Area Forecast Discussion
Issued by NWS Caribou, ME
Issued by NWS Caribou, ME
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800 FXUS61 KCAR 311728 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 128 PM EDT Fri May 31 2024 .SYNOPSIS... High pressure slowly builds in this weekend, with low pressure approaching from the east on Sunday. Weak high pressure returns through Tuesday. && .NEAR TERM /THROUGH TONIGHT/... 130 pm update... Appears as though convective temps have been reached this afternoon. Cu is developing, mainly over the higher elevations. Light echoes are being seen on Quebec/s St. Francoise radar over the North Woods. These may be high clouds or virga but doubtful that much is reaching the ground as of 17z. Hires models continue to show convective showers developing acrs wrn zones this afternoon. Cannot rule out an isold lightning strike at some point this afternoon given low frzg levels, but CAPES are pretty puny. Will continue to watch vis satellite and regional radars and may have to yank thunder out with fcst package. Previous Discussion... A cool start to the morning with some patchy to areas of frost across the North and some river valley fog. Today, the 500mb low pressure begins to drift NE of the Gaspe Peninsula with the trof axis extending south to the Maine/New Brunswick border and drifts east into the Maritimes by later in the day. 1026mb surface high pressure drifts slowly east over Lake Erie today which is still too far away to full take over control of our weather. Hi-Res models have been consistent since yesterday diving a piece of 500mb vorticity on the backside of the trof into Maine this afternoon. The day starts out mostly sunny but turns partly sunny and hi-res CAMs consistent on producing some convection this afternoon. Modeled soundings continue to show steep low-level lapse rates around 9C/km with mid levels approaching 7C/km. Although its a well mixed below 850mb there is some SBCAPE up to 200-400j/kg expected. Given the lower freezing levels and convective temperatures around 67-69F we can expect a few isolated to scattered showers. Given the thermodynamics described above cannot rule out a few isolated lightning strikes so opted to add isolated thunder to the grids. The best chance for any showers and thunder will be tight to where the vorticity transects the state today which will be from the Moosehead Region south to Bangor then perhaps Bar Harbor. Everywhere else will remain dry with just some cu. High temperatures today will be in the mid to upper 60s across the north and with the light north wind it will be a downslope off the Longfellow Mtns so expect upper 60s to low 70s in the Highlands to the Downeast coast. Given the temperatures on the coast and the very cold Gulf of Maine waters have hoisted a Beach Hazard Statement at the request of the United States Coast Guard. Tonight, showers end very quickly this evening with the loss of daytime heating and drier air works into the area. Partly cloudy skies become clear but a warmer airmass associated with the approaching 500mb ridge works into the area. This means although there will be a steep low-level inversion around 500-1000ft the surface temperatures wont be as cold despite decoupling. Expect upper 30s to low 40s across the north with mid 40s for the Central Highlands to the Downeast coast. Decent weather conditions expected for skywatchers on the potential for more Northern Lights activity given the G2 Geomagnetic Storm Watch issued by the NWS Space Weather Prediction Center. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... The upper level longwave trough will begin to shift eastward through the day on Saturday. As this occurs, a north-south oriented jet streak will pull southwards through the state, with the front right entrance region crossing over the forecast area. This synoptic setup will setup will support instability across the forecast area. What is lacking for the day on Saturday is any significant source of moisture for shower or storm development. Given this environment, an afternoon cumulus field is likely, especially across the eastern half of the forecast area. A ridge will begin to build into the area Saturday night into Sunday, which will provide subsidence to keep skies mostly clear and precip chances to a minimum. However, recent CAM guidance, such as in the NAM and RGEM, have begun to suggest that the ridge will build in a little more slowly than global models have been projecting. As the previous upper level trough begins to shift towards a neutral tilt, this slower solution maintains some weight. The consequence to a slower ridge build is that would allow for a surface low to retrograde far enough westward into New Brunswick to bring rain showers across the eastern Maine border. Moisture support would then come from the Canadian Maritimes, and synoptic instability provided by the upper level trough. Winds will be relatively light through this time, but upper level NE flow could lead to downsloping which will continue subsidence over NE Aroostook, downstream of higher terrain in New Brunswick, and keep the best chances for rain showers across Washington County. Even still, any rain that does develop will be light. && .LONG TERM /MONDAY THROUGH FRIDAY/... A ridge of high pressure will continue to slowly move into the area through the first half of the upcoming week, with mostly clear skies and little to no rain chances. Heading into the middle of the work week, moisture will begin to slowly return to the area, with enough moisture returning for diurnal cumulus to continue to build into showers and storms. This said, the synoptic pattern is likely to still be that of which is under at least some influence of a ridge, though shortwaves may approach from the west during this time. && .AVIATION /17Z FRIDAY THROUGH TUESDAY/... NEAR TERM: VFR next 24 hours. Gusty nw winds will diminish this evening before increasing again from the north after 15z Saturday. SHORT TERM: Saturday - Tuesday: Generally VFR conditions across all terminals, with winds light and variable each night. Saturday, N winds 5 to 10 kts, otherwise each day light N to NE winds around 5 kts. Slight chance (20%) of MVFR cigs on Monday with -SHRA and increased cloud cover for Washington County terminals up through eastern Aroostook KHUL through KCAR. && .MARINE... NEAR TERM: Winds/seas below SCA conditions through tonight. W-NW today less than 15kt becoming N around 5kt tonight. Seas 2-3ft today with a period of 7sec becoming 1-2ft tonight. Sea surface temperatures in the mid to upper 40s extend from the Downeast coast out 25nm and east to the Hague Line including Passamaquoddy Bay. SHORT TERM: Winds and seas will continue to remain below small craft advisory conditions through the weekend and into early next week. Winds will be light with gusts around 10 to 12 kts and generally offshore in direction, while seas sit around 1 to 2 ft. There is a chance for patchy fog over the waters Sunday night, reducing visibilities. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Beach Hazards Statement until 8 PM EDT this evening for MEZ029- 030. MARINE...None. && $$ Near Term...Buster/Sinko Short Term...AStrauser Long Term...AStrauser Aviation...Buster/Sinko/AStrauser Marine...Buster/Sinko/AStrauser