Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 252255 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 655 PM EDT Tue Jul 25 2017 .SYNOPSIS... High pressure will build across the region through Wednesday. A cold front will cross the region later Thursday through Thursday night. && .NEAR TERM /THROUGH WEDNESDAY/... 630 PM Update: The most sig chg this update was to speed up the clrg across the Rgn by erly eve with latest sat imagery already showing mclr to clr skies. Otherwise, fcst hrly temps/dwpts were updated into the ovrngt based on obsvd hi temps and trends seen from latest late aftn/erly eve obsvd temps. Based on these trends, we lowered fcst ovrngt low temps across NW vly lctns a few deg F based on lower obsvd dwpts then previously fcstd already in place. Orgnl Disc: High pressure will build across the region tonight through Wednesday. Cloud cover will decrease this evening leaving clear skies overnight. Could also have patchy fog late tonight across Downeast areas. Mostly sunny skies and warmer temperatures will occur Wednesday. Low temperatures tonight will range from the mid to upper 40s north, to around 50 to the lower 50s Downeast. High temperatures Wednesday will range from the upper 70s to lower 80s across much of the forecast area, with mid to upper 70s along the Downeast coast where onshore winds will develop. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... Unsettled for Thursday and cooler for Friday. A weak occluded front is forecast to lift across the region early Thursday. Model guidance still shows some discrepancy in regards to timing of the initial round of showers. The 12z NAM was by far the slowest w/the timing and less rainfall while the GFS and Canadian Global support an earlier arrival of the showers w/more rainfall. There is some mid level forcing w/this front along w/some moisture through 700mbs. This would be enough to set off some activity. The 12z run of the ECMWF aligns closer to the GFS and Canadian w/the timing and rainfall. Given all this, decided on a faster timing and brought 40-50% pops to the north and central areas by between 6-8 am. These showers look like they will move through quickly w/a break in the action. Another round of activity which will be showers and possible tstms by the afternoon into evening as a pre-frontal trof ahead of the cold front moves into the region. Some instability is does appear to be there and if some heating can be realized, then the atmosphere would destabilize. The GFS is more bullish and the NAM w/its instability and steeper lapse rates. The GFS showed CAPE of 800-1200 joules w/0-6km around 25 kts or so. The NAM is weaker but does show some shear and meager lapse rates around 6.0 c/km. Moisture does appear to be available w/PWATS 1+ inches. Temps were raised a category from the previous forecast w/the expected brief heating. This would mean 70s to around 80 for central areas. I say brief, because concern is that cloud cover hanging on would keep substantial heating to a minimum and thus cutting back tstm potential. Attm, decided to include the mention for tstms but the confidence is not high enough to include any enhanced wording attm. The later shifts can look into this further as we move closer in. The associated cold front is expected to slide across the region later Thursday night w/showers and any leftover storms ending by late evening. Cooler air is set to follow in behind the front for Friday w/some sunshine and clouds. Daytime temps for Friday will most likely be below normal for late July. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... High pres at the surface set to settle across the region into the weekend. Aloft will remain an upper trof across northern New England. The trof axis will be a focus for the chance for some showers across the northern and western areas especially on Sunday. This along with some clouds would limit heating and hence cut down on daytime temps. Decided to stay temps just below norms for Saturday and near normal readings for Sunday. The next shot for any shower activity looks to be on Monday as a cold front is shown by the long range guidance to slide across the region in the afternoon. Given the setup, it looks like the potential for convection is there. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: Variable conditions are possible with any patchy fog Downeast late tonight. Otherwise, VFR conditions are expected across the region tonight through Wednesday. SHORT TERM: MVFR conditions w/some IFR on Thursday. The IFR will be mainly across KBGR and KBHB due to s flow in off the Gulf of Maine. Showers will be the main wx element w/the threat for some tstms for the northern terminals. Improving conditions for northern areas later Thursday night into Friday to VFR while from KBGR to KBHB will see hang onto IFR/MVFR. Conditions are expected to improve for all terminals by later Friday into Saturday. && .MARINE... NEAR TERM: Winds/seas will remain below small craft advisory levels tonight through Wednesday. SHORT TERM: No headlines are anticipated for this cycle. Stayed w/winds 10-15 kts into Friday w/a few gusts closing in around 20 kts for the outer waters. The cold front should clear the region later Friday into Saturday w/high pres settling in from the wnw. Thus, winds will drop back off to around 10 kt in Sunday. Seas will creep up to around 4 ft along the outer zones into Friday. Seas will drop back as the front cross the waters and winds turn more offshore. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...VJN Short Term...Hewitt Long Term...Hewitt Aviation...VJN/Hewitt Marine...VJN/Hewitt

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