Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 231035 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 635 AM EDT Fri Jun 23 2017 .SYNOPSIS... A warm front will lift across the region today, followed by a cold front tonight into Saturday. Another cold front will begin to cross the region later Sunday night. && .NEAR TERM /THROUGH TONIGHT/... 630am update... Increased pops in southern zones this morning while decreasing pops in northern zones this morning. The area of precip will shift northward during the day and be enhanced by elevated instability later in the day and evening. It now looks like the frontal inversion and low clouds will be more extensive across the entire area this afternoon. The best axis of elevated instability for later this afternoon and evening appears to be southern Piscataquis County towards Houlton and Mars Hill. Southern Piscataquis County is probably the most vulnerable area for the heaviest rainfall this evening and any potential urban and small stream flooding issues. Previous discussion... The big story today will be a warm front separating the cool and dry air mass that had been in place over the last two days from a very warm and moist air mass that will push into the forecast area briefly tonight. This boundary features deep tropical moisture originating from the remnants of Tropical Storm Cindy. At this time, the south edge of the warm front features a nearly continuous line of thunderstorm activity from Iowa to upstate New York. These storms will ride northeastward into the forecast area later this morning well north of the warm frontal boundary and will tend to weaken as they cross the state into a more stable environment. These initial showers are not likely to produce any thunder. Later in the afternoon as the warm frontal boundary creeps northward...elevated instability in the forecast area will increase. Surface-based instability is not particularly likely today with the possible exception of southwest Piscataquis County. Any surface-based convection in that location late this afternoon could be worrisome given the helicity and low LCLs. In general, cloud cover and a developing frontal inversion/low clouds ahead of the warm front will inhibit development of storms. However, storms will develop to the southwest of the forecast area and advect along the warm frontal boundary into the area later this afternoon and through the night. The bulk of the activity will be north of a line from Dover-Foxcroft to Houlton and slowly lift northward during the evening. The problem is that PWATs will approach 2 inches with a deep warm cloud layer and a decent LLJ. With this moisture and efficient rainfall processes, training cells could put down a lot of rain and heighten urban and small stream flooding concerns this evening. The warm front looks like it will be somewhat stationary in northern zones through the night until low pressure drifts across the area late tonight and brings a cold front southward. Further south along the coast, heavy rains are not much of a worry, but fog will thicken tonight. Lows tonight will be in the mid 60s with dew points also in the mid 60s. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... A cold front will exit Downeast areas early Saturday with an upper level disturbance crossing the region during the afternoon. A chance of showers will occur across the region Saturday along with a mostly cloudy morning and mostly/partly cloudy afternoon. Showers are possible early Saturday night across northern areas. Otherwise, partly cloudy skies are expected Saturday night. A trof crosses the region Sunday with partly sunny skies along with a chance of showers. Low pressure crossing northern Maine Sunday night will draw a cold front toward northern portions of the forecast area late. Showers are possible across the region Sunday night, with the better chances across northern areas. Otherwise, expect mostly cloudy skies north with partly/mostly cloudy skies across the remainder of the forecast area. Temperatures will be at slightly above normal levels Saturday, with near normal level temperatures Sunday. && .LONG TERM /MONDAY THROUGH THURSDAY/... Unsettled conditions are expected across the region Monday through Thursday. The cold front will stall across the region Monday with a chance of showers and thunderstorms. A series of disturbances will lift across the region Tuesday into Wednesday in advance of an upper level trof which will then cross the region later Wednesday into Thursday. The disturbances and upper trof will produce occasional showers Tuesday into Thursday along with generally partly cloudy skies. Temperatures will be at near normal levels Monday through Thursday. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... NEAR TERM: VFR conditions this morning will deteriorate this afternoon...becoming IFR due to cigs north of HUL and along the coast towards BHB. The low cigs will reach BGR in the evening. Embedded thunderstorms to FL350 along a warm front will be a significant threat later this afternoon and evening. The worst may be towards GNR and MLT later this afternoon and spread northward and eastward in the evening. The thunderstorm coverage will probably be fairly widespread by early this evening along the south edge of the warm front. These storms will support hail, but strong winds are less likely due to the stable layer and low cigs near the surface. SHORT TERM: MVFR/IFR conditions are expected across the region early Saturday. Generally expect VFR conditions later Saturday into Sunday. Variable conditions, generally ranging from VFR to IFR, are expected across the region Sunday night into early Monday. Variable conditions are then expected with thunderstorms Monday afternoon. Generally expect VFR conditions Monday night into Tuesday, though occasional MVFR conditions will remain possible. && .MARINE... NEAR TERM: Although downward adjustments were made to guidance due to very stable near-surface conditions, a tight pressure gradient may yield a few gusts near 25 kts tonight and some seas reaching over 5 ft. This will be just for the outer waters and will leave the SCA in place. Fog will develop this morning and thicken later today into tonight. SHORT TERM: Small craft advisory level seas are possible Saturday. Conditions are then expected to be below small craft advisory levels Saturday night into Sunday night. Visibilities will be reduced in showers and fog Saturday into early Saturday night. Showers are then possible again later Sunday into Sunday night. && .HYDROLOGY... There is potential for very heavy downpours later this afternoon and tonight along a slow moving warm frontal boundary. The highest risk at this time will be mostly north of a line from Dover-Foxcroft towards Houlton. Urban and small stream flooding are the risks as several inches of rain could fall within a very short duration. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory from 5 PM this afternoon to 8 AM EDT Saturday for ANZ050-051. && $$ Near Term...MCW Short Term...Norcross Long Term...Norcross Aviation...MCW/Norcross Marine...MCW/Norcross Hydrology...MCW

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