Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 190807 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 407 AM EDT Mon Jun 19 2017 .SYNOPSIS...
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A cold front will slowly press into our very humid air mass today. The front will stall across the region tonight as a weather disturbance tracks north along the front. The cold front will continue east of the area on Tuesday.
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&& .NEAR TERM /THROUGH TONIGHT/...
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High pressure well east of the area combined with low pressure lifting north from the Great Lakes will maintain a very warm and humid flow of air from the south today. A cold front will slowly press into the area today bringing a line of showers and thunderstorms in from the west. Some of these storms may be intense with heavy downpours and strong winds. Precipitable water levels are expected to be close to 2 inches and capes up to 1500 J/Kg ahead of this front. Flash flooding will continue to be the greatest risk from any storms. The challenge in eastern areas will be how long it will take to clear away the low stratus. Low clouds will likely persist through the morning with some breaks of sunshine during the midday. The earlier we can get some sunshine, the more heating will be likely and the more unstable the air may become. The front will slowly push across the area later today through tonight. A shortwave running up the front overnight will likely enhance rainfall tonight, especially across central and northeastern areas. The flash flood watch will continue tonight with the potential for heavy downpours continuing.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
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An unsettled pattern to persist through Wednesday w/the threat for convection as the upper trof remains over the region. On Tuesday, showers w/heavy rainfall will be moving to the ene in the morning w/the heaviest amounts across the ne and downeast areas. Mid level forcing shown by the NAM and GFS match up well w/the rainfall placement. There will be a lull in the action through late morning w/low clouds hanging on. The atmosphere however looks like it will destabilize by early afternoon w/the potential for convection to fire. The big questions are where? and how strong? The cold front is forecast to slide into the region in the afternoon and evening. The 00z runs of the GFS and NAM suggest the greatest threat for tstms to develop across northern and central areas w/the best chance for heating. The downeast region could stay under the ssw flow w/low clouds hanging on to keep things a bit more stable. A look at some of the instability parameters shows CAPES of 1000+ joules w/mid level lapse rates hitting 6.5 c/km allowing for updraft potential. Inverted V type soundings show downburst potential w/the storms. Another point to make is the upper levels will be cooling as WBZs drop to 7.5-8k ft. This would lead to hail potential. Given that SPC`s Day 2 outlook has the CWA in a General risk, decided to hold off on any enhanced wording for winds or hail. The daycrew can assess this further today w/the later model guidance. Activity will wind down Tuesday evening as the cold front slides across the region. As the upper trof remains across the region, another sfc boundary is shown by the GFS, ECMWF and even the Canadian Global to move across the region. There is some mid level forcing to kick off some showers. The atmosphere does look like it will destabilize enough in the afternoon as the blyr heats up w/some sunshine. This will be enough to allow for thunderstorms to develop. The coverage is not expected to be as organized as expected for Tuesday. CAPE of 700-1200 joules is forecast by the GFS w/the highest values across northern and western areas along w/some shear(25kts at 0-6km). Therefore, decided to include thunderstorms in the forecast for Wednesday afternoon w/no enhanced wording attm. This too can be assessed further by the daycrew.
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
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Near seasonal temps expected for this term w/above normal temps. Showers and storms look like they will diminish Wednesday evening w/the loss of heating. Overnight lows are forecast to be in the low to mid 50s. High pres set to ridge across the region on Thursday to provide a decent day w/sunshine and comfortable temps in the 70s and lower 80s. Another frontal system is forecast by the long range guidance to bring showers and the potential for tstms. As a matter of fact the unsettled pattern holds into Saturday w/the threat for more showers and possible storms. Used a blend of the guidance attm going w/40-50% pops for this period.
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&& .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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NEAR TERM: IFR Conditions in low clouds are expected to persist today and tonight. Some southerly wind shear is possible, and thunderstorms with heavy downpours may affect parts of the area this afternoon. SHORT TERM: IFR/MVFR early becoming VFR by midday Tuesday w/the exception for KBHB as this site could stay socked in w/low stratus and fog and IFR. This looks like it will hold for KBHB into Tuesday evening. From KBGR on north, the potential for TSRAs is there into Tuesday evening w/some storms being strong. This could lead to a period of IFR/MVFR in the evening w/VFR returning later in the evening right into Wednesday. Again as will be the case on Tuesday, some TSRAs could lead to be a brief period of MVFR in the afternoon. KBHB will see a gradual improvement to VFR later Tuesday night into Wednesday. VFR for all terminals on Thursday.
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&& .MARINE...
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NEAR TERM: A SCA will be up today and tonight, Seas will build over 5 FT and south winds will likely gust up to 25 kt tonight. Dense fog will likely continue to produce very low visibilities over the waters due to the humid air. SHORT TERM: Decided to extend the SCA through mid morning Tuesday as ssw winds look like they will be gusting to 25 kts or so especially over the outer zones. Seas will be averaging 7-8 ft w/a swell component. Winds are expected to drop off below 15 kt by Tuesday evening right into Thursday. Seas however look like they will stay up to around 6 ft into Tuesday night w/the swell component holding strong. The latest run of the wave model showed seas dropping back below 6 ft by Wednesday and holding there into Thursday.
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&& .CAR WATCHES/WARNINGS/ADVISORIES...
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ME...Flash Flood Watch from this afternoon through Tuesday morning for MEZ001>006-010-011-015-031-032. Dense Fog Advisory until 8 AM EDT this morning for MEZ029-030. MARINE...Small Craft Advisory until 11 AM EDT Tuesday for ANZ050>052.
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&& $$ Near Term...Bloomer Short Term...Hewitt Long Term...Hewitt Aviation...Bloomer/Hewitt Marine...Bloomer/Hewitt

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