textproduct: Caribou

WHAT HAS CHANGED

Confidence in a Noreaster impacting the area from Monday into Tuesday has decreased.

KEY MESSAGES

1) iurnally-driven afternoon convection today will bring showers and isolated tstms to most of the region again this afternoon into the evening.

2) Intermittent rain Saturday night, then rain showers on Sunday. Areas experiencing stronger convection could see the localized ponding of water in known poor drainage areas. Fog late Saturday night and early Sunday morning could impact travel especially near the coast.

3) Another period of rain is from late Sunday night through Monday, with now a low chance for any widespread additional rainfall from Monday night into Tuesday.

DISCUSSION

KEY MESSAGE 1...iurnally-driven afternoon convection today will bring showers and isolated tstms to most of the region again this afternoon into the evening.

KEY MESSAGE 1 DESCRIPTION... Another shortwave passing through the area will take advantage of daytime heating to initiate pop up convection again today. The shortwave is tracking further south than yesterday causing showers to extend further south. Showers are currently popping up across the areas and are more widespread and numerous compared to yesterday. Isolated lightning and graupel are possible in some of the stronger showers.

KEY MESSAGE 2... Intermittent rain Saturday night, then rain showers on Sunday. Areas experiencing stronger convection could see the localized ponding of water in known poor drainage areas. Fog late Saturday night and early Sunday morning could impact travel especially near the coast.

KEY MESSAGE 2 DESCRIPTION... Wet weather returns Saturday evening and continues into Sunday. This occurs ahead of an approaching upper level shortwave trough with a developing surface low off the coast. For Saturday night, the best shot at rain will be along and south/east of I-95.Fog is possible areawide Saturday night, though the best threat of denser fog is Downeast, especially the coast, from Saturday night into early Sunday morning. This will be advection marine fog thanks to moist onshore flow.

A passing northern stream shortwave Sunday will bring another round of showers, with possible a rumble of thunder across northeast and east-central Maine Sunday afternoon, from Sunday into Sunday evening. The precipitation should come to an end from northwest to southeast late Sunday afternoon and Sunday evening as at the surface a cold front pushes to the southeast through the state. While on average only a few tenths of an inch of additional rainfall is expected across any given basin, localized moderate to heavy rainfall in any stronger convection could cause the localized ponding of water in known poor drainage areas.

With showalter indices between 2-4C and a few hundred J/kg of CAPE could possibly have a rumble of thunder across Eastern Aroostook, Northern and Central Penobscot and Northern Washington Counties as well. In addition, any strong convection, with or without thunder, could produce small hail.

KEY MESSAGE 3... Another period of rain is from late Sunday night through Monday, with now a low chance for any widespread additional rainfall from Monday night into Tuesday.

KEY MESSAGE 3 DESCRIPTION... A northern stream shortwave approaches from the west Sunday night then crosses the area Monday, with weak surface low pressure passing near the Maine Coast Sunday night then on through New Brunswick into the eastern Maritimes on Monday. This will bring another round of rain, mainly over eastern and southern Maine from Sunday night into Monday. Generally only a few tenths of additional rainfall is expected, with once again locally moderate rainfall possible.

Most model solutions now keep a developing ocean low far enough out to sea, that the area more likely than not should experience limited, if any rainfall from late Monday into Tuesday. If trends hold, Monday night could end up being dry, with some mainly diurnally driven showers on Tuesday.

The main change this forecast cycle was a shift south in the extent of the main forcing at the base of a full latitude trough that approaches from the west Monday and Monday night, then pushes into Maine on Tuesday. The corresponding coastal low is now forecast to pass well south/southeast of Cape Cod Monday and Monday night, then well south of Nova Scotia Tuesday. In general this storm track produces little to no impacts over northern and eastern Maine.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

This evening...VFR for all terminals tonight. Northern terminals could see heavy rain showers with small hail and lightning in stronger showers. TEMPO for gusty winds up to 25 kt in any heavy showers. Weaker showers are expected for southern terminals. WNW winds at 5-10 kt with gusts to 15 kt.

Tonight...VFR. Winds light and variable.

Saturday...VFR in the morning for all terminals. Southern terminals may see MVFR conditions due to rain in the afternoon. Light SW winds in the morning. SSW winds at 5-15 kt in the afternoon.

Saturday night...MVFR or lower possible at southern terminals with VFR at northern terminals. SE winds G15-20KT possible northern terminals and LLWS possible at southern terminals.

Sunday: MVFR or lower likely with any stronger convection. LLWS possible at southern terminals.

Sunday night-Monday: MVFR or lower possible at southern/eastern terminals. NW-N winds G15KT possible Sunday night.

Monday night-Tuesday: VFR, with a very low chance of MVFR or lower at southern terminals. There is also a very low chance of MVFR in any showers at northern terminals on Tuesday.

Tuesday night-Wednesday: VFR. S-SW winds G15-20KT possible Wednesday afternoon.

MARINE

Below SCA conditions expected through Saturday. A few gusts up to 25 kt are possible this afternoon for coastal waters. As the coastal low passes to the south Saturday night, winds and waves will ramp up to reach small craft conditions on coastal waters, with the potential for fog also.

With SCA conditions on the coastal ocean and intra-coastal waters on Sunday, have hoisted an SCA there through 22Z on Sunday. Gusts of 25-30 kt are likely on the outer waters on Sunday as well. From Sunday night-Wednesday sub-SCA conditions are forecast on the intra-coastal and coastal ocean waters, with winds 20 kt or less and seas 5 ft or less on the outer waters during this time frame.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory from 8 PM Saturday to 6 PM EDT Sunday for ANZ050>052.