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. --
266 FXUS61 KGYX 051547 AAA AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 1047 AM EST Mon Dec 5 2016 .SYNOPSIS... A weak low pressure system will bring some light snow to the region on today. High pressure will settle in for Tuesday. Low pressure may affect the region with more light rain or snow Thursday with colder air following for Friday and over the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Update...Have increased PoP on a line NE of about LEB to MHT. Snow continues...banded at times...as relatively warmer air aloft slams into very cold air mass over Downeast and the Crown of Maine. Brief burst of 1/2 to 1 inch per hour have been reported and should continue for areas around PWM and NE for the next couple of hours. With 12z kgyx sounding wet bulb temps near -10C from the surface thru 600 mb...any lift is in or near the snow growth zone. Snowfall ratios should be above climatological norms. So I have also bumped snowfall amounts up an inch or so...with max totals around 3 inches near the mtns...where Ely inflow will enhance lift. Finally forecast soundings are pretty devoid of a warm nose...so I have kept precip types snow or rain based on surface wet bulb temps. Any mixed hydrometeors are most likely heavily rimed flakes than sleet actually mixing in. Prev Disc... Radiational cooling dominated the first half of last night with clear skies and light winds. Early this morning, clouds will continue to thicken and lower. A north wind has developed along the coast which will keep an inversion in place. Currently forecasting cooler readings today than most model guidance would suggest. A wet bulbing effect will keep our atmosphere on the chilly side today as the snow attempts to fall through a layer of very dry air in the lower portions of the atmosphere. The chilly temperatures and low dew points will allow most of the precipitation to fall in the form of snow with only a few of the coastal islands may see a mix with rain at times. Although the system moving through the region remains weak, sufficient inflow from the Gulf of Maine and low level convergence will allow for light snow to progress eastward today. Some of the precipitation will remain as virga at the onset due to the initial conditions described above. Nevertheless, an inch or two snowfall expected most areas today. Onset time will be critical with possible very slick conditions for the morning commute over southern New Hampshire. A special weather statement has been issued for this possibility. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... The light snow will be over in most areas by evening, with the exception of the Rockland and Penobscot Bay area which may hold onto some evening flurries as the weak surface trough and associated short wave aloft exit to our east. Clearing skies will lead to more chilly conditions with the new snow cover. A surface ridge of high pressure will reestablish itself over New England on Tuesday. Some high thin cloudiness may enter southern areas late in the day as low pressure moves up and then off the Mid Atlantic coast. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Several fast moving short waves will move through the region through the outlook period. The first will be Tuesday night into Wednesday with a period of light snow and the next will be on Thursday with another bout of light snow or snow showers. Nothing more than light accumulations are expected with these moisture starved systems. Models are finally in general agreement of no major development of any coastal storms with these short waves. By Friday and into the weekend much colder Canadian air moves across the region on a broad northwest flow aloft and at the surface. Mountain orographic snow showers can be expected Friday into Saturday with the cold northwest flow. The coldest air mass of the season can be expected to arrive late Friday and into the weekend. && .AVIATION /16Z MONDAY THROUGH FRIDAY/... Short Term...Marginal conditions for LLWS however the wind speeds aloft from the southwest are not overly strong. Some IFR and possibly a brief period of LIFR conditions today. Conditions improve to VFR for tonight and Tuesday. Long Term...MVFR conditions expected Tuesday night into Wednesday and again on Thursday. && .MARINE... Short Term...Winds and seas will remain below Small Craft Advisory criteria for the most part in the short term. There will be a period this evening with the trough exiting to the east with gusty conditions. Westerly winds will be just below SCA criteria. Long Term...Late in the week a strong west to northwest flow combined with strong cold air advection will develop with winds possibly approaching gale force Friday into Friday night. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Legro

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.