Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 261052 AFDGYX Area Forecast Discussion National Weather Service Gray ME 652 AM EDT Wed Apr 26 2017 .SYNOPSIS... Cloudy, cool, and wet conditions are expected today through tonight as weakening low pressure along the mid atlantic coast very slowly moves north to over Cape Cod Thursday and then into the Gulf of Maine Thursday night. Expect an inch or two of rain east of the mountains through tonight. By Thursday there will be some improvement west of the mountains with warmer temperatures arriving, while east of the mountains it will remain cloudy and cool. Improving conditions and warmer temperatures across all areas arrive for Friday. A cold front will pass through the region Saturday with Canadian high pressure following for Sunday. Another storm system looks to bring rain early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 645 am update: Rain across the area will continue. POPS look good. Ingested latest obs data and only very minor tweaks to temps since they have been fairly constant as well as uniform due to the broad onshore flow. Previous Discussion: Low pres centered along the DELMARVA coast will very slowly track northeast today. This will continue the bands of rain to rotate north across the region combined with a raw onshore flow. Temperatures will remain cool today considering water temps still only in the lower to mid 40s and with onshore winds can`t see temps moving much above 50 except over western areas of NH. For practical purposes used blend of CONSALL with a weight of the cooler NAMDNG for max temps today. This reflects a cooler temp forecast today rather than straight guidance off of the mav/met and some other models. POPS forecast and qpf remains similar to prior forecast model runs. QPF still looks heaviest toward coastal areas with much less in the mountains and headwaters, generally around a half inch or so. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Tonight and Thursday the area of low pressure weakens as it tracks northeast to over Cape Cod and then eventually into the Gulf of Maine by late Thursday. A weak but continued onshore flow will continue with the rain tonight becoming more scattered by Thursday. Due to the low level air mass being at supersaturation, areas of drizzle and fog over eastern and coastal areas are expected into Thursday, this may continue through the day especially along the coast. Guidance temps were once again moderated for to the cooler side for highs on Thursday with the NAMDNG guidance. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... The long period period looks to feature a pretty progressive pattern across the Northeastern states as weather systems move through pretty quickly. A warm frontal boundary looks to remain to our south Thursday night. This will mean continued cool weather along with fog and drizzle. The main question is how long does it take for the murky low level airmass to be shunted out. Most guidance does so pretty quickly on Friday while the latest ECMWF keeps it around. This will have an impact on sensible weather such as temperatures, clouds, and precip. For now took a blend of the guidance while giving the ECMWF some credence. The best chance of warming into the 70s will be across southern zones with northern/eastern zones having the best probability of staying in the low level soup for a good portion of the day. In addition, much of the 00z model suite has a decent amount of elevated instability Friday morning in advance of a short wave trough, so cannot rule out thunder during this time as well. Thereafter, a cold front will move across the region during the day on Saturday. At this time PoPs look to be minimal at best as this front will be moisture-starved. A cool, Canadian air mass will be ushered in behind the front for Saturday night and Sunday. The early next week period looks to get unsettled once again as another potent Plains system ejects out toward the Northeast. This may mean more rain, fog, and drizzle for the area as current model guidance generally agrees on onshore flow north of a warm frontal boundary here which is pretty typical for spring. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... Short Term...IFR/LIFR conditions in rain and areas of drizzle and patchy fog today and tonight across most areas. LLWS expected over eastern and southern areas this morning into the afternoon due to the low level southeast flow aloft while damming/nosing of high allowing light nne surface winds. Conditions over western NH and northwest of the White Mountains may remain MVFR. Low clouds and possible fog and drizzle will keep conditions IFR through Thursday over eastern and southern areas of ME while conditions over western NH and across the mountains may be mainly MVFR Thursday. Long Term... IFR conditions are likely Thursday night in low clouds and fog. Conditions will likely improve Friday, especially afternoon. However, MVFR conditions are still likely along the coast as well as northern and central zones. Still a chance IFR conditions could hang on in those areas all day Friday into Friday night as onshore flow continues. VFR conditions return for Saturday and Sunday. && .MARINE... Short Term...The easterly flow shifts to southeast today as low pressure approaches. Winds diminish below advisory levels but wave heights will remain at or above 5 FT over the outer waters for several days due to a continued onshore fetch. Inside the protected bays, seas should subside to a 2-4 ft range so no SCA`s will be needed. Long Term... Thurs night and Fri...Small Craft conditions remain likely outside the bays, mainly for seas. Sat and Sat night...Small Craft conditions once again possible in association with cold frontal passage.VRB03 && .FIRE WEATHER... Expect wet conditions area-wide today into tonight. Could see somewhat warmer temperatures west of the mountains on Thursday while it remains cloudy, cool, and damp east of the mountains into Friday. && .HYDROLOGY... With continued snow melt river levels remain high. Add another 1 inch of rain on top of that and at least a few rivers could rise close to flood stage. At this time no river is forecast to reach flood stage, but it would not be out of the question for some minor flooding to occur depending on how much rain falls in key areas. && .TIDES/COASTAL FLOODING... High tide tonight is 11.5 FT. Although winds will become more southeasterly at this point, there will likely be a residual surge in the Gulf of Maine which could cause another 0.5 to 1 FT surge leading to the potential for minor coastal flooding and splash over. The highest nighttime astronomical high tides are 11.7 FT after midnight Friday and again Saturday mornings. With a prolonged onshore fetch, albeit light, some minor problems are possible on these tides as well. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Coastal Flood Advisory from 10 PM this evening to 2 AM EDT Thursday for MEZ023-024. NH...Coastal Flood Advisory from 10 PM this evening to 2 AM EDT Thursday for NHZ014. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ150- 152-154. Small Craft Advisory for hazardous seas from 8 PM this evening to 8 PM EDT Friday for ANZ150-152-154. && $$ NEAR TERM...Marine SHORT TERM...Marine LONG TERM...Ekster

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