textproduct: Gray - Portland

WHAT HAS CHANGED

Shower chances have been increased tonight into Saturday.

Trending warming for the beginning of next week.

KEY MESSAGES

1. Chances for rain showers and higher elevation snow return tonight and continue over the upcoming weekend. More clouds and showers will likely keep daytime temperatures cooler this weekend.

2. A period of warm and breezy conditions are likely Monday through Wednesday next week with temperatures peaking on Tuesday in the 70s.

3. Unsettle weather returns late Wednesday into Friday with periods of rain brining another beneficial soaking rain to the region. This period of rain and warmth will jump start the green-up, ending the spring fire season for coastal areas.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION... Dry and somewhat breezy conditions prevail this afternoon before the daytime cloud cover and winds fade as the sun sets this evening. Skies should be mostly clear initially, and with light winds there will be an opportunity for good radiational cooling. However, looking to the west, an area of showers associated with a shortwave aloft is currently moving across the Ohio Valley, and this feature will approach northern New England later this evening. As it does so, clouds will increase across the area, but how quickly is key to how low temperatures will get before leveling off or even coming up. Areas farther to the north and east should stay clearer for a longer duration, so temps may still reach the low-mid 30s to allow for patchy frost. Farther to the west where the clouds move in faster, I have lows in the upper 30s to lower 40s.

Secondly, this shortwave is expected to bring a round of rain showers into NH around or just after midnight with a gradual expansion to the east into western ME overnight and through Saturday morning. Additional shower development is then likely through the rest of Saturday (and maybe a storm or two in southern NH) as broad cyclonic flow/lift continue across the area with an upper low slowly moving eastward across Quebec. However, the degree of shower coverage the rest of the day is a bit uncertain. Outside of showers, mostly cloudy skies should limit Saturday's high temperatures to the 50s, possibly 40s in some areas.

As an aside, it will be more winter-like in the higher elevations with snow and subfreezing wind chills making for dangerous hiking conditions. A few inches of snow are possible on the highest peaks. Can't rule out snow briefly mixing in for some of the northern valley floors, but accumulation is not expected.

A deepening low pressure then begins to lift to the N/NNE offshore of the Eastern Seaboard Saturday night and Sunday. It's expected to remain well offshore, but yet still close enough to bring increasing moisture and additional chances for rain showers, especially along the coast and even moreso the Midcoast and Kennebec Valley. These areas have 60-80% rain chances with over 0.50" of rain possible. Chances for showers diminish with northward and westward extent but could further increase if the low trends westward and vice versa if it trends more to the east. North to northwest winds may also get a bit breezy on Sunday with gusts to around 25 mph possible.

KEY MESSAGE 2 DESCRIPTION... Models over the last few days have continued to trend a retrograding the trough further west over early next week with continued upward trend in height rises over the coastal Atlantic as the Bermuda high continues to amplify. Looks like this will open up the region to persist and relatively strong southwest WAA starting Monday and lasting into Wednesday. This will bring 850mb of +14C to the region and strong enough gradient flow to prevent the sea breeze front from penetrating inland much. The result will be 60s on Monday and 70s on Tuesday before cooling slightly on Wednesday back into the 60s as cloud cover should begin to increase, but some 70s could be possible again for Southern NH. This should lead to rapid green-up after the recent rain with leaves beginning to come out in earnest.

KEY MESSAGE 3 DESCRIPTION... Potential for a period of much needed soaking rains late Wednesday into Friday as a broad 500mb trough digs into the Great Lakes region. There is still some spread on the timing of this trough, but most guidance is in agreement a cold front will push into the region later Wednesday before stalling out in vicinity of the Gulf of Maine, with a surface wave developing over the Mid-Atlantic and moving north into New England later on Thursday bringing more widespread rain. NBM mean has a strong signal at this point even with the long lead time of 1+ inches of rain. Will have to watch how this trends, but with green-up coming into full gear, this will be optimal timing to help drought conditions as surface water depletion will begin to kick into full gear over the next few weeks.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

Through 18Z Saturday...VFR into this evening. A round of showers will move into the area overnight into Saturday morning and could produce MVFR to IFR restrictions, with highest chances at LEB and HIE.

Saturday will be mostly cloudy with cigs ranging from MVFR to VFR. Scattered showers may also produce visibility reductions.

Outlook:

Saturday night-Sunday: Restrictions are becoming more likely as moisture increases from a low pressure passing well to the south and east. Highest probabilities for IFR are currently for the western ME terminals due to low stratus and rain showers, but if the low trends farther west, chances for restrictions will increase across NH. North to northwest winds could also gust to 20-25 kt at times. Improvement is possible later in the day Sunday.

Sunday Night: Mainly VFR, MVFR cigs could be possible late Sunday night across the north.

Monday through Wednesday midday: Mainly VFR expected, with gusty southwest winds.

Wednesday Night through Friday Morning: Unsettled weather expected with rain showers on Wednesday transitioning to widespread rain by Thursday. Expect periods of IFR and LIFR conditions due to low ceilings.

MARINE

SCA conditions continue over the coastal waters into early this evening as seas remain near or just above 5 ft. These will then subside through tonight and Saturday as high pressure becomes centered south of the Gulf of Maine. Winds turn more north to northwesterly Saturday night and into Sunday as strong low pressure passes south and east of the waters. It could be close enough to bring SCA level gusts to the coastal waters and will have to monitor any westward trends in the low that may bring gusts to near gale force over the outer waters.

Period of enhanced winds expected to begin later Monday and last into Mid-week. Southwest winds will increase in response to building high pressure over the Atlantic seaboard. Currently feel model guidance is a little to robust on speeds due to more limited mixing heights as SST remain around 50 degrees. Either way, SCA are guaranteed, and Gale Warnings especially Wednesday can't be ruled out.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ150- 152-154.