Area Forecast Discussion
Issued by NWS Caribou, ME
Issued by NWS Caribou, ME
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834 FXUS61 KCAR 121922 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 322 PM EDT Fri Jul 12 2024 .SYNOPSIS... A disturbance will cross the region Saturday. High pressure will cross the region Sunday. A cold front will begin to approach Tuesday. The front stalls over the region on Wednesday. && .NEAR TERM /THROUGH SATURDAY/... The upper level ridge over the Mid Atlantic and the weak upper level trof over the Great Lakes will continue to funnel tropical moisture into the region tonight and Saturday. For this evening and early tonight, high res models show very isolated showers in the north and continuing clouds. For after midnight, shortwave energy will move into the region. This will help usher the areas of fog and isolated to scattered showers across the area, but mainly in the south. Temps in the mid 60s. For Saturday, showers will start to increase and spread across the north as the upper level trof starts to move over the state. This trof will create a frontal boundary at the surface, where instability can develop in the afternoon. Model guidance shows the boundary setting up across the Bangor Region and Interior Downeast where the majority of instability is. Upper air model sounding show CAPE >1000 J/kg, steep lapse rates, upper level divergence. Thunderstorms are expected to be pulse storms with the weaker bulk shear across the area. However, with the higher lapse rates, moderate DCAPE, and higher PWATS, some thunderstorms could produce heavy rain and gusty winds. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... For Saturday night, the upper trough will quickly move through the area and convection will end during the evening. There are some signs of elevated instability persisting through the evening and have maintained mention of thunderstorms until about 10 pm. Clearing skies develop as the night progresses, but do not foresee temperatures dropping below the low to mid 60s in the humid air mass. The moisture will help produce patchy fog inland and more expansive areas of fog for the Downeast coast. On Sunday, a dry upper ridge moves through the area. The lack of clouds and subsidence will help propel temperatures back into the mid to upper 80s across the area. A deep mixed layer may even allow a few 90s. Expect little relief even at the coast with the west-southwest flow. Will probably need to issue a Beach Hazards Statement due to the cold water temps. Heat indices will likely remain a few degrees below advisory criteria. In terms of convection, expect the subsidence and a cap to inhibit formation of any storms. High pressure and clear skies remain in place Sunday night, but so will the humid air mass. Once again, lows will only drop into the mid 60s for most of the area...a bit warmer than the previous night. High temperatures on Monday will again climb into the upper 80s with a few 90F readings possible. No change in humidity means another day close to Heat Advisory criteria. The only differences from Sunday will be a cooler day on the coast due to a more onshore flow, and the possibility of afternoon convection. A weak, compact shortwave propagating in a fast northern stream flow would be the culprit to destabilize the atmosphere, but there is little agreement in guidance on the evolution and timing of this feature...possibly because it may be an MCS that has yet to form. Therefore, confidence is not high and have generally only assigned 15 to 30 percent PoPs for Monday afternoon with an eye towards further reductions. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... There are signs of a temporary break in the heat later next week as a fairly strong upper trough digs southward from Canada towards the northeastern US. However, the price for the cool off will be continued heat early next week and the potential for strong thunderstorms Tuesday and Wednesday. Upper level ridging starts to break down Tuesday, but not before the most of the area experiences another day in the upper 80s. It may end up as the warmest day of the week, and the most likely day for any heat advisories. Onshore southerly winds will provide some relief for the Downeast coast. As the vigorous upper trough digs southward towards the Great Lakes region, a weakening occlusion will approach the area late day with the potential for afternoon thunderstorms. The risk will be greatest in the northern zones. Deep layer shear will increase during the afternoon and the potential for strong storms is there. The front tends to hang up over the area Tuesday night into Wednesday as the upper trough continues to dig southward into the Great Lakes region. The stalled front seems likely to become a conduit for strong thunderstorms on Wednesday afternoon. Impressive deep layer shear and steep low level lapse rates are two factors that prompt concerns for even more severe potential than Tuesday. The front is expected to sweep across the area later Wednesday and a markedly cooler air mass with dew points back in more comfortable 50s seems likely. High temps will trend back towards seasonable readings for Thursday and Friday. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... NEAR TERM: Aroostook Terminals...VFR/MVFR conditions this evening will improve to VFR by tonight and remain through Saturday. WSW winds around 5 kts. Downeast Terminals...VFR conditions this evening and early tonight. Then decreasing to MVFR/IFR with possible LIFR in patchy to areas of fog. By Saturday, conditions improve by late morning to VFR/MVFR then remain for the day. WSW winds around 5 kts. SHORT TERM: Saturday night...Chance of IFR to LIFR vis in fog for BHB, coastal sites and possibly as far north as BGR. Expect generally VFR further north with light winds. Sunday...VFR with light SW winds. Sunday night...Chance of IFR to LIFR vis in fog for BHB and coastal sites. Monday...Generally VFR. Slight chance of afternoon thunderstorms, mostly west of a GNR to HUL line. Light winds. Monday night...Slight chance of IFR to LIFR vis in fog for BHB and coastal sites. Otherwise, VFR with light winds. Tuesday...VFR outside of scattered afternoon thunderstorms, mostly north of GNR and HUL. Light winds. && .MARINE... NEAR TERM: A Small Craft Advisory continues until midnight tonight with seas 4-7 ft. After midnight, winds and seas will decrease below SCA conditions and remain through Saturday. SHORT TERM: Fog will be the primary concern until a strong cold front moves through later Wednesday. Thunderstorms will become a slight concern Tuesday evening, and a bigger concern later Wednesday with a strong cold front moving across the waters. Continued to adjust guidance winds and seas down due to strong low level stability. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory until midnight EDT tonight for ANZ050-051. && $$ Near Term...LaFlash Short Term...MCW Long Term...MCW Aviation...LaFlash/MCW Marine...LaFlash/MCW