecast surge values remain around 2 ft at maximum...and this lines up well with the current products.
The last GYX upper air observation was March 25 at 12Z. Unfortunately, a disruption in gas supply has temporarily halted observations from GYX. The order has been placed but a date of delivery remains TBD.
The Sugarloaf NWR transmitter remains off the air with an unknown restoration time.
NOAA Gray/Portland ME Office - Watches - Warnings - Advisories
ME...Coastal Flood Advisory until 3am EDT Friday for MEZ023>028. Winter Storm Watch from Thursday morning through Friday afternoon for MEZ007>009-012>014. NH...Coastal Flood Advisory until 3am EDT Friday for NHZ014. Winter Storm Watch from Thursday morning through Friday afternoon for NHZ001. MARINE...Gale Watch from Thursday afternoon through Friday afternoon for ANZ150>154.