Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 270128 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 928 PM EDT Mon Jun 26 2017 .SYNOPSIS... A trough of low pressure will remain to our west through mid week. Weather disturbances lifting out of the trough will cross the area Tuesday afternoon and again on Wednesday. A larger area of low pressure may approach late Thursday. && .NEAR TERM /THROUGH TUESDAY/...
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9:28 PM Update...A nice evening across the CWA with cool temperatures and comfortable dew points. Much of the diurnal cu dissipated, but satellite still showing some mid level clouds, especially across parts of Piscataquis, northern and central Penobscot, and eastern Aroostook counties. A strong shortwave is evident on satellite pictures across Michigan this evening, and this feature will weaken and move into western New England by this time Tue evening. Made some tweaks to the sky condition based on the latest satellite pictures, and also slowed the arrive of the showers based on the latest radar and near term model trends. Previous discussion... Attention will turn to the potential for strong tstms on Tuesday. Skies are expected to go mostly clear this evening w/the loss of diurnal effects. Winds will lighten up as well. A cooler airmass in place coupled w/the clearing and light winds will lead to a cool night coming up. We are talking temperatures dropping into the 40s across the northern 1/2 of the CWA w/some sites back across the crown seeing upper 30s. This will be especially true for the low lying sites. Central and downeast sites will see 50-55. Decided on some patchy fog by early Tuesday morning(09-12z) as blyr winds turn to the se. Tuesday could be a challenging day as the short range guidance in including the NAM/GEM and GFS suggest the potential for some convection. Atmosphere is forecast to destabilize during the day as a weak warm front at the surface lifts n. Aloft, cold temps and a decent jet streak of 40 kts is forecast to be in place. Question is how quickly will the clouds make their way into the region which could dampen strong convection. The 12z run of the NAM and GFS show enough heating to allow for convective initiation. CAPE of 500-700 joules w/shear of 30 kts in the 0-6km layer is noted. Plus, steep low/mid level lapse rates allowing for updraft potential. V-notch in the llvls favorable for downburst potential if storms can build. Given all this and per collaboration w/GYX and BTV, decided to add enhanced wording to the forecast for hail and gusty winds. Would not be surprised to see a few cells reach near severe limits. Again, this all hinges on duration of sufficient heating. Attm, SPC has the region in a General Risk but they do mention the threat for small hail potential for northern New England with cold pool aloft. Another threat to consider is the heavy rainfall potential as storms will be oriented along a ssw direction w/some training of cells. Daytime temps are forecast to be in the upper 60s to lower 70s across the n and w while central and downeast should see low to mid 70s.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... A shortwave lifting across the area Tuesday evening will bring showers and some embedded thunderstorms early. By midnight, the shortwave should lift northeast and out of the area as skies remain partly to mostly cloudy. Another shortwave, associated with the upper level trough lifting out will cross the area on Wednesday bringing another chance for showers and some thunderstorms. Capes are modest Tuesday evening and again Wednesday up to 500 J/KG across the area. The forecast challenge may be in determining how much heating occurs each day with skies generally expected to be partly to mostly cloudy leading up to Tuesday evening and again on Wednesday. Showers will taper off Wednesday evening. Another low in the fast west to east flow will approach on Thursday bringing another chance for showers, especially during the afternoon. Guidance varies quite a bit on the speed of this system with the NAM bringing a well organized rainstorm in late Thursday but the GFS just bringing an increased chance for showers as the new system approaches. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Showers will be likely Thursday night as low pressure approaches and warm, humid air is pulled north over relatively cooler air across our area. A period of steady rain may fall across the north. Showers and maybe some embedded thunderstorms will continue to be likely on Friday with the upper low sliding across the region. Yet another low may approach Saturday into Sunday bringing a chance for more rain, possibly heavy in some areas with ample moisture lifting north over the region. Unsettled weather may continue into the following week with an active west to east flow and shortwaves sliding in from the west. There are some signs that longwave ridging could eventually push our way very late next week or early the week afternoon bringing a possibility of warmer, less rainy weather as we approach the second week in July. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... NEAR TERM: Generally VFR w/a brief period of mvfr vsbys for patchy fog Tuesday morning. The threat for tstms Tuesday afternoon could lead to MVFR and perhaps IFR briefly. SHORT TERM: IFR conditions in low clouds and rain are likely Tuesday night, improving to MVFR or VFR as clouds lift early Wednesday morning. Conditions may drop to MVFR at times Wednesday as more clouds and variable low cloudiness push across. Mainly VFR to occasionally MVFR conditions are likely Thursday, possibly dropping to MVFR or IFR late in the day in Rain. && .MARINE... NEAR TERM: No headlines expected this term. SSW winds to pick up later Tuesday at 10-15 kts w/seas to build to 4 ft especially over the outer zones. SHORT TERM: Winds and seas are expected to be below SCA Tuesday through the end of the week. Fog may limit visibilities over the water as humid air lifts north across the Gulf of Maine. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...CB/Hewitt Short Term...Bloomer Long Term...Bloomer Aviation...CB/Hewitt/Bloomer Marine...CB/Hewitt/Bloomer

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