Area forecast discussion National Weather Service Gray ME 338 PM EDT Sat may 25 2013 Synopsis... low pressure will move slowly through the Gulf of Maine tonight and Sunday then move into the Maritimes Sunday night. High pressure will build in from the west Monday then shift offshore on Tuesday. A warm front will move across the region Wednesday and Wednesday night followed by a large building ridge of high pressure with very warm temperatures for late in the week. && Near term /until 6 am Sunday morning/... slow moving low moving NE through the Gulf of ME tonight will continue rain across the forecast area. However...as colder air moves in and the freezing level drops with the cutoff strengthening and drifting overhead the rain will mix with or change to snow with some ice pellets/freezing rain possible as well across the higher elevations...mainly above 2000 feet. Some light snow accumulation possible with 1 to 4 inches possible above 4000 feet. Gusty northerly winds will ease up only a little overnight as temperatures only drop a few degrees with cloud cover and prcp. Look for lows in the 30s north and upper 30s to Lower/Middle 40s S. Generally used a blend of NAM/GFS and met/mav guidance for the near term forecast. Flood Watch now for all of the western ME Montana and foothill zones and northern New Hampshire. See the hydrology discussion below for more details. && Short term /6 am Sunday morning through Sunday night/... the surface low continues to move slowly NE Sunday then accelerates into the Maritimes Sunday night. Thus expect the rain /or mixed prcp at higher elevations above 2000 feet/ to gradually end or at least taper off on Sunday then come to an end Sunday night from SW to NE. Some clearing likely late Sunday night especially SW zones. Generally used a blend of GFS/NAM, met/mav and HPC/rfc quantitative precipitation forecast for the short term forecast. && Long term /Monday through Saturday/... high pressure builds across the region for Monday and Tuesday before moving offshore Tuesday night. A warm front will approach from the west Wednesday and move through the area by later Wednesday night producing showers ahead and along the warm front. On Thursday a large ridge of high pressure that will build over the eastern third of the US will also build north across New England for both Thursday and Friday bringing very warm and humid conditions to the area. Used a blend of the mav/met temperatures for 4th/5th periods. Used gmos for maximum temperatures but had to raise temperatures some for Thu/Fri/Sat. For mins use the bias adjacent mex guidance. && Aviation /19z Saturday through Thursday/... short term /through Sunday night/...mainly IFR/LIFR tonight with conditions improving Sunday and Sunday night to VFR. Mixed prcp at higher elevations developing tonight then ending Sunday/Sunday evening. Long term... VFR conds xcpt MVFR conds Wednesday/Wednesday night in any showers. && Marine... short term /tonight through Sunday night/...will extend the Small Craft Advisory through 11 PM this evening for wind gusts and seas based on latest buoy reports and slow track of surface low. Winds let up overnight but seas will be slow to subside over the open waters. May need to extend the Small Craft Advisory at least for hazardous seas over the open waters for late tonight and possibly into Sunday as well. Long term...no flags Monday or Tuesday...by Wednesday an increasing southerly flow may allow Small Craft Advisory conds to develop. && Fire weather... fire weather danger very low. Excessive rainfall past several days and more rain or even mixed prcp over the higher terrain through tonight and only slowly letting up Sunday along with green up over much if not all of the forecast area. && Hydrology... generally used a blend of GFS/HPC/rfc quantitative precipitation forecast. 24 hour quantitative precipitation forecast amounts tonight through Sunday around 1/2 inch with some amounts topping 1 inch possible across north/Montana foothill zones due to upslope enhancement with low/middle level winds advecting moisture in off the Atlantic. Will expand the Flood Watch to include Somerset County /thru 8 am Sunday/ where a river Flood Warning is currently in effect for the Kennebec at Skowhegan. && Tides/coastal flooding... the predicted high tide is 11.8 feet at 1158 PM tonight at pwm. Tidal flood stage is 12.0 feet. There has been a surge of 1/4 to just under 1/2 feet over the past couple days. Now that winds are from the north that may be lowered a bit...but still could see the tide reach the 12 feet benchmark for minimal coastal flooding. More significant are the wave over the coastal waters...running 5 feet at the pwm buoy. Wave action will create some splashover and beach erosion. Will issue a coastal Flood Advisory for the high tide around midnight tonight. && Gyx watches/warnings/advisories... ME...Flood Watch through Sunday morning for mez007>009-012>014. Coastal Flood Advisory from 10 PM this evening to 2 am EDT Sunday for mez023>028. New Hampshire...Flood Watch through Sunday morning for nhz001>005. Coastal Flood Advisory from 10 PM this evening to 2 am EDT Sunday for nhz014. Marine...Small Craft Advisory until 11 PM EDT this evening for anz150>154. && $$