Area Forecast Discussion
Issued by NWS Caribou, ME
Issued by NWS Caribou, ME
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497 FXUS61 KCAR 161015 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 615 AM EDT Tue Jul 16 2024 .SYNOPSIS... Several weak troughs of low pressure will cross the area through Wednesday. A cold front crosses the region Wednesday night and early Thursday morning. A trough of low pressure passes through the area Thursday, followed by high pressure building in through Friday night. A cold front approaches from the west on Saturday. && .NEAR TERM /THROUGH TONIGHT/... 615 AM Update: Showers and storms continue to make their way from west to east across the forecast area this morning. A few stronger storms may produce gusty winds, though with the residual nocturnal inversion in place, gusts will struggle to make it to the surface. Heavy rain is expected with any convection today, and it has already been seen that rainfall rates are already exceeding 2 inches per hour in storms currently out in the North Woods. Previous Discussion: Early this morning, a line of showers and storms is making its way into the forecast area from the west. Though storms are more isolated in nature this morning, any thunderstorm that does move into the region has the potential for heavy rain. CAPE remains elevated above the nocturnal inversion, but is nonzero at around 400 J/kg. Additionally, mid level lapse rates are marginal at around 6 C/km across the northeastern portion of the CWA. Effective shear also is low to marginal at around 20 kts, though locally higher shear can be seen in areas of active storms at this time. All of these ingredients together lead to the continued support for some isolated morning convection to continue to roll across the northern half of the CWA. Downeast, fog continues to roll inland from the coast, and patchy dense fog is expected along the immediate coast. The current line of showers and storms will move out to the east through the late morning hours, but more showers and storms may develop through the afternoon due to diurnal heating. Once again, as PWs lift above 1.5 inches across the area (which is significantly above the average of closer to 1.1 inches this time of year) and the warm cloud layer remains deep with substantial warmth in the area, efficient rain processes remain a threat. Any storms that develop through the afternoon could contain heavy rainfall that may lead to localized ponding and flooding of low lying and poor drainage areas. Mostly cloudy skies through much of the day will limit incoming solar radiation, but southwesterly flow under the current synoptic setup will support continued warm, moist air advection into the region, and maintain elevated heat indices (what it feels like). The Heat Advisory remains for Southern Penobscot County, and most of the rest of the forecast area will also see heat indices rise into the upper 80s to lower 90s today. Remember to avoid overexertion during peak heating hours and stay hydrated. Warmth will continue into the night tonight, with lows only falling into the upper 60s to lower 70s, and dewpoints remaining in the mid to upper 60s. This will offer little relief after heat of the day. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... The region is under SW flow aloft Wednesday and Wednesday night. Shortwaves embedded in the flow will trigger isolated to scattered showers and thunderstorms during the afternoon/evening hours. CAPES are now progged only in the 400-800 J/kg range, but still see 40-45KT of bulk shear Wednesday afternoon/early evening - so there is still the potential for strong to possibly isolated severe thunderstorms, with the main threat being strong gusty winds. Precipitable waters are forecast in the 1.5-2.25 inch range (lowest far NW zones - highest over southern portions of the central highlands/Bangor Region) - so locally heavy rainfall is a threat as well. This could produce minor flooding of known poor drainage/low lying areas and an isolated flash flood cannot be completely ruled out. The threat for strong/severe storms and locally heavy rainfall will continued to be highlighted in the HWO. Wednesday also will be another hot day with highs running from around 80 over N Somerset to around 90 across portions of the Central Highlands, the Bangor/Penobscot Region and interior Downeast Maine. Dewpoints in the latter area should be around 70 with resulting heat indices likely into the lower-mid 90s. If things hold, a heat advisory could be required for at least portions of the southern Central Highlands, Bangor/Penobscot Region and interior Downeast Maine Wednesday. Lows Wednesday night should be around 10 degrees above normal. A northern stream trough approaches Thursday, then moves into the region Thursday night. The passage of the 850 mb cold front Thursday (which is lagging a bit behind the surface cold front) could result in more isolated to scattered showers, with possibly some elevated thunder as well, especially over the NW 1/2 of the region. The low levels dry out Thursday night, and other than possibly some lingering showers early in the evening, it should be dry. It will be noticeably less humid on Thursday, with dewpoints falling through the 60s during the day and even into the mid to upper 50s in the North Woods by late afternoon. Highs on Thursday should be near to slightly above normal and around 5 or so degrees cooler than on Wednesday. Lows on Thursday night should be near normal. && .LONG TERM /FRIDAY THROUGH MONDAY/... A northern stream trough exits to the east on Friday, the low to mid levels should be sufficiently dry to preclude any precipitation. The region should be under WSW flow aloft Saturday into Saturday night as it remains on the base of a northern stream closed low centered over N Central Quebec. The axis of this low then translates to the east sometime late Saturday or Sunday. The models differ on the timing, strength and impact of this system. For now have slight chance pops late Saturday afternoon/night over NW portions of the area, then on Sunday from Northern Downeast Maine on north. The region then remains at the base of the close low as it lifts into the Maritimes and transitions to an east-west orientation. This should help to keep most forcing to our north, and the region dry Sunday night and Monday as a result. Temperatures should be near to slightly above normal Friday- Saturday night, then below normal across most of the North and near normal elsewhere Sunday-Monday. && .AVIATION /10Z TUESDAY THROUGH SATURDAY/... NEAR TERM: Generally VFR conditions to continue across northern terminals over the next 24 hours. BHB will slowly improve from IFR through the morning. BGR may see a brief drop in cigs and vis as the fog pushes further inland, but is just far enough inland where they could also stay VFR through the night. A line of showers and storms will push into the area through the early morning hours, and should stay north of BGR, hence no VCTS in the TAF. However, GNR up through FVE has a chance of seeing early morning lightning. Chance for showers and storms through the day on Tuesday across all terminals, with brief MVFR conditions possible in any rain. A return of IFR is possible at BHB and any terminal which sees rain during the day on Tuesday into Tuesday night. Winds light and variable through the early morning hours, becoming SW at 5 to 10 kts with gusts to 20 kts or higher in any storms. Light and variable winds return Tuesday night. SHORT TERM: Wednesday-Wednesday night...VFR, except MVFR possible in any fog Wednesday morning and with any stronger convection/thunderstorms Wednesday afternoon/evening. Thursday...VFR, except for brief periods of MVFR possible in any showers. W_NW winds G15KT possible. Thursday night-Saturday...VFR. W winds G15-20KT possible Saturday. && .MARINE... NEAR TERM: Conditions should remain below small craft advisory levels through today and tonight, though winds may gust 20 kts on the coastal waters and seas could approach 5 ft on the outermost reaches of the coastal waters. Patchy dense fog may remain on the waters through today and into the night tonight, reducing visibility to below 1 NM at times. SHORT TERM: Marine fog could limit visibilities to under 1nm Wednesday morning and again from Wednesday night into Thursday. The coastal ocean waters should see wind gusts and/or seas just under SCA limits Wednesday- Thursday night, with the intra- coastal waters well below SCA limits. All waters should be well below SCA levels Friday- Saturday. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Heat Advisory from 2 PM this afternoon to 6 PM EDT this evening for MEZ015. MARINE...None. && $$ Near Term...AStrauser Short Term...Maloit Long Term...Maloit Aviation...AStrauser/Maloit Marine...AStrauser/Maloit