842 FXUS61 KGYX 161943 AFDGYX Area Forecast Discussion National Weather Service Gray ME 343 PM EDT Mon Jul 16 2018 .SYNOPSIS... Very warm and increasingly humid conditions are expected to continue into Tuesday across New Hampshire and western Maine. The large bank of fog and low clouds over the Gulf of Maine is forecast to move back inland tonight. Areas of dense fog are likely along the coast...and may extend well inland by morning. A cold front will approach through the day...with showers and thunderstorms expected along and ahead of it. Some early day rain and embedded thunder will give way to partial sun and allow for another round of afternoon storms. Some of these may be severe...with damaging winds the main threat along with torrential rainfall. Showers and storms push off the coast Tuesday evening...with cool and drier air moving in behind it. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... A humid airmass continues to move into the region overnight resulting in fairly widespread fog. Satellite shows a stratus deck just offshore which will move inland after sunset with the coastal plain rapidly dropping visibilities. Coastal cameras indicate low visibility already present along the immediate coastline. A Dense Fog advisory has been issued for the coast as well as portions of interior southwestern Maine. Further east through Androscoggin and Kennebec county it is less confident that the marine layer will make it all the way inland again as weak westerly flow begins overnight and this area will need to be monitored. Similarly across southern New Hampshire the marine layer is currently suppressing convection in portions of eastern Rockingham county but there is less confidence of the fog extending eastwards towards Manchester and Nashua. This area will also need to be monitored for an expansion of the dense fog advisory. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Tuesday will be a classic severe weather set up. The morning starts off with fog and low stratus along the coast. This fog will dissipate by mid morning leaving a humid airmass primed for convection. A cold front approaching from the west will be the trigger needed to get storms going. The front will arrive into our far northwestern zones in the early morning crossing the entire area from west to east reaching the coastline around 22Z. With CAPE values of 1500 J/kg along with shear of 30+ kts expect an organized convective line with severe wind gusts as the main threat. Ahead of the line the humid airmass and low level southerly and onshore flow will provide some low level turning of the winds. If any storms are able to initiate ahead of the main line there will be a threat for tornadoes within these cells. In addition to the severe threat, flash flooding will be a concern. Dewpoints in the upper 60s to near 70s with PWAT values approaching 2" will provide plenty of moisture for storms. Coupled with a deep warm rain layer and you get very heavy rain rates. The big issue here will be whether the storms are training in one location. If the line is able to remain progressive through the entire region significant flooding would likely be avoided however even minor changes in direction of the line will serve to focus the precipitation in one area. Despite the potential for flooding have opted not to issue a Flash Flood watch at this point as the total area likely to experience flooding will likely be relatively small and with the line passing through the entire region its hard to favor one portion of the CWA over another for flood risk. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Generally quiet extended forecast behind Tue cold front. High pressure will build in in its wake...and more or less hold thru the end of the week. Ridging build in aloft...and allows surface high to hold over the region. Model guidance is hinting at NWrn Atlantic ridging to try and build Wwd towards the end of the period...which will help to keep the next trof delayed. The multi-model consensus however does have the next rain chances moving in over the weekend...as deep SWly flow sets up on the Wrn side of the ridge. Though it is at the tail end of the range of guidance at this time...NAEFS mean PWATs are already forecast to climb towards +2 standard deviations. That would mean after a brief break...a return to humid conditions and possible torrential rainfall in showers/storms for the weekend. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... Short Term... Fog and status visible just offshore on satellite will move inland rapidly after sunset tonight dropping coastal locations to LIFR in fog. Further inland IFR fog is possible but less confident as the Marine airmass may not extend inland as far as AUG or IZG. The far northern valleys will also see fog extending from BML to 4B0 and throughout the Androscoggin and Connecticut valleys. Long Term...Expecting VFR conditions to hold thru the end of the week. As high pressure moves in for the latter half of the week...afternoon sea breezes are likely as well as nocturnal valley fog inland. && .MARINE... Short Term...Dense fog will remain over the coastal waters through tomorrow. Southwesterly flow will increase ahead of a cold front moving through Tuesday evening and and SCA has been issued for the outer waters. Long Term...Winds and seas expected to remain below SCA thresholds thru the end of the week. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Dense Fog Advisory from 10 PM this evening to 8 AM EDT Tuesday for MEZ018-019-023>028. NH...Dense Fog Advisory from 10 PM this evening to 8 AM EDT Tuesday for NHZ010-014. MARINE...Small Craft Advisory from 10 AM Tuesday to midnight EDT Tuesday night for ANZ150-152-154. && $$ NEAR TERM...Curtis SHORT TERM...Curtis LONG TERM...Legro AVIATION...Curtis/Legro MARINE...Curtis/Legro