####018006438#### FXUS66 KSGX 170445 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 945 PM PDT Fri May 16 2025 .SYNOPSIS... Cooler conditions with increased winds and cloud coverage expected over the weekend. Low clouds are expected to fill in much of the coastal basin each night and morning. There are chances of light rain and drizzle west of the mountains tonight into Saturday and Saturday night into Sunday. Warmer conditions with a shallower marine layer is expected for next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Update: Satellite imagery reveals that low clouds have begun to fill back in across most of the coastal and some of the inland areas of San Diego and Orange Counties. There could be some drizzle possible by later this evening and through the early morning hours tomorrow. The latest HRRR shows that there could be a few showers developing by later in the evening tomorrow, mostly for the foothills and west- facing slopes, and likely only very light with accumulations of no more than 0.10 of an inch total for most areas through midnight tomorrow. By Sunday morning, most precip should come to an end, with perhaps only a couple lingering showers over the coastal and inland areas of San Diego County. Winds have also begun to increase for the mountains and deserts, prompting the issuance of and Air Quality Alert by South Coast AQMD for the Coachella Valley, due to blowing dust. This is currently in effect until 9 AM Sunday. These winds will begin to subside by later in the evening tomorrow, and likely not need to issue an extension to the Wind Advisory already in effect until 2 AM Sunday morning. From there, drier and slightly warmer temperatures on Sunday will be followed by a much more drastic warmup going into the middle of next week as a strong ridge begins to build back in over the region. (Previous discussion submitted at 145 PM): A trough of low pressure will start to dig into the Pacific Northwest later tonight. Cross sections of our local WRF are indicating a fairly deep saturated layer for tonight into Saturday morning. Current indications are this layer will be saturated enough to produce areas of drizzle or light rain west of the mountains and on mountain slopes during that time. Minimal accumulations are expected with chances of rainfall totals reaching or exceeding 0.10" at 5 percent or less. As the low pressure system begins to dig south into the Great Basin Saturday afternoon and evening, rain chances increase especially for San Diego County. Any rainfall is expected to be light, but more widespread across the coastal basin compared to what is expected tonight into Saturday morning. It's unlikely rainfall totals will exceed 0.20" for the coast and valleys and 0.40" for the coastal mountain slopes. The most likely places for accumulating rainfall are in the San Diego coast, valleys, and mountains. Stronger, gusty southwest to west winds are expected for the desert slopes of the mountains and deserts for Saturday afternoon into Saturday night. Stronger gusts of 45 to 55 mph with isolated gusts to 70 mph in the northern Coachella Valley below the San Gorgonio Pass are expected. Gusty west winds will continue Sunday afternoon and evening but not quite as strong with gusts to 40 to 50 mph and isolated gusts to 65 mph through wind prone passes. High pressure will bring dry weather with warming Monday through Thursday. Conditions will warm quite rapidly between Sunday and Monday, especially in the valleys and mountain foothills due to a brief period of offshore winds. Highs in the valleys and foothills will be up to 10 degrees warmer on Monday compared to Sunday. As early as Tuesday, highs along the coast and valleys will be 10 to 15 degrees above average. The warming will spread further inland for Wednesday and Thursday. For Wednesday and Thursday, NBM chances for high temperatures in the warmer portions of the Inland Empire to exceed 100 are around 45 to 55 percent with NBM chances for the warmer portions of the lower deserts to exceed 110 on Thursday at 5 to 10 percent. The marine layer will become shallower with night and morning coastal low clouds not extending inland past the far western valleys for Wednesday and Thursday. && .AVIATION... 170330Z...Coast/Valleys...Low clouds based 1500-2100 ft MSL with tops to 2700 ft have developed along the coast and will move to fill the entire coastal basin to the western foothills by 09-11Z. Patchy drizzle is possible overnight between 08-18Z, which could locally lower vis to 4-6SM and cigs to 1000-1500 ft MSL. Partial clearing will occur for eastern valleys after 18Z, but most other areas will remain BKN-OVC all day, though cigs will rise to 2000-3000 ft MSL. More scattered light showers/drizzle are expected after 00Z Sun. Mountains/Deserts...SCT high clouds late tonight. Local west to south gusts 25-40 kts over the desert foothills and through passes will become more widespread through the deserts and strengthen to 35- 55 kt after 17Z Sat, producing strong up/downdrafts in the lee of mountains such as vcnty KPSP. && .MARINE... Onshore winds gusting near 20 kts near San Clemente Island late Saturday into early Sunday may lead to some choppy seas in the outer waters for Saturday evening. Otherwise, no hazardous marine conditions expected through Wednesday. && .BEACHES... Elevated surf will impact beaches Sunday and Monday. Expected surf of 4-6 feet would produce a high rip current risk. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory from noon Saturday to 2 AM PDT Sunday for Apple and Lucerne Valleys-Riverside County Mountains-San Bernardino County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning. PZ...None. && $$ UPDATE...Stewey PUBLIC...CO AVIATION/MARINE...CSP ####018004676#### FXUS64 KLCH 170444 AFDLCH Area Forecast Discussion National Weather Service Lake Charles LA 1144 PM CDT Fri May 16 2025 ...New AVIATION... .KEY MESSAGES... - Moderate to Major heat risk is noted through the weekend as a prolonged period of above normal hot and humid weather will persist. - An upper level ridge will keep any significant chance for rain out of the forecast into early next week. - Trends show a cold front moving through next Tuesday night/Wednesday morning that will bring a chance for rain along with cooler nights and less humid days. && .SHORT TERM... (Tonight through Sunday night) Issued at 250 PM CDT Fri May 16 2025 A warm and humid Friday afternoon is ongoing across the forecast area as we remain entrenched beneath upper level ridging. Unfortunately, this pattern doesn't look to break any time soon, with more of the same warm and humid weather on tap for the weekend. Ridging aloft will keep any precipitation at bay, while breezy onshore flow resulting from surface high pressure centered near FL will keep an steady influx of warm and moist air into the region. The combination of warm and humid air at the surface and lack of any precip will result in above average temps throughout the weekend, with highs topping out in the upper 80s to mid 90s and lows falling into the low to mid 70s. Apparent temps are forecast to peak in the lower 100s across central LA and interior SE TX each afternoon, while closer to the coast apparent temps in the mid to upper 90s can be expected. The NWS Heat Risk tool depicts Moderate to Major Heat Risk both Sat and Sun (level 2 and 3 out of 4), so heat safety should be a top priority this weekend. 17 && .LONG TERM... (Monday through next Thursday) Issued at 250 PM CDT Fri May 16 2025 Moving into the work week, more of the same hot and humid weather is on tap for Monday and Tuesday, with highs again reaching into the upper 80s to lower 90s each afternoon amid mostly sunny skies. However, a pattern change does finally look to arrive late Tuesday as a deepening upper level trough dives across the Plains and sends a cold front across the SErn US. Models are in good agreement with the front arriving late Tuesday night into early Wednesday morning, exiting the region by midday Wednesday. This boundary will likely be accompanied by some showers and thunderstorms, which will likely begin to affect interior SE TX and parts of CENLA by Tuesday evening, spreading southeastward from there overnight. Any lingering convection should come to an end through Wednesday morning, as a dry WNW/NW flow develops overhead aloft and the cold front exits to our east/southeast. Dry and slightly cooler air will filter into the region throughout the day Wednesday, resulting in a rather pleasant middle and end to to the work week. Dewpoints are forecasted to hang out in the mid 50s to lower 60s from at least Wed through Fri, while high temps top out in the low to mid 80s. After the precip accompanying the front dry weather is expected through the end of the week as well. 17 && .AVIATION... (06Z TAFS) Issued at 1137 PM CDT Fri May 16 2025 Warm humid air advecting north from the Gulf will lead to mainly MVFR ceilings overnights. Guidance is suggestive of lower CIGs near daybreak around AEX and ARA, however, these don't appear to be widespread. Ceilings will remain MVFR through much of the AM hours, gradually trending toward VFR in early afternoon. Visibilities will flirt with MVFR through the latter overnight hours into dawn due to low level haze. Light but consistent southerly winds should mitigate BR/FG inland. 30 && .MARINE... Issued at 250 PM CDT Fri May 16 2025 High pressure at the surface will continue to ridge across the northern Gulf through the weekend into early next week, resulting in several more days of light to moderate onshore flow, low seas, and dry conditions. Winds and seas begin to pick up a bit by Tuesday as a front approaches from the north, tightening the pressure gradient overhead and eventually bringing our next chance of rain by early Wed. && .PRELIMINARY POINT TEMPS/POPS... AEX 92 74 92 72 / 0 10 10 0 LCH 87 75 87 74 / 0 0 0 0 LFT 88 75 88 74 / 0 0 0 0 BPT 89 75 89 75 / 0 0 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...None. && $$ SHORT TERM...17 LONG TERM....17 AVIATION...30