Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
858 FXUS61 KGYX 190952 AFDGYX Area Forecast Discussion National Weather Service Gray ME 552 AM EDT Sat Sep 19 2026 .WHAT HAS CHANGED... A brisk morning across the northern valleys with valleys in vicinity of the Whites seeing morning temperatures in the lower 30s. Adjusted this morning`s temperature trends to factor in these cooler values as other locations bottom in the mid to lower 40s. && .KEY MESSAGES... 1. Low pressure will bring a period of rain Sunday into Sunday night after a fair weather day today. 2. High pressure brings mostly fair weather Monday through Wednesday with temperatures running below normal. && .DISCUSSION... KEY MESSAGE 1 DESCRIPTION... High pressure crests overhead today allowing for sunny skies, highs in the 60s and lighter winds that what we saw on Friday. A seabreeze is likely on the coast this afternoon. A short wave trough will approach from the west tonight with rapidly increasing clouds. Increasing forcing for ascent will aid in a shield of rain moving in from the west Sunday morning. This will then spread eastward to the rest of the forecast area by early afternoon. There remains uncertainty in amounts at this time as convection to our southwest could rob our area of deeper moisture. Either way the highest amounts should be across southern NH where the rainfall could be somewhat beneficial. Hourly temperatures may be non-diurnal during the day Sunday as the rain shield impinges on a relatively dry air mass, i.e, temperatures should fall some as the late morning and afternoon progresses. KEY MESSAGE 2 DESCRIPTION... Ensemble guidance is in strong agreement that high pressure will move across Canada and arrive in Quebec on Monday. This high to our north will allow for temperatures to run cooler than normal through the week, with highs in the 60s and lows in the upper 30s and lower 40s. Frost does appear to be a possibility Tuesday, Wednesday and Thursday nights north of the mountains. At the end of the week, models show the potential for a coastal low to impact the region. A high degree of storm track uncertainty remains, but the low could allow for some much needed rainfall on Thursday and Friday if the low takes a more westerly track. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... Through 06z Sunday...VFR conditions are expected today. Winds will be lighter than yesterday, and a seabreeze is expected on the coastal plain during the afternoon. VFR conditions tonight with increasing high clouds. Outlook... Sunday and Sunday night: SHRA increases in coverage west to east during the afternoon. This likely spreads MVFR and IFR cigs across the area into Sunday evening and overnight. Rain rates across southern NH and far southern ME may also bring MVFR vis at times. Monday-Wednesday: Mainly VFR, outside of overnight valley fog. && .MARINE... Winds and seas likely remain below SCA thresholds today into Monday while a wave of low pressure passes south of the waters but Sunday night. This low will bring periods of rain and potential for fog Sunday afternoon and evening. A NE gradient will develop late Monday through mid week as high pressure builds in from the north and a coastal low develops near the Mid Atlantic. NE winds could gust around 25 kts at times with seas building 5-6 feet by late Wednesday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ DISCUSSION...Cornwell/Ekster/Palmer