####018006392#### FXUS66 KLOX 170950 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 250 AM PDT Mon Aug 17 2026 .SYNOPSIS...17/245 AM. Night through morning marine layer clouds will be confined to the near coastal areas through much of this week. Warmer and drier conditions are expected away from the immediate coast, with peak heat likely being Tuesday through Thursday when moderate heat risk is expected in warmest locations. && .SHORT TERM (TDY-WED)...17/245 AM. Over the next three days a very large and hot upper high, currently centered over TX, will shift to the west and end up over AZ. Hgts will no change much and will sit near 594 dam through the period. The sfc gradients will not exhibit much change either. The N/S gradient will be near neutral in the morning and weakly onshore in the afternoon. The W/E gradient will be weakly onshore in the morning and moderately onshore in the afternoons. Marine layer clouds will be confined to the coastal sections. Good confidence that the Central Coast will have the low clouds each morning. Less confidence for the csts south of Pt Conception where beaches could be clear on any given morning. The high pressure, hier than normal hgts and weaker than normal onshore flow will bring another round of heat to Srn CA. Most areas will see 2 to 4 degrees of warming today although some vly areas will see up to 6 degrees. This warming will bring warmer than normal temps to all areas save for the Central Coast which will end up 2 or 3 degrees blo normal. Another 2 to 4 degrees of warming (locally 6 degrees across the Central Coast) Tuesday will bring above normal max temps to all areas. Most areas will see 1 or 2 degrees of additional warming on Wednesday. The strong inversion, much warmer than normal sea sfc temps and the warm atmosphere will also bring warmer than normal overnight low temps to much of the area. Most cst/vly locations will only have lows in the upper 60s to lower 70s. The combination of warmer than normal highs and lows will bring significant heat risk to many areas. HEat advisories were issued Sunday for the San Fernando, San Gabriel, and Santa Clarita Valleys as well as the lower mtn elevations. There is a 40 percent chance the downtown LA area, the VTA county vlys, and the Santa Monica mtns will also need heat advisories starting Wednesday. Please see the product LAXNPWLOX for all of the details. Gusty north winds will affect southwest Santa Barbara County and the I-5 corridor near the Grapevine each evening and overnight. While most of these winds are expected to remain below advisory levels, there is a chance for advisory level winds in the Gaviota to San Marcos Pass area. .LONG TERM (THU-SUN)...17/245 AM. Thursday will greatly resemble Wednesday as there will be little change in any of the synoptic parameters. The only change will be some cooling across the Central Coast as that area will have a stronger sea breeze. There will be a little bit of cooling on Friday mostly due to an increase in mid and high level clouds. Still max temps will remain well above normal. The upper high is forecast to migrate to the four corners area which will set up SE monsoon flow over Srn CA. PWs approach 1.5" across Srn LA county. This influx of moisture will allow for a non zero chc of showers or TSTMs to develop over the mtns and Antelope Vly. The upper high will be nudged to the east for the weekend as a weak trof moves through the PACNW and the northern half of the state. The weak lift from the trof may bring a little better low cloud development although this is far from certain. Look for 1 to 2 degrees of cooling each day - maybe a little more for SLO county due to the proximity to the trof. The cooling will bring most areas north of Pt Conception down to near or below normal temps. South of Pt Conception, however, most max temps will remain a few degrees above normal. && .AVIATION...17/0945Z. At 0832Z at KLAX, the marine layer was at 900 feet deep. The top of the inversion was near 1800 feet with a temperature of 26 C. High confidence in VFR TAFs for KBUR, KVNY, KPMD & KWJF. Low to moderate confidence in remaining TAFs. VFR timing may be off +/- 90 minutes. Cig hgt may be off by +/- 200 ft. There is a 20 percent chc of no cigs at any site south of Pt Conception. KLAX...Moderate confidence in TAF. There is a 30 percent chc of OVC008 conds. No significant east wind component expected. KBUR...High confidence in VFR TAF. && .MARINE...17/250 AM. Moderate to high confidence in forecast. Current Small Craft Advisory (SCA) for gusty winds over the outer waters from near Point Conception southward to San Nicolas Island and in the vicinity of the Channel Islands is on track. Good chance for SCA winds to be ongoing from through much of the week over all of the outer waters starting this evening. Nearshore along the Central Coast, afternoon through evening SCA winds are likely Tuesday through Friday. For the inner waters, SCA winds will affect the western SBA Channel this afternoon and tonight. This pattern will continue, with SCA winds in the afternoon and overnight period, decreasing into the morning hours each day. For PZZ655, SCA winds are not expected, although local gusts to 25 knots are likely nearshore in the afternoon and evening hours through Wednesday. Building short period seas are expected over the next several days, likely rising to around 7-9 feet over the outer waters. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory in effect from 10 AM Tuesday to 8 PM PDT Thursday for zones 38-88-343>345-351-353-371>373-375-376-379-380-548. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Tuesday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Wednesday for zones 673-676. (See LAXMWWLOX). && $$ PUBLIC...Rorke AVIATION...Rorke MARINE...Ciliberti SYNOPSIS...Gomberg/Ciliberti weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox ####018004828#### FXUS66 KSEW 170952 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 252 AM PDT Mon Aug 17 2026 .SYNOPSIS... A trough will move across the region late Monday into Tuesday. A warmer and drier trend will commence mid to late week as a ridge starts to build into the region, however shower and thunderstorm chances increase again heading into next weekend as the next system approaches the region. && .SHORT TERM /TODAY THROUGH WEDNESDAY/... 500mb pattern remains largely unchanged as broad troughing continues over the NE PAC and ridging noses into the PNW. Low- level onshore flow readily apparent on satellite as marine stratus once again stretches from the coastal waters to the western WA interior under mid-high level cloud coverage. It'll be another day of morning clouds afternoon sun across the area with high temperatures around seasonal average. Monday's weather is expected to be carbon copies of both Tuesday and Wednesday's. Global deterministic model guidance are in lock- step over a Rex Block continuing over the NE PAC, maintaining a rather stagnant pattern. Morning clouds and afternoon sun with highs in the mid 70s to lower 80s in the forecast. Overnight lows will be generally in the 50s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Ensemble guidance suggest near normal temperatures and onshore flow at the low levels maintaining morning clouds with afternoon clearing for the midweek time period. Dry conditions likely continue through the end of the week. Around Friday, expect that the ridge over the Rockies/Great Basin amplifies with the next upper trough approaching the west coast. This will likely bring a shift in the pattern with the potential for precipitation and cooler temperatures, along with thunderstorm chances increasing into Saturday. && .AVIATION... A retrograding upper trough will maintain diffluent flow over western Washington this morning. Marine stratus with LIFR cigs continues to inch its way eastward across the area this morning, and is expected to reach the metro area by around sunrise. Some locations are beginning to see impacts to visibility as the stratus lowers to ground level. Models are indicating a fairly rapid clear out this morning, with most terminals clearing out by around 17-19Z, with areas along the coast and Strait of Juan de Fuca being the last to clear. VFR conditions then prevail with high clouds passing overhead. Stratus is then expected to redevelop late tonight and spread inland overnight into Tuesday morning. Light west to northwest winds will increase to around 4 to 8 kt by late this morning and persist through the rest of the day. KSEA...VFR cigs early this morning will deteriorate to LIFR once marine stratus arrives at the terminal, around 12-13Z this morning. Models are indicating a fairly rapid clear out time, around 17-19Z. VFR conditions then prevail through the remainder of the day, with stratus expected to return again early Tuesday morning. Light and variable winds will return to NW/N this morning and increase to around 5-8 kt by late morning and remain like so through tonight. 62 && .MARINE... High pressure will remain over the far offshore waters and slowly build through the week, which will maintain northwesterly winds over the coastal waters. Winds look to increase late tonight into Tuesday over the outermost waters, which may develop steep seas around 6-7 ft with a dominant period of 7 seconds. The threat for steep seas may continue through mid-week. Westerly pushes down the Strait of Juan de Fuca look to continue into next week, but will weaken each day. Gusts may occasionally reach 20-25 kt at times, in particular this evening and Tuesday evening (up to 50% chance), but no additional headlines are planned at this time. 62 && .FIRE WEATHER... Onshore flow and excellent overnight humidity recoveries will help mitigate fire weather conditions across western Washington through the first half of the week before a warming and drying trend commences mid to late week. While some uncertainty remains in the long term pattern, guidance continues to suggest that the next storm system will arrive by the weekend, increasing the chances for shower and thunderstorm activity across the area and potentially resulting in the return to elevated to critical fire weather conditions. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 3 AM PDT early this morning for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. && $$ ####018004237#### FXUS61 KCAR 170952 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 552 AM EDT Mon Aug 17 2026 .WHAT HAS CHANGED... Update for 12z aviation discussion - Increasing confidence in lower QPF amounts Wednesday-Thursday && .KEY MESSAGES... 1) Rain moving in from the west with locally heavy rainfall possible over central and northern portions of the area early this morning. Flooding is not expected. 2) Chance for showers Wednesday afternoon into Thursday as a cold front crosses the area. && .DISCUSSION... KEY MESSAGE 1...Rain moving in from the west with locally heavy rainfall possible over central and northern portions of the area early this morning. Flooding is not expected. KEY MESSAGE 1 DESCRIPTION... Occluded front sitting just to the east of James Bay and the Ontario/Quebec border as of 05z. Most of the heavy rain is just now entering into nw portions of the CWA. This looks to be the co-located with the low-level jet and gradient of higher pwats per latest TPW satellite imagery. Guidance is now indicating this will shift east thru 12z this morning. At the same time surface boundary enhancing lift in srn Quebec, just to the north of New England and expect this to track into the Central Highlands within the next 2-3 hours. As it heads into the western Maine mountains orographic may help enhance heavy rainfall early this morning thus have kept heaviest totals thru 12z over the Central Highlands. LLJ pushes east into NB by 15z this morning with steady rain coming to an end. However with front still lingering back to the west there will be plenty of forcing to keep showers going over most of the area this afternoon and evening. Have continued with trend of prior shift with slgt chc to lochc pops this afternoon and evening before increasing to likely tonight as coastal low rides to the south of the waters overnight. Patchy fog expected over most of the area tonight as occluded front pretty much dies in place. Downeast likely to see areas of fog late tonight with humid airmass remaining in place. KEY MESSAGE 2...Chance for showers Wednesday afternoon into Thursday as a cold front crosses the area. KEY MESSAGE 2 DESCRIPTION... As the low pressure system exits over the Maritimes, the next low pressure system centered over the Hudson Bay begins to track E. The associated cold front is expected to move into the region Wednesday evening and exit Thursday afternoon. Ensemble models have been trending towards a drier solution with isolated showers. Little QPF is expected with these showers. There is a possibility for a few rumbles of thunder but nothing severe. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... Today...MVFR/IFR, occasional LIFR. Rain may be heavy at times early this morning. Isolated tstm may be possible in the afternoon but confidence remains too low to include. S winds 10-20kts. LLWS at FL020 from 200 at 30-35kts at Aroostook terminals for the next 1-2 hours. Tonight...IFR or lower with fog developing all terminals. S winds 5kts become near calm late. Tuesday...Mainly VFR with MVFR in showers and an isolated tstm in the afternoon. ENE winds 5-10kts. Tuesday night: VFR. Light and variable winds. Wednesday-Wednesday night: VFR early, with increasing chance for MVFR/IFR for north terminals into the afternoon as isolated showers and thunderstorms move into the area. SW winds 5 to 10 kts. Thursday-Thursday night: VFR. Winds W to NW at 5 to 10 kts, light and variable overnight. Friday: VFR. W winds 5-10 kts. && .MARINE... Winds remain aob 20kts over all waters thru Tuesday. Seas increase to near 4ft this afternoon before diminishing this evening. Seas remain between 1-3 feet into Tuesday afternoon before increasing above 5ft over waters from 25-60NM. Winds and seas below SCA criteria mid to late week. Generally SW winds, gusts to 15 kt, over the waters. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ DISCUSSION...21/JMM AVIATION...21/JMM