565 FXUS61 KGYX 161925 AFDGYX Area Forecast Discussion National Weather Service Gray ME 325 PM EDT Sun Oct 16 2022 .SYNOPSIS... High pressure keeps the forecast area dry through tonight. A slow moving low pressure system over the Great Lakes starts to track toward the St Lawrence Valley Monday and passes to our north and west Tuesday. This system brings increasing chances for showers Monday and a period of steady rain that could be heavy at times along the Mid Coast Tuesday. A drying trend is expected Tuesday night into Wednesday with mostly dry weather expected to last through the end of the week. && .NEAR TERM /THROUGH TONIGHT/... Primary concern overnight will be fog development. Hi-res guidance favors a band of fog forming along the coast after dark...while typically bullish aviation guidance remains clear. The stratus deck already is in place over the coastal waters and seabreeze flow is also already pulling that back towards the coast. I suspect that will mean clouds will move inland after sunset and lower thru the late evening until it becomes a fog bank. So I have sided with the more aggressive cloud/visibility guidance. Given that confidence was not yet high that areas of fog let alone dense fog form...I have not issued any headlines with this update. With a little more cloud cover and a little more southerly flow...temps will be a little warmer than last night and interior valley fog will be less likely. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... Chances for showers increase thru the day as the frontal system slowly approaches. The flow direction will support higher PoP along the southern slopes of the mtns. Overall the QPF will be on the light side on average with the heavier amounts waiting until late Mon night or Tue to arrive. Abundant cloud cover and continued southerly flow will keep temps mild overnight Mon. && .LONG TERM /TUESDAY THROUGH SUNDAY/... A deep upper low will be over Michigan on Monday and will slowly shift eastward over the eastern Great Lakes Tuesday. This system will draw deep moisture into eastern New England originating from an Atmospheric River extending back to the SE US Coast. Global models generally agree there will be an axis of moderate to heavy rain directed into Mid Coast Maine Tuesday afternoon with lighter rain across far western Maine and New Hampshire. The upper low starts to lift poleward Tuesday night and Wednesday with axis of rain pushing east of the area. The upper low continues to lift to the north and east through the end of the week with mostly dry weather and a slight warming trend into next weekend. The main weather concern in the long term period will be the potential for moderate to heavy rain on Tuesday. Moisture advection will increase Tuesday morning along the eastern periphery of the upper low with PWATs climbing above 1 inch across much of Maine. A cold/occluded front will be oriented along the ME/NH border Tuesday morning and will push east through the day with a wave of low pressure forming along the boundary. At this time rainfall amounts do not look as prolific and widespread as those seen from the last event on October 13-14, although there are signs the wave of low pressure may slow the eastward progression of the front and prolonging the axis of heaviest rainfall along the Mid Coast and far eastern zones. Current QPF forecast brings 1 to 1.5 inches along the Mid Coast through southeastern Somerset County with amounts dropping off sharply west of the Kennebec River. Back across far western Maine and New Hampshire QPF amounts top out under 0.5 inches except for slightly higher amounts in the White Mountains. Additionally, winds are not expected to be nearly as strong as the past event with the core of the LLJ topping out around 50 kts and only grazes portions of the Mid Coast before translating east. Current peak wind forecasts top out around 30 MPH Tuesday afternoon near Pen Bay with areas to the west seeing peak winds generally under 25 mph. Precipitation chances drop off from west to east Tuesday afternoon and evening. Portions of southern and western NH may see skies turning mostly sunny by mid Tuesday afternoon. The primary axis of rainfall is progged to push east of the CWA by day break Wednesday, while some minor timing differences do show up here amongst model solutions. Will continue to monitor trends in how quickly rain exits east as a longer duration over eastern zones will elevate hydro concerns while current guidance suggests any flooding threat will be east of the CWA. Skies continue to turn partly to mostly clear Tuesday night into Wednesday with Wednesday looking mostly dry with highs in the 50s. The upper low over the eastern Great lakes continues to lift north into Quebec Thursday while cyclonic flow aloft remains over the CWA. This will bring some clouds along and north of the mountains Thursday with mostly clear skies south of the mountains with highs ranging from the upper 40s north to mid 50s south. Dry weather is expected to close out the week with a warming trend into next weekend as the upper level pattern turns more zonal. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... Short Term...VFR conditions now are expected to give way to deteriorating conditions near the coast tonight. An arcing band of fog/stratus is expected to develop along the coast...with LIFR conditions. LAMP guidance is not particularly bullish...but given the stratus deck exists now I anticipate it moving inland after sunset. I used HREF probabilities of 70 percent or higher to introduce fog to TAFs. While CIGs should lift some Mon morning...I expect at least MVFR to move back in during the afternoon as SHRA enter the area. Long Term...Rain and low cigs Tuesday morning will bring flight restrictions, likely to IFR thresholds to most terminals Tuesday morning with improvement expected across NH terminals Tuesday afternoon and evening. KRKD and KAUG will continue to see RA and low cigs through Tuesday night and continued flight restrictions. VFR is then expected for all Wednesday through the end of the week, although cannot rule out valley fog impacting the usual terminals at night. && .MARINE... Short Term...Winds and seas are expected to remain below SCA thresholds thru Mon night. Areas of fog are also expected to develop after sunset as moist advection increases. Fog/stratus may linger thru much of the day Mon as flow remains southerly. Long Term...Strong southerly winds will approach 25 kts near Pen Bay Tuesday with seas building to 5-8 feet by Tuesday night. Persistent SW flow Wednesday through the second half of the week will keep seas elevated to 5-6 ft through Thursday morning and may not drop below 5 ft along the outer waters offshore of the Mid Coast until Friday morning. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Legro SHORT TERM...Legro LONG TERM...Schroeter