Penobscot Bay Marine Forecast
|Today...Se Winds Up To 10 Kt. Seas 1 Foot Or Less. A Slight Chance Of Rain This Afternoon.|
|Tonight...E Winds 10 To 15 Kt, Increasing To 15 To 20 Kt After Midnight. Gusts Up To 30 Kt. Seas 2 To 4 Ft. Rain And Snow.|
|Mon...Ne Winds 10 To 20 Kt With Gusts Up To 30 Kt. Seas 2 To 4 Ft. Snow And Rain Showers Likely.|
|Mon Night...Ne Winds 10 To 20 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft. Showers Likely In The Evening. Snow Showers Likely. Vsby 1 To 3 Nm.|
|Tue...N Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 3 Ft. A Chance Of Snow Showers. A Chance Of Showers In The Afternoon. Vsby 1 To 3 Nm.|
|Tue Night...N Winds Around 10 Kt. Seas 1 Foot Or Less. Patchy Drizzle.|
|Wed...N Winds 5 To 10 Kt. Seas 1 Foot Or Less. Patchy Drizzle.|
|Wed Night...N Winds 5 To 10 Kt. Seas 1 Foot Or Less. Patchy Drizzle.|
|Thu...N Winds Around 10 Kt With Gusts Up To 20 Kt. Seas 1 Foot Or Less. Patchy Drizzle.|
|Thu Night...N Winds Around 10 Kt With Gusts Up To 20 Kt. Seas Around 2 Ft. A Chance Of Showers With Patchy Drizzle.|
Area Forecast Discussion|
National Weather Service Gray ME
335am EDT Sunday Mar 29 2020
Low pressure is developing to the south of New England while a warm front lifts into the area from the southwest. This will spread a mix of snow, sleet, and rain across northern New England today and tonight. The low is slow to move out over the next few days with rain and snow showers possibly continuing through midweek.
Near Term - Today
We've already seen some light rain across southern New Hampshire early this morning associated with a weak area of low pressure trying to form near New York City. These showers are not expected to make much progress northeast until the larger scale warm front moves into the area around midday. That's when more widespread precipitation is expected... likely in the afternoon and evening. As precipitation arrives, dry air in place across Maine and northern New Hampshire will allow the temperature to cool from evaporation and lead to a change to snow and sleet. Temperatures fall to around freezing at ground level as a cold air dam develops east of the mountains. Biggest question mark is precipitation type and this is largely still questionable due to surface temperatures. I based this forecast largely on the NAM and its derivatives as it handles these situations better overall and was the coldest source of guidance. Several inches of wet snow and sleet is possible, with the areas most likely to see several inches currently covered by a Winter Weather Advisory. Closer to the coast the temperature may be too warm to support more significant accumulations, though we will need to watch it.
Short Term - Tonight .SHORT TERM /TONIGHT AND MONDAY/... Monday
Band of steadier precipitation along the mid level warm front lifts northeast overnight. Thus expect the heaviest snow to end in the evening or shortly after midnight. However, surface low pressure lingers just offshore of Cape Cod, so additional low level moisture being slung in from the Atlantic will keep some showers in the forecast all the way through the day Monday. Temperatures cool as the low shifts a bit to the east and opens us up to more cold advection from the northeast. Thus expect most areas to go over to snow tonight into Monday, though accumulations are currently expected to be minor.
Long Term - Monday Night Through Saturday
For this week, the large scale pattern will be the main determining factor. To our east a strong block is forming over the prime meridian. As it does, we'll find the the upper level low that arrives today will have nowhere to go and thus remain overhead through much of the week bringing continued cool and overcast conditions.
Monday night will see light snow and rain showers continue throughout the region as the surface low stacks with the upper low and begins to weaken.
Tuesday those showers continue to decrease in coverage as the low weakens and just a few snow showers hold on in the mountains. The overcast skies will remain however and help to keep temperatures into the 40s.
Tuesday Night the dynamics and widespread shower activity have left the region leaving just the upper low to sit and spin. Near the surface we'll see more and more moisture trapped off the water with the resulting low cloud cover, and some fog and drizzle possible especially through the midcoast and downeast. Have kept patchy drizzle in this region for a full 48 hours. Expect a few breaks in that time but overall classic wet April conditions. In addition to the immediate coastline, the low level moisture may move inland into the coastal plain somewhat, with areas as far as Augusta showing the saturated lower levels on forecast soundings. Further inland the colder surface temperatures would make this light precipitation either freezing drizzle or very light snow. With less confidence in this and no way to put "SNizzle" in the grids have opted to leave drizzle confined to the coast.
The overcast skies continue through Wednesday and into the end of the week but by Thursday there starts to be a warming trend. Temperatures will such back into the 50s across the southern portion of the region with the CT river valley seeing some of the warmest temperatures as some sun peaks in.
By the end of the week, the upper level low moves out just in time for another system to pass to our south.
Easterly winds increase today as low pressure develops near New York City. Expect gusts of 25 to 30 KT at times by this evening. The onshore easterly flow will also allow the highest waves to push into the western Gulf of Maine with 7 to 10 FT waves likely. Current Small Craft Advisory goes through Monday morning, but we may need to extend this further.
Long Term...SCA (Small Craft Advisory) conditions will subside as the low decays. With low pressure right overhead, winds and seas should remain calm through the week however low clouds, and areas of fog and drizzle are possible particularly on the eastern part of the waters.
The last GYX upper air observation was March 25 at 12Z. Unfortunately a disruption in gas supply has temporarily halted observations from GYX. It is not known when supplies will be restored and upper air observations resumed.
NOAA Gray/Portland ME Office - Watches - Warnings - Advisories
ME...Winter Weather Advisory from 10am this morning to 4am EDT Monday for MEZ007>009-013-014. NH...None.
Small Craft Advisory from 4pm this afternoon to 6am EDT Monday for ANZ150>154.