textproduct: Caribou

WHAT HAS CHANGED

- 530 AM Update: The Dense Fog Advisory has been cancelled as fog has dissipated and moved out of the area

- Slowed the onset and exit timing of the cold front today by a few hours based on current observations and trends

- Added slight chance for rain showers behind the front with weak shortwave following that primary synoptic feature

KEY MESSAGES

1) Rain moves through the area today, though drought relief is unlikely.

2) Widespread frost is expected for northern areas, with patchy frost elsewhere in interior Downeast.

3) Another round of rain is possible Monday followed by gusty westerly winds on Tuesday.

DISCUSSION

KEY MESSAGE 1...Rain moves through the area today, though drought relief is unlikely.

KEY MESSAGE 1 DESCRIPTION... A cold front continues to push southeast towards our forecast area, though remains west of the Saint Lawrence River Valley as of 3 AM this morning. The front should push through the northern half of the forecast area by late morning, then through the Downeast region through this afternoon and early evening hours. This timing has slowed down with recent model runs, and the front may continue to slow down to a crawl through the state, leading to a slow exit this evening off the coast. Forecast rain totals today remain below a quarter of an inch, with many areas receiving less than a tenth of an inch. The catch is that should a coastal low begin to develop along the front as it approaches the Downeast coast, this could locally enhance rainfall amounts. Overall, there will be little if any impact on the ongoing D1-D3 drought conditions.

Additionally, a 700 mb shortwave will follow behind this front tonight, and could lead to lingering rain showers, particularly in the north, through the overnight hours. However, not much additional rainfall is anticipated from this feature.

KEY MESSAGE 2...Widespread frost is expected for northern areas, with patchy frost elsewhere for the Bangor region and interior Downeast.

KEY MESSAGE 2 DESCRIPTION... High pressure builds in behind the cold front Saturday, and, with clearing clouds, will lead to temperatures falling well below freezing overnight for northern areas. Temperatures will fall into the low to mid 30s for central areas, with lows in the low 40s for near coastal areas. This could provide the first frost of the season for some areas in the Bangor region and interior Downeast. There is some uncertainty, however, of how far south the frost could get. The exact position of the high pressure, any coastal breezes, and any high cirrus clouds could all influence the extent of frost. Regardless, people should be prepared to protect any vulnerable vegetation across the area, especially if they are in lower lying areas that typically get colder. The frost/freeze program has ended for all counties except Hancock and Washington counties, so frost headlines would not be issued for Penobscot, Piscataquis, northern Somerset, or Aroostook counties. Coastal Downeast should stay warm enough to limit any frost, though check the forecast for updates.

KEY MESSAGE 3...Another round of rain is possible Monday followed by gusty westerly winds on Tuesday.

KEY MESSAGE 3 DESCRIPTION... Sunday night a cold surface high pressure that will have brought widespread frost Sunday AM shifts to the east over the Maritimes. A potent vertically stacked low pressure system tracks into north-central Quebec with a trailing potent cold front. That front will swing across the CWA on Monday at the same time as a low pressure exits off the Mid-Atlantic coast. The interaction between the high pressure and the two lows provides significant uncertainty about rainfall. A few scenarios are currently playing out in the ensemble models. 1. The high pressure could dominate forcing the lows to stay to the north and south, limiting precip. 2. The Canadian low could enhance the coastal low as it rides the coast north, bringing more substantial precip to coastal areas. 3. The Canadian low could dominate, bringing enhanced precipitation along its cold front from the moisture over the southeast low. At this time, uncertainty from the models is high, so forecast confidence is low, with a wide range of precipitation values.

Increasing confidence that Tuesday, as the low pressure system deepens in the Northern Maritimes, we can expect strong surface high pressure to dive over the eastern Great Lakes. This will lead to a strong pressure gradient between the low and high resulting in gusty W-WNW winds developing in the morning and peaking midday. Probabilities for 35+ mph wind gusts have increased to 70-90% with 40+ mph probabilities now 40-60%, mainly for Millinocket and areas north. There is ensemble guidance suggesting a potential of wind headlines but still uncertainty exists on exact expected wind speeds/gusts. However, it is likely that significant leaf loss may be possible in areas of Northern Maine where peak foliage has been reached. Additional leaf loss possible in the Central Highlands to Downeast Maine where the foliage is moderate to high. Continue to monitor the forecast for updates, as models begin to get a better handle on the atmospheric set up.

AVIATION /09Z FRIDAY THROUGH TUESDAY/

Today...MVFR conditions continue at northern terminals as rain enters the area, with Downeast terminals beginning VFR then lowering to MVFR as rain moves in this afternoon. Winds SW 5 to 10 kts shift NW behind a cold front, with gusts 20 to 25 kts possible this afternoon.

Tonight...Improvement to VFR across all terminals, though lingering MVFR possible at KFVE through KPQI with scattered rain showers through around 06z. Winds N to NW at around 5 kts.

Saturday-Saturday night...VFR. Light and variable winds.

Sunday...VFR. S winds G15KT possible Sunday.

Sunday night-Monday...MVFR or lower possible in rain. S winds Sunday night shift to W Monday with gusts to 20 knots.

Monday night-Tuesday. VFR/MVFR north. VFR Downeast. Northwest/west winds 15 to 25 knots with gusts up to around 30 knots Monday night. Northwest/west winds 20 to 30 knots with gusts up to 35 to 40 knots Tuesday.

MARINE

Today, SW winds remain under 20 kts and seas generally under 5 ft within 25 nm. Seas could briefly reach 5 ft around 25 nm offshore this afternoon, but should quickly subside this evening. Rain tonight could limit visibility. Winds shift NW overnight tonight.

From Saturday into Sunday, N/NW winds over the waters out to 60nm should be 20 kt or less and seas 4 ft or less. Sub-SCA conditions expected on the coastal waters Monday, with gusts to around 25 kt and seas around 5 ft possible on the waters from 25-60nm.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...None.