Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 170426 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1126 PM EST Tue Jan 16 2018 .SYNOPSIS... Developing low pressure off the mid atlantic coast will intensify as it moves rapidly northeast through the Gulf of Maine on Wednesday. High pressure builds eastward into the region late in the week and into the weekend with a return southwest flow bringing warmer temperatures by the weekend. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 1125 PM...Minor ESTF update to reflect the current mesonet and radar trends in near term grids. Prev disc... 836 PM Update... Minor changes to the forecast as the snowfall event begins. Have adjusted PoPs to better match latest CAM forecasts as well as current radar trends. Inverted coastal low pressure is developing off the Delmarva Peninsula and will make its way north overnight spreading snow to the remainder of New England tomorrow. 528 PM Update... Light precipitation has begun for portions of NH and ME...with ceilings beginning to drop. A few stations are reporting light snow and this trend will continue with snow spreading from west to east tonight and increasing in heaviness with time. Forecast is on track at this time. Will be refreshing products shortly. Previous discussion... All headlines remain in place from the noon time update. Model data incomplete here today but the general consensus is for the progressive upper trof over the Great Lakes to continue to move east and allow development of a weak surface low off DELMARVA tonight. With the southwest flow ahead of the upper trof, the low will track northeast. Tonight ahead of this low, a WAA pattern develops spreading snow from south to north rather quickly. Toward morning additional moisture influx off the ocean combined with increasing UVV will allow the snow to increase in intensity. Accumulating snow over southern and coastal areas can be expected toward morning. Temps will be cold so all snow expected no issues with PTYPE. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Models tracking sfc low parallel and closer to the ME/NH coast than prior runs. They have become in line with prior runs of the EURO which had shown great continuity for this system and also the higher in forecast QPF amounts. With the track being closer to the coast, we have nudged QPF and snowfall totals higher over southern and coastal areas with the highest amounts being along the midcoast areas. QPF amounts should be in the range of .50-.75 inches over coastal areas which should generate snowfall amounts of 5-10 inches midcoast Maine with 5-8 inches over southern and south central NH and interior adjacent areas to the Maine coast. Amounts further north and in the mountains will be significantly less. With winds from the north and some cold air damming to occur find it hard for temps to reach above freezing along the coast so lowered temps a few degrees. By later in the day the center of low pressure will move rapidly northeast and be off the coast of downeast Maine so lingering snows will continue but the heaviest will be over. Clearing will occur Wednesday night as the upper trof and surface low quickly exit to the east. Temps in the wake of the system will be seasonable with overnight lows generally in the teens to lower 20s. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Little in the way of significant weather is in the cards Thu through the weekend. Temperatures are however expected to warm once again - into the 40s in many areas over the weekend. The next system of interest continues to be a potentially decent precip maker - with warm air flooding in from the south (at least aloft anyway) Monday-Tuesday timeframe. Therefore will continue to monitor trends for potential mixed precip and/or rain which could cause additional ice jam problems. Ice could end up being an issue as well-especially up north. && .AVIATION /04Z WEDNESDAY THROUGH SUNDAY/... Short Term...Conditions will deteriorate to MVFR then IFR from southwest to northeast tonight as snow spreads across the region. Conditions will be IFR to ocnl LIFR from 09z-18z. By late Wed conditions improve and become VFR Wed night. Long Term...Occasional MVFR conditions in snow showers in the mountains Thu and Fri otherwise widespread VFR expected through the weekend. && .MARINE... Short Term...Offshore swells continue to slowly subside. Winds are light. Will continue a SCA due to Hazardous Seas for the southwest offshore portion of the waters into early this evening. Winds will remain below SCA conditions tonight into Wed night, but offshore swells will increase Wed through Wed night so have issued a SCA for Hazardous seas over the outer waters for that time frame. Long Term...SCA to low-end gale conditions will be possible Saturday. && .HYDROLOGY... All rivers but the Kennebec at AUG have fallen below flood stage, but ice jams have frozen into place in some areas. Rivers will still need to be monitored as these jams could move without notice. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory until 7 PM EST Wednesday for MEZ012>014. Winter Storm Warning until 7 PM EST Wednesday for MEZ018>028. NH...Winter Weather Advisory until 4 PM EST Wednesday for NHZ003>007. Winter Storm Warning until 4 PM EST Wednesday for NHZ008>015. MARINE...Small Craft Advisory for hazardous seas from 6 AM Wednesday to 7 AM EST Thursday for ANZ150-152-154. && $$ ES

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