Area Forecast Discussion
Issued by NWS Portland, ME

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KGYX 152326 AFDGYX Area Forecast Discussion National Weather Service Gray ME 726 PM EDT Thu Mar 15 2018 .SYNOPSIS... A broad area of low pressure will spin over the Canadian maritimes tonight and Friday, with snow showers continuing in portions of the mountains. Temperatures will be a little cooler than normal with abundant cloud cover. The next trough will drop down out of the Canadian Arctic and arrive in New England on Saturday with colder conditions expected for the weekend. && .NEAR TERM /TONIGHT/...
-- Changed Discussion --
730PM UPDATE... Have made only minor adjustments to the forecast for tonight. Drier air is moving in from the northwest overnight, which should help to shut down the upslope snows which have only been sparsely reported in recent hours, thus have lowered PoP as the night goes on. No other significant changes were made. ORIGINAL DISCUSSION... Some ridging aloft allowed for partial clearing today, however some CU did fill in during the daytime as the atmosphere remains rather unstable. Most of the cloudiness and moisture will remain over the upslope regions of the mountains as a WNW flow continue to produce snow showers. This will be mainly terrain driven precipitation with the valley floors remaining relatively dry. A couple inches of snow is possible across the higher peaks. There will be a well mixed atmosphere overnight with cold air advection occurring. H8 readings fall to the -9C to -14C readings by morning. Overnight lows will mainly run in a relatively small range from the mid teens in the north to the mid 20s in the south.
-- End Changed Discussion --
&& .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... Plenty of clouds will remain over upslope areas with some snow shower activity continuing. More sun is expected in the south. It will be chilly and breezy with temperatures continuing to be below normal for this time of the year. Another reinforcing shot of cold air arrives Friday evening with the passage of an upper level trough and a surface cold front. Cold air advection will be maxed out during the overnight hours. H8 temperatures drop down to -16C to -22C from south to north by Saturday morning. With gusty winds it will feel even colder than the projected single numbers for lows in the north to mainly in the teens in the south. Will need to watch for a couple snow showers or even possibly a snow squall with this shot of cold air during the night potentially making it down into southern areas. The atmosphere will remain unstable with a large upper low overhead. && .LONG TERM /SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
Most people like snow for the holidays...and the extended forecast is looking increasingly likely that holiday may be Easter. The next 7 days should ensure the majority of the current snow pack remains at the end of next week. For starters upper low rotating around NErn Canada will propel a chunk of very cold air across the region this weekend. H8 temps around -20 C...around 2 standard deviations below normal...will set the stage for afternoon temps struggling to break the freezing mark. The angle of delivery...from the awfully favorable for minimal moderation of this air mass. In fact on Sat...I have temps remaining in the 20s for much of the area as the core of the coldest air is overhead. As the trof axis passes some snow shower activity is also possible...though significant accumulation is not expected. Only slight moderation is expected into early next cold...Canadian high pressure edges towards the area. We will remain in the cyclonic flow upstream of the upper low...and that will allow fresh supply of cold air. Sun and Mon both look to be at least 10 degrees cooler than normal. Then the focus turns to model guidance still remains in broad agreement in a higher than normal chance for precip. Again I am not willing to delve too much into deterministic and ensemble guidance is now trending towards a more convoluted evolution involving one baroclinic zones and two low pressures back to back. Ensemble guidance is showing significant spread among the individual members...and so this is a low confidence forecast. In fact the ECMWF EPS has a mean surface low off the East Coast for over 48 hours...due to multiple S/WV trofs triggering cyclogenesis events in that window. It is safe to say there will be a storm system to track in the mid to late week time frame...but my feeling is that models will eventually focus on one S/WV. For that reason PoP has it is potentially spread out over more days due to uncertainty. As things stand now though there is high pressure in a good location to hold cold air...and more than enough forcing aloft for a coastal storm. This one will have to be watched closely.
-- End Changed Discussion --
&& .AVIATION /00Z FRIDAY THROUGH TUESDAY/... Short Term...Mainly VFR conditions in the short term portion of the forecast (through Friday night). There will likely be periods of MVFR conditions in low ceiling or any snow showers at HIE with low clouds at times at LEB and AUG. Long Term...Widespread VFR conditions are expected this weekend into early next week. Gusty WNW flow will continue Sat...with surface gusts to near 20 kts. High pressure will gradually nose in thru early next week...continuing VFR conditions thru Tue. && .MARINE... Short Term...Have extended the SCAs tonight through Friday night for the outer waters and just for Friday and Friday night for the bays. Winds may approach gale force in a few spots Friday night, however confidence is not high enough at this time for gale watches or warnings. Long Term...SCA conditions will continue for the coastal waters Sat. As deeper mixing occurs during the day a few gusts near gale force are possible well outside the bays. Will likely see a brief lull in SCA conditions Sun into Mon as high pressure noses into the area. By midweek NE flow will be increasing...and SCAs...possibly gale force winds...are likely. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory from 6 AM Friday to 6 AM EDT Saturday for ANZ151-153. Small Craft Advisory until 6 AM EDT Saturday for ANZ150-152- 154. && $$ NEAR TERM UPDATE...Kimble SHORT TERM...Cannon LONG TERM...Legro is the U.S. government's official web portal to all federal, state and local government web resources and services.