textproduct: Gray - Portland

WHAT HAS CHANGED

Very little change to the going forecast this morning as the forecast is going as planned.

Previously...

Went a little cooler on dewpoints and as a result lowered relative humidity during the day. A coastal storm on Sunday continues to track slightly closer to the coastline.

KEY MESSAGES

1. A brief respite from unsettled weather arrives today, but chances for precipitation return tonight and Saturday.

2. A trough continues to bring cool conditions through the weekend, while a coastal storm tracks offshore on Sunday.

3. Warmer weather makes a return early next week, followed by another chance of rain for the second half of the week.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

Gradual clearing will continue thru morning as northwest winds downslope and scatter out the low level cloud cover/moisture. Forecast soundings show pretty deep mixing today, thru at least 850 mb. This suggests dewpoints could bottom out in the lower 20s to upper teens. This results in a fairly widespread area of 20 to 25 percent minimum RH, but winds are relatively light and the entire area just received a soaking rain. So while dry the fire weather concerns are relatively low.

Precip chances return tonight, albeit not very organized chances. Cold pool swings thru aloft and daytime heating may be enough for some instability showers to pop up. It will also be fairly chilly thru the column and potentially pretty dry in the lower levels. The strongest of the showers may result in some graupel/small hail mixing in with rain at times. Some light accumulating snow may occur in the mountains later tonight into Saturday morning.

KEY MESSAGE 2 DESCRIPTION...

Cool conditions remain in place through Sunday as a trough lingers across the Northeast. At the same time, low pressure tracks up the Eastern Seaboard offshore, likely bringing a period of steady rain to at least the coast. This storm has continued it's westward trend over the last few days, with coastal areas likely to see a period of rain late Saturday night and Sunday. It's worth noting that this storm will be ejecting from the Southeastern US and tracking up the coast. In winter, these southern stream storms that eject from the south tend to trend further north and west up until the event, which was observed on several occasions this past winter. Whether this rule holds true into May remains to be seen, but there is reason to believe this storm could continue to come further west still.

Another reason to watch the track of this system is that another 50 miles further west and the precip shield would push into the higher elevations across the interior. Should the precip make it this far west, temperature profiles would support a switch to snow across at least the higher terrain. Heavier precip rates would only further support this. It's too early to call for this, but it is a potential scenario to be considered. The system then pulls away during the day on Sunday.

KEY MESSAGE 3 DESCRIPTION...

Part of the pattern bringing the Sunday system closer to the coast also supports more of a warm up early next week. Over the last few days the models have trended with retrograding the trough toward the west over the weekend and early next week. This also provides the opportunity for a narrow ridge to build in along the East Coast, allowing for warmer air to spread northward. Highs in the 60s looks to make a return for Monday, then 70s are likely by Tuesday.

A cold front slowly approaches from the west through midweek, but the retrograding pattern has also caused this feature to arrive much later. Thinking a couple days ago was that this front would be here on Tuesday, but now there's question if it will even reach New England by Thursday. This keeps at least one more warm day on the table for Wednesday, before rain chances then increase again for Wednesday night and Thursday.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

IFR or lower conditions becoming more scattered and localized as winds become more northwesterly and downslope off the higher terrain this morning. VFR conditions expected for most of the area today. Some lingering MVFR CIGs will remain possible in the mtns. Widespread VFR this afternoon with deep mixing likely even bringing any CIGs well above all but the highest peaks.

Outlook:

Saturday: Generally VFR conditions expected. Scattered showers are possible with local MVFR or lower conditions.

Saturday Night: Clouds thicken and lower with MVFR possible. IFR bases possible near the coast along with some fog. SHRA for coastal terminals, uncertain if these make it towards AUG/CON.

Sunday: MVFR ceilings continue through the morning with SHRA. Gradual improvement towards VFR SW to NE into the early evening hours.

Sunday Night: Mainly VFR, valley fog possible.

Monday through Tuesday night: Mainly VFR expected, but some marine fog will be possible along the coast starting Tuesday.

MARINE

Winds will remain offshore until Sat, but generally remain on the lighter side. Seas however will remain above 5 feet on the coastal waters into this afternoon SCA continues for those zones and the outer portions of Casco Bay.

Broad high pressure brings generally fair conditions into Saturday night. Low pressure then tracks northeastward just outside the Gulf of Maine. SCA conditions are possible on Sunday into early next week with a period of northerly flow and building seas. Southerly flow then increases by Tuesday ahead of an approaching cold front, with SCA conditions possible again.

GYX WATCHES/WARNINGS/ADVISORIES

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