Mont Biencourt snow report

575 FXUS61 KCAR 210712 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 312 AM EDT Sun Jun 21 2026 .WHAT HAS CHANGED... - 3 AM Update: quick update to temperatures through today based on current observations and trends. - Increasing confidence in track and timing of low Monday night into Tuesday. - Increased winds and gusts with the Monday night system. && .KEY MESSAGES... 1) Slow moving showers and thunderstorms today could lead to localized significant rainfall. 2) A low pressure system passes through the region Monday night into Tuesday, while track remains uncertain. 3) Prolonged troughing in the Northeast will lead to multiple rounds of showers and storms this week. && .DISCUSSION... KEY MESSAGE 1...Slow moving showers and thunderstorms today could lead to localized significant rainfall. KEY MESSAGE 1 DESCRIPTION... Continued instability under the broad upper level trough will support diurnal showers and storm development through the day today. For the Central Highlands down through the Interior Downeast region, 500 to 1000 J/kg of CAPE could be available for supporting convective growth. Forecast soundings present this CAPE in a tall, skinny manner, which can be indicative of support for efficient rainfall processes. Additionally, PWATs are forecast to sit around 1.1 to 1.2 inches. KCAR PWAT climatology for today has 1.06 inches for the 75th percentile, and 1.28 inches for the 90th percentile, with the forecast PWAT for today falling between these two percentiles and being marginal for efficient rainfall potential. Since the highest CAPE values support convection closer to the Bangor region, will consider the KGYX PWAT climatology for today as well, which has 1.22 inches for the 75th percentile and 1.47 inches for the 90th percentile, so the forecast values for the Bangor area fall a little short of the prime target for efficient rainfall potential, which would be exceeding the 90th percentile. Forecast warm cloud layer from forecast soundings is also below what would be needed for efficient rainfall potential, with warm cloud layer being forecast at around 5 kft, half of the 10 kft that is textbook for tropical type rainfall rates. Of highest concern though, given all that has been discussed above, is the storm motion. With little to no steering flow, any showers and storms that develop will be slow to move, and likely to collapse near where they developed, leading to any moderate rainfall to occur over the same area through the life of the shower or storm. This environment could lead to localized significant rainfall that may even result in localized ponding in any poorly drained areas. Flash flood guidance does remain high in the primary area of concern, with 1 hour FFG of 1.3 to 2 inches and 3 hour FFG 2 to 3 inches. KEY MESSAGE 2...A low pressure system passes through the region Monday night into Tuesday, while track remains uncertain. KEY MESSAGE 2 DESCRIPTION... Shortwave moves through region Monday afternoon into Tuesday evening. With this system, moisture quickly increases throughout Maine, and rain showers, with an isolated thunderstorm, are possible, mainly to the north. Models seem to favor the general path of the low pressure staying just south of Maine, but there is uncertainty in the exact track. Models have better agreement on timing of system. Models that seem to have a more southern low pressure system, bring less precipitation to the Downeast region, while models favoring a farther north low pressure system, bring more precipitation to the Downeast region. Global models seem to be trending northeast with the low, bringing more rain to the coastline. Stuck with the NBM again for this update, since it shows the general trend well between models. The best chance for precipitation is going to be interior and coastal Downeast, with gradually lighter showers expanding farther inland. How far inland the precipitation reaches, is going to depend on the track. Looking at between 1 to 1.5 inches of rain possible Downeast. Minimal instability could lead to some isolated thunderstorms in the Central Highlands and northern regions Monday afternoon as the low approaches from the southwest. Southerly flow should keep Downeast stable enough to avoid convection. Around 500 J/kg of CAPE, and some decent low-level lapse rates could get some thunder rumbles over the region in the afternoon. Decreased thunder chances however, since shear and helicity look weak, and some CIN is present. Will have to continue to monitor to see how trends progress. KEY MESSAGE 3...Prolonged troughing in the Northeast will lead to multiple rounds of showers and storms this week. KEY MESSAGE 3 DESCRIPTION... Positive PNA pattern over the Atlantic parks a high pressure system over the west, resulting in prolonged troughing over the region, with multiple rounds of rain showers moving through. Cool temperatures generally in the 70s. Overnight lows generally in the 50s. Prolonged trough results in multiple rounds of showers, with chances for thunderstorms each afternoon. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... Early this morning...High level clouds presently across the north should help and limit fog development, though brief periods of BR remain possible at northern terminals from KHUL north. Winds light and variable. Today...VFR conditions continue across all terminals. Scattered showers and thunderstorms this afternoon, particularly from KGNR down through KBGR and throughout the Downeast region. Winds light and variable. Tonight...VFR conditions continue across all terminals, though patchy fog could briefly build in late, limiting visibility to IFR/LIFR late at terminals which see rainfall during the day. Winds light and variable. Monday - Monday night...MVFR/IFR in rain showers at all terminals, and with a chance of thunderstorms at KFVE/KCAR/KPQI/KHUL. S winds at 5 to 10 kts, becoming E at 5 to 10 kts overnight. Fog possible at all terminals Monday night, with KBGR and KBHB possibly in thicker fog. Tuesday - Tuesday night... MVFR/IFR in rain showers at all terminals, and with a chance of thunderstorms at KFVE/KCAR/KPQI/KHUL. Improving to VFR late afternoon, though fog could lower visibility at all terminals Tuesday night. E/SE winds at 5 to 10 kts, gusting to 15 to 20 kts, shifting to NW 5 to 10 kts. Wednesday - Wednesday night...Mainly VFR. Possible MVFR at KFVE/KCAR/KPQI/KHUL in the afternoon with showers and chance of thunderstorms. NW winds at 5 to 10 kts. Become light and variable overnight. Thursday...Possible MVFR at KFVE/KCAR/KPQI/KHUL, in the afternoon with showers and chance of thunderstorms. S/SE winds at 5 - 10 kts. && .MARINE... Winds remain below 25 kts and seas less than 5 ft across all waters today through tonight. Below SCA conditions Monday. Seas creep up to 5 ft on Tuesday into Wednesday. Rain and patchy fog Monday night into Tuesday. Chance for thunderstorms Tuesday. Winds early Tuesday could be about 20 kt, with some gusts 25 kt to near 30 kt. S winds on Monday, shift to the NW on Tuesday night. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ DISCUSSION...AES/JMM AVIATION...AES/JMM